Publication Date:
2015-04-19
Description:
Over 1000 earthquakes struck the northwest of Kangding on the Xianshuihe fault in southwest China between November 22 and 29, 2014, including two largest events of Mw 5.9 and Mw 5.6. The hypocenters of 799 relocated earthquakes suggest that two independent mainshock–aftershock sub-sequences occurred on the Selaha and Zheduotang branches of the Xianshuihe fault, respectively. Fault slip inversion results from one InSAR interferogram (09/26/2014-12/05/2014) show that the Mw 5.9 mainshock produced a maximum slip of ~0.47 m at the depth of ~9 km. However, there is no distinct slip associated with the Mw 5.6 mainshock. The InSAR determined moment is 2.36 × 10 18 N m with a rigidity of 30 GPa, equivalent to Mw 6.2, which is about two-fold the total seismic moment of all the recorded earthquakes during the InSAR time span. This large discrepancy between geodetic and seismic moment estimates indicates that there was probably rapid aseismic afterslip in the two weeks following the Mw 5.9 mainshock. The released seismic energy of this earthquake sequence is far less than the accumulated strain energy since the 1955 M earthquake on the same fault branch, which implies that the seismic risk on the Selaha-Kangding segment of the Xianshuihe fault remains high.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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