TOMOGRAPHIC IMAGERY OF P WAVE VELOCITY STRUCTURE IN THREE GORGES REGION
三峡地区P波速度层析成像研究

The P wave velocity structure is studied on the basis of the 17 324 P wave arrive data recorded by the Three Gorges seismic telemetry network and other ten stations around it from 2001 to 2006.The result of the tomography indicates that the lateral inhomogeneity of the P wave velocity structure in the region is significant.The distribution of the velocity in shallow layer is closely related to the geological tectonic of the surface.The change of the P wave velocity from upper crust to lower crust is consistent with the evolution history of the tectonic stress filed.The Zigui M5.1 earthquake occured in sharp gradient zones of velocity and located between the zones of low velocity and high velocity zone.