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A Simultaneous Multiphase Approach to Determine P-Wave and S-Wave Attenuation of the Crust and Upper Mantle

Lawrence Livermore National Laboratory, 7000 East Avenue L-046, P.O. Box 808 Livermore, California 94551

We have generalized the methodology of our regional amplitude tomography from the Lg phase to the four primary regional phases (Pn, Pg, Sn, Lg). Differences in the geometrical spreading, source term, site term, and travel paths are accounted for, while event source parameters such as seismic moment are consistent among phases. In the process, we have developed the first comprehensive regional P-wave and S-wave attenuation model of the crust and upper mantle by simultaneously using the amplitudes of four regional phases. When applied to an area encompassing the Middle East, eastern Europe, western Asia, south Asia, and northeast Africa for the 1–2 Hz passband, we find large differences in the attenuation of the lithosphere across the region. The tectonic Tethys collision zone has high attenuation, while stable outlying regions have low attenuation. While crust and mantle Q variations are often consistent, we do find several notable areas where they differ considerably but are appropriate given the region’s tectonic history. Lastly, the relative values of Qp and Qs indicate that scattering Q is likely the dominant source of attenuation in the crust at these frequencies.