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Journal: |
Journal of Geophysical Research 2018 No.9
clicks:142 |
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Title:
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Author:
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Xin Zhong Yin1 , Jiu Hui Chen1 , Zhigang Peng2 , Xiaofeng Meng3,4, Qi Yuan Liu1, Biao Guo1, and Shun Cheng Li1 |
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Adress: |
1State Key Laboratory of Earthquake Dynamics, Institute of Geology, CEA, Beijing, China, |
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Abstract:
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Using seismic data recorded by a dense temporary seismic array, we apply a waveform
matched-filter technique and obtain an early aftershock catalog around the mainshock rupture zone of
the 2008 Wenchuan, Sichuan, China, earthquake. Specifically, we use 1,273 events in a relocated aftershock
catalog as templates and scan through the waveforms within 7 days following the mainshock. We obtain
up to ∼5.3 and ∼10 times more aftershocks than the standard and relocated catalogs, respectively. We find
that early aftershocks mostly occurred below 10 km depth, downdip to large coseismic slip areas. Early
aftershocks also show minor along-strike migration with time since the mainshock, indicating triggering
of afterslip following the mainshock. From the epicentral region to Beichuan where the mainshock slip
was primarily reverse faulting, early aftershocks illustrated the Yingxiu-Beichuan and Guanxian-Jiangyou
faults as high-angle listric feature and rooted to a gentle dipping plane at the depth of ∼20 km. The
aftershocks in the northeast segment of the Longmen Shan faults mostly occurred along a near-vertical
dipping fault, consistent with the primary strike-slip component of mainshock slip in this region. In addition,
differences in early and long-term aftershock distribution indicate significant postseismic deformation along
the conjugate Xiaoyudong fault. Our results help to illuminate the deep geometry of the Longmen Shan
fault zone and the early evolution after the Wenchuan mainshock, which provides additional constraints to
the mechanism of plateau uplifting. |
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