HR: 13:55h
AN: S23D-02    [Abstracts]
TI: Tomographic Image of Subducting Lithosphere beneath Indonesia
AU: * Pesicek, J
EM: pesicek@geology.wisc.edu
AF: University of Wisconsin-Madison, 1215 W Dayton St., Madison, WI 53706,
AU: Thurber, C
EM: clifft@geology.wisc.edu
AF: University of Wisconsin-Madison, 1215 W Dayton St., Madison, WI 53706,
AU: Widiyantoro, S
EM: sriwid@geoph.itb.ac.id
AF: Bandung Institute of Technology, Jalan Ganesha 10, Bandung, 40132, Indonesia
AU: Engdahl, E R
EM: engdahl@iaspei.org
AF: University of Colorado, Campus Box 390 UCB, Boulder, CO 80309,
AU: DeShon, H
EM: hdeshon@memphis.edu
AF: CERI, University of Memphis, 3890 Central Ave., Memphis, TN 38152,
AB: We present tomography results for Indonesia, with emphasis on the Sumatra region, from the inversion of teleseismic arrival times for regional earthquakes occurring during the period 1918-2006 and global earthquakes occurring 1964-2006. The earthquake locations are well-constrained teleseismically by the Engdahl, van der Hilst, and Buland (EHB) method of single event relocation and cover the region 15 degrees S to 25 degrees N, 90 to 135 degrees E. We invert these data using a finely-gridded regional model (0.5 degrees horizontally) nested within a coarsely-gridded global model (5 degrees horizontally). Cell thicknesses increase with depth from the surface, where they are 35 km and 110 km thick for the regional and global grids, respectively. The use of the coarse global grid helps minimize the effects of lateral heterogeneity from outside the region of interest. We trace rays through the ak135 global velocity model for primary phases and depth phases. Inclusion of data from the 2004-2005 megathrust sequences greatly improves ray path sampling and resolution in the Sumatra region as compared to previous models for the region. Preliminary, single-iteration results show clear recovery of the high- velocity slab in much of the region, with significant variations in the dip of the slab observed along the 2004-2005 rupture zones, consistent with dips inferred by EHB event relocations. In addition, our results illuminate plate boundary structure at the northern end of the trench offshore Burma where oceanic subduction transitions into continental collision. Synthetic and checkerboard resolution tests will be used to assess the quality of the results, and future versions will benefit from an iterative solution and improved phase data.
DE: 7270 Tomography (6982, 8180)
DE: 8123 Dynamics: seismotectonics
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
DE: 8180 Tomography (6982, 7270)
SC: Seismology [S]
MN: 2007 Fall Meeting