Structure of the crust and uppermost mantle beneath the western United States revealed by ambient noise and earthquake tomography

Abstract : Ambient noise tomography and multiple plane wave earthquake tomography are new methods of surface wave analysis that yield much more highly refined information about the crust and uppermost mantle than traditional surface wave techniques. Applied together to data observed at more than 300 broadband seismic stations from the Transportable Array component of the EarthScope USArray, these methods yield surface wave dispersion curves from 8 to 100 s period across the entire western United States with unprecedented resolution. We use the local Rayleigh wave phase speed curves to construct a unified isotropic 3-D V_s model to a depth of about 150 km. Crustal and uppermost mantle features that underlie the western United States are revealed in striking relief. As the USArray continues to sweep eastward across the United States, the substructure of the entire country will be unveiled.