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.