HR: 0800h
AN: T41B-1304    [Abstracts]
TI: Postseismic Displacements of the 1999 Mw 7.6 Chi-Chi, Taiwan Earthquake: 1999-2004 Survey-mode GPS Measurements in Central Taiwan
AU: * Chen, H
EM: lsb23012@mail.lsb.gov.tw
AF: Land Survey Bureau, 4F No 497 Sec. 2,Liming RD., Taichung City, 408 Taiwan
AU: * Chen, H
EM: lsb23012@mail.lsb.gov.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Rau, R
EM: raurj@mail.ncku.edu.tw
AF: Land Survey Bureau, 4F No 497 Sec. 2,Liming RD., Taichung City, 408 Taiwan
AU: Tseng, C
EM: Tseng@sgrc.ncku.edu.tw
AF: Land Survey Bureau, 4F No 497 Sec. 2,Liming RD., Taichung City, 408 Taiwan
AB: The 1999 Mw 7.6 Chi-Chi, Taiwan earthquake caused an approximately 100-km-long surface rupture and more than 2000 people death. The coseismic displacements are about 1.1-9.1 m on the hanging wall of the Chelunpu (CLP) and Tamaopu (TMP) fault. To maintain the national coordinate system and realize the post-Chi-Chi displacement, the Land Survey Bureau (LSB) of Taiwan deployed ten survey-mode GPS measurements in central Taiwan after the Chi-Chi earthquake between December 1999 and December 2004. 94 GPS stations were measured each time, each session lasted 7 hours. Bernese 4.2 software was used to process the GPS data. The precise orbits data were obtained from International GPS Service (IGS) data center. The observed data were constrained on the station S01R, located on the stable Chinese continental margin. Results show that the Chi-Chi source areas remain active even five years after the main shock. Post-seismic horizontal displacements show that most post-seismic deformations occur along the hanging-wall of the CLP fault and TMP fault. Displacement at east of TMP fault is nearly 130-20 mm from south to north. Between CLP fault and TMP fault the displacement is nearly 40-60 mm in NS direction and 100-130 mm in EW direction. Velocity in this region decreases from south to north. The post-seismic displacement of the foot-wall of CLP fault is not significant and is less than 20 mm. Post-seismic horizontal displacement of 2002-2004 at east of TMP fault is about 40-100 mm from south to north. From 2002 to 2004, displacement is about 29-50 mm between CLP fault and TMP fault and is about 2-20 mm on the west of the CLP fault. The five-year post-Chi-Chi deformation in central Taiwan provides us a great opportunity to examine how the tectonic stress changes in the source region after a large earthquake occurred.
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7209 Earthquake dynamics (1242)
DE: 7212 Earthquake ground motions and engineering seismology
SC: Tectonophysics [T]
MN: Fall Meeting 2005