HR: 13:40h
AN: T13F-01    [Abstracts]
TI: Present-day Crustal Deformation in the Fold and Thrust belt of Southwestern Taiwan
AU: * Yu, S
EM: yusb@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Rd. Sec.2, Taipei, TW 115 Taiwan
AU: Tsai, M
EM: u7154400@cc.ncu.edu.tw
AF: Institute of Geophysics, National Central University, 300 Chungta Rd., Chungli, TW 320 Taiwan
AU: Kuo, L
EM: kuo@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Rd. Sec.2, Taipei, TW 115 Taiwan
AU: Chen, H
EM: chenhy@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Rd. Sec.2, Taipei, TW 115 Taiwan
AB: A converging rate of 80 mm/yr is observed across the Taiwan arc-continent collision zone, and approximately half of the convergence is accommodated in the fold and thrust belt of southwestern Taiwan. A dense continuous GPS array of about 40 stations was established in the area and put into operation in 1998-2001. Furthermore, more than 100 densely-deployed campaign-surveyed stations have been occupied annually since 1998. The GPS data collected from these continuous and campaign-surveyed stations for the time period between 1998 and 2003 were utilized to study the present-day crustal deformation in southwestern Taiwan. With respect to Penghu, the velocity field in the Chiayi-Tainan area shows crustal motion with maximum rates of 35-40 mm/yr in the west-northwest to west directions. In the Kaohsiung area, the crustal motion changes the direction to southwest and the rate reaches 45 mm/yr. A significant discontinuity on station velocities was detected between Kangshan and Chiaotou, the surface trace of an unknown right-lateral strike-slip fault may pass through this location. Near-surface creep of 8 mm/yr was also found across the Liuchia fault. GPS observations from several near-fault sites indicate that there is no surface creep on the Chukou, Hsinhua, and Houchiali faults. As a consequence of the collision between the Luzon arc and Chinese continental margin, the Chia-Nan area is undergoing E-W compressional tectonic stress and results in a rapid contracting rate of up to 40 mm/yr. On the other hand, extrusion tectonics is prominent in the Kaohsiung-Pingtung area. Preliminary dislocation modeling studies show the interseismic slip is mainly along a sub-horizontal decollement at a depth of 6-10 km with a slip rate of 45 mm/yr. The model predicts elastic strain accumulation at the western end of decollement, i.e., the active thrust fault system, that will be released in the future earthquakes.
DE: 7223 Seismic hazard assessment and prediction
DE: 3210 Modeling
DE: 1206 Crustal movements--interplate (8155)
DE: 1243 Space geodetic surveys
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting