HR: 0800h
AN: T51C-0462    [Abstracts]
TI: Broadband Seismic Imaging of Western Himalaya, Ladakh and Karakoram
AU: * Rai, S S
EM: ssrai_ngri@rediffmail.com
AF: National Geophysical Research Institute,, Uppal Road, Hyderabad, 500 007 India
AU: Singh, M P
AF: National Geophysical Research Institute,, Uppal Road, Hyderabad, 500 007 India
AU: Gupta, S
AF: National Geophysical Research Institute,, Uppal Road, Hyderabad, 500 007 India
AU: Chandra, S
AF: National Geophysical Research Institute,, Uppal Road, Hyderabad, 500 007 India
AU: Prakasam, K S
AF: National Geophysical Research Institute,, Uppal Road, Hyderabad, 500 007 India
AU: Gaur, V K
EM: gaur@cmmacs.ernet.in
AF: Indian Institute of Astrophysics,, Koramangala, Bangalore, 560034 India
AU: Priestley, K
EM: keith@esc.cam.ac.in
AF: Bullard Laboratories,, University of Cambridge, Cambridge, CB3 0EZ United Kingdom
AB: We present crust and mantle structure of the western Himalaya, Ladakh and Karakoram using teleseismic waveform data recorded on a 17 station broadband seismic network. 15 of the stations were operated along a N-S profile from Delhi (29 $\deg$N) to Karakoram (35 $\deg$N) and two on the eastern Ladakh. These stations were operated during Sept. 2002 - Dec. 2003 with station spacing varying from 40-70 km. The station configuration included CMG3T seismometer and REFTEK 72A-07 data logger recording waveforms at 20 samples per sec in continuous mode. We modeled good quality earthquake waveforms in terms of crustal S-wave velocity variation with depth and also the mantle layering using P-to-S converted receiver function approach. Important results are as follows- The Moho depth increases progressively from 40 km beneath Indo-Gangetic plain to $\sim$60 km below the Zanskar. Further north, below Indus suture, Ladakh and Karakoram the Moho depth is 70, 75 and 80 km, respectively. Apart from the mid crust low velocity below Indus suture and Ladakh, we observe a very significant velocity inversion in the mid crust from Indo-Gangetic plain to Main Central Thrust. The 410 and 660 km discontinuities are sharp and generally agree with the global reference model IASP91 along the profile. We also modeled the P-wave travel time data to define lateral velocity variation in crust and upper mantle.
DE: 8045 Role of fluids
DE: 8105 Continental margins and sedimentary basins
DE: 7205 Continental crust (1242)
DE: 1020 Composition of the crust
DE: 0905 Continental structures (8109, 8110)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting