Moho complexity in southern California revealed by local PmP and
teleseismic Ps waves
Abstract
The Moho discontinuity plays an important role in crustal growth and
evolution. In this study, we delineate the Moho geometry in southern
California by jointly using local Moho-reflected waves PmP and
teleseismic Moho-converted waves Ps. To well constrain the Moho
geometry, we have developed a two-stage process to pick PmP waves and
have created a reliable PmP travel time data set with a total of 10,192
picks. We have also extracted 38,648 high-quality P-wave receiver
functions (RFs). The Moho depth is initially estimated via the common
conversion point (CCP) stacking of RFs and then refined by inverting the
PmP travel time data in a community velocity model (CVM-H, version
15.1.1). The newly built Moho geometry is generally consistent with the
California Moho Model version 1.0 (CMM-1.0), that is, a shallow Moho
beneath the Salton Trough (23 km), a uniformly shallow Moho beneath the
Mojave Desert and the Basin and Range (<29 km), and a sliver
of deep Moho under the western Peninsular Ranges, the eastern Transverse
Ranges, and the western Sierra Nevada (>34 km). However,
our Moho model reveals some new features different from the CMM–1.0,
such as a deep Moho (∼34 km) beneath the northern end of the central and
western Transverse Ranges, consistent with the observation of deep
seismicities due to a thick brittle crust there. We also find a gradual
transition from the lower crust to the uppermost mantle beneath the
western Peninsular Ranges, leading to the rareness of pickable PmP waves
as well as weak Moho-converted signals there.