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Distribution of seismic wave speed changes associated with the 12 May 2008 Mw 7.9 Wenchuan earthquake
Author(s) -
Chen Jiu Hui,
Froment Bérénice,
Liu Qi Yuan,
Campillo Michel
Publication year - 2010
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 - 10.1029/2010gl044582
Subject(s) - seismology , seismometer , geology , seismic microzonation , seismic noise , seismic wave , fault (geology) , environmental seismic intensity scale , seismic gap , earthquake scenario , geodesy , seismic hazard
We used continuous recordings in Sichuan, China to track the temporal change of the seismic wave speed at a regional scale, for 2 years including the Wenchuan Mw 7.9 earthquake. The data are recorded by a temporary network of 156 broad‐band seismographs in a region that covers the southern 2/3 of the fault activated during the earthquake. A doublet analysis applied on the codas of seismic noise cross correlation functions is used to detect temporal velocity changes. We found clear evidence that the seismic velocity drops by up to 0.08% in the fault region just after the earthquake with fluctuations within 0.02% before the earthquake. We compared the measurements in different sub‐arrays to get a spatial distribution of the velocity changes. This distribution is consistent with the volumetric strain change during the Wenchuan earthquake and shows that the co‐seismic velocity change is not controlled by the response of sediments.