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SEISMOLOGICAL AND GEOLOGICAL INVESTIGATION FOR EARTHQUAKE
HAZARD IN THE GREATER ACCRA METROPOLITAN AREA
This thesis is submitted to the
DEPARTMENT OF NUCLEAR SCIENCES AND APPLICATIONS
GRADUATE SCHOOL OF NUCLEAR AND ALLIED SCIENCES
UNIVERSITY OF GHANA
BY
MAXIMILLIAN-ROBERT SELORM DOKU
10362761
BSC PHYSICS (KNUST), 2007
In Partial Fulfillment of the Requirement for the Award of
MASTER OF PHILOSOPHY DEGREE
in
NUCLEAR EARTH SCIENCES
JULY, 2013.
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DECLARATION
I, Maximillian-Robert Selorm Doku hereby declare that, with the exception of references
to other people’s works which have been duly acknowledged, this work is the result of
my own research undertaken under the supervision of Dr. Paulina Ekua Amponsah and .
Prof. Dickson Adomako and has not been presented for any other degree in this
university or elsewhere, either in part or whole.
…………………………….. ……..……………………
Maximillian-Robert Selorm Doku Date
(Student)
……………………………. ….………………………
Dr. Paulina Ekua Amponsah Prof. Dickson Adomako
Supervisor Co-Supervisor
……………………………. ……..……………………
Date Date
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DEDICATION
This work is dedicated to my late mum, Esther Vugbagba.
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ACKNOWLEDGEMENTS
I am very grateful to God Almighty for His guidance throughout this work.
Secondly, my appreciation goes in no small way to my supervisors Dr. Paulina
Ekua Amponsah and Prof. Dickson Adomako. They have been very inspiring and
tolerant of my shortcomings.
My sincere gratitude goes to my contemporaries and senior colleagues who have
contributed in one way or the other to my work (School of Nuclear and Allied
Sciences; Earth Sciences Department, University of Ghana and Ghana Atomic
Energy Commission).
My dad and siblings have also been very supportive, thank you all.
Finally, my sincere gratitude goes out to all those who have not been mentioned,
God bless you.
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TABLE OF CONTENTS
CONTENTS PAGES
Declaration……………………………………………………………………………...….i
Dedication………………………………………………………………………………....ii
Acknowledgement……………………………………………………………………..…iii
Table of Contents……………………………………………………………....................iv
List of Tables…………………………………………………………………………....viii
List of Figures…………………………………………………………………….............ix
List of Abbreviations………………………………………………………………..…….x
List of Symbols…………………………………………………………………………...xi
Abstract……………………………………………………………………………..……xii
CHAPTER ONE.............................................................................................................1
1.0 INTRODUCTION………………………………………………………………….....1
1.1 Background…………………………………………………………………………....1
1.2 Problem Statement………………………………………………………………….....7
1.3 Justification…………………………………………………………………………....8
1.4 Objectives………………………………………………………………………..……9
CHAPTER TWO……………………………………………………………….……10
2.0 LITERATURE REVIEW………………………………………………..…………..10
2.1 Previous Works Related to the Study...…………………...…………...……..........10
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2.2 The b-Value and Earthquake Occurrence ……………………………………….12
2.3 Geologic Structures and Seismicity ……………………………………………..13
2.4 Seismicity of GAMA As Compared To Other Intraplate Regions……….…….14
CHAPTER THREE…………………………………………………………..............17
3.0 STUDY AREA……………………………………………………………..……17
3.1 Location……………………………………………………………………….…17
3.2 Geology of the Study Area……………………………………………………....19
3.3 Soils………………………………………………………………………...........22
3.4 Climate and Vegetation…………………………………………………..............23
3.4.1 Climate…………………………………………………………………………...23
3.4.2 Vegetation…………………………………………………………………..……23
3.5 Delimitation of Study Area……………………………………………………....24
CHAPTER FOUR…………………………………………………………………….26
4.0 METHODOLOGY…………………………………………………………..............26
4.1 Desk Study…………………...…………………………………………………...….26
4.2 Earthquake Catalogue ………...…………………………………………...………26
4.2.1 Data Collection…………...…………………………………………..……28
4.2.2 Interpolation of Earthquake Magnitudes…...………………………..…….28
4.2.3 Relocation of Events………………………...……………………..............28
4.2.4 Magnitude Unification………………………...………………………...…29
4.3 Seismicity and Epicentral Intensity Maps………...………………………................31
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4.4 Evaluation of b-Value………………………………………………...……..............32
CHAPTER FIVE……………………………………………………….…………..…36
5.0 RESULTS AND DISCUSSION…………………...……………………………..….36
5.1 Results………………………………………………………………………………..36
5.1.1 Earthquake Catalogue……………………………………………...............36
5.1.2 Seismicity and Epicentral Intensity Maps……………………….................63
5.1.3 b-Value Evaluation…………………………………………………….…..67
5.1.3.1 Linear Least Square Fit…………………………………….................67
5.1.3.2 Maximum Likelihood Estimation……………………………….……69
5.1.4 Relationship between Earthquake Effects and
Geology………………………………………………………….................71
5.2 Discussion……………………………………………………………………………73
CHAPTER SIX………………………………………………………………..………77
CONCLUSION AND RECOMMENDATION…………………………………..……...77
6.0 Conclusion…………………………………………………………………...............77
6.1 Recommendations……………………………………………………………………78
REFERENCES……………………………………………………………………….….79
APPENDICES……………………………………………………………………….…..84
APPENDIX A…………………………………………………………………................84
Definition of Key Terms…………………………………………………………………84
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APPENDIX B…………………………………………………………………................91
Matlab Interpolation……………………………………………………………...............91
(α) Command and Results…………………….……………………………………...…..91
(β) Matlab Window……………………………………………………………………...93
APPENDIX C……………………………………………………………………….…..94
Latitude/Longitude Conversion to Metres……………………………………………….94
(a) Window 1…………………………………………………………………….…..94
(b) Window 2…………………………….………………………………………….95
(c) Epicentral Intensity Table……………..…………………………………...…….96
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LIST OF TABLES
Table 2.1: Ghana’s Seismicity
Table 5.1: Earthquake Catalogue of Ghana and Its Immediate Neighbours (1615 to 2012)
Table 5.2: Magnitudes and Cumulative Number of Events
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LIST OF FIGURES
Figure 3.1: Topographical Map of Study Area (Modified from the Topographic map of
Ghana, 1972)
Figure 3.2: Geology of the Study Area (Extracted from the Geological Map of Ghana,
2009)
Fig. 4.1: Flow Chart for Developing GAMA Seismicity Catalogue
Figure 5.1: Seismicity map of the study area
Figure 5.2: A Plot of the Epicentral Intensity Map of the Study Area
Figure 5.3 Graph Indicating the Plot of Cumulative Number of Events against
Magnitudes
Figure 5.4: Epicentral Intensity Superimposed on the Geology of Location
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LIST OF ABBREVIATIONS
NADMO National Disaster Management Organization
GAMA Greater Accra Metropolitan Area
WWSSN World Wide Standard Seismograph Network
CTBTO Comprehensive Test Ban Treaty Organization
GAEC Ghana Atomic Energy Commission
NDC National Data Centre
ISC International Seismological Centre
GPS Global Positioning System
GIS Geographical Information System
PGA Peak Ground Acceleration
PGV Peak Ground Velocity
PF Pan-African Front
WAC West African Craton
CIGTM Cote d’Ivoire – Ghana Transform Margin
CBF Coastal boundary fault
GBC Ghana Building Code
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LIST OF SYMBOLS
µ Micro
é Latin small letter e with acute
√ Square root
α Alpha
β Beta
ᵞ Gamma
° Degree
ML Local or Richter Magnitude
Mb Body-Wave Magnitude
Ms Surface-Wave Magnitude
MD Duration Magnitude
MM Surface-Wave Magnitude (Measured from macroseismic events)
Mw Moment Magnitude
Mo Seismic Moment
M Magnitude
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ABSTARCT
A seismological and geological investigation for earthquake hazard in the Greater Accra
Metropolitan Area was undertaken. The research was aimed at employing a mathematical
model to estimate the seismic stress for the study area by generating a complete, unified
and harmonized earthquake catalogue spanning 1615 to 2012. Seismic events were
sourced from Leydecker, G. and P. Amponsah, (1986), Ambraseys and Adams, (1986),
Amponsah (2008), Geological Survey Department, Accra, Ghana, Amponsah (2002),
National Earthquake Information Service, United States Geological Survey, Denver,
Colorado 80225, USA, the International Seismological Centre and the National Data
Centre of the Ghana Atomic Energy Commission. Events occurring in the study area
were used to create an Epicentral Intensity Map and a seismicity map of the study area
after interpolation of missing seismic magnitudes.
The least square method and the maximum likelihood estimation method were employed
to evaluate b-values of 0.6 and 0.9 respectively for the study area. A thematic map of
epicentral intensity superimposed on the geology of the study area was also developed to
help understand the relationship between the virtually fractured, jointed and sheared
geology and the seismic events. The results obtained are indicative of the fact that the
stress level of GAMA has a telling effect on its seismicity and also the events are
prevalent at fractured, jointed and sheared zones.
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CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
Globally nobody is immune from disasters or disaster related losses. Therefore, this gives
us enough reason to study them to know how best they can be handled in case they strike.
Disasters are hazard situations that pose a level of threat to life, property or the
environment. There are two major types of disasters. These are natural and man-made
disasters. Hazards, on the other hand, are exposure or vulnerability to harm or risk
(Microsoft Encarta Premium, 2009). Natural disasters include floods, fires, tropical
cyclones, earthquakes, tsunamis and others which are environmentally related. However,
hazards that strike in low vulnerability regions never become disasters.
Natural and man-made hazards usually come with deadly forces or retribution. Man-
made hazards, however, are associated with transport, industry and health. Geological
hazards include internal earth processes such as earthquakes, volcanic activities,
emissions and related geophysical processes such as mass movements, landslides,
rockslides, surface collapses and debris or mud flows are also hazardous.
In Ghana, disasters that can be identified include drought, earthquake, epidemics, storm,
mass movement, extreme temperature, flood, insect infestation etc. The National Disaster
Management Organization (NADMO) of Ghana in collaboration with other Agencies has
been in the fore front trying to mitigate these hazard situations.
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The Ghana Building Code (GBC) has clearly appreciated the relevance of mitigating
measures to be taken to avert future disaster when flood and earthquakes occur in
unplanned areas (GBC, 1988). The code, which was recently reviewed under the Africa
Adaptation Program on Climate change recognized that buildings are the essential
components of all human settlements and the focal point for all human endeavours for
quality living. The review also observed that the GBC was not observable by
development authorities, thus it lacks legal backing.
Building codes of Brazil and India have also been reviewed and it was realized that
whereas these countries’ codes specifically try to make provisions for earthquake, that of
Ghana has paid more attention to floods, environmental degradation and fire and has not
categorically tackled earthquake disaster. The review has however pointed out the hazard
profile to include
Perennial flooding
Seismic activity
Fire
Air pollution
Disease
Environmental degradation and
Coastal erosion
(CASA ASSSOCIATI, 2012)
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One major disaster which has received some attention in Ghana is earthquake. Before the
first documented earthquake in 1615, knowledge about earthquake was very scanty and
not well understood.
In 1930, Charles F. Richter, a Californian Seismologist introduced the concept of
earthquake magnitude, ML (local magnitude), of focal depths 0-700 m of the Woods-
Anderson torsion instrument already in use (Kossobokov, 2005). Since then various
magnitude units have evolved, some of which are the Mb (body-wave magnitude), Ms
(surface-wave magnitude) and Mw (the moment magnitude). Rather than relying on
measured seismogram peaks, the Mw scale is tied to the seismic moment (Mo) of an
earthquake. Additionally, in 1942, Guttenberg B. and Richter C. F. introduced the
concept of relating earthquake data to the stress level in the ground, later called the
Gutenberg – Richter relation. The idea of relating the frequency of earthquakes and the
total number of earthquakes for specified periods threw more light on how earthquake
monitoring can help mitigate disasters.
In Ghana, with special attention to the Greater Accra Metropolitan Area (GAMA), there
is a tendency to conclude from a seismological and geological perspective that the stable
continental region is really ‘stable’. However, the history of earthquakes in Ghana and
the sub region (dating back to 1615) proves otherwise (Amponsah, 2002). The major
ones are the 1615 earthquake at Elmina and the 1636 earthquake with epicenter at Axim
(5.7 M) which buried some miners alive after the collapse of the Portuguese mines. In
1862, Accra recorded 6.5 M earthquake killing three people (Junner, 1941). The most
affected areas were the Usher and James forts and the Christianborg Castle which were
rendered inhabitable. Additionally, the earthquake was registered as far as Togo. The
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1939 earthquake (with epicenter located at Nyanyano) of the same magnitude as that of
1862 (intensity IX) and injuring 133 people has gone down in Ghana’s history as the
worse incident. However, the 6.5 M earthquake of intensity VIII on the modified mercalli
scale killed 17 people (Amponsah et al., 2012). The GAMA with population of 77000
experienced 17 deaths in the intensity VIII earthquake of 1939 (Amponsah, 2004).
According to the 2010 population and housing census, GAMA currently has a population
of about 3, 000, 000 (Ghana Statistical Service, 2010). Hence, there is the need to
catalogue earthquake events to help understand what is happening in the area in order to
plan for the future. Earthquakes have had huge impacts on various countries such as
Haiti, Turkey and Ghana where there were loss of lives and properties. However,
effective application of science and engineering principles to the development of the built
environment has helped reduce the risk faced by earthquake-threatened cities of the
developed world like the United States of America. Apparently, this cannot be said of
developing countries like Ghana, where clear building codes have not been established
and where simple regulations exist they are not followed (Allotey et al., 2010).
Ghana recorded first earthquake in 1914, (Junner, 1941). Since then various significant
attempts have been made by successive governments to help expand knowledge in
seismic activities in the country and the sub-region. These national policy initiatives have
led to the creation of national database of seismic activities and have gone a long way to
support knowledge in geology of the coast of Ghana. With a continuum of risks
associated with earthquakes, the installation of Milne’s single-boom seismograph in the
country was important. The instrument was used to locate hypocenters and to record
earthquake magnitudes. In 1973, a seismograph observatory equipped with A World
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Wide Standard Seismograph Network (WWSSN) system was established at Kukurantumi
in the Eastern Region of Ghana.
The observatory operated continuously until October 1974 and then intermittently until
continuous recording began again in 1977 (Amponsah, 2004). It had a nine station radio
telemetric network with a central recording station at the head office of the Geological
Survey Department in Accra until 2003 (analogue recording system) (Amponsah, 2004).
Currently a digital recording system has been procured by the Government of Ghana. The
facility is located in the Achimota forest, Accra, working under the authority of the
Ghana Geological Survey Department (Opoku, 2012). The new network, with the central
observatory in Accra would help enhance the monitoring of earthquakes and other forms
of seismic activities. There are six seismic substations located at Morontuo,
Kukurantumi, Shai Hills, Akosombo, Ho and Weija respectively. These stations are
generating and transmitting data to the central observatory. Between 1636 and 2006,
magnitudes ranging from 4.0 to 6.5 were recorded (Opoku, 2012). The seismic data being
generated would help in a more efficient and effective land use planning, revision of
building codes and policy formulation and the designating standards for official
structures such as nuclear power plants, bridges, dams, overhead transportation systems
and shopping centers. Events recorded can be used to locate earthquake prone areas
through the generation of isoseismal maps and epicentral intensity maps. Peak ground
acceleration can be calculated for and therefore hazard maps can be easily generated as
well.
Observatories across the world are usually used to enhance the development of disaster
mitigation strategies which usually help to reduce the effect of future earthquakes.
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Therefore, planning of post-earthquake reconstruction programs to facilitate the
development of well-defined insurance policies for protection against earthquakes is
necessary. Also, enhancing public education on the need to sensitizing people of
earthquake prone zones and their consequences cannot be overemphasized. Additionally,
seismic data also plays significant roles in mapping active faults in a region. Currently
measures are ripe for the installation of strong motion accelerometers on the Bui,
Barekese and Owabi dams as well as quarry sensor equipment to be installed on mining
and quarry sites to monitor man-made seismic hazard levels in the country (Wereko,
2012). To enhance the effective monitoring of earthquakes, the Comprehensive Nuclear
Test Ban Treaty Organization (CTBTO) in conjunction with the Ghana Atomic Energy
Commission (GAEC) has established the National Data Center (NDC) which has also
been accessing seismic data from the International Data Centre since August, 2010.
Interestingly, records obtained up to December, 2012 indicate earthquake events as high
as magnitude 4.0 in and around the Greater Accra Metropolitan Area.
The relevance of earthquake data to petrochemical exploration, knowledge of local
mechanisms of the subsurface and monitoring of nuclear tests cannot be overemphasized
(Judson and Kauffman, 1990). Therefore data obtained by the Ghana Geological Survey
Department and the Ghana National Petroleum Corporation played a meaningful role in
discovering oil and gas in commercial quantities in 2007. The relevance of these data
(Seismic events) to study the seismicity of GAMA by conducting a seismological and
geological investigation for earthquake hazard cannot be overemphasized.
Earthquakes occur in many forms, but most intraplate earthquakes tend to be
concentrated along pre-existing zones of weakness (including faults zones, suture zones,
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failed drifts and other tectonic boundaries) (Sykes, 1978). A careful study of the regional
tectonic setting and evolution shows that south-east Ghana and its offshore are
characterized by three areas with distinct tectonic zones. These are the Akuapem Fault
Zone, Faults in the Coastal areas and Shelf, Fenyi –Yakoe and Adina Faults (Amponsah
et al., 2012). These fault zones cannot be isolated when it comes to exploring possible
contributions to past seismic events.
The research is therefore aimed at quantifying the stress level of the GAMA by first
cataloging all seismic data available up to 2012 and geologically investigating earthquake
hazard by employing a mathematical model.
1.2 PROBLEM STATEMENT
Ghana has experienced significant damages resulting from earthquakes dating as far back
as 1615. The 1939 earthquake has been the most significant in terms of damage to life
and property. Therefore, many researchers have employed seismic data and geology to
create hazard maps, delineating fault zones in the area of study. Accra, the capital city of
Ghana has experienced some damaging earthquakes and tremors in the recent past
(Amponsah, 2004).
However, the researchers failed to harmonize all the earthquake catalogue and models to
estimate the stress level of the Greater Accra Metropolitan Area (GAMA) both
seismologically and geologically and have never calculated the b-value from past
earthquake catalogues available. This is necessary to serve as a guide for policy makers,
engineers and fellow scientists in making critical decisions on settlements.
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1.3 JUSTIFICATION
The 1986 study of earthquakes in West Africa showed Accra to be the most seismically
active in the region (Ambraseys and Adams, 1986). Additionally, a study of world
seismicity indicates the presence of a major preexisting tectonic boundary landward of
large oceanic transform faults such as suture zones near Accra. This is indicative of a
potential large shock in the future (Sykes, 1978). The Cameroon line and the
Ngaourandéré fault zone are situated near the boundary between the Congo and the Pan-
African belt deformation that extends as far as west of Accra (McConnell, 1969). The
seismicity of Accra is one of the best examples of activity near the end of a fractured
zone. Earthquakes in intraplate areas are not distributed at random but they occur mainly
along faults and other zones of weakness associated with the last major orogeny of a
region (Sykes, 1978).
Also, there is no detailed seismic hazard assessment map of the Greater Accra
Metropolitan Area available to help with proper seismic micro-zonation of the city
(Allotey et al., 2010). The development of thematic mapping with the identification and
characterization of seismically active zones constitute the framework for seismic hazard
assessment. However, this is impossible without a comprehensive earthquake catalogue
and an evaluation of the b-value which explains the stress level of the area.
Just like a seismicity map, an epicentral intensity map is also very important to evaluate
the possible degree of damage should earthquakes of such magnitudes occur again.
Moreover, previous works have been silent on the use of the b-value in evaluating the
stress level of the Greater Accra Metropolitan Area and coming up with relevant models
to support this value. The importance of the b-value as an earthquake precursor cannot be
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overemphasized. Systematic study of b-values in New Zealand has shown that within the
vicinity of forthcoming large earthquakes there is initially an increase in b-value and then
a return to normal (Smith, 1981). Thus, fluctuating b-values of an area could serve as a
clue for an imminent earthquake. Critical examples include the Caracas and San
Fernando earthquakes which show the same phenomenon (Smith, 1981). The b-value can
be used as earthquake precursor. Therefore this makes the research in the area very
relevant.
1.4 OBJECTIVES
The research is aimed at employing a mathematical model to estimate the seismic stress
for the Greater Accra Metropolitan Area.
Specific objectives include:
1. Creating a comprehensive and homogenized earthquake catalogue for Ghana
from 1615 to 2012.
2. Evaluating the stress level of GAMA by calculating the b-value from the
catalogue.
