HR: 0800h
AN: S11B-0558    [Abstracts]
TI: Constraints on Mantle Heterogeneities Inferred From Forward Modeling of Seismic Wave Scattering
AU: * Alisic, L
EM: alisic@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Tromp, J
EM: jtromp@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AB: One of the open questions in geophysics is how small-scale heterogeneities in wave speed are distributed within the Earth's mantle. These heterogeneities can be caused by temperature and/or compositional variations, and are assumed to have a profound influence on mantle dynamics. Conversely, insight in the characteristics of the heterogeneities would yield valuable clues on aspects of mantle dynamics such as mixing. The aim of this study is to utilize scattering of seismic waves by heterogeneities to constrain their characteristics, such as size, directivity, strength and location. This is accomplished by adding heterogeneities to a smooth global velocity model, which is then used as input for the global spectral-element software SPECFEM3D_GLOBE. This code produces synthetic seismograms of the full wave field, where phases such as PKP arrive in a scattered manner because of the presence of the heterogeneities. In this study, different distributions of heterogeneities are created, with varying dimensions, strength and depth range. Comparison of the synthetic seismograms of these models with actual data includes analysis of precursors to PKP waves. This procedure allows us to determine if and how well we can constrain the characteristics of small-scale heterogeneities in the Earth's mantle.
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting