Skip to Main Content
Skip Nav Destination
GEOREF RECORD

A dense block model representing western continental United States deformation for the 2023 update to the National Seismic Hazard Model

Eileen L. Evans
A dense block model representing western continental United States deformation for the 2023 update to the National Seismic Hazard Model
Seismological Research Letters (August 2022) 93 (6): 3024-3036

Abstract

Seismic hazard assessment, such as the U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM), relies on estimates of fault slip rate based on geology and/or geodetic observations such as the Global Navigation Satellite System (GNSS), including the Global Positioning System. Geodetic fault slip rates may be estimated within a 3D spherical block model, in which the crust is divided into microplates bounded by mapped faults; fault slip rates are determined by the relative rotations of adjacent microplates. Uncertainty in selecting appropriate block-bounding faults and in forming closed microplates has limited the interpretability of block models for seismic hazard modeling. By introducing an automated block closure algorithm and regularizing the resulting densely spaced block model with total variation regularization, I develop the densest and most complete block model of the western continental United States to date. The model includes 853 blocks bounded by 1017 geologically identified fault sections from the USGS NSHM Fault Sections database. Microplate rotations and fault slip rates are constrained by 4979 GNSS velocities and 1243 geologic slip rates. I identify a regularized solution that fits the GNSS velocity field with a root mean square misfit of 1.9 mm/yr and reproduces 57% of geologic slip rates within reported geologic uncertainty and model sensitivity, consistent with other geodetic-based models in this Focus Section. This block model includes slip on faults that are not included in the USGS NSHM Fault sections database (but are required to form closed blocks) for an estimate of "off-fault" deformation of 3.62 X 10 (super 19) N.m/yr, 56% of the total calculated moment accumulation rate in the model.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 93
Serial Issue: 6
Title: A dense block model representing western continental United States deformation for the 2023 update to the National Seismic Hazard Model
Author(s): Evans, Eileen L.
Affiliation: California State University, Department of Geological Sciences, Northridge, CA, United States
Pages: 3024-3036
Published: 20220831
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 38
Accession Number: 2022-052425
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Part of a special issue entitled Deformation models of fault slip for the 2023 update
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202239
Close Modal

or Create an Account

Close Modal
Close Modal