3. Generating a seismicity map.
4. Coming up with an epicentral intensity map.
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CHAPTER TWO
LITERATURE REVIEW
2.1 PREVIOUS WORKS RELATED TO THE STUDY
A detailed report on the earthquakes in Ghana and a detailed analysis of the 1939 (6.5 M)
earthquake has been given by Junner (1941). A geophysical investigation for the
seismicity of the Weija area, Essel (1997) asserts that the area is seismically active. Using
geological data to study earthquakes, Rajendran (2000) asserts that in many compression
settings, faults tend to develop as splays or blind thrusts and not reach the surface. The
rupture that reaches the surface tends to develop complex geometries. From the
earthquake hazard point of view, it can be established that most earthquakes are
temporally and/or spatially associated with weak zones. It is also observed that the
Cameroon line and the Ngaourandere fault zone are situated near the boundary between
the Congo and a belt of Pan-African deformation that extends as far as west of Accra
(Sykes, 1978). Bacon and Quaah (1981) also attribute most of the epicenters occurring
south of Weija, to be due to the existence of an old thrust zone which has been
reactivated. Amponsah (2004) is of the view that most of the earthquakes in Ghana occur
in the western part of Accra at the junction of the two major fault systems, thus, the
Coastal boundary fault and Akwapim fault zone.
It has been observed that earthquakes in Ghana are concentrated in the area where the
Akwapim fault intersects the coastal boundary fault. According to Amponsah (2002),
seismic activity in Ghana is concentrated in the southeastern sector, at the junction
between the two major active faults.
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However, the seismic stratigraphic record of transpression and uplift on the Romanche
transform margin offshore Ghana shows that the neotectonic activity around the Pan-
African Structures may involve tectonic inversion (Attoh et al., 2003). Attoh et al.
(2005) also tried to link the enhanced neotectonic activity near the south of the PF to the
intersection of the PF and the Coastal boundary fault (CBF).
Additionally, Talwani (1998) also observes that although large earthquakes in
continental interiors are much less frequent than those along plate boundaries, they have
been responsible for a disproportionate amount of destruction. In furtherance of this he
asserted that the nature of the seismicity in continental interiors is not well understood as
that of its plate boundaries. Factors influencing earthquake generation in such areas
include:
i. Rheological properties of the medium
ii. Nature of fault zones associated and
iii. Stress conditions
Earthquakes in Ghana are concentrated in the wider area where the Akwapim fault zone
intersects the coastal boundary fault (Amponsah, 2004). Some of the epicenters have
been located offshore and may be related to the activeness of the coastal boundary fault.
The epicenters are related to the active parts of the faults, although because of many
sources of inaccuracies it is not possible to assign them to individual faults or fault
sections. Amponsah et al. (2009) modeled seismic ground motion of GAMA for land use
planning and disaster mitigation by deterministic computation, using a hybrid method
based on the modal summation and finite difference method. Peak Ground Accelerations
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(PGAs) calculated ranged from 0.14 g to 0.57 g. It was observed that areas underlain by
unconsolidated sediments experience the greatest shakings. Mavonga and Durrheim
(2009) compiled all available catalogues in the region 14 º S to 6 º N and 10 º E to 32 º E
from 1910 to 2008 for the Democratic Republic of Congo and surrounding areas. They
calculated the b-values for three key active areas namely, Upemba-Moero Rift, Congo
Basin and Western Rift and obtained 0.813, 1.020 and 0.773 respectively.
The above works have laid credence to the fact that earthquake hazard in some parts of
the stable continental region are real. However, none has tried calculating the b-value for
the Greater Accra Metropolitan Area. The research is therefore aimed at calculating the
b-value to help examine its characteristic impact on GAMA and find out if it has any
bearing on earthquake hazard.
2.2 THE b-VALUE AND EARTHQUAKE OCCURRENCE
Earthquakes are not uniformly distributed in time, space and magnitude. The distribution
of earthquakes with respect to magnitudes exhibits scale invariability and obeys a power
law usually referred to as the magnitude-frequency relation.
The relation however, exhibits some deviation from linearity which is due to the fact that
magnitude scales saturate and also there are problems associated with the way
magnitudes are measured. Sometimes the catalogues available to work with are too short
and rarer large magnitudes are missing (Kulhanek, 2005). Whereas Kagan (1999)
believes that b-values rarely change, others like Felzer (2006) with a lot of credible
publications believe there are significant spatial and temporal variations in b-values.
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Instrumental data shows that large earthquakes (M ≥ 7.2) are less frequent than expected
from smaller ones. Also, with small-time sampling, b-value is reasonably well estimated
from smaller earthquakes, but not for large ones. High and low stress can cause
earthquake series with low and and high b-values respectively. This is an observation that
can be used to study stress levels and structural anomalies in the crust and/or upper
mantle (subduction) (Kulhanek, 2005). According to Wiemer et al (1998), earthquake
predictions and identification of volumes of active magma is possible when this
observation is employed.
2.3 GEOLOGIC STRUCTURES AND SEISMICITY
Generally, GAMA is low-lying. With reference to Nyanyano, the epicenter of the 1939
earthquake, prominent ranges of hills running from north-east direction from the coast
and rising to more than 600 feet above sea level occur. In fact, the area is slightly
undulating (Junner, 1941).
The effects of earthquakes on buildings and other structures vary greatly depending on
the underlying rocks. The tectonogeological units of GAMA are interspersed with the
five distinct tectonogeological units of Ghana. These include
The paleoproterozoic complex of the West African Craton (WAC)
The Voltaian basin of the WAC
The Akwapim Togo belt
The Pan-African province of neoproterozoic metamorphic age
Several small sedimentary basins of Post-African age
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The tectonic setup of GAMA and its offshore area is characterized by three areas with
distinct tectonic elements namely, the Akwapim fault zone, faults in the coastal area and
near coast shelf with the coastal boundary fault as main feature, and the Romanche
fracture zone (Amponsah et al., 2012).
Attoh et al. (2005) were also convinced that neotectonic activity along the Pan-African
structures may involve tectonic inversion as well as tectonic reactivation along the
seismic Pan-African fracture zone (which may have occurred in the Paleozoic era and
again more recently along the Pan-African sutures)
To understand the phenomena of intraplate seismicity of the study area, the connection
between the Pan-African Structures and seismic activity along the coast of Ghana must
be well examined. This is evident in the several events recorded on and off-shore GAMA.
The seismic stratigraphic record of the Ghana margin also strongly indicates that sub-
aerial erosion related to uplift was later than or accompanied the folding, rather than
earlier and as such transpressional deformation likely contributed to the uplift along the
Cote d’Ivoire – Ghana Transform Margin (CIGTM) (Attoh et al. 2003)
In certain areas in Accra such as Weija, where the Akwapimian rocks have been observed
to contain bands of soft Phyllite and are fractured and faulted, the area has recorded a lot
of seismic activity.
2.4 SEISMICITY OF GAMA AS COMPARED TO OTHER INTRAPLATE
REGIONS
Comparing the epicenters of earthquakes for the period 1900 to 1973, it may be
concluded that the seismicity of the West Coast of Africa is low (Singh et al., 2009).
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Additionally, like other intraplate regions, GAMA, some parts of the Scandinavia and
Greenland have recorded earthquakes of magnitude 2.5 and above (Gregersen, 2006).
The East African Rift System has also recorded earthquakes with average focal depth of
20 km. However, the Eastern Rift seismic activity seems to be more concentrated in
swarms of certain areas. In Ghana, the most damaging earthquake was the 1939
earthquake, which recorded a focal depth of 18 km at Nyanyano, near Accra-Ghana. The
disaster took seventeen (17) lives and hundreds were injured (Amponsah et al., 2012).
Table 2.1 gives a brief breakdown of Ghana’s seismicity indicating concentration of
activities in GAMA.
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Table 2.1: Ghana’s Seismicity
Year Magnitude Remarks
1615 - Felt in Elmina
1636 5.7 Felt in Axim. Buildings as well as underground workings of
Portuguese mines collapsed.
1862 6.5 Every building in Accra was razed to the ground. The Osu
Castle and Forts in Accra were rendered uninhabitable. The
shocks were felt in Togo where water in the Mono river fell
much below its normal level.
1906 5.0 Many buildings in Accra particularly castles and forts were
cracked. The earthquake was felt in other areas as far as Togo.
1939 6.5 Intensity was greatest in areas between Accra, Weija, Gomoa
Fete and Nyanyano. The computed peak ground acceleration
ranges from 0.14g to 0.57g corresponding to VII to IX on the
Modified Mercalli Scale. In Accra 16 people were killed with
133 injuries.
1964 4.5 Felt mainly in Akosombo.
1969 4.7 Felt mainly in Accra.
1997 3.8 Felt mainly in Accra
2003 4.8 Felt in some parts of Accra
2011 4.0 Near Coast of Ghana/Togo
2012 4.2 Near the Coast of Accra
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CHAPTER THREE
STUDY AREA
3.1 LOCATION
Accra, the capital city of Ghana is located at 5 ° 30 ' and 0 ° 10 ' W and has a population
of about two million three hundred thousand people (Ghana Statistical Service, 2012).
The Greater Accra Metropolitan Area (GAMA) comprises about four administrative
districts with a total area of about 1,000 square kilometers, which includes the Accra
Metropolis, the Tema Metropolis, the Ashaiman Municipal, the Adenta Municipal, and
the Ga district assemblies (recently divided into Ga East and Ga West). GAMA is the
most industrialized area in Ghana and is the most dominant center of commerce, finance,
manufacturing, education and trade (Allotey et al., 2010).
The map of the study area is shown in fig. 3.1
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Fig. 3.1: Topographical map of study area (Modified from the Topographic
map of Ghana, 1972)
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3.2 GEOLOGY OF THE STUDY AREA
The geology of the Greater Accra Metropolitan Area, (GAMA) comprises six geological
formations (Fig. 3.1). These are:
Unconsolidated and poorly consolidated sediments and soils of Quarternary and
Tertiary age; covering areas such as Korlebu, Abossey Okai, Mataheko,
Adabraka, Achimota, Dansoman and Odorkor. This formation is dominated by
Red Continental Deposits; Marine Fluvial or Lacustrine Sediments; Consolidated
Beach Sediments and Unconsolidated or Slightly Consolidated Cobble
Colluviums (Muff and Efa, 2006). The area is mostly interspersed with thickly
bedded sandstones and mica schists.
The Accraian Group of Devonian age comprising the Upper Sandstone-Shale
Formation, Middle Shale Formation and Lower Sandstone Formation covers areas
such as North Kaneshie, Osu, Kanda, Kpehe, Alajo and the city center Accra (the
capital). This area is mostly underlain by thickly bedded sandstones interbedded
with shale.
The Voltaian Supergroup of Lower Paleozoic age is mainly made of Quartzose
and impure sandstones. The system covers areas such as Anamorley and parts of
Olobu and Ablekuma.
The Togo Structural Units are made up of quartz veins, phyllite and phyllonite,
quartz schist (sericitic quartz schist) and quartzites. The Structural Units cover
areas such as Weija, Mandela, Nyanyano, Anyaa, Oblogo, Sowutuom, Burma
Camp, Dome, Ofankor, Kwabenya and parts of the Ghana Atomic Energy
Commission. The Togo Structural Units are of Upper Precambrian age. Key
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among these rocks includes granitoid and biotite gneiss, quartzite minor mica
schist and thickly bedded sandstones.
The Dahomeyan Supergroup comprises the basement rocks of Middle-Late
Precambrian age. This comprises quartz schist, Orthogneiss, Metamicrogabbro
and Amphibolites and Scistose Marbles. Madina, parts of Atomic Energy
Commission and Mpehuasem are located on this formation. The Supergroup is
specifically underlain by garnet amphibolite gneiss covering Amrahia, Ashaiman,
Tema and Nungua as well.
Also, forming part of the Greater Accra Metropolitan Area geology is the Middle
Precambrian aged Granitic intrusions made of deeply weathered Granitoid-
Pegmatite Complex and covering Adzen Kotoku, Amasaman and Oduman.
The geology of GAMA is generally interspersed with lineaments, concealed,
observed and thrust faults and shear zones as pictured in the geological map (Fig
3.2). The weak coastal boundary faults with mild stones along the coast
characterized by shear zones, joints and fractures re-emphasize the non-uniformity
in geology in GAMA. Additionally, they are older fault zones reactivated by
continental fragmentation (Singh et al., 2009; Rajendran, 2000). Key faults in the
study area include
i. Longitudinal faults
(a) Eastern boundary faults
(b) Western boundary faults
ii. Faults parallel and sub-parallel to the coast
iii. Northerly striking faults and
iv. Transverse faults
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Fig. 3.2: Geology of the Study Area (Extracted from the Geological Map of Ghana, 2009)
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3.3 SOILS
The soils in the study area are categorized into four main groups, namely: drift materials,
alluvial and marine motted clays, residual clays and gravels and lateritic sandy clay soils
(Muff and Efa, 2006; Kortatsi et al., 2008).
The drift materials result from deposits by wind-blown erosion whilst the alluvial and
marine motted clays of comparatively recent origin are derived from underlying shales
((Muff and Efa, 2006; Kortatsi et al., 2008). Weathered quartzites, gneiss and schist rocks
produce the residual clays and gravels whilst the laterite sandy clay comes from the
Accraian sandstone bedrock formations. There are pockets of alluvial “black cotton” soils
found in many low lying poorly drained areas. Soils in GAMA have heavy organic
content and expand and contract readily causing major problems with foundations and
footings (Muff and Efa, 2006; Kortatsi et al., 2008).
Concrete foundations are prone to attacks from highly acidic laterite soils present in some
areas, thereby causing honeycombing. Large areas of coalluvial laterite gravels and sands
are near the foothills.
Three main erosion types are prevalent in the metropolis. These are;
i. Sheet erosion: this occurs mainly on the steeper foothill slopes where the natural
vegetation cover has been removed due to the adoption of bad farming practices.
ii. Gully erosion: this occurs mainly along major drainage channels
iii. Wind erosion: this is confined to coastal and dune areas. Coastal erosion is a very
serious problem in GAMA (it is estimated that part of the coastline is retreating at
a rate of 0.5metres per year) (Muff and Efa, 2006; Kortatsi et al., 2008).
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3.4 CLIMATE AND VEGETATION
3.4.1 Climate
Accra lies in the Coastal Savannah Zone. There are two main rainy seasons with an
annual rainfall of about 730 mm (primarily during the two rainy seasons). The following
bulletins highlight the key aspects of GAMA’s climate. The first rainy season starts from
May to Mid-July and the second rainy season starts from Mid-August to October. Rain
falls in intensive short storms and where drainage is poor, local flooding occurs.
Temperature variations during the year are very little with mean monthly temperatures
between 24.7 °C in August and 28 °C in March and an annual average temperature of
26.8 °C. The climatic condition of the Greater Accra Metropolitan Area is such that
daylight hours are uniform throughout the year since the study area is closer to the
equator. Relative humidity is generally high (i.e., 65% at mid-afternoon to 95% at night).
-
The wind direction is predominantly WSW to WNW (wind speed is usually 8 to 16 kmh
1 -1
). The maximum wind speed in GAMA is usually 107.4 kmh , thus about 58 knots. At
the foothill slopes of the Akwapim hills the wind velocity increases and gives rise to
slightly cooler temperatures (Muff and Efa, 2006; Kortatsi et al., 2008).
3.4.2 Vegetation
The study area is characterized by terrestrial and aquatic vegetations.
The terrestrial vegetation is altered in recent past century due to climatic and other
factors. GAMA was earlier covered by dense forest of which only few remnant trees are
visible today. The vegetative structures are similar to those of the Southern Shale, Sudan
and Guinea Savannas all of which lie north of the Accra plains. These have been imposed
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by climatic change and gradient of the plains and cultivation of the land. There are three
broad terrestrial vegetative zones namely
i. Shrub land: This occurs in the western outskirts and in the north towards
Aburi hills. Dense clusters of small trees and shrubs which grow to
average height of about 5 metres are present.
ii. Grass land: They are a mixture of species found in the undergrowth of
forests. The grasses are short and rarely grow beyond 1 metre.
iii. The Coastal zone is further made of two vegetations. They include the
wetlands and the dunes.
A number of introduced trees and shrubs thrive in GAMA. In the Accra area, trees like
Neems, Mangoes, Cassias and Avocados and Palms. Shrubs like Bouganvillia also exist.
The coast is mainly dominated by mangroves and Coconut plantations.
Aquatic vegetation in GAMA comprises mangroves and salt marsh grasses. These are
common in the intertidal zone whilst sea grasses and attached algae can be seen around
the rocky areas and wave cut platforms. The aquatic vegetation is increased due to
erosion (exposing bedrock especially to the east of Tema). The ocean floor sea grasses
are confined to a few sheltered areas of the coastline and the lagoons (Muff and Efa,
2006; Kortatsi et al., 2008).
3.5 DELIMITATION OF STUDY AREA
To clearly understand the seismicity of GAMA, the area needs delimitation. Immediate
environments around GAMA must be compared to other areas of similar geology such as
Togo, Burkina Faso and Cote d’Ivoire. It is well known that earthquakes have no
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geographical boundary. The inclusion of these places would also help obtain enough data
for the stress estimation of the study area. Mavonga and Durrheim in the Probabilistic
Seismic Hazard Assessment for the Democratic Republic of Congo and surrounding
areas calculated the b-values by including data from the sub-region (Mavonga and
Durrheim, 2009). In analyzing seismic activities in Ghana, seismic data from the
immediate neighbours of Ghana were also considered (Amponsah, 2004).
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CHAPTER FOUR
METHODOLOGY
4.1 DESK STUDY
The necessary information relevant to the study was gathered from the Accra
Metropolitan Assembly, Ghana Geological Survey Department and the National Data
Centre of the Ghana Atomic Energy Commission. Additionally, other research works
conducted in the area were also gathered to have a fair knowledge about seismic activities
in the study area. Some of these communities such as Accra Central, Weija, Kwabenya
and Nyanyano were visited to gain an insight into current structural readiness in case any
of the past events is repeated. In Accra Central, short buildings are being replaced with
high rising ones. Weija on the other hand has become a bit developed with modern
structures but most unplanned settlements surround the lake. This area is noted for high
seismic activity from past seismicity evaluations. Kwabenya and Nyanyano lands are
being given out for development but no significant attempt has been made to build
earthquake resistant structures even though modern structures in these places are stronger
than earlier ones.
4.2 EARTHQUAKE CATALOGUE
The most important and essential parameter for hazard studies is the earthquake catalogue
(Parvez et al., 2001). Earthquake data from 1615 to 2012 was used for this seismological
and geological investigation. The flow chart below (Fig. 4.1) demonstrates the processes
involved in generating the catalogue
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SORTING OF SORTING OF
EXISTING CATALOGUE FROM CATALOGUE
CATALOGUE ISC FROM NDC
EXAMINATION
FUSION OF ALL CATALOGUES
RELOCATION OF EVENTS
MATLAB INTERPOLATION OF EVENTS
MAGNITUDE UNIFICATION
FINAL SORTING TO KEEP EVENTS WITH
MAGNITUDE ≥ 2
Fig. 4.1: Flow Chart for Developing GAMA Seismicity Catalogue
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4.2.1 Data Collection
Seismic events spanning 1615 to May 2003 was obtained from Amponsah et al. (2012).
Events from June 2003 to December 2009 were obtained from the International
Seismological Centre (ISC, 2012) using rectangular grid. The rest of the data was
obtained from the National Data Centre at the Ghana Atomic Energy Commission.
4.2.2 Interpolation of Earthquake Magnitudes
The Matlab Programming Software was used to generate the magnitudes of events
without magnitudes. In that, the input data include years and their corresponding
magnitudes. Some of these include 1636, 1862 and 2012 with their corresponding
average magnitude for events being 5.8 M, 5.7 M and 6.2 M. This was done in the editor
window. After entering this data and running it, the output data was then displayed in the
command window. For years with multiple records, an average of the event magnitude
was calculated. In order to validate the program, years of known magnitude of events
were commanded. On running the program the results affirmed the already known
magnitudes. The results are accordingly expounded in Chapter five.
4.2.3 Relocation of Events
Some events from Amponsah et al. (2012) were relocated to reflect the present day areas
that experienced the earthquake. This would help in better interpretation of the
earthquake hazard in the Greater Accra Metropolitan Area. In some cases the events were
not exactly at city centers and the relocation of the events would help in estimating the
best intensity of the seismic events if they should occur in present day. In some cases
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where the relocation is unable to clearly identify the epicenter from the Google Maps
Application Software, the Global Positioning System (GPS) was used to identify the area
concerned. This was mainly done in areas such as Weija, Nyanyano and the City of
Accra which have recorded significant earthquakes and tremors in the recent past.
4.2.4 Magnitude Unification
The catalogue produced contained various magnitude units. These include the Local
Magnitude, ML, the Body-wave Magnitude, Mb, the Duration Magnitude, MD and the
Surface-Wave Magnitude for macroseismal data, MM. The different magnitude scales
used in describing the size of the earthquakes in the catalogue calls for unification and
harmonization. All the units must be converted to one single unit where possible, since
the earthquake magnitude scale is one of the most fundamental earthquake source
parameters used for catalogues. Drawing a unified relationship between these scales
would help in a better hazard and risk assessment by improving on uniformity and
continuity of the data. The moment magnitude was used because it is a direct indicator of
the seismic moment of an event and also this magnitude relates to some physical
parameters of the fault such as the amount of slip (Hanks and Kanamori, 1979; Mavonga
and Durrheim, 2009).
