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| Source model of the 11th July 2004 Zhongba earthquake revealed from the joint inversion of InSAR and seismological data |
| Shengji Wei1, Sidao Ni2, Xianjie Zha3, Zhenjie Wang3, Don Helmberger1 |
1 Seismological Laboratory of California Institute of Technology, Pasadena, CA 91125, USA
2 Key Laboratory of Dynamical Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China
3 Mengcheng National Geophysical Observatory, Department of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China |
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Abstract We use interferometric synthetic aperture radar (InSAR) and broadband seismic waveform data to estimate a source model of the 11th July, 2004 MW6.2 Zhongba earthquake, Tibet of China. This event occurred within the seismically active zone of southwestern Tibetan Plateau where the east-west extension of the upper crust is observed. Because of limitations in one pair of InSAR data available, there are trade-offs among centroid depth, rupture area and amount of slip. Available seismic data tightly constrain the focal mechanism and centroid depth of the earthquake but not the horizontal location. Together, two complementary data sets can be used to identify the actual fault plane, better constrain the slip model and event location. We first use regional seismic waveform to estimate point source mechanism, then InSAR data is used to obtain better location. Finally, a joint inversion of teleseismic P-waves and InSAR data is performed to obtain a distributed model. Our preferred point source mechanism indicates a seismic moment of ~2.2×1018 N·m (~MW6.2), a fault plane solution of 171°(342°)/42°(48°)/-83°(-97°), corresponding to strike/dip/rake, and a depth of 11 km. The fault plane with strike of 171° and dip of 42° is identified as the ruptured fault with the aid of InSAR data. The preferred source model features compact area of slips between depth of 5–11 km and 10 km along strike with maximum slip amplitude of about 1.5 m.
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Received: 02 November 2010
Published: 10 April 2011
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| Fund:National Natural Science Foundation of China (Nos.40821160549 and 41074032), CAS Knowledge Innovation Program (No. KZCX2-YW-116-1), Joint Seismological Science Fundation of China (Nos.200808078 and 200708035) |
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Corresponding Authors:
Sidao Ni
E-mail: sdni@whigg.ac.cn
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