Ambient seismic noise and teleseismic tomography in the western USA: High-resolution 3-D model of the crust and upper mantle from Earthscope/USArray

Abstract

Short-period surface wave dispersion measurements are extremely hard to obtain from teleseismic events due to scattering and attenuation. Ambient seismic noise is rich in short-period surface waves from which the Rayleigh wave Green function between pairs of stations can be extracted by cross-correlating long noise sequences. Tomography based on surface wave dispersion obtained from the estimated Green functions has been shown to produce high-resolution, short-period (6–30 s) surface wave dispersion maps that principally image crustal geological units (e.g., southern California: Shapiro et al., 2006; Europe: Yang et al., 2007). In this study, we measure phase velocity dispersion curves from the ambient noise cross-correlations to obtain phase velocity maps at periods from 6 to 30 using data from the transportable array component of USArray. A two-plane-wave tomography method including finite-frequency effects was employed to obtain phase velocity maps at complementary periods from 25 to 150 using teleseismic events. The combined phase velocity data set from 6 to 150 is used to invert for high-resolution 3-D Vs structure from the surface to ∼ 200 km depth beneath the western USA. The new 3-D Vs model can be used to interpret regional tectonics, model seismic wave propagation, and improve earthquake location.