HR: 0800h
AN: S51A-0126 [Abstracts]
TI: Focal Mechanisms Of Recent Small To Moderate Sized Earthquakes And Seismogenic Faulting In The Korean
Peninsula
AU: * Shin, J
EM: jinsoo@kigam.re.kr
AF: Korea Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30,
Gajeong-dong, Yuseong-gu, Daejeon, 305-350
Korea, Republic of
AU: Kang, T
EM: tskang@snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu,
Seoul, 151-747
Korea, Republic of
AU: Baag, C
EM: baagce@snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu,
Seoul, 151-747
Korea, Republic of
AU: Lee, H
EM: leel@kigam.re.kr
AF: Korea Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30,
Gajeong-dong, Yuseong-gu, Daejeon, 305-350
Korea, Republic of
AB:
We estimate faulting geometry of 88 small to moderate sized earthquakes since 2001 in and around the Korean Peninsula using
polarities of first-arrival P-waves recorded by the local seismic network in Korea. Overall pattern of the inverted solutions
indicates a combination of thrust and strike-slip faulting characterized by nodal planes striking in the WNW-ESE direction
although some biases for small events exist owing to the local heterogeneity of stress field. We analyze the stress fields
acting in and around the Korean Peninsula by inverting the compressional and tensional axes of the focal mechanisms. The
results show a compressional regime with maximum stress in the NE-SW direction, coinciding with the direction of compression
derived from geological information. Some moderate earthquakes show misfits of nodal planes and slip vectors with respect to
the stress tensor. In particular, the 29 May 2004, Mw=5.1, offshore Uljin, Korea, earthquake shows the nearly north-trending
nodal plane with thrust faulting motion. This indicates that strain orientation of earthquakes occurring in and around the
Korean Peninsula varies significantly owing to the orientations of preexisting faults.
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting