HR: 1340h
AN: S43B-1000    [Abstracts]
TI: An Investigation of the Subsurface Structure and P- and S-wave Velocities in the Taipei Basin, Taiwan
AU: * Chen, Y
EM: s1622014@cc.ncu.edu.tw
AF: US Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, CA 94025 United States
AU: * Chen, Y
EM: s1622014@cc.ncu.edu.tw
AF: National Central University of Taiwan, 300 Chungda Rd., Chungli, 320 Taiwan
AU: Lee, Y
EM: shane@usgs.gov
AF: National Central University of Taiwan, 300 Chungda Rd., Chungli, 320 Taiwan
AU: Wang, C
EM: wangcy@cc.ncu.edu.tw
AF: National Central University of Taiwan, 300 Chungda Rd., Chungli, 320 Taiwan
AB: Over the past ten years, the Taiwan Central Geological Survey has conducted a wide-range of investigations of the Taipei basin by drilling over 30 wells (100-700m). During the same period, we have also scanned the basin area (20$\times$20 km) using over 300 shallow P-wave reflection seismic lines and many S-wave surveys (including S-wave reflection and surface-wave dispersion analysis: MASW). The purpose of this report is to present our compilation of these seismic data, incorporating it with the borehole drilling results to better describe the Tertiary basement, the Quaternary layers above the basement, and their P- and S-wave velocities. It is found that : 1) the deepest part of the basin basement is probably at the outlet of the Tanshui river, i.e., at the NW corner of the basin; 2) the Kanchiao fault forms a boundary bisecting the basin into a deep NW part and a shallow SE part; 3) the Sungshan and Chingmei formations are relatively flat deposits on the top, which implies the existence of a quiet deposition period since about 100,000 years ago; 4) the P- and S-wave velocities inside the basin are 1500-2200 m/s and 170-880 m/s in sediments, and 3000 m/s and 1500 m/s for the basement, respectively. A detailed 3D P- and S-wave velocity distribution is now available for other research in the Taipei basin.
DE: 7223 Seismic hazard assessment and prediction
DE: 8105 Continental margins and sedimentary basins
DE: 7205 Continental crust (1242)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting