Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rau, R.-J. Articles by Shin, T.-C. Search for Related Content GeoRef GeoRef Citation

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

Department of Geological Sciences State University of New York at Binghamton, Binghamton, New York 13902-6000
Seismological Observation Center Central Weather Bureau, Taiwan, R.O.C.

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 in depths from 3 to 43 km, occurred in the area where mountain building is taking place. The data used were recorded between March 1991 and July 1994. Of the 97 earthquakes studied, the focal mechanisms of 23 of these determined on the basis of a 3D velocity model are remarkably different from the routine 1D results. In order to correct for the effect of attenuation on P- and S-wave amplitudes, Q_P and Q_S are determined using the spectral ratio method. Q_P ranges from 289 to 330 and Q_S from 201 to 301. The SH/P amplitude ratios are found to be very effective as constraints for choosing the best solutions among those consistent with the polarities. The resulting focal mechanisms show a high degree of variability across the island, but in terms of tectonic stress regimes, they show consistent patterns. They provide a glimpse of the mechanical processes under the Taiwan orogen.

This article has been cited by other articles:

				Y. Tan and D. Helmberger A New Method for Determining Small Earthquake Source Parameters Using Short-Period P Waves Bulletin of the Seismological Society of America, August 1, 2007; 97(4): 1176 - 1195. [Abstract] [Full Text] [PDF]

				Source Process of the Chi-Chi Earthquake: A Joint Inversion of Strong Motion Data and Global Positioning System Data with a Multifault Model Bulletin of the Seismological Society of America, October 1, 2004; 91(5): 1128 - 1143.

				Estimates of Stress Drop of the Chi-Chi, Taiwan, Earthquake of 20 September 1999 from Near-Field Seismograms Bulletin of the Seismological Society of America, October 1, 2004; 91(5): 1158 - 1166.

				Seismic Attenuation and Peak Ground Acceleration in Taiwan Bulletin of the Seismological Society of America, October 1, 2004; 91(5): 1229 - 1246.

				Using S/P Amplitude Ratios to Constrain the Focal Mechanisms of Small Earthquakes Bulletin of the Seismological Society of America, December 1, 2003; 93(6): 2434 - 2444.

				A New Method for Determining First-Motion Focal Mechanisms Bulletin of the Seismological Society of America, August 1, 2002; 92(6): 2264 - 2276.

				L. S. Teng, C. T. Lee, Y. B. Tsai, and L.-Y. Hsiao Slab breakoff as a mechanism for flipping of subduction polarity in Taiwan Geology, February 1, 2000; 28(2): 155 - 158. [Abstract] [Full Text] [PDF]

				A. Nakamura, S. Horiuchi, and A. Hasegawa Joint focal mechanism determination with source-region station corrections using short-period body-wave amplitude data Bulletin of the Seismological Society of America, April 1, 1999; 89(2): 373 - 383. [Abstract] [PDF]