Refining Upper Mantle Models Beneath the Western United States

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There have been major advances in synthetic computational techniques and USArray will provide unprecedented amounts of data for analysis. As demonstrated in this proposal, several recent 3D surface wave tomographic models predict synthetics matching array data at periods greater than about 20s. These models augmented by enhanced bodywave tomographic images will be used to constrain the modeling of triplication data. Converted phases, i.e., Ps, etc., will be generated synthetically to verify these 3D models. We will investigate efficient routines for the modeling of the seismic data using 1D, 2D, and 3D codes and apply our techniques to older GSN, LRSM, and WWSSN data along with modern data (PASSCAL, CISN, Baja Array, etc.). Spectral-element (SEM) and Green's functions 2D finite-difference generated from this 3D model will allow more precise information about earthquakes to be determined (Historic and Future) and the extension of our local automated real-time source estimation system to cover events throughout the Western United States (M3.5). Directivity estimates for significant events can be obtained from site-corrected stations and artificial Shake-map simulations generated to assist emergency services and field operations. Our broadband Green's functions will be provided to the community (within hours) along with movies showing radiated seismic waves and interactive software. These efforts will assist our own students and others in examining broadband seismograms with a clear view of what is source and what is structure.