HR: 0800h
AN: T51A-0316    [Abstracts]
TI: Evidence of a slab of subducted lithosphere beneath central Taiwan from teleseismic S waves
AU: * Chen, P
EM: bob@earth.ncu.edu.tw
AF: Institute of Geophysics, National Central University, No. 300, Jhongda Rd, Jhongli, 32001, Taiwan
AU: Chiao, L
EM: chiao@ntu.edu.tw
AF: Institute of Oceanography, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan
AB: Knowing whether there is a slab of subducted lithosphere beneath central Taiwan is important for our understanding of the regional tectonic evolution. Seismic waves propagating through a slab exhibit earlier arrivals, smaller amplitudes, and broader waveforms relative to those undisturbed. While P waves from Tonga- Kermadec deep and intermediate-depth earthquakes, relative to Kinmen station, exhibit reduced amplitudes and travel times for central Taiwan stations (Chen et al., 2004), we incorporate observations of S wave in this study to have better constraint. The Generic Array Processing (GAP) software package (Koper, 2005) is applied to process data recorded by Broadband Array in Taiwan Seismology (BATS). Genetic algorithm (GA) is used to simultaneously determine relative arrival times of BAT¡¦s stations with the cost function based on sum of cross- correlation over each pair stations. Preliminary results show that S waves of Tonga-Kermadec events exhibit stronger travel time reductions than those of P waves for central Taiwan stations, consistent with the effects of an eastern dipping aseismic slab. The possibility of crustal effects can be eliminated by having contrary observations for Hindu Kush events. Amplitude information will be included in further study.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8123 Dynamics: seismotectonics
DE: 8180 Tomography (6982, 7270)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting