ALBERT

Description: In view of the historically devastating earthquakes in Ghana, this study employed regional satellite gravity data to reveal the extension of the crustal network of fractures emanating from the seismically active zone in the Gulf of Guinea and its implications on Coulomb stress transfer of the June 22nd, 1939 Accra earthquake. The Accra earthquake (M=6.5), Ghana is one of the most devastating intra-plate earthquakes in sub-Sahara west African region. In order to carry out the Coulomb stress transfer study, we utilized the Fault Plane Solutions (FPS) obtained from the waveform inversion of Yarwood and Doser (1979), which revealed that the earthquake composed of two events (6.1 Mw and 6.4 Mw). This study resolved the static Coulomb Failure Stress (CFS) change onto the finite fault models of the 6.4 Mw and 6.1 Mw earthquakes and its effect on associated receiver faults. The gravity study revealed swarms of fractures emanating from the gulf of Guinea and connected with the Akwapim and Coastal boundary faults favored the enhanced CFS to generate the 6.1 Mw due to transmission of stress from the seismically active zones in the Gulf of Guinea (boundary between the African plate and the South-American plate). The 6.4 Mw main shock was explained to correlate with release of seismic energy from the associated secondarily stressed prominent strike-slip (Akwapim) fault and strike-slip (coastal boundary fault). The direction of Coulomb stress transfer and the receiver faults of the 6.4 Mw main event have been mapped for the next big magnitude earthquake preparedness.