Reconstructing the source rupture process and ground motion time history of the 1935 Hsinchu-Taichung Earthquake (ML7.1) in Taiwan

Abstract:

On 21 April 1935, a large earthquake with a local magnitude of M_L7.1 struck central Taiwan, named the Hsinchu-Taichung earthquake. Its epicenter was located in Miaoli County and the surface rupture went through the Taichung metropolitan area. The focal depth was estimated to be less than 10 km. This earthquake was associated with two major seismic faults: the northern one is the Shihtan thrust fault; the southern one is the Tuntzuchiao right-lateral strike-slip fault which separated from the Shihtan fault by about 30 km. This earthquake have been investigated by several studies and various fault models were been proposed. However, due to complicate regional structures in the source area, the detailed fault geometry and coseismic slip distribution of this event are still not clear. In this study, we investigated the influence of fault geometry and source slip distribution based on these previously proposed fault models for the Hsinchu-Taichung earthquake. There are three main types of fault models: (1) two-segment fault planes without a blind fault, (2) complicate fault planes with three blind faults, and (3) four-segment fault planes with two blind faults. We investigated the spatial slip distribution based on these fault models from source inversion analysis by using the triangulation data. The preferred fault geometry and slip distribution derived from the inversion results were discussed. Finally, a forward 3D ground motion simulation based on the inverted source model was carried out to reconstruct the ShakeMap and ground motion time history during the Hsinchu-Taichung earthquake.