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Joint analysis of the 2014 Kangding, southwest China, earthquake sequence with seismicity relocation and InSAR inversion
Author(s) -
Jiang Guoyan,
Wen Yangmao,
Liu Yajing,
Xu Xiwei,
Fang Lihua,
Chen Guihua,
Gong Meng,
Xu Caijun
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063750
Subject(s) - seismology , aftershock , geology , interferometric synthetic aperture radar , seismic moment , seismic gap , hypocenter , slip (aerodynamics) , moment magnitude scale , induced seismicity , geodesy , fault (geology) , synthetic aperture radar , scaling , remote sensing , physics , geometry , mathematics , thermodynamics
Over 1000 earthquakes struck the northwest of Kangding on the Xianshuihe fault in southwest China between 22 and 29 November 2014, including two largest events of M w 5.9 and M w 5.6. The hypocenters of 799 relocated earthquakes suggest that two independent main shock‐aftershock subsequences occurred on the Selaha and Zheduotang branches of the Xianshuihe fault, respectively. Fault slip inversion results from one interferometric synthetic aperture radar (InSAR) interferogram (26 September 2014 to 5 December 2014) show that the M w 5.9 main shock produced a maximum slip of ~0.47 m at the depth of ~9 km. However, there is no distinct slip associated with the M w 5.6 main shock. The InSAR determined moment is 2.36 × 10 18 Nm with a rigidity of 30 GPa, equivalent to M w 6.2, which is about twofold 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 2 weeks following the M w 5.9 main shock. The released seismic energy of this earthquake sequence is far less than the accumulated strain energy since the 1955 M 7 1 2 earthquake on the same fault branch, which implies that the seismic risk on the Selaha‐Kangding segment of the Xianshuihe fault remains high.