51. Confirmation of the double-asperity model for the 2016 MW 6.6 Akto earthquake (NW China) by seismic and InSAR data
- Author
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Wanpeng Feng, Xu Zhang, Lu Li, Lisheng Xu, and Lei Yi
- Subjects
010504 meteorology & atmospheric sciences ,Hypocenter ,Geology ,Slip (materials science) ,010502 geochemistry & geophysics ,01 natural sciences ,Sinistral and dextral ,Interferometric synthetic aperture radar ,Seismic moment ,Waveform ,Seismic risk ,Seismology ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Asperity (materials science) - Abstract
On November 25, 2016, an MW 6.6 earthquake struck Akto, a county in the Xinjiang Autonomous Region of China. This earthquake nucleated on the dextral steep-dip strike-slip segment of the Muji fault, in the western Tibetan Plateau. In this study we conducted a joint inversion using a higher number of data than in previous works (i.e., teleseismic P and SH waveform, near-field seismic waveform, and coseismic InSAR displacement data), in order to analyze the spatiotemporal rupture process of this seismic event. The results of the joint inversion showed that the event consisted in a primarily unilateral rupture toward east-southeast (along the Muji fault) and that 90% of the scalar seismic moment was released in the first 18 s. Moreover, we confirmed the occurrence of two major asperities: the first one located right next to the hypocenter, and the second one ~30–35 km east of the hypocenter. The first asperity was found at a deeper depth than the second asperity; additionally, it was larger and had a smaller slip. The results of the Coulomb stress change analysis suggested that the rupture of the first asperity triggered the rupture of the second one. The heterogeneity of the on-fault slip revealed the heterogeneity of the inherent strength and stress of the Muji fault; moreover, the clear slip deficit area, characterized by a high Coulomb stress, might indicate a high seismic risk.
- Published
- 2019