Distribution of seismic wave speed changes associated with the 12 May 2008 Mw 7.9 Wenchuan earthquake
Article first published online: 17 SEP 2010
Copyright 2010 by the American Geophysical Union.
Geophysical Research Letters
Volume 37, Issue 18, September 2010
How to Cite
2010), Distribution of seismic wave speed changes associated with the 12 May 2008 Mw 7.9 Wenchuan earthquake, Geophys. Res. Lett., 37, L18302, doi:10.1029/2010GL044582., , , and (
- Issue published online: 17 SEP 2010
- Article first published online: 17 SEP 2010
- Manuscript Accepted: 12 JUL 2010
- Manuscript Received: 4 JUL 2010
- Wenchuan earthquake;
- seismic velocity;
- ambient noise
 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.