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Spatial‐temporal evolutions of early aftershocks following the 2013 M w 6.6 Lushan earthquake in Sichuan, China
Author(s) -
Wu Jing,
Yao Dongdong,
Meng Xiaofeng,
Peng Zhigang,
Su Jinrong,
Long Feng
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2016jb013706
Subject(s) - aftershock , seismology , geology , foreshock , shock (circulatory) , induced seismicity , crust , geodesy , geophysics , medicine
We perform a comprehensive detection of early aftershocks following the 2013 M w 6.6 Lushan earthquake, which occurred in the southern Longmenshan Fault Zone in Sichuan Province, China, about 5 years after the 2008 M w 7.9 Wenchuan earthquake. We use events in both standard and relocated catalogs as templates to scan through continuous waveforms 2 days before and 3 days after the main shock. We successfully reduce the magnitude of completeness M c by more than 1 order and obtain up to 6 times more events than listed in both catalogs. Aftershocks in the first hour mostly occur around the main shock slip region, and aftershocks at later times show systematic expansions in the along‐strike, perpendicular‐strike, and updip directions. Although postseismic deformation following the Lushan main shock has not been clearly identified, we suggest that early aftershock expansions are likely driven by afterslip of the Lushan main shock. This is consistent with the observations that most aftershocks were in the stress shadow of the Lushan main shock and that there was significant slip deficit in the top 10 km of the crust. We also find that seismicity on the back thrust fault was activated as soon as 20 min after the main shock, earlier than previously reported. We are unable to detect any clear foreshocks in the last 2 days before the Lushan main shock.