Abstract

We present SWUS-crust, a three-dimensional shear-wave velocity model of crustal structure in the western U.S. We use Rayleigh wave amplification measurements in the period range of 38-114 s, along with Love wave amplification measurements in the period range of 38-62 s, with the latter being inverted for the first time for crustal velocity structure. Amplification measurements have narrower depth sensitivity when compared to more traditional seismic observables such as surface wave dispersion measurements. In particular, we take advantage of the strong sensitivity of Love wave amplification measurements to the crust. We invert over 6,400 multi-frequency measurements using the Monte-Carlo based Neighbourhood Algorithm, which allows for uncertainty quantification. SWUS-crust confirms several features observed in previous models, such as high-velocity anomalies beneath the Columbia basin and low-velocity anomalies beneath the Basin and Range province. Certain features are sharpened in our model, such as the northern border of the High-Lava Plains in southern Oregon in the middle crust.