HR: 11:35h
AN: G12A-06    [Abstracts]
TI: A Block Model for the Interseismic Deformation in the Taiwan Arc-Continent Collision Zone
AU: * Tsai, M
EM: minchyen@earth.sinica.edu.tw
AF: Institute of Geophysics, National Central University, No.300, Jhongda Rd., Jhongli City, Taoyuan County, 32001, Taiwan
AU: Yu, S
EM: yusb@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Sec.2, Academia Rd., Nankang, Taipei County, 115, Taiwan
AU: Chen, H
EM: chenhy@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Sec.2, Academia Rd., Nankang, Taipei County, 115, Taiwan
AU: Chen, H
EM: hwchen@earth.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No.300, Jhongda Rd., Jhongli City, Taoyuan County, 32001, Taiwan
AB: The southern Taiwan is a key region for understanding the Taiwan arc-continent collision. The active collision between the Eurasia and Philippine Sea plates results in numerous folds and thrust faults in the area. A converging rate of about 80 mm/yr is observed across the collision zone. Approximately half of the convergence is accommodated in the fold and thrust belt of southwestern Taiwan and another half is taken up in the Longitudinal Valley and the Coastal Range in eastern Taiwan. In this area, a continuous GPS array of about 100 stations is now in operation and most of the 210 densely-deployed survey-mode sites have been occupied at least once annually since 1994. A detailed new velocity field is derived from GPS time series analysis of all available survey-mode and continuous GPS data in southern Taiwan from 1994 to 2006. With respect to Paisha (S01R), Penghu, located in the Chinese continental margin, the Luzon arc (Coastal Range, Lutao and Lanhsu) is moving northeastward at rates of 60-83 mm/yr. Across the Longitudinal Valley, a plate suture zone, a major velocity discontinuity of about 30 mm/yr is obvious. Crustal motion in the Chiayi-Tainan area of southwestern Taiwan shows nearly in the west direction with maximum rates of about 37-43 mm/yr and decrease to zero near the western coast. Further south in the Kaohsiung-Pingtung area, velocities increases southward and reaches 52-57 mm/yr in the southwest direction. Extrusion tectonics is significant here. Based on the new velocity field, a block model consisting of several blocks bounded by major active faults is employed to study the interseismic deformation in the Taiwan arc-continent collision zone. The block model includes the effects of block rotation and strain accumulation in an earthquake cycle. The block boundaries used are the Chukou Fault, Chishan Fault, Chaochou Fault, and Longitude Valley Fault. From this modeling study, we may estimate the present-day fault-slip rates of major active faults and detect the possible locations of blind faults. The results can be utilized in seismic hazard analysis.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8158 Plate motions: present and recent (3040)
SC: Geodesy [G]
MN: 2007 Fall Meeting