Pn Tomography of the Western United States using USArray

Pn Tomography of the Western United States using USArray Crustal thickness estimates. Thicker crust is observed in the Sierra Nevada, the Cascade Range, and southern Wyoming. In the northern Basin and Range province crustal thickness is reduced as expected in an extensional tectonic regime. The thinner crust in the southern Basin and Range is very distinct, with thicker crust indicated to the north below the Colorado Plateau.
In this study, we analyze Pn arrival times from the transportable stations of USArray to resolve crust and uppermost-mantle structure. Seismic tomography has the potential to provide detailed images of Earth structure, but is often limited by the coverage of the available seismic data. The USArray with its very dense and almost uniformly spaced stations has greatly improved tomographic resolution for much of the western United States. Because of the large contrast in seismic velocities between the lower crust and the upper mantle and the shallow velocity gradient in the upper mantle, Pn tomographic velocity perturbation images show results for a very confined depth in the uppermost mantle, complementing surface-wave or other body-wave tomographies that average anomalies over larger depth intervals.
</p><p>Acknowledgements: We thank Luciana Astiz and the operators of the Array Network Facility for making their phase picks available. This research was funded by grant EAR-0710881 from the National Science Foundation.</p>


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