Imaging the Earth's Converging Tectonic Plates
College: Liberal Arts and Sciences
Award year: 1999-2000
Data collected during the Chi-Chi earthquake sequence provide insights into active deformation of a young collision zone where a relic passive margin is partially preserved. We combined precise focal depths and fault plane solutions of over 40 events with a synthesis of subsurface geology to show that the most important seismogenic structure in central Taiwan is an out-of-sequence thrust away from the deformation front. Intriguingly, a second, sub-parallel seismogenic zone lies about 15 km deeper than the main thrust, a configuration never well-documented elsewhere. Contrary to previous proposals, neither the basal decollement nor relic normal faults appears to be seismogenic.