HR: 0800h
AN: T51A-0319    [Abstracts]
TI: S-Splitting Measurements and Taiwan Orogeny
AU: * Kuo-Chen, H
EM: kuochen.hao@gmail.com
AF: Dept. of Geological Sciences, Binghamton University, Binghamton, NY 13902, United States
AU: Wu, F T
EM: francis@binghamton.edu
AF: Dept. of Geological Sciences, Binghamton University, Binghamton, NY 13902, United States
AU: Okaya, D A
EM: okaya@usc.edu
AF: Dept. of Earth Sciences, USC, Los Angeles, CA 90089, United States
AU: Huang, B
EM: hwbs@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academic Sinica, Taipei, 115, Taiwan
AU: Liang, W
EM: wtl@earth.sinics.edu.tw
AF: Institute of Earth Sciences, Academic Sinica, Taipei, 115, Taiwan
AB: Shear wave splitting is the most widely used method of quantifying anisotropy in the upper mantle and crust. We use broadband teleseismic shear waves (SKS and SKKS) recorded at the newly deployed TAIGER stations as well as BATS and CWB networks in Taiwan to obtain the splitting parameters: the fast wave polarization direction (φ) and delay time (δt). Altogether 50 good quality measurements were added to the database. By adding our measurements to those made previously by Rau et al. (2000) and Huang et al. (2006) we see an interesting pattern that appears in many compressive orogens, i.e., the fast direction following the local structural trend. This is especially true for the new measurements in the area around the Peikang basement high: they wrap around the high. In northernmost Taiwan the structural trend turns to nearly EW and the measured fast directions, both new and from the previous results, follow it. In terms of delay times at a station significant variations are sometimes observed; they appear to be a function of event back-azimuth and/or phase used (ScS, SKS or SKKS). The maximum delay time (2.6 sec) is at ENLB near the northern end of the Coastal Range and the minimum delay time (0.4 sec) is at KNMB just offshore of southeastern China. The connection between the crustal imprint and fast direction measurements, the effect of lateral variation of anisotropy as well as comparing mantle and crustal fabrics are to be elucidated.
DE: 8108 Continental tectonics: compressional
DE: 8160 Rheology: general (1236, 8032)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting