HR: 1340h
AN: S53B-0196    [Abstracts]
TI: Study Of Attenuation Structure Based On The Dense Networks Around South Korea
AU: * Chung, T
EM: chungtw@sejong.ac.kr
AF: Sejong University, Kwanjin-ku, Seoul, 143-747 Korea, Republic of
AU: Matsumoto, S
EM: matumoto@sevo.kyushu-u.ac.jp
AF: Kyushu University, Shin-zan 2-5643-29, Shimabara, 855-0843 Japan
AB: There are few seismic studies of South Korea because this region has relatively quiet seismicity as a typical intraplate environment and lack of seismic stations (e.g. Lee et al., 2003). Recently, however, the densification of regional seismic network has been proceeded in S. Korea since 1999. Based on the dense network data, we first reported not only focal mechanisms of nationwide microseismicity (Chung et al., 2004) but also body wave attenuation structure for several regions (Chung and Sato, 2001; Kim et al., 2004) in S. Korea. These attenuation studies using the coda normalization method (CNM) showed very low {\it Q$_{P}$$^{-1}$} and {\it Q$_{S}$$^{-1}$} values comparable to those of seismically stable regions. By using the CNM, we also studied {\it Q$_{Lg}$$^{-1}$} value (Chung and Lee, 2003), which is similarly low value with {\it Q$_{S}$$^{-1}$}. To compensate the lack of data, the source pair/receiver pair method (SPRP) was applied to 71 earthquakes for further {\it Q$_{Lg}$$^{-1}$} attenuation study (Chung et al., 2004). The SPRP provided nearly 1500 source-receiver pairs and reproduced {\it Q$_{Lg}$$^{-1}$} for all frequencies less than 0.002, which is a reasonable value for a seismically inactive region. Lately, we have continued to analyze {\it Lg} attenuation structure by adding dense Japanese network located in Kyushu, near southeast of S. Korea. In this analysis, we used the reversed two-station method for collinearly aligned event and receiver pairs to correct azimuthal effect of {\it Lg} in the previous SPRP study. {\bf Refernces} Chung, T.W. and, H. Sato, 2001, BSSA, v.91, 1867-1874. Chung, T.W. and, K. Lee, 2003, BSSA, v.93, 1401-1406. Lee, K., N.S. Chung, and, T.W. Chung, 2003, BSSA, v.93, 2131-2145. Kim, K.D., T.W.Chung, J.B. Kyung, 2004, BSSA, v.94, 1070-1078. Chung, T.W., J.C. Park, and W. Kim, 2004, PEPI, in submitted. Chung, T.W., Y.K. Park, I.B.Kang, and K. Lee, 2004, BSSA, in submitted.
DE: 9320 Asia
DE: 7230 Seismicity and seismotectonics
DE: 7205 Continental crust (1242)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting