Statistical Analysis of Seismicity in the Horn of Africa

Abstract

The Horn of Africa is considered as one of the seismically active regions on the African continent because of the Main Ethiopian rift system, one of the most active rift systems within the East African rift system. Therefore, it is essential to continuously analyze the seismicity to assess seismic hazards in a region of interest. To this end, seismicity information for the Horn of Africa was collected from ISC catalogues from the year 1973 to 2022 in the latitude range of 0N - 20N and the longitude range of 30E -52E from the surface to 700km below the surface. Then, as a measure of the seismicity in the Horn, Gutenberg's parameters and the spatial variation of the seismic moment were examined. According to the findings, the North Main Ethiopian Rift (NMER) is under more stress than the Central Main Ethiopian Rift (CMER) regarding seismic moment release. The Richter and Guttenberg's constants of a=6.85, b=0.88 and Mc=4.5 were obtained across the whole Horn of Africa, whereas the corresponding values for NMER, CMER and SMER were a=5.6, b=0.78, Mc=4.5; a=5.9, b=0.87, Mc=4.5; and a=6.9, b=1.03, Mc=5.0 respectively. Overall, the distribution of focal depths and magnitude showed that the distribution of seismicity in the Horn of Africa is shallow with an average focal depth of around 11 km.