HR: 1340h
AN: T43A-1381    [Abstracts]
TI: Constraints on the Crust and Uppermost Mantle Structure of the Indian Shield From Regional Seismic Waveforms
AU: * Julia, J
EM: jordi@seis.sc.edu
AF: University of South Carolina, Department of Geological Sciences 701 Sumter St., Columbia, SC 29201
AU: Owens, T J
EM: owens@seis.sc.edu
AF: University of South Carolina, Department of Geological Sciences 701 Sumter St., Columbia, SC 29201
AU: Rai, S S
EM: raiss@rediffmail.com
AF: NGRI, Uppal Rd, Hyderabad, 500007 India
AB: The Indian Shield can be regarded as an amalgamation of several Precambrian terranes, ranging in age from early Archean to late Proterozoic. Knowledge of the crust and uppermost mantle structure of this region is important to improve our understanding of the Precambrian evolution of continents. Seismic characterization of the shield, however, is restricted to scattered receiver function studies at single seismic stations, some early teleseismic surface wave studies and a few, short-range seismic profiles. We have been collaborating since the late 1990s to collect broadband data in southern India for the purpose of characterizing the crust and upper mantle structure throughout India. Data from 22 different sites have been collected for periods of 6 months to 2 years. The network recorded high-quality regional seismic waveforms originating from earthquakes along the Himalayan front ranging in magnitude from 4.6 to 7.4. The paths to our stations in southern India provide unique sampling of the entire peninsula from North to South. Additionally, a number of intraplate events were recorded, mostly occuring in the Khachh basin to the East. The surface-wave propagation signature is clear in the waveforms at periods as long as 50 seconds for most of these paths. We use this signature to obtain first-pass models of the regional structure of the Indian shield. The resulting models are then utilized to obtain focal mechanisms for the regional event sources and to determine more detailed regional waveform models of structure using higher frequencies. We expect the results of our analysis will help characterize the Indian Shield structure on a regional scale and refine our understanding of Precambrian crustal evolution.
DE: 7205 Continental crust (1219)
DE: 7255 Surface waves and free oscillations
DE: 8038 Regional crustal structure
DE: 8103 Continental cratons
DE: 8125 Evolution of the Earth (0325)
SC: Tectonophysics [T]
MN: Fall Meeting 2005