HR: 0800h
AN: T51A-0318    [Abstracts]
TI: Surface strain field in transition from arc-continent collision to subduction: GPS measurements in northern Taiwan, 1995-2005
AU: * Rau, R
EM: raurj@mail.ncku.edu.tw
AF: National Cheng Kung University, Department of Earth Sciences, National Cheng Kung University, Tainan, 701, Taiwan
AU: Ching, K
EM: kuenmiao@yahoo.com.tw
AF: National Cheng Kung University, Department of Earth Sciences, National Cheng Kung University, Tainan, 701, Taiwan
AU: Hsu, M
EM: raurj@mail.ncku.edu.tw
AF: National Cheng Kung University, Department of Earth Sciences, National Cheng Kung University, Tainan, 701, Taiwan
AU: Hu, J
EM: jchu@ntu.edu.tw
AF: National Taiwan University, Department of Geosciences, National Taiwan University, Taipei, 10617, Taiwan
AU: Lee, J
EM: jclee@earth.sinica.edu.tw
AF: Academia Sinica, Institute of Earth Sciences, Academia Sinica, Taipei, 115, Taiwan
AB: We present Global Positioning System (GPS) measurements for the period 1995-2005 at 126 sites in northern Taiwan. Based on surface strain field from the results, we describe the transitional tectonics from arc-continent (Luzon-Chinese) collision to the converging Ryukyu arc-trench subduction. Station velocities relative to the stable Chinese continental margin station, S01R, were derived from coordinate time-series of each station by solving weighted least-squares problems. Horizontal velocity field shows vectors of 0.3-7.3 mm/yr toward the NW in the south-western part of the network (Hsinchu area); velocities of 1.0-7.8 mm/yr from south to north rotating from 8° to 143° in the northern area of the network (Taipei area); and a clockwise rotation from west to east with vectors of 9.3-41.2 mm/yr from 53° to 146° in southeastern part of the network (Ilan area). Patterns of strain rate field show, from west to east, dominant NNW-SSE shortening in the Hsinchu area; N-S shortening and E-W lengthening in the Taipei area; and predominant NE-SW compression and NW-SE extension in the Ilan area. Furthermore, prominent clockwise block-rotation is indicated, respectively, in the northernmost Foothills-Hsuehshan Range and the northernmost Eastern Central Range. The northernmost Foothills- Hsueshan Range, bounded by a strike-slip fault to the north, is characterized by coherent motion (low internal strain rate of < 0.20 μstrain/yr) with the best fitting Euler pole located near the northeastern tip of the Ilan plain. For the northernmost Eastern Central Range, although showing block-like rotation motion, a large uncertainty was found for the best fitting Euler vector. Trench roll-back and back-arc opening probably superpose onto the arc-continent collision-induced rotation in the northernmost Eastern Central Range.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 8104 Continental margins: convergent
DE: 8108 Continental tectonics: compressional
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting