Regional Network focal mechanism determination using 3D velocity model and SH/P amplitude ratio

摘要: Abstract High-quality focal mechanisms within the Taiwan Seismic Network are determined utilizing first motions, SH/P amplitude ratios, and hypocentral locations obtained in a joint tomographic inversion. The small-to-moderate (2.7 ≦ M L 5.7) events, ranging depths from 3 to 43 km, occurred area where mountain building is taking place. data used were recorded between March 1991 July 1994. Of 97 earthquakes studied, of 23 these on basis 3D velocity model remarkably different routine 1D results. In order correct for effect attenuation P - S -wave amplitudes, Q using spectral ratio method. ranges 289 330 201 301. ratios found be very effective as constraints choosing best solutions among those consistent with polarities. resulting show high degree variability across island, but terms tectonic stress regimes, they patterns. They provide glimpse mechanical processes under orogen.