The Focal Property of the 2014 Ms6.3 Kangding, China Earthquake and its Resulting Stress Changes on Surrounding Faults

Abstract:

An Ms6.3 earthquake struck Kangding County, Garze Tibetan Autonomous Prefecture in Sichuan province on November 22, 2014 and is one of the destructive earthquakes on the eastern boundary of Chuandian rhomb faulted-block in southwestern China, where is one of the areas with strong seismic activity in continent. During the earthquake, at least 5 people killed, 65 injured, lots of homes were collapsed and thousands people displaced. Ending the history that no large earthquake occurs at Xianshuihe fault zone for nearly 30 years, this moderate earthquake arouses the highly attention of many seismologists, not only for the serious disaster, but also for the potential seismic risk in and surrounding the epicenter.

In order to better understand the seismogenic structure and the seismic risk of the source region, we collect teleseismic waveforms from IRIS and broadband seismograms from seismograph network in Yunnan and its surrounding provinces, and apply CAP method to grid search the focal mechanism and centroid depth of the earthquake. And the rupture process of this event is investigated based on finite fault inversion method. After that, we calculate stress influences on Kangding earthquake from the Wenchuan and Lushan earthquake, and study the stress changes on Xianshuihe Fault caused by the Kanding earthquake to assess the future seismic hazard.

The result shows that the epicenter of Kangding earthquake is 101.689°E and 30.262°N, with a focal depth of 9 km and magnitude of about Mw6.0. The two nodal planes of focal mechanism are 235°/82°/-173° and 144°/83°/-8°. Considering the tectonic background, the latter nodal plane is adopted as the parameters of receiver fault while calculating the stress changes on the hypocenter of Kangding earthquake. the major slip is located around the hypocenter, spanning ~8 km along dip and ~10 km along strike with a maximum slip of 0.5 m. The stress accumulation on the Kangding-Daofu segment, surrounding to the epicenter of the 2014 Kangding earthquake, is increased by the 2008 Wenchuan earthquake but the influences from the 2013 Lushan earthquake is very weak, which can be ignored. And the stress changes caused by the Kanding earthquake increase the stress accumulations on northwest section of Kangding-daofu segment, which will raise the future seismic hazard.