Tectonic Summary
Magnitude 6.8 LAKE TANGANYIKA REGION, CONGO-TANZANIA
Monday, December 05, 2005 at 12:19:56 UTC
Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver
The earthquake occurred in the Western Rift of the East African rift system. The East African rift system is a multi-branched, approximately 3000-km-long, zone of crustal extension that passes through eastern Africa from Djibouti and Eritrea on the north to Malawi on the south. The rift-system is the boundary between the Africa plate on the west and the Somalia plate on the east. At the earthquake?s latitude, the Africa and Somalia plates are spreading apart at a rate of about four millimeters per year. The earthquake occurred beneath Lake Tanganyika, the basin of which was created by the rifting process. The largest earthquake to have occurred in the rift system since 1900 had a magnitude of about 7.6. Earthquakes within the East African rift system occur as the result of both normal faulting and strike-slip faulting.
