The chi-Chi earthquake sequence: active, out-of-sequence thrust faulting in taiwan
We combined precise focal depths and fault plane solutions of more than 40 events from the 20 September 1999 Chi-Chi earthquake sequence with a synthesis of subsurface geology to show that the dominant structure for generating earthquakes in central Taiwan is a moderately dipping (20 degrees to 30 degrees ) thrust fault away from the deformation front. A second, subparallel seismic zone lies about 15 kilometers below the main thrust. These seismic zones differ from previous models, indicating that both the basal decollement and relic normal faults are aseismic.
Kao
H
Institute of Earth Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, Republic of China. Department of Geology and Mid-America Earthquake (MAE) Center, University of Illinois, Urbana, IL 61801, USA.
Chen
WP