CSRM-1.0: A China Seismological Reference Model

Abstract

High-resolution seismic model is crucial for advancing our understandings on geological processes and enhancing seismic hazard mitigation programs. We construct a high-resolution China Seismological Reference Model (CSRM-1.0) in the top 100 km of the crust and uppermost mantle in continental China following a top-down construction process. The employed seismic constraints include P-wave polarization angle from tele-seismic event, short-period Rayleigh wave ellipticity from ambient noise, long-period Rayleigh wave ellipticity from earthquake data, receiver function, empirical Green's function from ambient noise, Rayleigh wave phase/group velocity dispersion curves from regional earthquakes, and Pn-wave travel time extracted from seismic data of 4,435 stations. CSRM-1.0 has a spatial crustal resolution of ∼60 km beneath the north-south seismic belt and trans-North China orogen regions and ∼120 km beneath the rest of continental China, and a spatial mantle resolution of ∼300 km. CSRM-1.0 exhibits prominent velocity heterogeneities in the crust and uppermost mantle and an eastward thinning of the crust, geographically correlating with geological settings. CSRM-1.0 improvements include accurate estimation of shallow seismic structure, increased spatial resolution and improved model accuracy. Crustal composition inferred from CSRM-1.0 exhibits a general transition from a felsic upper crust to a mafic lower crust. Mafic rocks in the lower crust are found predominantly along inter-block boundaries and sporadically within the interiors of blocks, likely resulted from preferential inter-block intrusions of magmas related to various oceanic plate subductions and the Emeishan mantle plume. This study contributes seismic constraints and CSRM-1.0 to the CSRM product center (http://chinageorefmodel.org) as a backbone open-access geophysical cyberinfrastructure.