HR: 0830h
AN: S31E-0818    [PDF]
TI: Seismic Structure of India from Regional Waveform Matching
AU: Gaur, V
EM: gaur@cmmacs.ernet.in
AF: Indian Institute of Astrophysics, II Block, Koramangala, Bangalore, 560 034 India
AU: * Maggi, A
EM: alessia.maggi@eost.u-strasbg.fr
AF: EOST, 5 rue Descartes, Strasbourg, 67084 France
AU: Priestley, K
EM: keith@madingley.org
AF: Bullard Laboratories University of Cambridge, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Rai, S
EM: ssrai_ngri@rediffmail.com
AF: National Geophysical Research Institute, Uppal Road, Hyderabad, 500 007 India
AB: We use a neighborhood adaptive grid search procedure and reflectivity synthetics to model regional distance range (500-2000~km) seismograms recorded in India and to determine the variation in the crust and uppermost mantle structure across the subcontinent. The portions of the regional waveform which are most influenced by the crust and uppermost mantle structure are the 10-100~s period Pnl and fundamental mode surface waves. We use the adaptive grid search algorithm to match both portions of the seismogram simultaneously. This procedure results in a family of 1-D path average crust and upper mantle velocity and attenuation models whose propagation characteristics closely match those of the real Earth. Our data set currently consist of $\sim$20 seismograms whose propagation paths are primarily confined to the Ganges Basin in north India and the East Dharwar Craton of south India. The East Dharwar Craton has a simple and uniform structure consisting of a 36$\pm$2 km thick two layer crust, and an uppermost mantle with a sub-Moho velocity of 4.5~km/s. The structure of northern India is more complicated, with pronounced low velocities in the upper crustal layer due to the large sediment thicknesses in the Ganges basin.
DE: 7205 Continental crust (1242)
DE: 7215 Earthquake parameters
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2003 Fall Meeting