HR: 0800h
AN: S11B-0555    [Abstracts]
TI: Transition Zone Structure Beneath the Tibetan Plateau From P-Wave Triplications
AU: * Chu, R
EM: chur@eas.slu.edu
AF: Saint Louis University, 3642 Lindell Blvd., St. Louis, MO 63108, United States
AU: Zhu, L
EM: lupei@eas.slu.edu
AF: Saint Louis University, 3642 Lindell Blvd., St. Louis, MO 63108, United States
AU: Helmberger, D V
EM: helm@gps.caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AB: We use upper-mantle triplication waveforms to determine upper mantle velocity structure beneath the Tibetan plateau. The data were recorded from 1500 earthquakes in the distance range between 12 and 30 degrees by more than 300 temporary and permanent seismic stations around Tibet since 1990. To eliminate source signatures in the waveforms and isolate structural responses, we developed a new method to estimate the source time function (STF) using records at teleseismic distances. A time-domain iterative deconvolution algorithm was used to remove the estimated STF from the data. The source-free triplicated P waveforms were then stacked and modeled using generalized ray theory. Preliminary results show that the 660-km discontinuity beneath the plateau is deeper than the global average, and the velocity contrast across the discontinuity is smaller in central Tibet.
DE: 7200 SEISMOLOGY
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8104 Continental margins: convergent
SC: Seismology [S]
MN: 2007 Fall Meeting