Reassessment of the macro parameters for the Lake Tanganyika earthquake of 13 December 1910 in East Africa

The Lake Tanganyika M_S7.3 earthquake that occurred in the East African Rift System （EARS） on 13 December 1910 is one of the largest known earthquakes in Africa since 1880, whose seismic history is unrecorded. Because of lack of data, this major earthquake is rarely mentioned in the EARS seismological literature. The analysis reported here is based on a 1911 German language booklet written by Huys, titled " The Lake Tanganyika Earthquake of 13 December 1910”, which is in the collection of the National Library of China. Using the method of historical seismic relative intensity, and by excluding the damage overlap effects from the foreshocks and the strong aftershocks after two hours of the main shock, macro parameters of the M_S7.3 main shock are reassessed. The results show that the macro epicenter of the earthquake is located at the central region of Lake Tanganyika （7°S, 30°E） with maximum seismic intensity of Ⅷ and with isoseismals major axis oriented NE−SW. These data fill certain gaps in the records of African earthquakes. It also provides reference for revisions of the micro seismic parameters, and provides geophysical evidence to restrict the ambiguity of the nodal planes in the focal mechanism solution. In the big picture, this analysis also provides information for the geophysical understanding of the early development of the western branch of EARS. With regard to application, these macro parameters offer data for seismic risk assessment in Tanzania, which are needed in large construction projects.