Seismological, meteorological and geochemical investigation for earthquake hazard in the Greater Accra metropolitan area

Abstract

Seismological, Meteorological and Geochemical investigations for earthquake hazard were carried out in the Greater Accra Metropolitan Area (GAMA). An earthquake catalogue generated was used to calculate the b-value (seismic stress) by the Linear Least Square (LLS) method and the Maximum Likelihood Estimation (MLE) method. The Geographic Information System (GIS) was used to generate epicentral intensity and isoseismal maps from the catalogue. The meteorological investigation involved the use of precipitation data from the coastal belt of the synoptic stations of the Ghana Meteorological Agency (plotted with the seismic data to identify possible correlation). The isotopic anomaly analysis to investigate the geochemical effect was done by evaluating radon concentrations in soil gas and water using the Solid State Nuclear Track Detector (SSNTD) and the Electret Passive Environmental Radon Monitor (EPERM®). Detectors were buried at Tema, Ashaiman, Weija, Donkunah and Kwabenya over a one-year period (January 2018 to December 2018). An average b-value of 0.63 was evaluated by the LLS Method and 0.88 for the MLE Method. The epicentral intensity, frequency and isoseismal maps show a detailed distribution of earth tremors of magnitudes less than . The meteorological investigation shows a not very strong Pearson’s correlation coefficient of precipitation with seismicity (r=0.4 and p value=0.04). Geochemical investigations also show a very weak positive Pearson’s Correlation Coefficient of radon emanation and seismicity (r=0.1 and p-value=0.69).