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Three-Dimensional Seismic Velocity Model for the Cascadia Subduction Zone with Shallow Soils and Topography, Version 1.7

Open-File Report 2025-1045
By: , , , , and 
https://doi.org/10.3133/ofr20251045

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Abstract

The U.S. Geological Survey’s seismic velocity model for the Cascadia Subduction Zone provides P- and S-wave velocity (VP and VS, respectively) information from 40.2° to 50.0° N. latitude and −129.0° to −121.0° W. longitude, and is used to support a variety of research topics, including three-dimensional (3D) earthquake simulations and seismic hazard assessment in the Pacific Northwest. This report describes an update to the previous version (v) 1.6 of the 3D seismic velocity model for the Cascadia Subduction Zone. This new model (herein referred to as v1.7) contains more detailed near-surface structure for improved earthquake ground motion modeling. Updated features include the addition of a new shallow soil velocity model in the top few hundred meters and the option of adding user-specified topography. Although v1.6 of the Cascadia seismic velocity model has a minimum VS of 600 meters per second (m/s), the new model (v1.7) has a minimum VS of approximately 40 m/s. Overall, this update will allow for more accurate ground motion estimates from 3D simulations of scenario earthquakes in the Cascadia Subduction Zone region.

Suggested Citation

Wirth, E.A., Grant, A.R., Stone, I.P., Stephenson, W.J., and Frankel, A.D., 2025, Three-dimensional seismic velocity model for the Cascadia Subduction Zone with shallow soils and topography, version 1.7: U.S. Geological Survey Open-File Report 2025–1045, 18 p., https://doi.org/10.3133/ofr20251045.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Motivation for Updating Near-Surface Structure
  • Development and Integration of a Near-Surface Model
  • Simulation of the 2001 M6.8 Nisqually Earthquake
  • Summary and Opportunities for Model Improvement
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Three-dimensional seismic velocity model for the Cascadia Subduction Zone with shallow soils and topography, version 1.7
Series title Open-File Report
Series number 2025-1045
DOI 10.3133/ofr20251045
Publication Date September 19, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description Report: vi, 18 p.; Data Release
Country Canada, United States
State British Columbia, California, Oregon, Washington
Other Geospatial Cascadia Subduction Zone
Online Only (Y/N) Y
Additional publication details