The following relations were used to convert the various magnitude units to the Moment
Magnitude, Mw. However, for small events, magnitudes ML and Mb were considered to
give reliable measure of events (Hanks and Kanamori, 1979; Mavonga and Durrheim,
2009). Events spanning 1615 to 2003 were recorded in MD, MM and ML. MD was
converted to ML according to Brumbaugh (1987) as:
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ML = 0.936 MD – 0.16±22..……………………………………..………………4.1
where;
ML is the Local magnitude and MD is the Duration magnitude
This linear regression relation (equation 4.1) has been used for evaluating magnitudes in
local and regional seismic networks. One advantage of the duration magnitude however,
is that it allows rapid estimates for large number of local events (Brumbaugh, 1987).
The rest of the relations relied on during the harmonization include the following;
according to Hanks and Kanamori (1979) and Mavonga and Durrheim, (2009):
Ms = 2.08Mb – 5.65.….…………………………………………………………4.2
Mb = 0.481Ms + 2.716..…………………………………………………………4.3
2
Mb = 1.7 + 0.8ML – 0.01ML ….……...…..…………………………………….4.4
Mo
Log10 = 1.5Ms + 16.1± 0.1 5 ≤ Ms ≤ 7.5……………......……………4.5
Mo
Log10 = 1.5ML + 16.0 3 ≤ ML ≤ 7...………………...……...........4.6
Ms = 1.45ML – 3.2…….………………………………………..………….……4.7
Mb, ISC = 0.46Ms + 2.74.………………………………………………………..4.8
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Mo
Mw = 2/3 Log10 10.7……………………………………………………...….4.9
where;
Ms is the Seismic-wave magnitude
Mb is the Body-wave magnitude
Mo is the Seismic moment
ML is the Local magnitude
Mb, ISC is the Body-wave magnitude according to the ISC standards
Mw is the moment magnitude
The National Data Centre records captured in ML and Mb were maintained where the
conversion leads to a reduction in magnitude. This would help consider extreme
scenarios of earthquakes occurring instead of maintaining lesser earthquake magnitudes
that can only be used to evaluate less effect.
4.3 SEISMICITY AND EPICENTRAL INTENSITY MAPS
A seismicity map was generated to evaluate the frequency, magnitude and distribution of
earthquakes up to 2012. The epicentral intensity map was generated according to Herak
(2012) equation defined as:
I = M + 2 ………..……… …………………………………………………….4.10
where;
I is the epicentral intensity whilst M is the magnitude,
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Equation 4.10 was used to convert the magnitudes to epicentral intensities. The
coordinates, thus latitude and longitudes were also converted to metres using Franson
CoordTrans software (version 2.3). The conversion helps to arrive at a more accurate
location of the epicenters as compared to the latitude-longitude approach. The epicentral
intensity was plotted using the Geographical Information System, GIS. The plot also
indicates the distribution of earthquakes in space in the Greater Accra Metropolitan Area
as shown in Figure 5.1.
4.4 EVALUATION OF b-VALUE
Two approaches were adopted to evaluate the b-value. These are the;
i. Linear least square fit
ii. Maximum likelihood estimation
The linear least square fit is the Guttenberg-Richter approach which uses the Guttenberg-
Richter magnitude frequency relationship (Guttenberg and Richter, 1942). This empirical
relation expresses the relationship between magnitude and the total number of
earthquakes in a given area and the time period of at least that magnitude. The relation is
given as:
Log10 N ( ≥ M ) = a – bM…………………….……...............................................4.11
where,
N is no. of events with magnitude ≥ M,
M is the magnitude of the events,
a and b are constants, thus a describes the seismic activity (log number of events with
M=0). It is determined by the event rate and for certain region depends upon the volume
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and time window considered. b, which is typically close to 1, is a tectonic parameter
describing the relative abundance of large to smaller shocks. It seems to represent
properties of the seismic medium in some respect, like stress and/or material conditions
in the focal region (Kulhanek, 2005).
Comparing equation 4.11 to the equation of a straight line (equation 4.12),
y=c+mx…………………...................................................................................4.12
where;
y represents plots on the vertical coordinate
x represents plots on the horizontal coordinate
c represents the y-intercept
m represents the gradient of the plot of y against x
Then equation 4.11 can be re-written as:
y = Log10 N ( ≥ M )…………………………………………………………..4.13
x = M………………………………………………………….……………...4.14
and the gradient
m = -b………………………………………………………………..……..….4.15
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Log10 N ( ≥ M ) was evaluated from the catalogue with the corresponding cumulative
magnitude M as shown in Table 5.1,
The result obtained from the plot of equation 4.13 against equation 4.14 was used to
evaluate the b-value (the slope of the graph) according to the equations 4.11, 4.12, 4.13,
4.14 and 4.15. One interesting feature of this method is that all the Log10 N (≥M) values
evaluated take part in the calculation (Chen et al., 2003).
Marzorcchi and Sandri (2003), Lombardi (2003) and Felzer (2006) approaches were
adopted to estimate the b-value by the maximum likelihood process using the equation
4.16 given below
b=1/ [ln10 (mav- mc)]………………………...……………………………………..….4.16
where;
b represents the b-value
mav represents the average magnitude from the catalogue and
mc represents the threshold or cut off magnitude (usually carefully selected from the
sharp curve exhibited by chart). The completeness of the earthquake catalogue, i.e. the
estimation of the so-called threshold magnitude mc is critical. In general, mc magnitude of
data set is obtained from the Guttenberg-Richter relation plot (plotting Log10 N ( ≥ M )
against the magnitudes, M). mc is the level at which the data falls below the line of best
fit (Lin et al., 2008; Wang and Shieh, 2004)
Marzorcchi and Sandri (2003) reviewed and gave new insights on the estimation of b-
value and its corresponding uncertainty. The new insights given involved the introduction
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of the maximum likelihood estimation method and further went on to calculate the
uncertainties associated. Lombardi (2003), on the other hand, used the maximum
likelihood estimator to calculate the b-value of mainshocks and compared the results to
the Guttenberg-Richter method of least square fit. Felzer (2006), in calculating
Californian seismicity rates from the earthquake catalogue for time-independent hazard
analysis adopted the maximum likelihood estimation method.
According to Aki (1965), the uncertainty associated with b-value calculation is given by
σb =b/√N……………………………………………………………………………..…4.17
where σb represents the uncertainty, b represents the b-value and N represents the
number of earthquakes under consideration
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CHAPTER FIVE
RESULTS AND DISCUSSION
5.1 RESULTS
5.1.1 EARTHQUAKE CATALOGUE
An earthquake catalogue has been created, and this is an improvement on the one
generated by Amponsah et al. (2012). In all, 554 events from 1615 to 2012 from Ghana
and its neigbouring countries were used in this study. The interpolated earthquake
magnitudes were computed using Matlab software which generated the earthquake
magnitudes between 2.9Mw and 6.6Mw. The catalogue is shown in Table 5.1
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Table 5.1: Earthquake Catalogue of Ghana and its Immediate Neighbours (1615 to 2012)
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1615 5.1 -1.3 8 AMB Elmina,Ghana
1636 12 18 14 5.1 -2.2 5.8 9 AMB Axim, Fort Duma, Awoin, Ghana
1788 7.6 1.7 5.7 8 AMB Agunah/Togo, Abomey/Benin
1836 12 5.1 -1.3 6.3 6.5 AMB Cape Coast, Ghana
1858 5.6 -0.2 6.6 6 AMB Accra, Ghana
1861 6 0 6.6 5 AMB Akropong Akwapim, Ghana
1862 7 10 8 15 7 0.4 6.6 9 700 AMB Kpando, Ghana
1870 11 23 12 5.3 -0.7 4.6 5 AMB Apam, Ghana
1871 1 26 20 5.5 -0.4 4.7 6 AMB Accra, Ghana
1872 4 14 23 5.5 -0.4 5.0 7 AMB Accra, Ghana
1879 2 11 6 6.5 -3.3 5.8 8 380 AMB Abidjan-Cote d'Ivoire
1883 8 13 2 30 5.5 -0.4 4.7 6 150 AMB Accra, Ghana
1889 4 5 12 20 5.9 -0.2 4 4 AMB Amanokrom, Ghana
1894 5.5 -0.2 4.3 3.5 AMB Accra, Ghana
1906 11 20 21 0 6.5 0.3 12 5.1 7.5 250 ALY Near Ho-Ghana
1907 2 27 22 15 6.1 -0.9 4.1 4 AMB Kade, Ghana
1910 12 25 5.6 -0.2 4.0 5 AMB Accra, Ghana
1911 6 17 15 20 5.5 -0.2 4.0 4 AMB Accra, Ghana
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Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1912 5.5 -3.6 4.0 4 AMB Near Alepe, Cote d'Ivoire
1930 10 14 7.1 0.7 3.5 4 AMB Kpalime, Agu-Togo
1933 1 6 4 7 0.6 4 6 100 AMB Kpalime, Misahoe-Togo
1935 5 29 6.9 0.6 4.8 6 AMB Near Kpalime, Togo
1939 6 22 19 19 26 5.4 -0.25 18 6.4 8 680 ALY Coast of Accra, Ghana
1939 8 18 4 51 14 6.2 -0.3 5.4 6 AMB Koforidua, Ghana
1948 6.2 0.4 4.4 4 AMB Atimpoku, Ghana
1950 4 4 22 9 6.8 -4.6 4 4 AMB Dimbroko-Cote d'Ivoire
1950 10 20 15 21 45 7.5 0.5 4.0 4 AMB Kadjebi-Togo
1964 3 11 12 45 56 5.9 -0.39 4.4 6 AMB Amasaman, Ghana
1966 5.58 -0.35 4.6 4 10 ALY Weija, Ghana
1969 2 9 18 29 4 5.5 -0.2 17 4.9 5.5 190 ALY Accra, Ghana
1973 8 23 17 15 5.7 0.3 2.4 GSD Offshore-Lepongune
1973 11 28 11 33 21 7 0.8 1.9 GSD Forêt du Mont Haito, Togo
1974 1 11 5 29 52 5 -2.6 3.6 GSD Near Beku, Western Ghana
1974 1 16 17 8 50 6.5 0.5 1.9 GSD Kalakpa Game Production Reserve, Near Tsrefe-Ghana
1974 2 20 3 13 43 5 -2.6 3.1 GSD Near Beku, Western Ghana
1974 6 2 23 15 9 5.8 0.8 2.6 GSD Jogbove, Ghana
1974 6 8 15 3 5 5.1 2.5 3.4 GSD Togo
1977 2 2 2 56 5.77 -0.2 GSD Pokuase, Ghana
1977 2 25 1 19 6.02 -0.2 2.5 GSD In the Gulf of Guinea, Near Togo
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Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1977 3 1 20 50 5.72 -0.2 2.7 GSD Pokuase, Ghana
1977 3 1 20 58 5.58 -0.28 1.9 GSD Oblogo, Ghana
1977 4 15 23 46 5.95 -0.07 2.4 GSD Akropong, Ghana
1977 4 29 18 23 5.67 -0.2 2.5 GSD Pokuase, Ghana
1977 6 18 4 17 5.63 0.02 2.1 GSD Prampram, Ghana
1977 7 20 19 34 5.65 -0.28 2 GSD Pokuase, Ghana
1977 7 26 9 15 5.57 -0.38 2.4 GSD Weija, Ghana
1977 10 8 3 15 5.97 -0.03 2.8 GSD Adukrom, Ghana
1977 11 18 23 11 5.58 -0.38 2.2 GSD Weija, Ghana
1977 11 23 22 9 6 0.12 2 GSD Agomeda, Ghana
1978 2 7 1 44 6.58 0.13 2.8 GSD Peki, Ghana
1978 3 3 5 35 5.53 -0.38 3.0 GSD Near Ngleshi Amanfro, Ghana
1978 7 6 18 10 6.6 0.27 2 GSD Near Adzokoe, Ghana
1978 9 5 22 59 30 5.63 -0.35 3.7 4 AMB Weija, Ghana
1978 9 6 12 39 5.63 -0.35 2.1 GSD Weija, Ghana
1978 9 21 1 22 5.53 -0.4 1.9 GSD Nyanyanu, Ghana
1978 12 2 11 10 5.53 -0.37 1.9 GSD Kokrobite, Ghana
1979 1 9 13 58 53 5.58 -0.32 3.4 3.5 AMB Oblogo, Ghana
1979 1 25 9 0 5.5 -0.33 2.2 GSD Kasoa, Ghana
1979 3 9 20 16 5.57 -0.38 2.2 GSD Weija, Ghana
39
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1979 3 15 17 37 5.52 -0.35 2.3 GSD Botianor, Ghana
1979 6 18 18 51 5.5 -0.42 1.9 GSD Odupomkpehe, Ghana
1979 6 27 20 26 5.53 -0.43 2.1 GSD Obutu, Ghana
1979 6 28 21 54 5.77 -0.28 1.9 GSD Doboro, Ghana
1987 7 7 8 11 56 5.44 -0.4 2.7 GSD Offshore-Nyanyanu
1987 7 31 23 52 4 5.67 -0.26 1.9 GSD Pokuase, Ghana
1987 12 3 0 29 48 5.51 -0.26 3.0 GSD Offshore-Labadi, Ghana
1987 12 3 10 37 38 5.53 -0.41 3.0 GSD Obutu, Ghana
1988 2 27 0 51 4 5.5 -0.4 3.2 GSD Kasoa, Ghana
1988 3 6 12 15 8 5.63 -0.27 1.9 GSD Pokuase, Ghana
1988 3 20 19 9 50 5.56 -0.3 1.9 GSD Oblogo, Ghana
1988 3 25 1 0 35 5.6 -0.28 2 GSD Weija, Ghana
1988 3 29 16 54 4 5.6 -0.11 3.3 4 ISC Legon-Accra, Ghana
1988 4 24 13 18 46 5.61 -0.31 1.9 GSD Kwashiman, Ghana
1988 5 6 1 48 43 5.6 -0.32 2.1 GSD Oblogo, Ghana
1988 5 31 7 35 8 5.45 -0.37 2.3 GSD Offshore-Nyanyanu, Ghana
1988 12 5 5 12 43 5.48 -0.4 2.4 GSD Offshore-Nyanyanu, Ghana
1989 3 23 13 32 47 5.59 -0.33 1.9 GSD Kwashiman, Ghana
1989 6 27 18 28 9 5.31 -0.6 2.1 ISC Offshore-Winneba, Ghana
1990 2 12 1 34 41 5.61 -0.34 2.6 NEI Weija, Ghana
1990 4 14 11 43 26 5.59 -0.34 2.9 3 GSD Weija, Ghana
40
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1990 9 15 9 32 1 5.4 -0.55 3.3 GSD Offshore-Winneba, Ghana
1990 12 2 0 23 21 5.44 -0.41 2.6 GSD Offshore-Winneba, Ghana
1991 1 1 7 58 8 5.93 -0.12 2.3 GSD Akropong, Ghana
1991 3 6 14 54 33 5.61 -0.3 2.1 GSD Weija, Ghana
1991 3 6 16 50 33 5.62 -0.31 2.3 GSD Weija, Ghana
1991 3 27 22 18 2 5.64 -0.29 2.9 GSD Weija, Ghana
1991 6 30 20 44 18 5.62 -0.35 2.3 GSD Weija, Ghana
1991 8 23 9 51 6 5.62 -0.33 3.7 GSD Weija, Ghana
1991 10 23 0 14 12 5.53 -0.35 2.3 GSD Weija, Ghana
1993 4 3 22 33 10 5.5 -0.27 2.1 GSD Offshore-Nyanyanu, Ghana
1993 4 6 14 29 38 1.3 1.62 4.2 ISC In the Gulf of Guinea, near Benin
1993 5 7 1 40 46 5.53 -0.23 2.3 GSD Offshore-Botianor, Ghana
1993 6 22 14 55 39 5.63 -0.56 2.3 GSD Obrachere, Ghana
1993 6 27 3 38 23 5.53 -0.27 2.7 GSD Botianor, Ghana
1993 6 28 5 49 3 5.59 -0.32 2.4 GSD Weija, Ghana
1993 7 17 15 59 59 4.05 -2.44 2.7 ISC Gulf of Guinea
1993 9 8 3 52 39 5.52 -0.34 2.1 GSD Offshore-Nyanyanu, Ghana
1993 10 7 18 17 10 5.55 -0.36 2.3 GSD Weija, Ghana
1993 10 28 10 8 2 5.5 -0.34 2.1 GSD Offshore-Nyanyanu, Ghana
1994 1 15 19 51 41 5.38 -0.34 2.5 GSD Nyanyanu, Ghana
1994 1 17 5 49 27 5.47 0.55 2.3 GSD Brofo Yeduro, Ghana
41
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1994 1 27 18 28 1 5.6 -0.27 2.4 GSD Offshore-Botianor, Ghana
1994 8 26 12 48 20 5.47 -0.27 2 GSD Botianor, Ghana
1994 8 28 9 44 25 5.36 -0.32 1.9 GSD Nyanyanu, Ghana
1994 9 6 1 1 4 5.52 -0.37 2.3 GSD Odupomkpehe, Ghana
1994 9 6 17 30 54 7.65 -3.48 2.8 ISC Cote d'Ivoire, Ghana
1994 9 6 17 32 8 5.53 -0.42 2 GSD Obutu, Ghana
1994 10 22 12 4 2 5.6 -0.4 1.9 GSD Nyanyanu, Ghana
1994 11 10 9 38 3 5.54 -0.35 2.3 GSD Oblogo, Ghana
1994 12 7 1 21 7 5.52 -0.25 2 GSD Odupomkpehe, Ghana
1995 1 27 19 16 16 5.45 -0.3 2.2 GSD Offshore-Botianor, Ghana
1995 1 28 20 22 0 5.6 -0.28 2.3 GSD Botianor, Ghana
1995 1 28 20 33 14 5.6 -0.36 2.3 GSD Oblogo, Ghana
1995 1 28 20 39 14 5.55 -0.4 3.2 3 GSD Weija, Ghana
1995 2 1 3 44 17 5.63 -0.57 2.5 GSD Obrachere, Ghana
1995 2 1 3 45 20 5.63 -0.45 3.6 GSD Obrachere, Ghana
1995 2 1 3 58 39 5.6 -0.32 2.6 GSD Oblogo, Ghana
1995 3 9 18 55 18 5.58 -0.33 3.2 3 GSD Weija, Ghana
1995 5 3 19 34 1 5.55 -0.3 2.5 GSD Oblogo, Ghana
1995 6 27 23 43 0 5.52 -0.26 2.4 GSD Offshore-Botianor, Ghana
1995 10 12 1 8 35 5.5 -0.24 2.5 GSD Offshore-Botianor, Ghana
1995 10 27 20 1 33 5.5 -0.35 3.8 GSD Offshore-Kokrobite, Ghana
42
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1996 2 22 9 14 39 5.58 -0.45 3.4 GSD Teshie, Ghana
1996 2 23 9 15 7 5.28 -1.42 2.8 ISC Komenda, Ghana
1996 7 5 7 42 36 5.43 -0.34 3.0 GSD Offshore-Botianor, Ghana
1996 8 2 22 37 26 5.44 -0.48 2.4 GSD Fete, Ghana
1996 8 2 9 26 32 5.44 -0.47 2.3 GSD Fete, Ghana
1996 8 2 21 1 18 5.52 -0.49 2.4 GSD Obutu, Ghana
1996 8 31 3 4 59 5.44 -0.43 2.9 GSD Offshore-Fete, Ghana
1996 9 12 15 15 23 5.62 -0.27 2.3 GSD Pokuase, Ghana
1996 9 21 18 1 42 5.47 -0.27 2.4 GSD Offshore-Botianor, Ghana
1996 10 8 12 1 36 5.67 -0.32 2.2 GSD Manhea, Ghana
1996 10 21 14 19 10 5.82 -0.35 3.2 GSD Nsawam, Ghana
1997 1 8 9 35 37 5.63 -0.34 2.1 GSD Weija, Ghana
1997 2 14 23 26 7 5.66 -0.43 2.6 GSD Dantsera, Ghana
1997 2 14 23 29 5 5.67 -0.4 3.9 4.5 GSD Manhea, Ghana
1997 3 6 15 59 36 5.6 -0.38 2.2 GSD Manhea, Ghana
1997 3 6 16 17 0 5.65 -0.38 1.9 GSD Manhea, Ghana
1997 3 13 18 54 52 5.65 -0.34 2.2 GSD Weija, Ghana
1997 3 13 0 55 35 5.62 -0.34 2 GSD Weija, Ghana
1997 3 27 14 29 5 5.62 -0.34 2.3 GSD Weija, Ghana
1997 9 24 3 2 3 5.6 -0.33 2.3 GSD Weija, Ghana
1998 1 27 14 4 42 5.75 0.01 2 AMP Katamanso, Ghana
43
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
1998 11 19 0 5 2 5.72 0.28 2 AMP Offshore-Old Ningo, Ghana
1998 11 25 21 14 10 5.77 0.18 2.3 AMP Offshore-Gulf of Guinea
1998 12 23 16 15 23 5.25 -0.22 2 AMP Offshore-Nyanyanu, Ghana
1999 1 20 4 53 34 5.35 0 2.2 AMP Offshore-Tema, Ghana
1999 5 19 15 11 43 5.79 -0.25 2.5 AMP Abokobi, Ghana
1999 8 22 23 35 29 6.1 -1.29 2.6 AMP Ochereso, Ghana
1999 10 30 10 21 39 5.79 0.29 2.4 AMP Offshore-Old Ningo, Ghana
2000 1 30 14 58 19 5.3 -0.32 2.3 AMP Offshore-Labadi, Ghana
2000 4 17 6 29 23 6.59 0.48 2.1 AMP Akuse, Ghana
2000 6 8 21 38 38 5.32 -0.01 2.3 AMP Labadi, Ghana
2000 7 9 20 39 28 5.48 -0.14 2.1 AMP Aburi, Ghana
2000 8 14 0 2 42 5.78 -0.15 2.5 AMP Oyarifa, Ghana
2000 9 2 18 27 11 5.59 -0.86 2.2 AMP Odoben, Ghana
2000 11 8 8 18 29 5.66 2.6 2.6 AMP Offshore-Prampram, Ghana
2000 11 26 10 26 32 5.54 0.13 3.1 AMP Offshore-Tema, Ghana
2000 12 8 21 18 45 5.83 -0.24 2.7 AMP Aburi, Ghana
2001 9 22 8 58 34 5.56 0.18 2.2 AMP Offshore-Kpong, Ghana
2002 2 21 6 28 35 5.6 0.13 2.7 AMP Offshore-Tema, Ghana
2002 2 22 2 14 34 5.4 -0.5 2.8 AMP Senya-Breku, Ghana
2002 5 17 13 37 11 5.6 0.1 2.2 AMP Offshore-Tuba, Ghana
2002 6 7 1 31 22 5.65 -0.27 2.3 AMP Oblogo, Ghana
44
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2002 6 7 1 35 40 5.5 -0.3 3.0 AMP Offshore-Botianor, Ghana
2002 11 27 5 32 27 5.55 0.5 2 AMP Offshore-Tema, Ghana
2002 11 29 16 43 43 5.25 -0.6 2 AMP Offshore-Winneba, Ghana
2003 5 18 6 51 16 5.57 -0.32 2.9 AMP Weija, Ghana
2003 5 18 7 2 14 5.58 -0.32 2.2 AMP Weija, Ghana
2003 5 18 13 18 24 5.57 -0.38 2.6 AMP Weija, Ghana
2003 6 22 6 8 10 6.7 -1.9 2 2.9 86 ISC Kumasi-Sunyani Road, Ghana
2004 4 17 13 21 13 5.3 -2.6 2 3.2 115 ISC Elubo-Enchi Road, Ghana
2004 7 2 9 30 33 7.4 -7.1 2 3.2 114 ISC Man-Cote d'Ivoire
2005 9 29 16 39 18 3.7 -6.3 2 3.4 26 ISC North Atlantic Ocean-Near Cote d'Ivoire
2007 3 6 0 4 25 5.7 -6.9 50 3.9 68 ISC Tai National Park, Cote d'lvoire
2008 6 9 21 48 51 4.6 -3.9 50 4.2 150 ISC Gulf of Guinea, Cote d'Ivoire
2008 6 26 4 51 42 6.2 -4.7 20 4.2 140 ISC Tiassale-Cote d'Ivoire
2008 8 16 11 31 49 9.2 -1.5 30 4.2 100 ISC Daboya-Busunu Road, Ghana
2009 9 11 3 10 19 6.7 2.2 10 4.4 165 ISC Cotonou-Porto-Novo area, Benin
2009 10 23 10 31 35 9.4 -2.4 30 4.4 41 ISC Near Mole National Park, Ghana
2009 12 12 18 8 6 7.0 -1.9 2 4.4 80 ISC Near Kumasi, Ghana
2010 9 30 5 53 31.45 7.3 -2.1 4.4 142 NDC Nkinkanso, Ghana
2010 10 3 16 15 39.31 11.8 0.1 2.4 138 NDC Saltenga, Burkina Faso
2010 10 3 22 38 23.41 6.4 -6.2 4.1 157 NDC Guguha, Cote d'Ivoire
2010 10 30 1 40 31.7 5.6 -5.8 4.0 139 NDC Gogue, Cote d'Ivoire
45
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2010 11 4 1 12 38.13 6.7 -4.9 4.1 154 NDC Angouakoukro, Dimbokro, Cote d'Ivoire
2010 11 4 15 41 15.38 11.8 1.0 4.2 107 NDC Alondigwena, Burkina Faso
2010 11 7 3 4 49.12 10.7 0.0 3.9 124 NDC Dore, Northern Togo
2010 11 10 3 24 24.44 7.1 -6.1 4.2 20 NDC Bafla, Cote d'Ivoire
2010 11 10 3 56 32.03 1.1 -3.1 4.3 173 NDC Near coast of Ghana / Cote d'Ivoire
2010 11 14 8 8 36.25 6.7 -4.5 4.0 121 NDC Banngokro, Cote d'Ivoire
2010 11 17 22 33 42.48 -7.5 -13.3 4.6 104 NDC In the South Atlantic ocean
2010 11 20 5 11 59.15 8.7 -4.6 4.1 110 NDC Kapolokoro, Cote d'Ivoire
2010 11 21 2 52 46.99 11.8 3.1 4.3 19 NDC Boiffo, Benin
2010 11 22 7 22 20.93 7.3 -4.3 4.4 128 NDC Angoakro, Cote d'Ivoire
2010 11 22 9 25 59.82 6.8 -7.6 3.9 25 NDC Moyen-Cavally, d'Ivoire
2010 11 25 5 42 4.59 6.2 -6.0 2.8 159 NDC Fromager, Barouyo, Cote d'Ivoire
2010 11 26 21 1 6.94 5.3 -2.4 3.8 19 NDC Kwesikrom, Western Region, Ghana
2010 11 26 23 59 56.07 12.0 0.9 4.1 117 NDC Boumwana, Burkina Faso
2010 11 30 4 49 33.64 6.7 -4.4 4.1 110 NDC Nzi-Commoe, Aoussoukro, Cote d'Ivoire
2010 11 30 20 42 34.93 5.8 -4.9 4.3 100 NDC Su-Bandama, Guiguedou, Cote d'Ivoire
2010 12 1 16 5 44.72 7.3 -6.1 4.2 8 NDC Marahou, Zeizra, Cote d'Ivoire
2010 12 2 11 8 48.66 14.2 0.3 4.3 59 NDC Arbinda, Burkina Faso
2010 12 3 13 22 56.26 12.7 1.0 4.1 159 NDC Foadyendyengou, Burkina Faso
2010 12 3 15 34 11.82 7.8 -5.6 4.1 112 NDC Vallee du Bandama, Cote d'Ivoire
2010 12 4 17 3 29.08 13.6 0.5 2.3 18 NDC Sahel, Burkina Faso
46
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2010 12 5 1 7 29.27 12.7 0.4 4.0 48 NDC Louauga, Burkina Faso
2010 12 6 4 49 41.01 7.7 -3.9 3.8 125 NDC Nzi-Commoe, Kotobo, Cote d'Ivoire
2010 12 9 4 10 6.26 6.5 -5.3 4.1 84 NDC Fromager, Cote d'Ivoire
2010 12 11 4 59 17.66 6.5 -5.1 4.2 145 NDC Lacs, Cote d'Ivoire
2010 12 12 18 11 44.21 10.6 -3.1 3.8 74 NDC Sud-Ouest, Nako, Burkina Faso
2010 12 17 5 56 31.17 6.7 -4.8 4.2 12 NDC Dimbokro, Cote d'Ivoire
2010 12 22 4 3 43.48 -4.8 -11.8 4.3 141 NDC Off the coast of Liberia / Cote d'Ivoire
2010 12 22 4 6 37.05 5.8 -5.1 4.6 124 NDC Ble, Cote d'Ivoire
2010 12 29 7 12 58.47 1.7 -3.2 4.3 144 NDC Near Coast of Ghana / Cote d'Ivoire
2010 12 29 12 42 32.37 12.2 0.6 4.0 133 NDC Koulmyougou, Burkina Faso
2010 12 31 10 18 38.13 5.7 -4.4 4.1 82 NDC Yaobam, Cote d'Ivoire
2011 1 7 20 48 41.71 10.1 -2.8 4.1 109 NDC Bopiel, Burkina Faso
2011 1 9 10 24 48.64 -1.2 -18.0 4.3 136 NDC Off the Coast of West Africa
2011 1 10 2 29 59.1 -0.5 -5.4 4.2 93 NDC Off the Coast of Abidjan, Cote d'Ivoire
2011 1 11 15 41 42.68 -8.4 -5.2 4.3 92 NDC South Atlantic Ocean, Near Ghana
2011 1 14 12 56 43.87 3.7 -5.4 4.4 90 NDC Near Coast of Abidjan, Cote d'Ivoire
2011 1 15 3 18 43.86 12.2 -1.1 4.2 3 NDC Plateau - Central Region, Burkina Faso
2011 1 15 10 51 0.96 5.8 -6.0 4.1 147 NDC Seryo, Cote d'Ivoire
2011 1 17 2 3 38.94 11.8 2.0 4.2 127 NDC Logbobou, Burkina Faso
2011 1 17 19 0 29.82 -5.5 -4.5 4.3 131 NDC South Atlantic Ocean, Near Cote d'Ivoire
2011 1 21 19 4 6.19 6.2 -6.1 4.0 167 NDC Menekie, Cote d'Ivoire
47
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 1 26 15 43 58.1 6.1 -6.0 3.9 157 NDC Bogrenyoa, Cote d'Ivoire
2011 1 26 17 35 18.57 6.6 -4.8 4.1 131 NDC Assebrakro, Cote d'lvoire
2011 1 26 23 9 59.14 5.3 -4.7 4.3 179 NDC Baiede Cosron, Cote d'Ivoire
2011 1 27 5 28 7.3 6.7 -4.8 4.3 145 NDC Assebrakro , Cote d'Ivoire
2011 1 27 10 54 46.54 8.0 -4.5 4.1 110 NDC Vallee du Bandama, Cote d'Ivoire
2011 1 30 14 3 54.04 5.3 -4.7 4.2 72 NDC Baie de Cosrou, Cote d'Ivoire
2011 1 31 1 57 51.28 1.4 0.3 4.2 62 NDC South Atlantic Ocean, Near Ghana.
2011 1 31 3 13 23.99 6.4 -4.6 4.0 141 NDC Menou, Cote d'Ivoire
2011 1 31 15 33 7.21 4.9 -1.6 3.8 123 NDC Anoe, Sekondi Takoradi, Ghana
2011 2 3 6 1 5.72 0.0 1.6 4.1 100 NDC Off Coast of Ghana / Togo
2011 2 3 8 4 52.7 11.9 -4.4 2.3 132 NDC Kouka, Burkina Faso
2011 2 10 19 10 59.31 7.3 -3.6 3.7 144 NDC Komoe-Denou, Cote d'Ivoire
2011 2 12 17 59 58.76 12.5 1.2 4.3 133 NDC Boulmomgo, Burkina Faso
2011 2 16 20 16 14.74 6.1 -6.1 3.3 158 NDC Bakeyo, Cote d'Ivoire
2011 2 16 23 34 37.64 7.4 -3.6 4.2 142 NDC Katimasso, Cote d'Ivoire
2011 2 17 0 17 33.89 5.7 -5.8 3.7 143 NDC Gague, Cote d'Ivoire
2011 2 17 6 26 29.86 6.7 -4.8 4.2 148 NDC Bofrebo, Cote d'Ivoire
2011 2 17 13 40 20.78 6.8 -6.3 4.0 158 NDC Bebouo, Cote d'Ivoire
2011 2 19 9 22 49.37 5.8 -5.4 4.5 141 NDC Divo, Cote d'Ivoire
2011 2 23 17 50 37.19 4.3 -5.0 4.2 117 NDC Near the coast of Abidjan, Cote d'Ivoire
2011 2 23 19 4 15.46 6.2 -6.1 3.7 158 NDC Bodounyoa, Cote d'Ivoire
48
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 2 24 8 40 11.74 3.0 -3.3 4.4 53 NDC Near the Coast of Abidjan, Cote d'Ivoire
2011 2 28 18 39 14.13 5.9 -1.8 4.1 172 NDC Buabenso, Central Region, Ghana
2011 3 1 00 47 9.55 6.8 -4.7 4.2 54 NDC Koffi Aoussoukro, Cote d'Ivoire
2011 3 01 02 01 4.73 -5.4 -10.9 4.1 127 NDC Off the Coast of Liberia / Cote d'Ivoire
2011 3 01 03 46 29.91 -5.5 -11.1 4.3 142 NDC off the coast of Liberia / Cote d'Ivoire
2011 3 01 12 32 2.02 5.3 -5.0 4.2 105 NDC Tiebiessou, Cote d'Ivoire
2011 3 02 13 09 31.95 5.7 -5.9 4.5 173 NDC Solouriberipalehoin, Cote d'Ivoire
2011 3 07 00 35 3.37 -8.3 -2.6 3.9 51 NDC Off the Coast of Cote d'Ivoire / Ghana
2011 3 09 04 53 54.31 8.1 -4.9 4.2 55 NDC Tinbokoro, Cote d'Ivoire
2011 3 09 05 45 40.52 6.9 1.2 4.2 122 NDC Kpele, Togo
2011 3 10 13 52 13.60 1.1 1.3 4.0 104 NDC Near the Coast of Ghana / Togo
2011 3 10 17 45 49.75 6.2 -5.7 3.9 146 NDC Laouda, Cote d'Ivoire
2011 3 12 05 54 21.62 3.7 -3.4 4.3 102 NDC Near Coast of Abidjan, Cote d'Ivoire
2011 3 13 23 16 7.57 4.8 -5.4 4.2 114 NDC Near the Coast of Abidjan, Cote d'Ivoire
2011 3 14 09 31 24.29 6.8 -4.9 4.2 154 NDC Tokre-Yoakro, Cote d'Ivoire
2011 3 16 09 58 17.23 6.0 -3.3 4.3 146 NDC Ebikokorekrou, Cote d'Ivoire
2011 3 16 13 18 29.11 6.2 -3.5 4.0 3 NDC Mbasso, Cote d'Ivoire
2011 3 18 04 32 52.98 5.6 -4.0 3.9 55 NDC Brou Asse, Cote d'Ivoire
2011 3 18 17 12 40.26 12.7 -3.7 3.7 9 NDC Biss, Burkina Faso
2011 3 19 11 34 6.39 12.6 0.9 4.2 150 NDC Nyamanga, Burkina Faso
2011 3 21 16 20 32.21 5.3 -4.2 4.4 71 NDC Songon-M'bratte, Cote d'Ivoire
49
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 3 22 13 34 28.95 5.3 -5.5 4.2 113 NDC Mokta, Cote d'Ivoire
2011 3 22 13 40 2.49 12.4 0.9 4.5 24 NDC Kankantiana, Burkina Faso
2011 3 22 16 52 6.66 3.2 -0.7 2.9 64 NDC Gulf of Guinea, Near the Coast of Sekondi, Ghana
2011 3 23 08 16 46.92 8.4 -6.4 2.0 62 NDC Kasatou, Cote d'Ivoire
2011 3 24 07 07 31.79 8.4 -5.4 3.9 70 NDC Kafine, Cote d'Ivoire
2011 3 26 02 16 36.34 6.6 -4.9 3.8 34 NDC Dimbokro, Cote d'Ivoire
2011 3 26 04 06 48.21 6.4 -5.1 4.2 123 NDC Bringakro, Cote d'Ivoire
2011 3 27 08 21 30.69 7.2 -3.1 4.2 151 NDC Kokomia, Cote d'Ivoire
2011 3 29 16 56 8.87 8.6 -2.3 4.3 120 NDC Tinga, Northern Region, Ghana
2011 4 1 10 25 11.56 6.7 -4.8 4.0 88 NDC Bofrbo, Cote d'Ivoire
2011 4 1 16 46 27.96 11.9 0.2 3.8 128 NDC Kouare, Burkina Faso
2011 4 2 6 46 19.72 7.0 -2.5 4.2 171 NDC Mim, Brong Ahafo Region, Ghana
2011 4 2 23 2 41.55 5.9 -5.9 4.1 142 NDC Niali-Gribouo, Cote d'Ivoire
2011 4 3 14 29 32.08 10.0 0.0 4.2 45 NDC Nagale, Northern Region, Ghana
2011 4 3 17 23 7.82 -9.5 -2.7 4.3 116 NDC South Atlantic Ocean, Near ghana.
2011 4 3 22 44 43.95 6.5 0.7 3.8 137 NDC Agotime Kpetoe, Volta Region, Ghana
2011 4 4 2 17 20.5 6.1 -6.2 4.4 180 NDC Kripayo, Cote d'Ivoire
2011 4 7 5 20 49.58 4.1 -5.0 4.0 119 NDC Near the Coast of Abidjan, Cote d'Ivoire
2011 4 8 21 26 57.97 6.6 -4.6 4.4 124 NDC Frondobo, Cote d'Ivoire
2011 4 10 20 6 40.66 6.3 -3.7 3.9 14 NDC Ananguie, Cote d'Ivoire
2011 4 14 5 32 52.34 16.2 -6.3 3.9 31 NDC Natabouanga, Burkina Faso
50
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 4 14 13 55 18.82 12.5 0.5 4.0 150 NDC Natabouanga, Burkina Faso
2011 4 16 14 6 31.37 6.7 -4.9 2.4 133 NDC Angouakoukro, Cote d'Ivoire
2011 4 17 9 46 36.76 13.0 1.4 4.1 168 NDC Dimbokro, Cote d'Ivoire
2011 4 17 11 45 15.93 7.0 -4.8 3.9 3 NDC Angouakoukro, Cote d'Ivoire
2011 4 18 14 13 18.97 6.0 -5.2 4.3 100 NDC Zehiri, Cote d'Ivoire
2011 4 19 18 34 59.37 5.3 -4.4 4.3 70 NDC Dabou, Cote d'Ivoire
2011 4 20 0 37 18.21 7.5 -5.0 4.0 83 NDC Kouabo, Cote d'Ivoire
2011 4 23 11 36 28.61 5.4 -5.4 4.3 133 NDC Niakro, Cote d'Ivoire
2011 4 25 9 9 38.33 6.8 -5.5 4.3 176 NDC Boanfla, Cote d'Ivoire
2011 4 25 22 36 55.68 10.3 -0.6 2.2 134 NDC Bazai, Cote d'Ivoire
2011 4 26 22 2 45.6 6.7 -4.8 3.8 59 NDC Angouakoukro, Cote d'Ivoire
2011 5 06 20 07 38.97 1.1 -5.9 3.9 89 NDC Gulf of Guinea, Near cote d'Ivoire
2011 5 07 01 49 34.79 6.0 -3.8 4.0 28 NDC Adzope, Cote d'Ivoire
2011 5 09 06 27 22.32 12.8 1.3 4.2 140 NDC Est. Burkina Faso
2011 5 10 23 17 53.08 5.9 -5.3 4.3 133 NDC Cote d'Ivoire
2011 5 15 05 26 40.09 4.5 -1.3 4.4 126 NDC Gulf of Guinea, Near Ghana
2011 5 16 21 29 15.76 4.8 -5.2 4.1 115 NDC Gulf of Guinea, Near Cote d'Ivoire
2011 5 19 03 32 25.01 5.4 -5.4 4.0 95 NDC Cote d'Ivoire
2011 5 19 20 22 58.34 6.6 -4.9 4.2 39 NDC Cote d'Ivoire
2011 5 21 07 37 5.48 6.3 -4.6 4.1 146 NDC Nzi-Comoe, Cote d'Ivoire
2011 5 22 03 12 10.95 6.2 -5.3 4.3 145 NDC Sud-Bandama, Cote d'Ivoire
51
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 5 25 15 31 15.76 8.0 -3.7 4.2 125 NDC Cote d'Ivoire
2011 5 29 04 45 5.14 6.6 -4.7 4.1 100 NDC Cote d'Ivoire
2011 5 29 10 02 54.91 14.1 0.1 4.0 21 NDC Burkina Faso
2011 5 30 22 45 15.35 6.6 -4.8 3.9 138 NDC Cote d'Ivoire
2011 6 03 03 68 26.43 6.6 -6.2 4.4 160 NDC Haut-sassandra Cote d'Ivoire
2011 6 03 06 35 55.56 5.6 -4.4 3.8 74 NDC Cote d'Ivoire
2011 6 11 22 35 26.63 6.3 -5.2 4.3 130 NDC Bandama, Cote d'Ivoire
2011 6 12 05 31 53.92 6.8 -5.0 4.2 130 NDC Lacs, Cote d'Ivoire
2011 6 13 02 40 53.85 13.5 0.7 3.8 61 NDC Burkina Faso
2011 6 19 08 48 10.30 9.4 -2.7 4.4 128 NDC Black Volta, Ghana
2011 6 19 10 06 24.80 5.4 -5.2 4.2 103 NDC Sud-Bandama Cote d'Ivoire
2011 6 23 13 09 10.53 7.5 -2.2 2.4 142 NDC Odumase Rd Sunyani Ghana
2011 6 25 15 45 14.09 8.6 -5.4 2.2 102 NDC Cote d'Ivoire
2011 7 03 03 53 33.64 5.6 -2.8 4.4 7 NDC Omanpe, near Ghana Cote d'Ivoire border
2011 7 06 17 34 31.07 5.3 -5.0 4.2 111 NDC Lagunes, Cote d'Ivoire
2011 7 08 06 22 34.27 6.1 -4.9 4.1 121 NDC Singrobo, Cote d'Ivoire
2011 7 08 20 14 48.91 6.5 -3.5 4.1 20 NDC Akouaba, Cote d'Ivoire
2011 7 09 23 20 59.36 3.0 -5.6 4.6 111 NDC Near the coast of San-Pedro, Cote d'Ivoire
2011 7 09 23 36 18.67 -11.3 -10.3 4.1 138 NDC Off the Coast of Liberia/ Cote d'Ivoire
2011 7 10 16 19 54.38 5.3 -4.5 4.4 77 NDC Dabou, Cote d'Ivoire
2011 7 10 19 12 34.73 10.1 -6.8 3.8 86 NDC Zaniegue, Cote d'Ivoire
52
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 7 11 06 57 3.72 8.0 -5.1 4.0 103 NDC Kadyoukaha, Cote d'Ivoire
2011 7 13 08 32 50.26 5.2 -5.0 4.3 109 NDC Nzida, Cote d'Ivoire
2011 7 15 11 41 49.27 6.6 -4.8 3.9 130 NDC Dimbokro, Cote d'Ivoire
2011 7 17 18 55 11.58 7.0 -5.7 3.8 37 NDC Bouafle, Cote d'Ivoire
2011 7 18 17 51 47.11 5.3 -5.2 4.2 106 NDC Nzida, Cote d'Ivoire
2011 7 22 00 21 26.57 6.0 -4.5 4.1 32 NDC Rubino, Cote d'Ivoire
2011 7 23 05 23 36.66 7.1 -4.3 2.2 138 NDC Bocanda, Cote d'Ivoire
2011 7 25 04 43 5.35 -1.0 -7.4 4.1 105 NDC Off the Coast of Liberia/ Cote d'Ivoire
2011 8 06 12 41 55.52 5.4 -1.8 3.9 6 NDC Kwakuadjeikrom, W/R. Ghana.
2011 8 07 10 39 11.36 2.5 -5.7 4.3 108 NDC Near Coast of Cote d'Ivoire
2011 8 08 06 56 31.41 7.7 -3.9 4.3 105 NDC Koumasso, Cote d'lvoire
2011 8 09 06 21 32.28 6.7 -4.8 4.3 67 NDC Assesbrakro, Cote d'Ivoire
2011 8 13 23 37 21.11 5.7 -4.2 4.1 64 NDC Petit Yapo, Cote d'Ivoire
2011 8 14 08 01 0.20 6.5 -4.8 3.3 159 NDC Guesseguie, Cote d'lvoire
2011 8 17 00 54 34.49 4.2 -5.0 4.4 94 NDC In the Gulf of Guinea, Cote d'lvoire.
2011 8 17 12 30 9.77 4.4 -4.3 4.1 66 NDC Near Coast of Cote d'lvoire.
2011 8 17 14 29 14.37 6.1 -6.2 4.0 156 NDC Konayo, Cote d'Ivoire
2011 8 23 19 16 2.11 12.7 1.4 4.3 31 NDC Kowari, Burkina Faso
2011 9 01 00 29 11.69 6.8 -6.2 4.2 177 NDC Dignago, Cote d'lvoire
2011 9 04 12 27 4.63 -2.8 -7.8 4.0 67 NDC Off the Coast of Cote d'lvoire
2011 9 10 13 09 32.84 5.9 -6.1 3.8 151 NDC Gohie, Cote d'lvoire
53
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 9 11 06 48 14.70 2.6 -3.0 4.2 109 NDC Near coast of cote d'lvoire
2011 9 12 18 02 48.37 5.6 -4.0 4.1 114 NDC Nsakoi, Cote d'lvoire
2011 9 13 08 08 0.57 7.2 -3.6 4.6 154 NDC Yacasse, Cote d'lvoire
2011 9 14 15 44 54.62 10.8 -4.1 3.9 80 NDC Moribarasso, Burkina Faso
2011 9 15 20 29 24.94 11.7 2.7 4.5 116 NDC Guene, Benin
2011 9 20 22 57 7.05 12.2 1.7 4.3 73 NDC Byati, Burkina Faso
2011 9 21 18 12 47.42 5.3 -4.8 4.4 61 NDC Tiagba, Cote d'lvoire
2011 9 23 13 21 7.14 -0.8 -5.5 4.3 103 NDC Off the Coast of Cote d'lvoire
2011 9 23 21 19 58.57 6.1 -6.1 4.3 146 NDC Kripayo, Cote d'lvoire
2011 9 25 01 29 31.04 6.4 -3.5 4.3 171 NDC Blekoum, Cote d'lvoire
2011 9 26 05 02 6.07 6.1 -5.1 4.0 92 NDC Goudi, Cote d'lvoire,
2011 9 27 16 15 24.33 5.6 -4.0 4.1 55 NDC Nasakoi, Cote d'Ivoire
2011 9 27 19 00 52.98 4.1 -5.6 4.4 74 NDC Near coast of Cote d'lvoire
2011 9 29 09 39 3.45 3.9 -3.3 3.7 88 NDC Near coast Cote d'Ivoire.
2011 10 05 09 01 20.39 -0.4 -8.0 4.2 100 NDC Off the coast of Liberia / Cote d'lvoice
2011 10 07 08 57 10.78 6.5 -5.9 4.2 154 NDC Bahompa, Cote d'lvoire
2011 10 10 03 03 24.91 7.2 -4.5 4.3 74 NDC Kokoboukro, Cote d'lvoire
2011 10 11 21 51 48.76 6.2 -2.3 3.9 167 NDC Sefwi Bekwai, WR. Ghana
2011 10 12 23 14 42.79 13.4 0.9 4.0 9 NDC Satyouri, Burkina Faso
2011 10 13 03 52 6.63 8.8 -7.1 4.6 41 NDC Sebedian, Cote d'lvoire
2011 11 05 17 27 13.87 11.7 1.8 4.0 110 NDC Nampondi, Burkina Faso
2011 11 06 09 01 51.25 6.0 -6.1 4.5 153 NDC Digbahio, Cote d'lvoire
54
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2011 11 06 09 12 58.96 12.7 -4.1 4.2 95 NDC S oumbara, Burkina Faso
2011 11 08 21 08 44.95 12.7 -3.8 4.1 113 NDC Niankui, Burkina Faso
2011 11 14 06 13 15.63 6.7 -2.3 4.4 161 NDC Asuako, Ashanti Region, Ghana
2011 11 25 04 43 15.63 11.8 1.4 4.1 95 NDC Arli National Park, Burkina Faso
2011 11 25 09 31 14.44 6.6 -4.9 4.2 57 NDC Assebrakro, Cote d'lvoire
2011 11 27 22 18 14.52 7.4 -5.1 4.5 2 NDC Mbouedio, Cote d'lvoire
2011 11 28 01 29 59.91 6.5 -3.5 3.7 166 NDC Tanekron, Cote d'lvoire
2011 11 29 11 30 48.52 7.2 -5.4 4.4 22 NDC Gtogro, Cote d'lvoire
2011 12 03 09 26 8.58 -5.4 -5.6 4.7 136 NDC off the coast of Cote d'lvoire / Ghana
2011 12 04 08 42 6.94 7.9 -4.3 4.2 117 NDC Satama - Sokoura, Cote d'lvoire
2011 12 10 01 50 52.86 6.0 -5.0 4.3 91 NDC Sokogrobo, Cote d'lvoire
2011 12 11 16 40 26.94 7.2 -4.3 4.0 143 NDC Kamoukouanou, Cote d'lvoire
2011 12 17 20 40 10.21 13.4 0.8 4.1 11 NDC Satyouri, Burkina Faso
2011 12 26 09 51 58.54 4.4 -4.3 4.5 44 NDC Near Coast of Abidjan-Cote d'Ivoire
2011 12 26 13 29 45.81 11.8 1.8 4.0 101 NDC Tombaga, Burkina Faso.
2011 12 27 01 37 58.83 -6.3 -1.5 4.0 47 NDC Off the Coast of Cote d'lvoire / Ghana.
2011 12 27 09 26 18.89 7.8 -4.2 4.3 122 NDC Atokonou, Cote d'lvoire
2011 12 31 00 25 19.45 9.1 1.5 4.2 124 NDC Near Tchanba, Togo
2012 1 03 19 28 11.75 1.8 -0.5 4.3 97 NDC In the Sea, off Coast of Ghana
2012 1 06 00 20 22.52 0.7 -3.9 4.0 NDC In the Sea, off Coast of Ivory Coast
55
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 1 06 00 38 51.47 -13.67 -13.8 4.5 120 NDC In the Sea, off Coast of South Africa
2012 1 11 17 36 37.96 7.7 -6.1 4.0 48 NDC Kongaso, Cote d'lvoire
2012 1 20 10 07 0.85 7.0 -4.9 3.6 176 NDC Bocanda, Cote d'lvoire
2012 1 22 19 48 49.53 7.2 2.0 2.1 131 NDC Bhicon, Benin
2012 1 23 00 21 22.92 8.0 -4.4 4.0 91 NDC Messarandougou, Cote d'lvoire
2012 1 23 23 27 46.44 7.2 -4.1 3.7 135 NDC Daoukro, Cote d'lvoire
2012 2 05 01 17 53.46 4.0 -2.5 4.0 149 NDC Gulf of Gunea, Cote d'Ivoire / Ghana
2012 2 06 00 20 38.89 11.8 2.1 4.0 113 NDC Burkina Faso National Park, Burkina Faso
2012 2 06 10 12 45.06 3.9 -4.2 4.5 108 NDC Near Abidjan, Cote d'Ivoire
2012 2 07 16 41 27.01 6.7 -4.9 3.9 92 NDC Dimbokro, Cote d'lvoire
2012 2 10 22 02 41.90 6.2 -5.4 3.8 137 NDC Ovime, Cote d'lvoire
2012 2 16 04 16 13.84 5.9 -5.5 4.0 131 NDC Gabiakok, Cote d'lvoire
2012 2 20 01 52 52.99 6.4 -5.0 4.2 33 NDC Angbavia, Cote d'lvoire
2012 2 21 00 14 9.92 12.5 -1.7 4.1 123 NDC Koudouwogen, Burkina Faso
2012 2 22 06 37 57.74 5.8 -4.0 4.6 25 NDC Agbouille, Cote d'lvoire
2012 2 24 12 40 28.69 6.8 -5.0 4.1 150 NDC Park National d' Abokonamekro Cote d'lvoire
2012 3 10 01 32 43.70 3.0 -4.6 4.2 123 NDC Near Coast of Abidjan, Cote d'Ivoire
2012 3 10 02 36 37.92 3.5 -0.7 4.2 146 NDC Near Coast of Accra, Ghana
2012 3 11 03 57 16.50 7.5 -7.2 1.6 91 NDC Man, Cote d'lvoire
2012 3 12 05 33 20.60 5.3 -4.6 4.1 95 NDC Dabou, Cote d'Ivoire
2012 3 13 20 01 40.13 14.7 -1.3 3.8 113 NDC Sahel Reserve, Burkina Faso
56
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 3 14 18 19 51.21 5.5 -5.5 4.2 122 NDC Borodou, Ivory Coast
2012 3 18 04 57 42.36 7.1 -4.8 4.1 103 NDC Didievi, Ivory Coast.
2012 3 19 11 05 37.31 0.8 1.5 3.9 143 NDC Off the Coast of Ghana / Togo
2012 3 20 06 05 7.29 9.9 -3.7 2.7 126 NDC Kampti, Burkina Faso
2012 3 20 21 30 46.50 6.7 -4.9 3.9 58 NDC Dimbokro, Cote d'lvoire
2012 3 21 22 36 32.06 -14.4 -4.2 4.4 156 NDC Off the Coast of Ghana / Togo
2012 3 22 14 41 23.87 7.9 -4.1 4.0 119 NDC Groumania, Cote d'lvoire
2012 3 23 03 59 9.52 7.1 -5.9 4.3 167 NDC Bouafle, Cote d'lvoire
2012 3 27 23 32 42.80 12.3 1.4 4.1 106 NDC Kantchari, Burkina Faso
2012 3 31 10 14 8.98 6.7 -4.9 4.0 12 NDC Dimboko, Cote d'lvoire
2012 4 01 12 19 16.96 5.3 -4.5 4.0 95 NDC Toupah, Cote d'lvoire
2012 4 07 06 19 45.99 12.4 1.3 4.0 120 NDC Nalougou, Burkina Faso
2012 4 11 03 17 36.67 -3.3 -0.3 4.1 103 NDC Off the Coast of Ghana
2012 4 11 04 05 35.72 -3.9 3.5 4.1 27 NDC Off the Coast of Benin/Nigeria
2012 4 11 05 44 40.70 -16.8 -14.5 4.4 127 NDC Off the Coast of Liberia/Cote d'Ivoire
2012 4 13 14 57 17.25 6.8 -4.2 4.3 88 NDC Kotobi, Cote d'lvoire
2012 4 16 19 05 13.42 7.8 -5.6 3.9 69 NDC Bandama, Cote d'lvoire
2012 4 16 21 59 47.67 0.4 -10.8 4.2 131 NDC Off the Coast of Liberia/Cote d'Ivoire
2012 4 17 07 23 51.37 6.4 -6.2 6.2 165 NDC Sauuia, Cote d'Ivoire
2012 4 17 08 02 21.03 5.3 -4.8 4.1 46 NDC Bale de Cosrou, Cote d'lvoire
2012 4 19 00 14 58.90 4.2 -4.7 3.7 99 NDC Near Abidjan, Cote d'Ivoire
57
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 4 20 10 36 49.47 8.6 -5.6 4.1 60 NDC Niakaramandougou, Cote d'Ivoire
2012 4 24 04 11 41.65 13.5 0.9 4.0 18 NDC Burkina Faso
2012 4 24 11 06 3.71 13.6 0.9 3.2 81 NDC Burkina Faso
2012 4 24 19 15 13.57 7.1 -4.2 3.9 136 NDC Bocanda, Cote d'Ivoire
2012 4 26 22 21 55.70 5.3 -4.6 4.0 87 NDC laqune Ebrie, Cote d'lvoire
2012 4 27 06 19 43.29 7.0 -7.7 3.9 163 NDC Bangolo, Cote d'lvoire
2012 4 28 23 26 4.08 6.6 -4.9 4.0 46 NDC Toumodi, Cote d'Ivoire
2012 5 01 07 00 37.61 13.8 0.4 3.7 51 NDC Dori, Burkina -Faso
2012 5 03 09 22 51.93 6.5 -4.8 4.2 157 NDC Dimbokro, Cote d'Ivoire
2012 5 07 12 24 43.55 5.9 -6.6 4.4 167 NDC Badayo I, Cote d'Ivoire
2012 5 08 13 28 30.59 5.4 -3.0 3.9 11 NDC Affienou, Cote d'Ivoire
2012 5 08 18 28 59.54 5.9 -4.3 4.3 28 NDC Offa, Cote d'Ivoire
2012 5 09 14 49 50.37 -1.1 -13.2 6.2 133 NDC Off Coast of Liberia/Cote d'Ivoire
2012 5 11 16 36 58.82 6.7 -4.9 4.3 58 NDC Toumodi, Cote d'Ivoire
2012 5 14 03 38 21.48 6.6 -4.8 4.3 145 NDC Dimbokro, Cote d'Ivoire
2012 5 15 01 33 17.91 -4.9 -11.6 4.1 102 NDC Off Coast Of Liberia/Cote d'Ivoire
2012 5 17 04 59 5.89 5.9 -4.8 4.2 104 NDC Tiassale, Cote d'Ivoire
2012 5 18 11 55 6.21 -0.5 -6.7 4.2 127 NDC Off Coast of Liberia/Cote d'Ivoire
2012 5 18 15 00 52.35 5.8 -6.1 4.2 144 NDC Gohue, Cote d'Ivoire
2012 5 22 02 36 50.69 6.3 -3.3 4.0 69 NDC Apopromponou, Cote d'Ivoire
2012 5 25 02 59 58.70 5.3 -2.8 4.3 13 NDC Kwesinimpa Impa, Cote d'Ivoire
58
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 5 25 17 43 36.45 7.0 -4.2 4.0 77 NDC Daoukro, Cote d'Ivoire
2012 5 26 11 35 21.52 6.6 -4.8 4.0 127 NDC Daoukro, Cote d'Ivoire
2012 5 31 17 23 32.63 7.2 -6.7 4.1 8 NDC Vanona, Cote d'Ivoire
2012 5 31 19 25 57.48 6.6 -4.9 3.9 13 NDC Dimbokro, Cote d'Ivoire
2012 6 18 16 08 22.64 6.4 -5.4 3.8 57 NDC Oume,Cote d'lvoire
2012 6 20 00 59 14.49 7.0 2.2 2.5 131 NDC Foret d Agrime, Benin
2012 6 21 07 26 38.40 7.3 -7.2 2.4 17 NDC Man, Cote d'lvoire
2012 6 21 22 51 53.60 7.0 -6.0 4.3 18 NDC Brozra, Cote d'lvoire
2012 7 04 11 38 43.89 8.6 -6.6 4.1 58 NDC Kani, Cote d'lvoire
2012 7 15 14 20 21.92 7.1 -4.2 4.0 14 NDC Daoukro, Cote d'lvoire
2012 7 18 16 08 22.64 6.4 -5.4 3.8 57 NDC Oume, Cote d'lvoire
2012 7 28 06 00 13.51 6.1 -3.6 4.3 1 NDC Adzope, Cote d'lvoire
2012 7 30 11 16 51.29 6.0 -3.4 3.9 27 NDC Bettie, Cote d'lvoire
2012 8 4 12 59 22.40 13.0 -4.2 4.2 34 NDC Djibasso, Burkina Faso
2012 8 4 18 21 2.47 5.4 -4.4 4.8 30 NDC Orbaff, Cote d'lvoire
2012 8 5 19 11 45.08 11.9 2.4 4.0 83 NDC Diapaga, Burkina Faso
2012 8 6 13 6 31.78 -2.2 -6.5 4.0 42 NDC Off the Coast of Liberia/ Cote d'lvoire.
2012 8 6 15 11 11.34 11.2 -3.2 2.9 NDC Kantchari, Burkina Faso
2012 8 7 11 36 56.91 12.5 1.2 4.3 38 NDC Kantchari, Burkina Faso
2012 8 9 13 2 11.82 6.7 -4.8 4.4 3.7 NDC Dimbokro, Cote d'lvoire
2012 8 11 22 2 38.60 6.7 -3.5 4.2 31 NDC Abengouron, Cote d'lvoire.
