Seismogenic structures of the 1999 M-w 7.6 Chi-Chi, Taiwan, earthquake and its aftershocks

Abstract

High-resolution 3-D V-P and V-S velocity models around the source region of the M(w)7.6 Chi-Chi, Taiwan, earthquake show significant lateral and vertical variations. The mainshock occurred within a narrow low velocity zone along the Chelungpu fault. A sudden increase of velocity and seismicity took place across the Shuilikeng fault to the east. Most aftershocks were located in areas of high V-P and V-S. A sharp east-dipping zone extending from the Shuilikeng fault on the surface to a depth of about 15 km separates the low velocity region in the west from the high velocity region in the east. An apparent high-angle west-dipping seismic zone lies at depths of 15-30 km beneath the western Central Range. Numerous aftershocks with normal faulting were located west of the middle segment of the Chelungpu fault. (C) 2010 Elsevier BM. All rights reserved.