HR: 14:25h
AN: T13E-03    [Abstracts]
TI: Tomgraphic Structure of East Asia: Data and Results
AU: * Pei, S
EM: peisp@pku.edu.cn
AF: Peking University, Department of Geophysics School of Earth and Space Sciences, Beijing, 100871 China
AU: * Pei, S
EM: peisp@pku.edu.cn
AF: Institute of Tibetan Plateau Research, CAS, Beijing, 100085 China
AU: Chen, Y J
EM: johnyc@pku.edu.cn
AF: Peking University, Department of Geophysics School of Earth and Space Sciences, Beijing, 100871 China
AU: Zhao, D
AF: Ehime University, Geodynamics Research Center, Matsuyama, 790-8577 Japan
AU: Yin, A
AF: UCLA, Department of Earth and Space Sciences, Las Angeles, 90095 United States
AU: Ning, J
AF: Peking University, Department of Geophysics School of Earth and Space Sciences, Beijing, 100871 China
AU: Chen, X
AF: Peking University, Department of Geophysics School of Earth and Space Sciences, Beijing, 100871 China
AB: P-wave arrival times within the study area of 20§N-55§N and 100§E-145§E, were selected from three sources, including the ISC Bulletin of 1964-2001, the Annual Bulletin of Chinese Earthquakes of 1985-1998, and the Temporary Report of Chinese Earthquakes of 1999 to 2001. We also collected several thousands of P-wave arrival times recorded by Chinese regional networks in northeast China to improve the ray coverage there. Selection of earthquakes was based on the criteria that an individual teleseismic event has to be recorded not only by at least 10 stations but also by at least one station of the Chinese Seismic Networks. In total, we had selected 400,000 P-wave arrival times from 8002 regional earthquakes and 370,000 P-wave arrival times from 9000 teleseismic events. The combination of travel time residuals of regional earthquakes and relative travel time residuals of teleseismic events were used simultaneously in the tomographic inversion to determine the 3-D P-wave velocity structure above 1000 km depth. Moho depth variations in the region obtained from deep seismic reflection studies were incorporated in the tomographic inversion. Most important findings of this regional tomography are as follows. (1) No fast P-wave velocity anomalies can be related to subducted oceanic slabs beneath the 660-km discontinuity; instead the subducted oceanic slabs become flattened and stagnant in the transition zone. (2) The western end of the flat stagnant slabs is located ~ 1500 km west of the active trench in the western Pacific, which is correlated with the prominent surface topographic break in eastern China along the NNE-trending Taihang Mountain Range (~105øE). (3) Slow P-wave velocity anomalies are present at depths of 100-250 km below the active volcanic arc and the East Asia.
DE: 8110 Continental tectonics--general (0905)
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting