3D geologic framework for use with the U.S. Geological Survey National Crustal Model, Phase 1—Western United States

Abstract

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Building a multi‐scale, collaborative, and time‐integrated digital crust: The next stage of the Macrostrat data system

“…A growing set of available constraints from new stratigraphic datasets should allow the construction of high‐quality geologic framework models. Other efforts to produce generative framework models from dynamic constraints have seen impressive results (Boyd, 2019). Making progress in this direction will fulfil a longstanding goal for Macrostrat to become a fully defined spatial and temporal index of the Earth's rock record.…”

Science plan for improving three-dimensional seismic velocity models in the San Francisco Bay region, 2019–24

“…The USGS National Crustal Model (NCM) is being developed (Boyd, 2019a(Boyd, , 2019bShah and Boyd, 2018) to assist in the modeling of seismic hazards across the conterminous United States, initially by improving estimates of site response. This model is based in part on existing geologic and geophysical models and is composed of geophysical profiles, devoid of discontinuities across constituent model boundaries and county, state, and country borders.…”

Calibration of the U.S. Geological Survey National Crustal Model

“…Equations 2, 3, 5, 8, 10, 11, and 12 are combined and rearranged to solve for porosity as a function of shear-wave velocity, differential pressure, and shear modulus and density of the solid-rock matrix and pore-space material. Moduli and density of the solid-rock matrix are estimated by applying mineral physics information from the NCM Petrologic and Mineral Physics Database (Sowers and Boyd, 2019) to geologic profiles from the NCMGF (Boyd, 2019) that are adjusted by eye at each measurement location. Calibration proceeds by estimating A and B in equation 13 by using a robust linear least-squares regression for each rock type and age within the NCMGF and separately at each measurement location.…”

“…Each geophysical profile within the NCM is based on subsurface geology, porosity, effective and total stress, temperature, and mineral-and rock-physics theory. The primary elements used to construct the NCM are: (1) 3D geologic framework (Boyd, 2019), (2) petrologic and mineral physics database (Sowers and Boyd, 2019), (3) 3D temperature model (Boyd, 2020b), (4) calibration of a porosity model for the estimation of bulk rock density and seismic velocity (this report), and (5) validation. These elements make use of a host of geology, borehole, gravity, and seismic datasets to connect subsurface geological variability with geophysical attributes and seismic response.…”