Updates to and applications of the USGS National Crustal Model for seismic hazard studies

Edited by: L. Harvey Thorleifson



The U.S. Geological Survey (USGS) National Crustal Model (NCM) is being developed to assist in the modeling of seismic hazards across the conterminous United States. The NCM is composed of a grid of geophysical profiles, extending from the Earth’s surface into the upper mantle. It is constructed from a 3D geologic framework and geophysical rules defined by: (1) a petrologic and mineral physics database; (2) a 3D temperature model; and (3) a calibrated rock type- and age-dependent porosity model. Parameters needed to estimate site response for existing ground motion models (GMMs), including the time-averaged velocity in the upper 30 meters (VS30) and the depths to 1.0 and 2.5 km/s shear-wave velocity (Z1.0 and Z2.5), can be extracted from the NCM. As GMMs develop, other metrics could also be extracted or derived from the NCM such as sediment thickness and travel times, fundamental frequency, a fully frequency-dependent site response function, or 3D geophysical volumes for wavefield simulations. Application of the NCM may also benefit other aspects of seismic hazard analysis including better accounting for path-dependent attenuation and geometric spreading, more accurate estimation of earthquake source properties such as hypocentral location and stress drop, and calculation of crustal strength profiles that inform estimates of the base of seismicity.

Publication type Conference Paper
Publication Subtype Abstract or summary
Title Updates to and applications of the USGS National Crustal Model for seismic hazard studies
Year Published 2022
Language English
Publisher Minnesota Geological Survey
Contributing office(s) Geologic Hazards Science Center
Description 2 p.
Larger Work Type Report
Larger Work Subtype Organization Series
Larger Work Title OFR22-02, Geologic Mapping Forum 21/22 abstracts
First page 51
Last page 52
Conference Title Geologic Mapping Forum
Conference Location Virtual
Conference Date September 2021-April 2022
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