A Result of Relocation of Earthquakes in Taiwan from 1991 to 2005 by a New 3D Tomography Model
Reporter : Chen Jo-Hao
Abstract
There have been many efforts on the inversions of 3D P- and S-wave velocity structures using the CWBSN stations. In this study, we obtained the regional 3D P-wave and VP/VS structures by combining S-P times from the Taiwan Strong Motion Instrumentation Program (TSMIP) records with the P- and S-wave arrival times from the CWBSN stations, and we used the new 3D velocity model to relocate the earthquakes from CWBSN catalog. In this study, except for 90 CWBSN stations, we use three-prong approach to acquire further accuracy of the earthquake locations. First, authors include the S-P times from the TSMIP stations. Because of the ‘accurate S-P times records and The TSMIP consists of 680 digital accelerographs at free-field sites. Secondary, the offshore events are almost always outside the CWBSN network, so we incorporate the 18 Japan Meteorological Agency (JMA) stations improve the coverage to enhance the location accuracy to the east coast. Thirdly, we adopted 3D VP and VP/VS models in predicting the travel times of P and S waves. The effectiveness of the relocation results can be seen in three aspects: (1) the reduction in the residuals of P-wave arrival times and S-P times (2) a better understanding of the attenuation relationship between the peak-ground acceleration and epicentral distance, and (3) the geologically meaningful patterns of station corrections to P-wave arrival times and S-P times. Finally, we discuss the KIM ‘ s 3D tomogrophy model (2005) with the new 3D velocity model of this study (Wu, 2007) in the Longitudinal Valley .
Reference
Wu, Y. M , C. H. Chang , L. Zhao, T. L. Teng, and M. Nakamura. A Comprehensive Relocation of Earthquakes in Taiwan from 1991 to 2005. Bulletin of the Seismological Society of America, Vol. 98, No. 3, 2008.
Wu, Y. M., C. H. Chang, L. Zhao, J. B. H. Shyu, Y. G. Chen, K. Sieh, and J. P. Avouac. Seismic tomography of Taiwan: improved constraints from a dense network of strong-motion stations, J. Geophys. Res. 112, B08312, 2007.