HR: 1340h
AN: S23B-1370    [Abstracts]
TI: Finite-frequency sensitivity of seismic observables to mantle anisotropy based upon adjoint methods
AU: * Sieminski, A
EM: anne@geo.uu.nl
AF: Department of Earth Sciences Utrecht University, PO Box 80021, Utrecht, TA 3058, Netherlands
AU: Liu, Q
EM: lqy@gps.caltech.edu
AF: Seismological Laboratory, Californian Institute of Technology, Pasadena, CA 91125, United States
AU: Trampert, J
EM: jeannot@geo.uu.nl
AF: Department of Earth Sciences Utrecht University, PO Box 80021, Utrecht, TA 3058, Netherlands
AU: Tromp, J
EM: jtromp@gps.caltech.edu
AF: Seismological Laboratory, Californian Institute of Technology, Pasadena, CA 91125, United States
AB: We study the sensitivity of finite-frequency seismic waves to mantle anisotropy based upon kernels calculated by combining adjoint methods with spectral-element modeling of seismic wave propagation. We are mainly interested in surface-wave and SKS-splitting observables since these are the most popular data for studying mantle anisotropy. Anisotropy is described by the 21 elastic parameters naturally involved in asymptotic wave propagation in weakly anisotropic media. Our results illustrate the complexity of wave propagation in anisotropic models and emphasize the importance of full waveform modeling to accurately capture the sensitivity of finite- frequency data. The main characteristic of anisotropic sensitivity is a prominent path-dependence. For surface waves, significant effects due to mode coupling are also observed. They are a major feature for the higher modes. We investigate the sensitivity of SKS splitting through the 'splitting intensity', which characterizes the perturbation of the transverse signal. We show that this observable can efficiently be measured with a cross- correlation technique. SKS-splitting intensity 'senses' mantle anisotropy in a very different way than the surface waves. The sampling region of this observable is mainly confined to the upper mantle beneath the station, and it is sensitive to a much smaller number of elastic parameters.
DE: 7203 Body waves
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7255 Surface waves and free oscillations
DE: 7270 Tomography (6982, 8180)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting