Seismicity of southern Lake Tanganyika

Posted by pkm at Mar 06, 2015 09:35 PM |
Aude Lavayssiere (1), Ryan Gallacher (1), Derek Keir (1), Cindy Ebinger (2), Connor Drooff (2), Khalfan Mtelela (3) & Jon Bull (1) - (1) University of Southampton; (2) University of Rochester; (3) University of Dar Es Salaam

Global seismic networks document frequent and unusually deep earthquakes in East African rift sectors lacking central volcanoes.  The deep seismicity means that we can use earthquakes to probe the geometry and kinematics of fault systems throughout the crust, and to understand the distribution of strain between large offset border fault systems and intrabasinal faults.   The southern Tanganyika rift zone has the highest seismicity rate within East Africa during the period 1973-present, yet earlier temporary seismometer networks have been too sparse in space and time to relocate earthquakes with accuracies < 5-10 km in x, y, z, and those beneath the lake.  We address this issue by recording seismicity of southern Lake Tanganyika since June 2014 using a network at 12 broadband seismic stations. The distribution of earthquakes shows that deformation primarily occurs beneath the lake. Subsidiary earthquake activity occurs along the subparrallel Rukwa graben, and beneath the NE-SW striking Mweru rift. The distribution of earthquakes suggests the southern end of lake Tanganyika is characterized by a network of intersecting NNW and NE striking faults. The depths of earthquakes are distributed  throughout the crust, consistent with the relatively strong lithosphere.

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