2012 8 11 22 47 6.43 5.9 -4.5 2.9 28 NDC Aboude Mendeke, Cote d'lvoire
59
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 8 18 12 01 25.44 6.0 -3.62 4.2 158 NDC Adzope, Cote d'Ivoire
2012 8 19 12 18 20.06 11.8 1.7 4.3 74 NDC Near Tombaga, Burkina Faso
2012 8 21 06 45 56.74 6.2 -3.5 6.2 14 NDC Near Abengova, Cote d'Ivoire
2012 8 22 08 09 32.32 10.6 -1.9 2.0 135 NDC Bechembeli, Upper West, Ghana
2012 9 06 12 06 9.16 5.7 -4.8 4.0 96 NDC Ndouci, Cote d'lvoire
2012 9 17 20 17 21.53 7.7 -5.8 4.1 180 NDC Beoumi, Cote d'lvoire
2012 9 21 13 09 8.79 5.2 -6.9 2.2 138 NDC Tai National Park, Cote d'lvoire
2012 9 26 19 25 45.78 6.3 -0.5 4.2 136 NDC Near Kwabeng, Ghana
2012 10 12 03 53 21.21 4.6 -4.6 4.1 104 NDC Near the coast of Cote d'Ivoire
2012 10 12 14 27 24.23 5.8 -5.9 4.0 24 NDC Gueyo, Cote D'lvoire
2012 10 14 05 33 52.49 7.6 -6.5 4.3 30 NDC Vavoua, Cote D'lvoire
2012 10 23 04 56 4.92 11.8 1.3 4.1 91 NDC Arli natoinal park, Burkina Faso
2012 10 26 23 29 38.13 8.0 -4.4 4.2 112 NDC Satama Sokoro, Cote d'Ivoire
2012 10 27 03 40 18.09 6.7 -4.8 3.5 103 NDC Assebrakro, Cote d'Ivoire
2012 10 27 23 19 43.08 5.6 -4.0 3.9 39 NDC Atiekoi, Cote d'Ivoire
2012 10 29 14 30 48.63 8.4 -4.3 4.4 106 NDC Dabakala, Cote d'Ivoire
2012 10 30 09 55 10.53 6.4 -4.3 3.9 114 NDC Bongouanou, Cote d'Ivoire
2012 10 30 22 00 12.88 0.9 -6.4 4.1 116 NDC Coast of Cote d'Ivoire
2012 11 02 23 43 07.51 4.8 -2.8 3.8 15 NDC Gulf of Guinea, Near the Coast of Ghana
2012 11 04 00 30 50.40 12.2 1.8 4.1 95 NDC Near Touaga, Burkina Faso
2012 11 04 05 11 59.40 12.0 1.2 4.0 119 NDC Near Singou Reserve, Burkina Faso
60
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 11 07 00 30 17.22 7.1 -5.2 4.0 75 NDC Near Bomizabo, Cote d'Ivoire
2012 11 07 19 44 21.91 6.6 -6.3 4.4 26 NDC Near Saouia, Cote d'Ivoire
2012 11 13 10 27 31.19 6.1 -3.8 4.1 19 NDC Near Adzope, Cote d'Ivoire
2012 11 14 04 43 34.24 8.0 -4.5 4.2 101 NDC Near Dyaradougou, Cote d'Ivoire
2012 11 20 12 20 26.47 5.4 -4.2 4.2 43 NDC Near Attinguie, Cote d'Ivoire
2012 11 21 12 21 23.43 6.6 -4.9 4.5 44 NDC Near Totonou, Cote d'Ivoire
2012 11 25 17 48 53.42 6.8 -5.0 3.7 144 NDC Near Amandie, Cote d'Ivoire
2012 11 26 01 39 15.61 11.5 0.5 4.0 129 NDC Near Pama Reserve, Burkina Faso
2012 11 26 08 24 18.81 -2.8 -14.3 5.1 142 NDC Off the Coast of Liberia
2012 11 27 19 46 52.02 6.2 -4.6 4.4 179 NDC Rubino, Cote d'Ivoire
2012 11 29 01 17 19.96 5.3 -4.9 3.6 76 NDC Assagny National Park, Cote d'Ivoire
2012 11 30 01 56 39.94 5.7 -5.8 4.5 99 NDC Near Gague, Cote d'Ivoire
2012 12 01 13 42 32.09 7.6 -6.3 4.1 30 NDC Near vavoua, Cote d'Ivoire
2012 12 05 11 30 03.65 6.6 -5.5 4.4 25 NDC Near Konefia, Cote d'Ivoire
2012 12 06 06 58 51.91 6.8 -7.6 5.1 163 NDC Near Duekoue, Cote d'Ivoire
2012 12 07 15 34 28.29 14.3 -1.6 4.2 156 NDC Near Djibo, Burkina Faso
2012 12 07 18 34 35.78 7.3 -0.4 4.5 77 NDC Near Digya national park, Ghana
2012 12 09 01 35 56.37 3.8 -4.1 4.2 78 NDC Near the Coast of Cote d'Ivoire
2012 12 09 22 36 23.77 6.7 -4.9 4.2 40 NDC Near Dimbokro, Cote d'Ivoire
2012 12 12 09 32 48.20 0.8 0.1 4.4 147 NDC Off the Coast of Ghana
2012 12 13 11 43 02.34 3.7 -1.2 4.8 179 NDC Near the Coast of Ghana
61
University of Ghana http://ugspace.ug.edu.gh
Yr M D H Min Sec Lat Lon Dp ML Mb MM Mw Io RS Az Ref Location
2012 12 14 08 35 14.63 5.9 -3.6 3.8 165 NDC Near Abie, Cote d'Ivoire
2012 12 15 04 37 38.55 12.8 1.0 4.0 153 NDC Near Bossongri, Burkina Faso
2012 12 15 05 00 47.56 -7.4 -14.3 4.6 150 NDC Off the Coast of Liberia/Cote d'Ivoire
2012 12 16 03 07 46.73 6.4 -5.2 4.1 19 NDC Near Groudji, Cote d'Ivoire
2012 12 16 03 36 27.45 13.7 -0.2 4.1 3 NDC Near Bani, Burkina Faso
2012 12 16 14 31 45.04 5.4 -4.3 2.1 51 NDC Near Le Nieky, Cote de d'Ivoire
2012 12 17 11 46 35.72 0.9 1.5 4.5 22 NDC Off the Coast of Ghana
2012 12 19 16 04 59.29 6.3 -6.2 4.2 6 NDC Near Guberoua, Cote d'Ivoire
2012 12 23 13 22 23.88 6.8 -3.5 4.1 148 NDC Near Zinzenou, Cote d'Ivoire
2012 12 24 12 23 38.81 13.0 -4.3 4.6 150 NDC Near Mandiakui, Burkina Faso
2012 12 26 13 01 36.89 -3.5 -4.9 4.3 107 NDC Off the Coast of Cote d'Ivoire/Ghana
2012 12 26 13 47 31.02 4.6 -2.3 4.2 68 NDC Near the Coast of Ghana
62
University of Ghana http://ugspace.ug.edu.gh
References abbreviation list: ALY (Leydecker, G. and P. Amponsah), New estimation
of epicentral intensity and focal depth by macroseismic methods (using formula (1)),
based on the isoseismal radii, given by Ambraseys and Adams (1986); AMB, Ambraseys
and Adams (1986); AMP, Amponsah (2008); GSD, Geological Survey Department, 7th
Avenue, 6, P.O. Box M80, Accra, Ghana. The data for the years 1973–1997 were taken
from Amponsah (2002); ISC, International Seismological Centre, Pipers Lane, Thatcham,
Berkshire, United Kingdom RG19 4NS; admin@isc.ac.uk; JUN, Junner (1941); NEI,
National Earthquake Information Service (NEIS), United States Geological Survey,
Denver, Colorado 80225, USA; NDC, National Data Centre of the Ghana Atomic Energy
Commission, GAEC.
Description of the parameters in the earthquake catalogue: Yr, year; M, month; D,
day; H, hour; Min, minute; Sec, second; Lat, Latitude in degree; North; Long, longitude
in degree; negative = West; Dp, focal depth in kilometers; focal depth estimation only
with macroseismic data; ML, local magnitude; MD, duration magnitude; MM, surface
wave magnitude, based only on macroseismic data; Mw, moment magnitude; Io,
epicentral intensity estimated macroseismically; RS, radius of perceptibility in km;
Azimuth; Ref, reference; Location, location of earthquake
5.1.2 SEISMICITY AND EPICENTRAL INTENSITY MAPS
The seismicity map generated clearly defines the frequency of earthquakes, the
magnitudes prevalent and the distribution of these magnitudes from 1615 to 2012. The
seismicity map of the study area is shown in Figure 5.1. The converted latitudes and
longitudes of all the 554 events and their corresponding magnitudes and epicentral
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intensities are shown in Appendix C. The plot of these computed values is shown in
Figure 5.2.
The epicentral intensity map clearly defines the epicentral intensities evaluated. The
range of the epicentral intensity computed for the study area is from 3.6 to 8.2 whilst
earthquake magnitudes between 4 and 5 are highly present in GAMA. The plot shows
areas of high intensities to be western, south western (around Weija) and north eastern
Accra (6.02 to 8.6). Other areas include Kokrobitey, Kasoa and Nyanyano. South eastern
Kasoa and south western Amasaman, however, have low seismic intensities (3.6 to 5.97).
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Fig. 5.1: Seismicity map of the study area
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Fig. 5.2: A Plot of the Epicentral Intensity Map of the Study Area
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5.1.3 b-VALUE EVALUATION
5.1.3.1 Linear Least Square Fit
A cumulative frequency table of events and their corresponding number of occurrence is
shown in Table 5.2. This is the linear least square fit approach.
Table 5.2: Magnitudes and Cumulative Number of Events
M N≥ M Log(N≥ M)
2 553 2.742725131
2.5 447 2.650307523
3 405 2.607455023
3.5 381 2.580924976
4 311 2.492760389
4.5 47 1.672097858
5 16 1.204119983
5.5 11 1.041392685
6 8 0.903089987
6.5 3 0.477121255
The plot of graph showing the relationship between Log (N≥ M) and M is shown
in Figure 5.3.
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3.5
3
2.5
2
Log(N)
1.5
Linear (Log(N))
1
Log N ≥ M = 4.1761-0.5503M
0.5 R² = 0.9131
0
0 1 2 3 4 5 6 7
M
Fig. 5.3: Graph Indicating the Plot of Cumulative Number of Events against Magnitude
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Log N ≥ M
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The b-value has been evaluated from the graph Fig 5.3 employing the equation below:
Log (N≥ M) = a-bM…….………………………………………..………..……...5.1
where,
N is no. of events with magnitude ≥ M,
M is the magnitude of the events,
a and b are contants, thus a describes the seismic activity (log number of events with M =
0). It is determined by the event rate and for certain region depends upon the volume and
time window considered.
Thus comparing equation 5.1 and Figure 5.3, the b-value was computed as 0.6. The
2
Regression coefficient, R , is 0.9131. Thus, the variation in the regression is 91.31%
explained by the independent variable M, the magnitude of events.
5.1.3.2 Maximum Likelihood Estimation
The maximum likelihood estimation method was used to evaluate the b-value according
to Aki (1965), Marzorcchi and Sandri (2003), Lombardi (2003) and Felzer (2006)
b=1/ [ln10 (mav- mc)]…………………...……………………………………………….5.2
where,
b represents the b-value
mav represents the average magnitude from the catalogue and
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mc represents the threshold or cut off magnitude (usually carefully selected from the
sharp curve exhibited by chart). The completeness of the earthquake catalogue, i.e. the
estimation of the so-called threshold magnitude mc is critical. In general, mc magnitude of
data set is obtained from the Guttenberg-Richter relation plot (plotting Log10 N (≥ M)
against the magnitudes, M). mc is the level at which the data falls below the line of best
fit.
From Fig. 5.3 the threshold magnitude also known as the cut off magnitude, mc, was
evaluated as 4.5. The average magnitude was subsequently calculated from the catalogue
after applying the cut off magnitude. In calculating the average magnitude, mav, forty
seven (47) events were used. These include magnitudes 4.5 to 6.6. An average magnitude
of 5.0 was obtained.
The b-value was then calculated using equation 5.2 as
b=1/ [ln10 (5.0-4.5)] =0.864 ≈ 0.9,
The uncertainty associated with the analysis of the data was also calculated using the
equation below:
σb =b/√N……………………………………………………………….…………5.3
where;
σb represents the uncertainty,
b represents the b-value and
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N represents the number of earthquakes under consideration
σb =0.864/√47=0.126
5.1.4 RELATIONSHIP BETWEEN EARTHQUAKE EFFECTS AND GEOLOGY
To clearly understand the relationship between the geology of the study area and the
seismicity, the epicentral intensity map was superimposed on the geology map of the
study area as shown in Figure 5.4.
From the figure the south western GAMA is very active and therefore recorded a lot of
the events captured in the study area. Areas such as Nyanyano, Kokrobite, Pokuase,
Weija, Atomic, Kwabenya, Legon and the city centre Accra fall in this seismically active
zone. There are some events however offshore. The area is mostly covered with
sandstones which have been metamorphosed into quartzites. This process is usually
related to tectonic compression within orogenic belts. It is therefore not strange to see
most seismic events in the study area occurring here. These are also significant events
considering that they have epicentral intensities as high as 8.6.
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Fig. 5.4: Epicentral Intensity Superimposed on the Geology of Location
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5.2 DISCUSSION
The research work was aimed at investigating earthquake hazard in the Greater Accra
Metropolitan Area both by seismological and geological means. The seismological
method involved establishing a comprehensive earthquake catalogue in order to study the
history of earthquakes and earth tremors in the study area. The catalogue is an update of
the one produced by Amponsah et al. (2012) which involved the relocation of some
epicenters to reflect the current situation. There was also the interpolation of earthquake
magnitude for events without magnitudes (resulting in magnitudes between 2.9 Mw and
6.6 Mw). A completely homogenized earthquake catalogue was generated with most
seismic events occurring in and around Western Accra.
The seismicity map and epicentral intensity map generated from the catalogue clearly
shows the earthquake prone zones in the metropolis is mostly around Western Accra,
Nyanyano, Kasoa, Weija, Amasaman and Pokuase. It is also evident that major events are
occurring off the coast of Ghana (GAMA). This can be associated with the well-defined
unconsolidated and poorly consolidated sediments and soils which are prone to
liquefaction and the formation of sand vents and mud volcanoes as described by Muff
and Efa (2006). Events here can also be attributed to faults along the coast, some of
which cause major displacements (Muff and Efa, 2006). The fact that these events have
not been felt on-shore maybe indicative of silent and/or slow earthquakes (Singh et al.,
2009). These events may be as a result of the Coastal boundary faults as observed by
Sykes (1978) that the Cameroon line and the Ngaourandéré fault zone are situated near
the boundary between the Congo and a belt of Pan-African deformation that extends as
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far as West of Accra, Ghana and captured in the fault map of GAMA as modified from
Muff and Efa (2006) (Ennison et al., 2012).
To investigate the earthquake hazard in the Greater Accra Metropolitan Area, one key
objective was to calculate the b-value of GAMA from the earthquake catalogue that was
compiled. The linear least square fit method resulted in a b-value of 0.6 and the
maximum likelihood estimation of 0.9 approximately. The linear least square is
disproportionately influenced by the largest earthquakes whilst the maximum likelihood
estimation method weighs each earthquake equally. In fact, a b-value approximately 1 is
indicative of the fact that there are relatively smaller shocks to larger ones in an
earthquake catalogue. The b-value of 0.9, just like the earlier one (0.6) is in line with the
globally accepted b-value of approximately 1.0 (Chen et al., 2003; Lombardi, 2003;
Marzocchi and Sandri, 2003; Felzer, 2006; Kulhanek, 2005). According to Talwani
(1998), earthquake generation is influenced by several factors including the nature of the
fault zone and the stress conditions. The b-value obtained confirms the relative
abundance of large shocks to smaller shocks and is representative of stress and/or
material conditions in the study area (Kulhanek, 2005). The uncertainty calculated from
the maximum likelihood estimation of the b-value was 0.126 as compared to the
coefficient of determination of 0.9131 obtained from the linear least square fit. The errors
0.126 and 0.0869 respectively may be due to the incompleteness of the catalogue or
variations in scaling of magnitudes. The delimitation of the study area has lead to the
generation of enough data for the seismic stress evaluation (b-value calculation). The 554
events used in this research would have been unattainable. The two methods used to
evaluate the b-value were to test whether the best approach in terms of calculating the b-
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value. True to some schools of thought enumerated earlier the maximum likelihood
estimation method gave am improved b-value of 0.9.
The superimposition of the epicentral intensities on the geology map (Figure 5.4) further
confirms the earlier works pointing out seismic activity in the study area (Junner, 1941;
Amponsah, 2002; Amponsah, 2004; Muff and Efa, 2006; Amponsah, et al., 2009; Allotey
et al., 2010). The thematic maps (Figures 5.1, 5.2 and 5.4) further reveal the
accumulation of events around the Weija Lake and the numerous faults, thrusts and shear
zones around its vicinity. South western GAMA is very active and, therefore has
recorded a lot of the events captured in the study area. These areas include Nyanyano,
Kokrobite, Pokuase, Weija, Atomic, Kwabenya, Legon and the city centre Accra. Some
events are also recorded offshore. They are also significant events (they have epicentral
intensities as high as 8.6 and magnitudes to the tune of 6.6 Mw). The coast of Accra
records events of epicentral intensities as high as 6.02 to 6.15 of magnitudes ranging
between 4.02 and 4.15 whereas the offshore has epicentral intensities ranging from 3.6 to
8.6. It can be seen that all units of the Accraian sandstones have major faulting and
jointing and are prone to earthquakes. Seismological activity is greatest in the
unconsolidated sand and clay deposits around Sakumono, Densu Delta and South of
Weija, Nyanyano, along the Togo Series alluvium boundary and in the area underlain by
the Accraian rocks (Figure 5.3).
The faults, thrusts and shear zones (also confirmed by Junner, 1941; Amponsah, 2002;
Amponsah, 2004; Amponsah, et al., 2009; Allotey et al., 2010; Muff and Efa, 2006 and
Ennison et al., 2012) cannot be left out when discussing the possible contributions to
seismic activity in the study area. The blend of seismological and geological observations
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(the completely homogenized earthquake catalogue, the b-value calculated and the
epicentral intensity map generated) from the investigations agrees to the observation that
key areas of the Greater Accra Metropolitan Area are earthquake prone.
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CHAPTER SIX
CONCLUSION AND RECOMMENDATIONS
6.0 CONCLUSION
After the compilation of an earthquake catalogue for Ghana and its immediate neighbours
spanning the period 1615 to 2012, the seismicity map and the epicentral intensity map
generated are just supplementary. After the superimposition of the epicentral intensity
map on the geology map, the relationship between the seismic events and the geology has
been established. The epicentral intensity map developed from the comprehensively
harmonized earthquake catalogue generated has brought out the earthquake prone areas
in the Greater Accra Metropolitan Area. Some of these areas are Weija, Kasoa,
Nyanyano, Kokrobite, Southern Pokuase, Accra and offshore Accra. Nsawam, Madina
Nungua, Tema, Ashaiman, Amrahia, Oyibi, Dodowa, Aburi and Apolonia on the other
hand have not recorded very significant number of events. These areas may be said to be
seismically stable. Further studies may be required to confirm this assertion though.
Policy makers have no option but to rely on credible information on the seismicity
(Earthquake catalogue, b-value calculated, seismicity map and the epicentral intensity
map developed) of GAMA and update existing building codes and lay down clear
guidelines for settlement.
The calculated b-value (0.6 and 0.9), indicative of the prevalence of small shocks over
large ones, must be taken into consideration in order to locate more settlements at
stress/fault free areas such as those mentioned earlier.
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6.1 RECOMMENDATIONS
Based on the research work carried out it is recommended that
1. The earthquake catalogue compiled be relied upon to generate hazard maps
2. The seismicity map and the epicentral intensity map should serve as a guideline in
updating building codes
3. Future b-value evaluations must be done to further explain the stress conditions in
the metropolis
4. Further research must be carried out to assess the roles played by faults in
concentrating stress and generating earthquakes since the major thrust of
worldwide paleoseismological investigations has been to understand the temporal
and spatial behaviour of seismically active faults (Rajendran, 2000).
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Planning 1:50,000 of Greater Accra Metropolitan Area, Ghana Geological
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APPENDICES
APPENDIX A
DEFINITION OF KEY TERMS
The various terms that will reoccur in this research work are defined below
(a) Earthquakes
Earthquakes are the sudden release of strain energy accumulated in the rocks over
extensive periods of time in the upper part of the Earth. Earthquakes are classified as,
Slight (M<5.0), Moderate (5.0<M<6.9) and Great (M>7.0) depending upon the
magnitude on Richter’s scale. An earthquake having a magnitude, M<2.0 is termed as
microearthquake. Here M represents magnitude. Generally, the word earthquake is used
to describe any seismic event (whether natural or caused by humans) that generates
seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by
other events such as volcanic activity, landslides, mine blasts, and nuclear tests.
Earthquakes’ point of initial rupture is called its focus or hypocenter whilst the epicenter
is the point at ground level directly above the hypocenter.
An earthquake can be a Foreshock or an Aftershock depending on whether it occurs
before or after the Main shock respectively. Tectonic plates have internal stress fields
caused by their interactions with neighbouring plates and sedimentary loading or
unloading such as deglaciation. These stresses may be sufficient to cause failure along
existing fault planes, giving rise to intraplate earthquakes. Earthquakes are estimated with
magnitude and intensity measurements.
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Some earthquakes are directly associated with forces acting along the plate boundaries
and are called Inter-plate earthquakes. About 80% of the seismic energy is released by
inter-plate earthquakes. In contrast, earthquakes which occur at rather large distances
from the respective plate margins are called Intraplate earthquakes. They can be large and
because of their unexpectedness and infrequency can result in severe damage.
Earthquakes evidently cascade into aftershocks that readjust the hierarchical system of
blocks-and-faults in the locality of the main shock rupture.
Lines connecting points on the earth's surface along which the intensity due to an
earthquake is the same are referred to as Isoseismals. Isoseismals are usually a closed
curve around the epicenter.
(b) Magnitudes
A measure of earthquake strength based upon the amount of ground motion experienced
and corrected for the distance between the observation point and the epicenter (A point
on the surface of the Earth, vertically above the place of origin (Hypocenter or Focus) of
an earthquake). The measure of the strength of earthquakes or strain energy released is
usually determined by seismographic observations. Originally, a simple pendulum and a
needle suspended above a smoked glass plate allowed to distinguish primary and
secondary earthquake waves and an accurate statement about location of the earthquake
is established based on their timing.
In the early twentieth century the Russian Prince Boris Golitzyn invented analogue
seismographs (magnitude measuring instrument). Present seismographs are digital
instruments (Kossobokov, 2005).
