Constraining 3-D Shear Velocity and Anisotropy Structure Beneath the Tien Shan from Shear Wave Splitting and Surface Wave Tomography

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This award provides support for studying the structure of crust and upper mantle in the central Tien Shan by analyzing body and surface wave data. The Tien-Shan is the most active intracontinental mountain belt on the Earth and is a unique place for investigating the mechanism and dynamic process of mountain building within a tectonic plate. There are two components in this study: shear-wave splitting analyses and surface wave tomography. The data used in this project are recorded by the CHENGIS network, a three-year seismic experiment consisting of twenty-eight broadband stations, the KNET network, a regional long-term array of eleven stations, and two permanent GSN stations. Both SKS and regional S waves are analyzed to obtain shear-wave splitting parameters at the stations in the central Tien Shan. In addition, Rayleigh and Love wave data are used to solve for 3D variations of shear-wave velocity and anisotropy. Together, these analyses can help to answer how the thickness and the strength of the lithosphere vary across the central Tien Shan and whether the Tien Shan range is generated by crust shortening alone or by coherent deformation in the lithosphere.