HR: 15:10h
AN: T23F-07    [Abstracts]
TI: Attenuation Tomography of Northern California and the Yellow Sea / Korean Peninsula from Coda-source Normalized and Direct Lg Amplitudes
AU: * Ford, S R
EM: sean@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94720-4760, United States
AU: Dreger, D S
EM: dreger@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94720-4760, United States
AU: Phillips, W S
EM: wsp@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, United States
AU: Walter, W R
EM: bwalter@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, United States
AU: Mayeda, K
EM: kmayeda@yahoo.com
AF: Weston Geophysical, 181 Bedford Street, Suite 1, Lexington, MA 02420, United States
AU: Malagnini, L
EM: luca_malagnini@yahoo.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via de Vigna Murato 605, Roma, 00143, Italy
AB: We perform inversions for regional attenuation (1/Q) of Lg in two different regions. The path attenuation component of the Lg spectrum is isolated using the coda-source normalization method, which corrects the Lg spectral amplitude for the source using the stable, coda-derived source spectra. Tomographic images of Northern California agree well with one-dimensional (1-D) Lg Q estimated from five different methods. We note there is some tendency for tomographic smoothing to increase Q relative to targeted 1-D methods. For example in the San Francisco Bay Area, which contains high attenuation relative to the rest of it's region, Q is over- estimated by approximately 30. The over-estimation effect is investigated via the trade-off between resolution and error. We compare the coda-source normalized inversions with amplitude ratio tomography. Preliminary results in Northern California show that coda-source normalized amplitude tomography may produce better-resolved attenuation structure. We extend the analysis to the Yellow Sea / Korean Peninsula and compare with 1-D techniques.
DE: 5144 Wave attenuation
DE: 7218 Lithosphere (1236)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting