Earthquakes along Lake Kariba (Zimbabwe), where the seismicity is very active were relocated using the Modified Joint Hypocenter (MJHD) Method. After relocation, we found several earthquake clusters where many earthquakes concentrate in small areas
Furthermore, an estimation of fault planes of large earthquakes along the East Africa rift system has been carried out by means of relocated accurate hypocenter distribution. The Modified Joint Hypocenter Determination (MJHD) method was used for simultaneous relocation of each mainshock and its aftershocks and estimating the mainshock fault plane.
The following five large events with MW ≥ 6.8 were analyzed. The 2006 Mozambique earthquake (Mw = 7.0), 2005 Lake Tanganyika earthquake (Mw = 6.8), 1992 Zaire earthquake (Mw = 7.0) and two 1990 Sudan earthquakes (Mw = 7.0 and 7.1). P-wave arrival times to be used for relocation were taken from the International Seismological Center (ISC) and US Geological Survey (USGS) websites. Global stations were used for relocation because there was no local network available. The ISC and USGS normally fix the depth of earthquakes at 10km and because of this it becomes impossible to determine the fault planes by using the data obtained from them. However, since the MJHD method gives good location of events including focal depth, it becomes possible to determine the fault planes from aftershock distribution.
In this study, five different large events were relocated and their locations are consistent with the formation of the East Africa rift system and were also good enough to determine all the five fault planes. The obtained results will contribute to the understanding of tectonics in the East Africa rift system.