HR: 1340h
AN: S13B-1062    [Abstracts]
TI: Seismic Attenuation Structure of India Using Lg Coda Q Measurements
AU: * Rowlands, D P
EM: rowlands@esc.cam.ac.uk
AF: Bullard Laboratories, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Mitra, S
EM: mitra@esc.cam.ac.uk
AF: Bullard Laboratories, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Bonner, J L
EM: bonner@westongeophysical.com
AF: Weston Geophysical Corporation, 57 Bedford Road Suite 102, Lexington, MA 02420 United States
AU: Priestley, K
EM: keith@esc.cam.ac.uk
AF: Bullard Laboratories, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Rai, S S
EM: SSRAI\_NGRI@rediffmail.com
AF: NGRI, Uppal Road, Hyderabad, 500 007 India
AU: Gaur, V K
EM: gaur@ccmacs.ernet.in
AF: CMMACS, NAL Belur Campus, Bangalore, 560 037 India
AB: Q measurements from the coda of Lg waves provide excellent constraint on the attenuation structure along source-receiver paths. Lg coda Q values are strongly dependent on crustal structure and generally correlate very well with the tectonic histories of the regions sampled -- high Lg coda Q is typical of tectonically inactive regions (e.g., cratons) whilst low Lg coda Q is typical of tectonically active regions (e.g., active orogenic belts). We use a new tomographic algorithm and the most comprehensive dataset yet obtained from permanent and temporary seismic stations distributed throughout the Indian sub-continent to investigate variations of Lg coda Q in this region. Of particular interest are possible variations between the different cratons which comprise the Indian peninsula. For example, the presence of the Deccan Traps within a much older craton provides an excellent test of the sensitivity of Lg coda Q to relatively recent tectonic events. Initial results show that Lg coda Q varies between 450 and 700 for different regions within India and further analysis will be used to constrain the data in terms of geologic and tectonic provinces. We compare our observations of the scattering Q structure in India with those from previous intrinsic Q studies in the region in order to relate the different attenuation mechanisms.
DE: 7205 Continental crust (1242)
DE: 7218 Lithosphere and upper mantle
SC: Seismology [S]
MN: 2004 AGU Fall Meeting