HR: 1330h
AN: T12C-0481    [PDF]
TI: Deformation Mechanism of the southern ending of the Chi-Chi earthquake
AU: * Lee, Y
EM: dawn.forest@msa.hinet.net
AF: National Chung-Cheng University, 160, San-Hsing Min-Hsiung Chia-Yi Taiwan, R.O.C. 2Geological Survey, R.O.C., P.O. Box 968, Taipei, R.O.C., Chia-Yi, 621 Taiwan
AU: Lu, S
EM: ding@linx.moeacgs.gov.tw
AF: Central Geological Survey, Geological Survey, R.O.C., P.O. Box 968, Taipei, R.O.C, Taipei, 235 Taiwan
AU: Shih, T
EM: loose@linx.moeacgs.gov.tw
AF: Central Geological Survey, Geological Survey, R.O.C., P.O. Box 968, Taipei, R.O.C, Taipei, 235 Taiwan
AU: Ho, C
EM: hcs@linx.moeacgs.gov.w
AF: Central Geological Survey, Geological Survey, R.O.C., P.O. Box 968, Taipei, R.O.C, Taipei, 235 Taiwan
AU: Rau, R
EM: raurj@mail.ncku.edu.tw
AF: National Chen-Kung University, No.1, Ta-Hsueh Road, Tainan 701, Taiwan., Tainan, 701 Taiwan
AB: The 1999 Chi-Chi earthquake, Mw 7.6, which resulted a nearly 100-km length surface rupture, was caused by the activation of the low angle thrust Chelungpu fault. Previous studies show that in the southern segment of the Chelungpu fault, the N-S trending surface rupture turns into SW trending and becomes dominantly right lateral strike-slip faulting along the pre-existing Tachienshan fault. However, according to the coseismic GPS slip vector data and field surveys, we found that the NW-trending Luliao fault was also activated during the Chi-Chi earthquake and the SW trending surface rupture (Tachienshan fault) could extend to the west and along the Meishan fault, which was active at 1906, M=7.1. Therefore, we separate the southern end of the Chi-Chi earthquake into three blocks bounded by three coseismic active faults: the N-S trending Chelungpu fault with thrusting dominantly, SE trending Luliao fault with left-lateral strike slip faulting dominantly, and SW to EW trending Tachienshan-Meishan fault system (T-M fault) with right-lateral strike slip faulting dominantly. The strain compatibility of these three faults could explain the southern ends of the Chi-Chi earthquake. Furthermore, the deformation process could be derived according the characteristics of slip vector of surface rupture and GPS data. At first, the Chi-Chi earthquake ruptured southwestward and activated the Chelungpu fault and Tachienshan fault. Then, the Chi-Chi earthquake rotated clockwise to the NW direction and slipped northward accompanying the NW trending Luliao fault­Ýs development as the lateral ramp of the Chi-Chi earthquake. Finally, one month later the Meishan fault was triggered at October 22th, 1999.
DE: 8000 STRUCTURAL GEOLOGY (New field, replaces single entry 8165)
DE: 8123 Dynamics, seismotectonics
SC: Tectonophysics [T]
MN: 2003 Fall Meeting