HR: 1340h
AN: G53A-0873    [Abstracts]
TI: Modeling Studies of Crustal Deformation in the Fold and Thrust Belt of Southwestern Taiwan
AU: * Tsai, M
EM: u7154400@cc.ncu.edu.tw
AF: Institute of Geophysics, National Central University, 300 Jongda Road, Chungli, TW 320 Taiwan
AU: Yu, S
EM: yusb@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Road, Sec.2, Nankang, Taipei, TW 115 Taiwan
AU: Chen, H
EM: chenhy@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Road, Sec.2, Nankang, Taipei, TW 115 Taiwan
AU: Kuo, L
EM: kuo@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Road, Sec.2, Nankang, Taipei, TW 115 Taiwan
AU: Hsu, Y
EM: yaru@earth.sinica.edu.tw
AF: Seismological Lab, Caltech, 1200 E. California Blvd, Pasadena, CA 91125 United States
AB: Combining the continuous GPS data with results from near-fault dense-spacing GPS surveys, we may detect locations and deformations of blind faults and estimate the present-day fault-slip rates. Southwestern Taiwan is situated in an active tectonic region, numerous thrusts and folds were formed due to continuous collision between the Eurasia and Philippine Sea plates. A converging rate of about 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. In this area, we have a dense continuous GPS array of 34 stations and more than 120 densely-deployed campaign-surveyed stations have been surveyed annually since 1998. GPS data from 1993 to 2005 of these continuous and campaign-surveyed sites are employed to study the crustal deformation in southwestern Taiwan. The velocity field in southwestern Taiwan displays two different characteristics. With respect to Penghu (S01R), the crustal motion in the Chiayi-Tainan area shows maximum rates of 35-43 mm/yr in the west-northwest to west directions and decrease to nearly zero in the coastal area. On the other hand, the velocities increase southward and change their directions to southwest. It reaches 50 mm/yr in the Kaohsiung-Pingtung area. There is a 6 mm/yr discontinuity on station velocities across the Jiuchiunken­DMuchiliao­DLiuchia fault. No surface creep is detected in the Chukou and Chishan faults. Inverting the GPS data by using a dislocation model in elastic half-space, the results show the interseismic slip is mainly along a sub-horizontal decollement at a depth of 7-10 km with an average slip rate of 43 mm/yr. The model predicts elastic strain accumulation at the western end of decollement, with it­Ęs surface projection located near Chukou fault. A new finite element code PYLith will be utilized to give a more realistic model. Thus, we may have a better understanding on the characteristics and mechanism of present-day crustal deformation in southwestern Taiwan.
DE: 0545 Modeling (4255)
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 1243 Space geodetic surveys
DE: 3270 Time series analysis (1872, 4277, 4475)
SC: Geodesy [G]
MN: Fall Meeting 2005