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Magnitude Scales
Depending on the range of magnitude, epicentral distance and the type of seismic waves
considered in the computation, there are several magnitude scales in use. The most
common ones are
The Local Magnitude, ML
The Body-wave Magnitude, Mb
The Surface-wave Magnitude, Ms
Moment Magnitude, Mw
The first three magnitude scales depend on amplitude and time periods of seismic waves
and suffer from saturation effect at higher magnitudes. Applicability uniformly to all
magnitude ranges, epicentral distance and focal depths are other limitations the local
magnitude, body-wave magnitude and the surface-wave magnitude suffer (Kanamori,
1982). The moment magnitude scale was introduced to help solve these problems. It is
based on seismic moment, Mo which can help standardize all magnitudes and harmonize
earthquake catalogues. The moment magnitude is defined as
Mw = (2/3)log10Mo –10.7
Mo is the seismic moment defined by
Mo = µAd
where;
µ is the shear strength of the faulted block
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A is the area of the fault and
D is the average displacement on the fault
These parameters are determined from wave form analysis of the seismograms
produced by an earthquake. Seismic moment is measured in dyne-cm.
Another parameter commonly mentioned during hazard assessment is the intensity.
(c) Intensity
The subjective measure of the effects of an earthquake at a particular place on humans,
structures or the land itself is referred to as intensity. Currently the Modified Mercalli
Scale is used to measure earthquake intensity. The table below compares the intensity of
earthquakes and their corresponding magnitudes.
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Relationship Between Intensity and Magnitude of Earthquakes
Verbal
Intensity Magnitude Witness Observations
Description
I Instrumental 1 to 2 Detected only by seismographs
II Feeble 2 to 3 Noticed only by sensitive people
Resembling vibrations caused by
III Slight 3 to 4
heavy traffic
Felt by people walking; rocking of
IV Moderate 4
free standing objects
V Rather Strong 4 to 5 Sleepers awakened and bells ring
Trees sway, some damage from
VI Strong 5 to 6
overturning and falling object
VII Very Strong 6 General alarm, cracking of walls
Chimneys fall and there is some
VIII Destructive 6 to 7
damage to buildings
Ground begins to crack, houses begin
IX Ruinous 7
to collapse and pipes break
Ground badly cracked and many
X Disastrous 7 to 8 buildings are destroyed. There are
some landslides
Few buildings remain standing;
Very bridges and railways destroyed;
XI 8
Disastrous water, gas, electricity and telephones
out of action.
Total destruction; objects are thrown
XII Catastrophic ≥ 8 into the air, much heaving, shaking
and distortion of the ground
(d) Disaster, Risk and Hazard
Disasters are natural or man-made (or technological) hazard resulting in significant
physical damage or destruction, loss of life, or drastic change to the environment.
Usually, areas prone to earthquakes, floods, catastrophic accidents, fires or explosions are
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declared disaster zones. In contemporary academia, the consequences of inappropriately
managed risks are referred to as disasters.
Risks can mathematically be defined as
Risk = Hazard x Vulnerability – Capacity
Seismic hazards indicate the probable level of ground shaking occurring at a given point
within a certain period of time. They quantify the ground motion required at a particular
site (Gupta and Kijko, 2011).
Generally, society is faced with a continuum of risk ranging from everyday risks to
natural disasters like earthquakes (Allotey et al, 2010).
(e) Epicenter
It is the point on the surface of the Earth, vertically above the place of origin (Hypocenter
or Focus) of an earthquake. This point is expressed by its geographical coordinates in
terms of latitude and longitude.
(f) Seismicity and Aseismicity
Seismicity refers to the frequency of earthquake activity in a given area. Global
seismicity maps show that seismicity is the highest at the tectonic plates. Aseismicity on
the other hand, refers to the absence of frequent earthquakes of significant magnitude.
(g) Probabilistic and Deterministic Seismic Hazard Assessment
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A hazard assessment method is said to be probabilistic if it evaluates the likelihood or
frequency of a specified level of ground motion at a site during a specified exposure
time. On the other hand deterministic seismic hazard assessments are used to evaluate a
particular earthquake scenario.
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APPENDIX B
MATLAB INTERPOLATION
(α) Command and Results
year=[1636 1788 1862 1870 1871 1872 1879 1883 1889 1906 1907 1930
1933 1939 1950 1964 1969 1973 1974 1977 1978 1979 1987 1988 1989
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
2003 2009 2010 2011 2012];
magnitude=[5.8 5.7 6.6 4.6 4.7 5.0 5.8 4.7 4.0 5.1 4.1 3.5 4.0
6.4 4.0 4.4 4.9 2.4 3.6 2.8 3.7 3.4 2.7 3.3 2.1 3.3 3.7 2.0 4.2
2.8 3.8 3.4 4.6 2.3 2.6 3.1 2.2 3.0 2.9 4.4 4.6 4.6 6.2 ];
year1836=interp1(year,magnitude,1836);
year1858=interp1(year,magnitude,1858);
year1861=interp1(year,magnitude,1861);
year1894=interp1(year,magnitude,1894);
year1910=interp1(year,magnitude,1910);
year1911=interp1(year,magnitude,1911);
year1912=interp1(year,magnitude,1912);
year1935=interp1(year,magnitude,1935);
year1948=interp1(year,magnitude,1948);
year1950=interp1(year,magnitude,1950);
year1966=interp1(year,magnitude,1966);
year2003=interp1(year,magnitude,2003);
year2004=interp1(year,magnitude,2004);
year2005=interp1(year,magnitude,2005);
year2007=interp1(year,magnitude,2007);
year2008=interp1(year,magnitude,2008);
year2009=interp1(year,magnitude,2009);
year2011=interp1(year,magnitude,2011);
year2012=interp1(year,magnitude,2012)
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magnitude <1x43 double>
year <1x43 double>
year1836 6.283783783783783
year1858 6.551351351351351
year1861 6.587837837837838
year1894 4.323529411764706
year1910 4.021739130434782
year1911 3.995652173913043
year1912 3.969565217391304
year1935 4.800000000000000
year1948 4.436363636363637
year1950 4
year1966 4.600000000000001
year2003 2.900000000000000
year2004 3.150000000000000
year2005 3.400000000000000
year2007 3.900000000000000
year2008 4.150000000000000
year2009 4.400000000000000
year2011 4.600000000000000
year2012 6.200000000000000
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(β) Matlab Window
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APPENDIX C
LATITUDE/LONGITUDE CONVERSION TO METRES
(a) Window 1
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(b) Window 2
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(c) Epicentral Intensity Table
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.1 -1.3 564276.42 688477.58
5.1 -2.2 564082.76 588696.69 5.8 7.8
7.6 1.7 843201.58 1019028.93 5.7 7.7
5.1 -1.3 564276.42 688477.58 6.3 8.3
5.6 -0.2 620036.74 810244.6 6.6 8.6
6 0 664421.75 832188.14 6.6 8.6
7 0.4 775413.76 875780.19 6.6 8.6
5.3 -0.7 586608.06 754941.69 4.6 6.6
5.5 -0.4 608869.6 788118.82 4.7 6.7
5.5 -0.4 608869.6 788118.82 5.0 7.0
6.5 -3.3 718791.8 466851.19 5.8 7.8
5.5 -0.4 608869.6 788118.82 4.7 6.7
5.9 -0.2 653237.39 810081.84 4.0 6.0
5.5 -0.2 608969.9 810296.98 4.3 6.3
6.5 0.3 719973.6 865091.69 5.1 7.1
6.1 -0.9 675018.64 732442 4.1 6.1
5.6 -0.2 620036.72 810244.6 4.0 6.0
5.5 -0.2 608969.89 810296.98 4.0 6.0
5.5 -3.6 608275.81 433558.89 4.0 6.0
7.1 0.7 786741.8 908890.66 3.5 5.5
7 0.6 775578.78 897911.3 4.0 6.0
6.9 0.6 764503.06 897995.65 4.8 6.8
5.4 -0.25 597877.78 804802.61 6.4 8.4
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
6.2 -0.3 686380.83 798834.94 5.4 7.4
6.2 0.4 686827.31 876385.37 4.4 6.4
6.8 -4.6 752237.13 323198.64 4.0 6.0
7.5 0.5 830868.23 886417.59 4.0 6.0
5.9 -0.39 653135.08 789027.16 4.4 6.4
5.58 -0.35 617746.34 793623.45 4.6 6.6
5.5 -0.2 608969.89 810296.98 4.9 6.9
5.7 0.3 631397.14 865634.66 2.4 4.4
7 0.8 775753.3 920047.16 1.9 3.9
5 -2.6 552987.57 544364.84 3.6 5.6
6.5 0.5 720122.64 887243.41 1.9 3.9
5 -2.6 552987.57 544364.84 3.1 5.1
5.8 0.8 642816.99 921031.82 2.6 4.6
5.1 2.5 566640.18 1110573.39 3.4 5.4
5.77 -0.2 638850.39 810153.41 2.0 4.0
6.02 -0.2 666517.72 810014.36 2.5 4.5
5.72 -0.2 633316.95 810180.51 2.7 4.7
5.58 -0.28 617781.75 801384.65 1.9 3.9
6.23 -0.13 689800.1 817646.11 2.1 4.1
5.95 -0.07 658845.62 824460.34 2.4 4.4
5.67 -0.2 627783.52 810207.38 2.5 4.5
5.63 0.02 623478.49 834623.62 2.1 4.1
5.65 -0.28 625528.03 801348.63 2.0 4.0
5.57 -0.38 616624.92 790302.27 2.4 4.4
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.97 -0.03 661083.03 828881.49 2.8 4.8
5.58 -0.38 617731.45 790297.35 2.2 4.2
6 0.12 664496.09 845487.5 2.0 4.0
6.58 0.13 728710.12 846210.99 2.8 4.8
5.53 -0.38 612198.84 790321.87 3.0 5.0
6.6 0.27 731023.85 861697.12 2.0 4.0
5.63 -0.35 623279.08 793598.42 3.7 5.7
5.63 -0.35 623279.08 793598.42 2.1 4.1
5.53 -0.4 612189.09 788104.33 1.9 3.9
5.53 -0.37 612203.74 791430.65 1.9 3.9
5.58 -0.32 617761.4 796949.62 3.4 5.4
5.5 -0.33 608903.84 795880.77 2.2 4.2
5.57 -0.38 616624.92 790302.27 2.2 4.2
5.52 -0.35 611107.05 793653.18 2.3 4.3
5.5 -0.42 608859.97 785901.2 1.9 3.9
5.53 -0.43 612174.62 784778.08 2.1 4.1
5.77 -0.28 638807.39 801285.83 1.9 3.9
5.44 -0.4 602230.58 788147.57 2.7 4.7
5.67 -0.26 627751.7 803555.48 1.9 3.9
5.58 -0.32 617761.4 796949.62 2.5 4.5
5.51 -0.26 610045.64 803638.06 3.0 5.0
5.53 -0.41 612184.25 786995.57 3.0 5.0
5.5 -0.4 608869.59 788118.82 3.2 5.2
5.63 -0.27 623319.98 802467.65 1.9 3.9
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.56 -0.3 615558.35 799177.26 1.9 3.9
5.6 -0.28 619994.97 801374.41 2.0 4.0
5.6 -0.11 620085.14 820224.28 3.3 5.3
5.61 -0.31 621086.21 798043.15 1.9 3.9
5.6 -0.32 619974.55 796939.53 2.1 4.1
5.45 -0.37 603351.52 791469.58 2.3 4.3
5.48 -0.4 606656.59 788128.44 2.4 4.4
5.59 -0.33 618862.92 795835.87 1.9 3.9
5.31 -0.6 587756.43 766027.17 2.1 4.1
5.61 -0.34 621071.01 794717.12 2.6 4.6
5.59 -0.34 618857.89 794727.16 2.9 4.9
5.4 -0.55 597735.52 771532.48 3.3 5.3
5.44 -0.41 602225.82 787038.65 2.6 4.6
5.93 -0.12 656602.92 818930.74 2.3 4.3
5.61 -0.3 621091.31 799151.85 2.1 4.1
5.62 -0.31 622192.79 798038.06 2.3 4.3
5.64 -0.29 624416.24 800245.14 2.9 4.9
5.62 -0.35 622172.53 793603.45 2.3 4.3
5.62 -0.33 622182.62 795820.74 3.7 5.7
5.53 -0.35 612213.6 793648.25 2.3 4.3
5.62 -0.33 622182.62 795820.74 2.0 4.0
5.5 -0.27 608933.93 802534.21 2.1 4.1
1.3 1.62 144480.68 1014557.07 4.2 6.2
5.53 -0.23 612274.32 806954.57 2.3 4.3
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.63 -0.56 623177.51 770319.35 2.3 4.3
5.53 -0.27 612253.78 802518.99 2.7 4.7
5.59 -0.32 618867.97 796944.58 2.4 4.4
4.05 -2.44 447987.85 562183.67 2.7 4.7
5.52 -0.34 611112 794762.01 2.1 4.1
5.55 -0.36 614421.73 792529.59 2.3 4.3
5.5 -0.34 608898.89 794771.89 2.1 4.1
5.38 -0.34 595620.26 794830.41 2.5 4.5
5.47 0.55 606090.07 893520.29 2.3 4.3
5.6 -0.27 620000.12 802483.15 2.4 4.4
5.47 -0.27 605614.08 802549.35 2.0 4.0
5.36 -0.32 593416.83 797058.31 1.9 3.9
5.52 -0.37 611097.21 791435.55 2.3 4.3
7.65 -3.48 845937.29 447079.85 2.8 4.8
5.53 -0.42 612179.42 785886.82 2.0 4.0
5.6 -0.4 619934.62 788070.2 1.9 3.9
5.54 -0.35 613320.14 793643.31 2.3 4.3
5.52 -0.25 611157.38 804741.88 2.0 4.0
5.45 -0.3 603385.85 799232.35 2.2 4.2
5.6 -0.28 619994.96 801374.41 2.3 4.3
5.6 -0.36 619954.43 792504.79 2.3 4.3
5.53 -0.32 612228.53 796974.71 3.1 5.1
5.55 -0.4 614402.1 788094.62 3.2 5.2
5.63 -0.57 623172.89 769210.91 2.5 4.5
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.63 -0.45 623229.66 782512.68 3.6 5.6
5.6 -0.32 619974.54 796939.53 2.6 4.6
5.58 -0.33 617756.35 795840.89 3.2 5.2
5.55 -0.3 614451.75 799182.31 2.5 4.5
5.52 -0.26 611152.26 803632.97 2.4 4.4
5.5 -0.24 608949.23 805861.05 2.5 4.5
5.5 -0.35 608893.96 793663.02 3.8 5.8
5.57 0.06 616859.98 839094.24 2.2 4.2
5.58 -0.45 617697.35 782536.76 3.4 5.4
5.28 -1.42 584146.57 675121.64 2.8 4.8
5.43 -0.34 601153.02 794806.18 3.0 5.0
5.44 -0.48 602192.96 779276.41 2.4 4.4
5.44 -0.47 602197.6 780385.28 2.3 4.3
5.52 -0.49 611039.73 778130.48 2.4 4.4
5.44 -0.43 602216.33 784820.82 2.9 4.9
5.62 -0.27 622213.35 802472.83 2.3 4.3
5.47 -0.27 605614.08 802549.35 2.4 4.4
5.67 -0.32 627720.57 796903.91 2.2 4.2
5.82 -0.35 644303.56 793501.3 3.2 5.2
5.63 -0.34 623284.12 794707.04 2.1 4.1
5.66 -0.43 626558.83 784715.1 2.6 4.6
5.67 -0.4 627680.15 788035.65 3.9 5.9
5.6 -0.33 619969.48 795830.83 4.6 6.6
5.6 -0.38 619944.48 790287.48 2.2 4.2
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.65 -0.38 625477.09 790262.65 1.9 3.9
5.65 -0.34 625497.23 794696.93 2.2 4.2
5.62 -0.34 622177.56 794712.09 2.0 4.0
5.62 -0.34 622177.56 794712.09 2.3 4.3
5.6 -0.33 619969.48 795830.83 2.3 4.3
5.75 0.01 636755.43 833445.37 2.0 4.0
5.72 0.28 633598.8 863403.79 2.0 4.0
5.77 0.18 639071.73 852282.85 2.3 4.3
5.25 -0.22 581293.02 808204.91 2.0 4.0
5.35 0 592474.54 832561.18 2.2 4.2
5.79 -0.25 641036.65 804600.39 2.5 4.5
6.1 -1.29 674865.95 689264.14 2.6 4.6
5.79 0.29 641355.45 864468.17 2.4 4.4
5.3 -0.32 586777.42 797087.19 2.3 4.3
6.59 0.48 730074.11 884958.91 2.1 4.1
5.32 -0.01 589148.54 831467.85 2.3 4.3
5.48 -0.14 606787.95 816961.72 2.1 4.1
5.78 -0.15 639984.63 815690.4 2.5 4.5
5.59 -0.86 618622.43 737085.84 2.2 4.2
5.66 2.6 628930.8 1121137.05 2.6 4.6
5.54 0.13 613579.71 846875.93 3.1 5.1
5.83 -0.24 645468.65 805687.18 2.7 4.7
5.56 0.18 615823.37 852410.42 2.2 4.2
5.75 0.85 637315.22 926617.14 2.6 4.6
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.6 0.13 620221.77 846840.66 2.7 4.7
5.4 -0.5 597758.08 777076.97 2.8 4.8
5.6 0.1 620204.09 843513.29 2.2 4.2
5.65 -0.27 625533.21 802457.27 2.3 4.3
5.5 -0.3 608918.8 799207.45 3.0 5.0
5.55 0.5 614916.8 887919.12 2.0 4.0
5.25 -0.6 581118.45 766052.79 2.0 4.0
5.57 -0.32 616654.82 796954.66 2.9 4.9
5.58 -0.32 617761.39 796949.62 2.2 4.2
5.57 -0.38 616624.92 790302.27 2.6 4.6
6.7 -1.9 741026.58 621604.08 2.9 4.9
5.3 -2.6 586149.27 544344.04 3.2 5.2
7.4 -7.1 820361.41 47181.05 3.2 5.2
3.7 -6.3 409962.47 133361.63 3.4 5.4
5.7 -6.9 631813.31 67839.63 3.9 5.9
4.6 -3.9 508822.9 400187.67 4.2 6.2
6.2 -4.7 685921.24 311921.1 4.2 6.2
9.2 -1.5 1017607.06 664822.94 4.2 6.2
6.7 2.2 743944.79 1075515.02 4.4 6.4
9.4 -2.4 1039429.59 565898.62 4.4 6.4
7 -1.9 774195.49 621528.09 4.4 6.4
7.3 -2.1 807315.82 599369.14 1.9 3.9
11.8 0.1 1306599.81 837891.17 2.4 4.4
6.4 -6.2 708831.29 145956.02 4.1 6.1
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.4 -3.1 597189.59 488942.79 2.7 4.7
5.6 -5.8 620036.71 189798.46 4.0 6.0
6.7 -4.9 741296.92 289990.25 4.1 6.1
11.8 1 1307846.27 936112.99 4.2 6.2
10.7 0 1184699.36 828228.22 3.9 5.9
7.1 -6.1 786254.19 157524.83 4.2 6.2
1.1 -3.1 121902.75 488895.73 4.3 6.3
6.7 -4.5 741143.71 334218.57 4.0 6.0
-7.5 -13.3 -842195.43 -642412.23 4.6 6.6
8.7 -4.6 962356.93 323990.35 4.1 6.1
11.8 3.1 1311997.57 1165723.46 4.3 6.3
7.3 -4.3 807423.6 356513.19 4.4 6.4
6.8 -7.6 754368.04 -8814.78 3.9 5.9
6.2 -6 686559.56 167978.27 2.8 4.8
5.3 -2.4 586167.14 566505.97 3.8 5.8
12 0.9 1329854.2 924883.33 4.1 6.1
6.7 -4.4 741111.04 345274.34 4.1 6.1
5.8 -4.9 641756.66 289630.6 4.3 6.3
7.3 -6.1 808394.72 157675.17 4.2 6.2
14.2 0.3 1572648.17 856262.72 4.3 6.3
12.7 1 1407588.2 934632.79 4.1 6.1
7.8 -5.6 863373.63 213263.07 4.1 6.1
13.6 0.5 1506498.15 878852.98 2.3 4.3
12.7 0.4 1406660.08 869365.29 4.0 6.0
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
7.7 -3.9 851539.6 400764.64 3.8 5.8
6.7 -4.4 741111.04 345274.34 3.9 5.9
6.5 -5.3 719360.39 245649.7 4.1 6.1
6.5 -5.1 719264.11 267779.18 4.2 6.2
10.6 -3.1 1172047.81 489082.42 3.8 5.8
6.7 -4.8 741255.23 301048.19 4.2 6.2
-4.8 -11.8 -536554.82 -479652.5 4.3 6.3
5.8 -5.1 641834.88 267474.87 4.6 6.6
1.7 -3.2 188220.75 477775.56 4.3 6.3
12.2 12.2 1396653.91 2171532.15 4.0 6.0
5.7 -4.4 630538.26 344982.36 4.1 6.1
10.1 -2.8 1116771.26 521934.46 4.1 6.1
-1.2 -18 -137011.07 -1188300.98 4.3 6.3
-0.5 -5.4 -54990.68 232884.56 4.2 6.2
-8.4 -5.2 -928862.12 257758.54 4.3 6.3
3.7 -5.4 409640.72 233429.17 4.4 6.4
12.2 -1.1 1349683.61 706739.42 4.2 6.2
5.8 -6 642284 167735.61 4.1 6.1
11.8 2 1309605.15 1045366.08 4.2 6.2
-5.5 -4.5 -607810.12 333847.57 4.3 6.3
6.2 -6.1 686623.34 156899.71 4.0 6.0
6.1 -6 675490.62 167916.1 3.9 5.9
6.6 -4.8 730195.66 301007.92 4.1 6.1
5.3 -4.7 586393.33 311625.01 4.3 6.3
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Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
6.7 -4.8 741255.23 301048.19 4.3 6.3
8 -4.5 884900.83 334700.33 4.1 6.1
6.7 -2.2 740962.4 588442.69 2.2 4.2
5.3 -4.7 586393.33 311625.01 4.2 6.2
1.4 0.3 155320.23 867335.38 4.2 6.2
6.4 -4.6 708003.41 323056.57 4.0 6.0
4.9 -1.6 542082.61 655260.49 3.8 5.8
0 1.6 322.88 1012456.97 4.1 6.1
11.9 -4.4 1316170.56 347545.45 2.3 4.3
7.3 -3.6 807260.71 433791.27 3.7 5.7
12.5 1.2 1385761.06 956753.19 4.3 6.3
6.1 -6.1 675553.39 156835.45 3.3 5.3
7.4 -3.6 818315.84 433806.08 4.2 6.2
5.7 -5.8 631103.56 189851.78 3.7 5.7
6.7 -4.8 741255.23 301048.19 4.2 6.2
6.8 -6.3 753190.2 135173.27 4.0 6.0
5.8 -5.4 641966.92 234235.94 4.5 6.5
4.3 -5 475890.49 278042.82 4.2 6.2
6.2 -6.1 686623.34 156899.71 3.7 5.7
3 -3.3 331912.59 466683.37 4.4 6.4
5.9 -1.8 652600.83 632861.96 4.1 6.1
6.8 -4.7 752274.83 312144.13 4.2 6.2
-5.4 -10.9 -602268.45 -377962.53 4.1 6.1
-5.5 -11.1 -613728.19 -400184.69 4.3 6.3
106
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
5.3 -5 586492.61 278366.2 4.2 6.2
5.7 -5.9 631158.41 178765.1 4.5 6.5
-8.3 -2.6 -917149.63 544070.46 3.9 5.9
5.4 -5.3 597670.55 245142.82 4.3 6.3
8.1 -4.9 896143.83 290652.08 4.2 6.2
6.9 1.2 765047.41 964432.7 4.2 6.2
1.1 1.3 122248.92 978883.3 4.0 6.0
6.2 -5.7 686380.81 201208.13 3.9 5.9
3.7 -3.4 409289.98 455602.08 4.3 6.3
4.8 -5.4 531333.98 233807.41 4.2 6.2
6.8 -4.9 752357.14 290033.39 4.2 6.2
6 -3.3 663520.77 466819.67 4.3 6.3
6.2 -3.5 685645.74 444705.17 4.0 6.0
5.6 -4 619390.56 389265.58 3.9 5.9
12.7 -3.7 1404350.38 424019.04 3.7 5.7
12.6 0.9 1396341.6 923917.51 4.2 6.2
5.3 -4.2 586263.68 367045.44 4.4 6.4
5.3 -5.5 586693.95 222921.03 4.2 6.2
12.4 0.9 1374178.96 924244.6 4.5 6.5
3.2 -0.7 354300.94 755633.58 2.9 4.9
8.4 -6.4 930444.71 125497.39 2.0 4.0
8.4 -5.4 929628.67 235726.63 3.9 5.9
6.6 -4.9 730236.74 289947.74 3.8 5.8
6.4 -5.1 708202.68 267733.59 4.2 6.2
107
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
7.2 -3.1 796163.33 488980.91 4.2 6.2
8.6 -2.3 951000.11 577047.72 4.3 6.3
6.7 -4.8 741255.23 301048.19 4.0 6.0
11.9 0.2 1317795.92 848673.33 3.8 5.8
6.5 -4.6 719061.77 323091.28 4.0 6.0
7 -2.5 774082.65 555249.15 4.2 6.2
5.9 -5.9 653294.11 178878.48 4.1 6.1
10 0 1107205.25 828958.07 4.2 6.2
-9.5 -2.7 -1049808.33 532950.68 4.3 6.3
6.5 0.7 720280.5 909399.76 3.8 5.8
6.1 -6.2 675618.23 145753.77 4.4 6.4
4.1 -5 453770.38 277986.21 4.0 6.0
6.6 -4.6 730120.18 323126.53 4.4 6.4
6.3 -3.7 696725.65 422592.4 3.9 5.9
16.2 -6.3 1794173.98 147129.75 3.9 5.9
12.5 0.5 1384650.63 880536.11 4.0 6.0
6.7 -4.9 741296.92 289990.25 2.4 4.4
13 1.4 1441554.75 977598.83 4.1 6.1
7 -4.8 774434.18 301172.6 3.9 5.9
6 -5.2 664000.83 256483.38 4.3 6.3
5.3 -4.4 586310.17 344878.71 4.3 6.3
7.5 -5 829828.9 279313.77 4.0 6.0
5.4 -5.4 597713.4 234054.86 4.3 6.3
6.8 -5.5 752659.07 223685.09 4.3 6.3
108
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
10.3 -0.6 1139862.01 762884.53 2.2 4.2
6.7 -4.8 741255.24 301048.19 3.8 5.8
1.1 -5.9 122059.9 177234.7 3.9 5.9
6 -3.8 663576.33 411480.8 4.0 6.0
7.6 1.1 842525.81 952654.55 3.7 5.7
12.8 1.3 1419195.61 967098.41 4.2 6.2
5.9 -5.3 652983.63 245361.65 4.3 6.3
4.5 -1.3 497926.26 688642.45 4.4 6.4
4.8 -5.2 531259.34 256003.24 4.1 6.1
5.4 -5.4 597713.4 234054.86 4.0 6.0
6.6 -4.9 730236.75 289947.74 4.2 6.2
6.3 -4.6 696945.09 323022.39 4.1 6.1
6.2 -5.3 686171.86 245502.21 4.3 6.3
8 -3.7 884665.11 422878.31 4.2 6.2
6.6 -4.7 730156.81 312067.51 4.1 6.1
14.1 0.1 1561278.04 834799.71 4.0 6.0
6.6 -4.8 730195.67 301007.92 3.9 5.9
6.6 -6.2 730973.47 146096.22 4.4 6.4
5.6 -4.4 619481.19 344955.74 3.8 5.8
6.3 -5.2 697186.92 256620.02 4.3 6.3
6.8 -5 752401.73 278977.1 4.2 6.2
13.5 0.7 1495739.37 900694.64 3.8 5.8
9.4 -2.7 1039387.33 532959.64 4.4 6.4
5.4 -5.2 597629.54 256230.02 4.2 6.2
109
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
7.5 -2.2 829406.24 588289.99 2.4 4.4
8.6 -5.4 951757.66 235863.76 2.2 4.2
5.6 -2.8 619299.97 522171.65 4.4 6.4
5.3 -5 586492.62 278366.2 4.2 6.2
6.1 -4.9 674936.42 289744.75 4.1 6.1
6.5 -3.5 718809.27 444737.19 4.1 6.1
3 -5.6 332251.74 210992.8 4.6 6.6
-11.3 -10.3 -1258819.44 -298685.81 4.1 6.1
5.3 -4.5 586336.1 333794.65 4.4 6.4
10.1 -6.8 1119190.73 83388.05 3.8 5.8
8 -5.1 885190.27 268547.28 4.0 6.0
5.2 -5 575432.28 278330.84 4.3 6.3
6.6 -4.8 730195.67 301007.92 3.9 5.9
7 -5.7 774910.75 201688.19 3.8 5.8
5.3 -5.2 586567.77 256190.37 4.2 6.2
6 -4.5 663739 333994.3 4.1 6.1
7.1 -4.3 785309.1 356450.27 2.2 4.2
-1 -7.4 -110534.09 9985.08 4.1 6.1
5.4 -1.8 597319.79 632976.02 3.9 5.9
2.5 -5.7 276952.08 199742.9 4.3 6.3
7.7 -3.9 851539.6 400764.64 4.3 6.3
6.7 -4.8 741255.24 301048.19 4.3 6.3
5.7 -4.2 630488.31 367134.27 4.1 6.1
6.5 -4.8 719136.14 300968.26 3.3 5.3
110
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
4.2 -5 464830.42 278014.18 4.4 6.4
4.4 -4.3 486778.76 355771.26 4.1 6.1
6.1 -6.2 675618.23 145753.77 4.0 6.0
12.7 1.4 1408291.23 978168.19 4.3 6.3
6.3 -6.3 697829.31 134808.98 4.4 6.4
6.8 -6.2 753115.77 146240.71 4.2 6.2
-2.8 -7.8 -310252.76 -34109.4 4.0 6.0
5.9 -6.1 653413.59 156710.05 3.8 5.8
2.6 -3 287695.92 500021.53 4.2 6.2
5.6 -4 619390.57 389265.58 4.1 6.1
7.2 -3.6 796205.62 433776.65 4.6 6.6
10.8 -4.1 1194375.52 379763.32 3.9 5.9
11.7 2.7 1299963.88 1122158.82 4.5 6.5
12.2 1.7 1353403.25 1011816.83 4.3 6.3
5.3 -4.8 586424.64 300539.35 4.4 6.4
-0.8 -5.5 -88185.02 221763.25 4.3 6.3
6.1 -6.1 675553.4 156835.45 4.3 6.3
6.4 -3.5 707754.72 444726.35 4.3 6.3
6.1 -5.1 675018.63 267601.06 4.0 6.0
5.6 -4 619390.57 389265.58 4.1 6.1
4.1 -5.6 453961.91 211335.29 4.4 6.4
3.9 -3.3 431392.39 466714.74 3.7 5.7
-0.4 -8 -44058.11 -57069.75 4.2 6.2
6.5 -5.9 719701.92 179241.96 4.2 6.2
111
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
7.2 -4.5 796434.01 334393.84 4.3 6.3
6.2 -2.3 685670.78 577465.37 3.9 5.9
13.4 0.9 1484993.96 922557.68 4.0 6.0
12.7 -3.6 1404323.3 434876.93 3.9 5.9
8.8 -7.1 975514.31 48748.62 4.6 6.6
11.7 1.8 1298128.55 1023693.89 4.0 6.0
6 -6.1 664483.48 156772.23 4.5 6.5
12.7 -4.1 1404500.42 380585.08 4.2 6.2
12.7 -3.8 1404381.64 413160.94 4.1 6.1
6.7 -2.3 740945.51 577389.47 4.4 6.4
11.8 1.4 1308502.47 979797.75 4.1 6.1
6.6 -4.9 730236.74 289947.74 4.2 6.2
7.4 -5.1 818818.68 268221.07 4.5 6.5
6.5 -3.5 718809.26 444737.19 3.7 5.7
7.2 -5.4 796858.45 234971.15 4.4 6.4
-5.4 -5.6 -597163.11 211873.75 4.7 6.7
7.9 -4.3 873768.21 356712.38 4.2 6.2
6 -5 663915.89 278632.51 4.3 6.3
7.2 -4.3 796366.33 356481.51 4.0 6.0
13.4 0.8 1484824.72 911708.94 4.1 6.1
4.4 -4.3 486778.75 355771.26 4.5 6.5
11.8 1.8 1309221.78 1023504.15 4.0 6.0
-6.3 -1.5 -696272.21 665957.5 4.0 6.0
7.8 -4.2 862677.99 367706.14 4.3 6.3
112
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
9.1 1.5 1009286.34 994996.8 4.2 6.2
1.8 -0.5 199463.48 778169.59 4.3 6.3
0.7 -3.9 77701 399874.26 4.0 6.0
-13.67 -13.8 -1537268.12 -674206.81 4.5 6.5
4.4 -3.5 486671.69 444544.69 4.1 6.1
7.7 -6.1 852676.21 157988.32 4.0 6.0
7 -4.9 774477.7 290121.58 3.6 5.6
7.2 2 799191.71 1052736.81 2.1 4.1
8 -4.4 884861.98 345723.94 4.0 6.0
7.2 -4.1 796308.32 378567.48 3.7 5.7
4 -2.5 442456.63 555526.65 4.0 6.0
11.8 2.1 1309802.78 1056299.34 4.0 6.0
3.9 -4.2 431481.43 366785.26 4.5 6.5
6.7 -4.9 741296.92 289990.25 3.9 5.9
6.2 -5.4 686220.95 234429.91 3.8 5.8
5.9 -5.5 653079.13 223204.01 4.0 6.0
6.4 -5 708158.51 278799.45 4.2 6.2
12.5 -1.7 1382479.29 641286.36 4.1 6.1
5.8 -4 641501.55 389303.93 4.6 6.6
6.8 -5 752401.72 278977.1 4.1 6.1
3 -4.6 332038.11 322195.68 4.2 6.2
3.5 -0.7 387487.08 755555.62 4.2 6.2
7.5 -7.2 831548.4 36222.68 1.6 3.6
5.3 -4.6 586363.82 322710.1 4.1 6.1
113
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
14.7 -1.3 1626116.51 683063.92 3.8 5.8
5.5 -5.5 608822.22 223012 4.2 6.2
7.1 -4.8 785493.91 301215.28 4.1 6.1
0.8 1.5 89020.38 1001244.62 3.9 5.9
9.9 -3.7 1094733.05 423277.7 2.7 4.7
6.7 -4.9 741296.92 289990.25 3.9 5.9
-14.4 -4.2 -1591961.49 370645.57 4.4 6.4
7.9 -4.1 873704.7 378762.8 4.0 6.0
7.1 -5.9 786110.86 179640.45 4.3 6.3
12.3 1.4 1363940.34 978906.99 4.1 6.1
6.7 -4.9 741296.92 289990.25 4.0 6.0
5.3 -4.5 586336.09 333794.65 4.0 6.0
12.4 1.3 1374849.95 967825.95 4.0 6.0
-3.3 -0.3 -364831.55 800090.49 4.1 6.1
-3.9 3.5 -433541.4 1223219.27 4.1 6.1
-16.8 -14.5 -1893179.65 -732374.8 4.4 6.4
6.8 -4.2 752109.11 367411.74 4.3 6.3
7.8 -5.6 863373.62 213263.07 3.9 5.9
0.4 -10.8 44951.69 -370640.62 4.2 6.2
6.4 -6.2 708831.28 145956.02 6.2 8.2
5.3 -4.8 586424.63 300539.35 4.1 6.1
4.2 -4.7 464751.56 311325.88 3.7 5.7
8.6 -5.6 951901.51 213836.63 4.1 6.1
13.5 0.9 1496075.7 922381.92 4.0 6.0
114
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
13.6 0.9 1507157.5 922204.87 3.2 5.2
7.1 -4.2 785279.29 367495.85 3.9 5.9
5.3 -4.6 586363.82 322710.1 4.0 6.0
7 -7.7 776656.43 -19681.33 3.9 5.9
-9.1 -1.9 -1005754.39 620905.5 4.4 6.4
6.6 -4.9 730236.74 289947.74 4.0 6.0
13.8 0.4 1528497.23 867705.9 3.7 5.7
6.5 -4.8 719136.13 300968.26 4.2 6.2
5.9 -6.6 653747.33 101270.33 4.4 6.4
5.4 -3 597188.67 500021.53 3.9 5.9
5.9 -4.3 652625.67 356109.27 4.3 6.3
-1.1 -13.2 -123219.23 -640890.81 6.2 8.2
6.7 -4.9 741296.92 289990.25 4.3 6.3
6.6 -4.8 730195.66 301007.92 4.3 6.3
-4.9 -11.6 -547446.05 -457075.15 4.1 6.1
5.9 -4.8 652779.75 300742.94 4.2 6.2
-0.5 -6.7 -55057.66 88018.27 4.2 6.2
5.8 -6.1 642343.73 156648.92 4.2 6.2
6.3 -3.3 696683.25 466838.28 4.0 6.0
5.3 -2.8 586138.54 522182.65 4.3 6.3
7 -4.2 774222.52 367467.41 4.0 6.0
6.6 -4.8 730195.66 301007.92 4.0 6.0
7.2 -6.7 797818.75 91241.59 4.1 6.1
6.6 -4.9 730236.74 289947.74 3.9 5.9
115
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
6.4 -5.4 708348.16 234531.73 3.8 5.8
7 2.2 777241.75 1075153.43 2.5 4.5
7.3 -7.2 809381.31 36012.93 2.4 4.4
7 -6 775112.11 168511.9 4.3 6.3
8.6 -6.6 952794.24 103645.43 4.1 6.1
6.8 -5.5 752659.06 223685.09 4.2 6.2
7.1 -4.2 785279.29 367495.85 4.0 6.0
6.4 -5.4 708348.16 234531.73 3.8 5.8
6.1 -3.6 674602.61 433629.12 4.3 6.3
6 -3.4 663527.84 455752.23 3.9 5.9
13 -4.2 1437729.55 369880.44 4.2 6.2
5.4 -4.4 597367.14 344903.91 4.8 6.8
11.9 2.4 1321522.26 1088893.09 4.0 6.0
-2.2 -6.5 -243297.32 110588.11 4.0 6.0
11.2 -3.2 1238393.55 478187.08 2.9 4.9
12.5 1.2 1385761.06 956753.19 4.3 6.3
6.7 -4.8 741255.23 301048.19 4.4 6.4
6.7 -3.5 740918.48 444759.37 4.2 6.2
5.9 -4.5 652681.33 333964.27 2.9 4.9
6 -3.60 663548.04 433616.91 4.2 6.2
11.8 1.7 1309036.02 1012575.41 4.3 6.3
6.2 -3.5 685645.74 444705.17 6.2 8.2
10.6 -1.9 1172258.61 620358.61 2.0 4.0
5.7 -4.8 630661.24 300672.66 4.0 6.0
116
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
7.7 -5.8 852447.39 191115.27 4.1 6.1
5.2 -6.9 576417.78 67480.76 2.2 4.2
6.3 -0.5 -668899.44 -354701.98 4.2 6.2
4.6 -4.6 508958.88 322523.43 4.1 6.1
5.8 -5.9 642226.24 178821.3 4.0 6.0
6.3 -2.2 696741.54 588512.62 2.7 4.7
7.6 -6.5 841942.93 113714.5 4.3 6.3
11.8 1.3 1308332.5 968874.61 4.1 6.1
8 -4.4 884861.97 345723.94 4.2 6.2
6.7 -4.8 741255.23 301048.19 3.5 5.5
5.6 -4 619390.56 389265.58 3.9 5.9
8.4 -4.3 929056.74 356890.31 4.4 6.4
6.4 -4.3 707909.72 356243.73 3.9 5.9
0.9 -6.4 99974.07 121497.82 4.1 6.1
4.8 -2.8 530870.19 522199.64 3.8 5.8
12.2 1.8 1353594.91 1022729.24 4.1 6.1
12 1.2 1330336.18 957616.99 4.0 6.0
7.1 -5.2 785684.75 257016.84 4.0 6.0
6.6 -6.3 731045.75 135024.23 4.4 6.4
6.1 -3.8 674631.36 411497.08 4.1 6.1
8 -4.5 884900.82 334700.33 4.2 6.2
5.4 -4.2 597319.78 367067.04 4.2 6.2
6.6 -4.9 730236.74 289947.74 4.5 6.5
6.8 -5 752401.72 278977.1 3.7 5.7
117
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
11.5 0.5 1273885.52 881944.97 4.0 6.0
-2.8 -14.3 -315303.2 -764174.84 5.1 7.1
6.2 -4.6 685886.79 322988.75 4.4 6.4
5.3 -4.9 586457.72 289453.09 3.6 5.6
5.7 -5.8 631103.56 189851.78 4.5 6.5
7.6 -6.3 841769.22 135813.65 4.1 6.1
6.2 -6.2 686689.22 145820.11 3.2 5.2
6.6 -5.5 730529.94 223572.32 4.4 6.4
6.8 -7.6 754368.03 -8814.78 5.1 7.1
14.3 -1.6 1581644.33 651026.9 4.2 6.2
7.3 -0.4 808045.04 787110.23 4.5 6.5
3.8 -4.1 420410.96 377875.45 4.2 6.2
6.7 -4.9 741296.92 289990.25 4.2 6.2
0.8 0.1 88875.06 845120.6 4.4 6.4
3.7 -1.2 409482.82 699940.25 4.8 6.8
5.9 -3.6 652493.51 433604.91 3.8 5.8
12.8 1 1418670.84 934461.71 4.0 6.0
-7.4 -14.3 -833723.3 -754972.1 4.6 6.6
6.4 -5.2 708249.01 256667.04 4.1 6.1
13.7 -0.2 1516587.38 802898.09 4.1 6.1
5.4 -4.3 597342.55 355985.7 2.1 4.1
0.9 1.5 100107.58 1001231.63 4.5 6.5
6.3 -6.2 697760.23 145887.53 4.2 6.2
6.8 -3.5 751973.16 444770.72 4.1 6.1
118
University of Ghana http://ugspace.ug.edu.gh
Lat Lon Northing Easting Magnitude Epicentral Intensity, Io
13 -4.3 1437782.8 359033.73 4.6 6.6
-3.5 -4.9 -386744.66 288944.84 4.3 6.3
4.6 -2.3 508798.03 577668.84 4.2 6.2
119