Journal de géologie et géophysique
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Extensional Seismotectonic Motion and its Dynamics in the Eastern Margin of the Tibetan Plateau and its Surroundings

Jiren Xu and Zhixin Zhao

The seismotectonic motions and stress fields in the eastern margin of the Tibetan plateau and its surroundings were investigated by analyzing seismic data. The findings showed that volumes of normal faulting type events dislocating extensively along the N-S direction concentrated southwest of the Xianshuihe fault (SWXSH-NSNF). Moreover, volumes of normal faulting type events dislocating extensively along the E-W direction concentrated east of the lower reach of the Jinshajiang river (ELRJSJ-EWNF). The events are almost thrust faulting type ones along the Longmenshan fault. The P-axes aligned generally around the NE-SW direction in the western region and around the NW-SE direction in the eastern region in the eastern margin of the plateau, respectively. The seismogenic stress field in the eastern region in the eastern margin of the Tibetan plateau might be affected by the stress field on the South China block resulted by the collision between the Eurasian and the Philippine Sea plates in the Taiwan region and the subduction of the Philippine Sea plate along the Ryukyu trench. The longitudinal boundary of the P-axis orientations of stress field between the eastern and western regions in the eastern margin of the Tibetan plateau lay along about longitude 100°E-101°E, being within the eastern margin of the Tibetan plateau. The above stress boundary does not coincide with the tectonic boundary between the Tibetan plateau and the South China block.