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Evaluation of 2-D Shear-Wave Velocity Models and VS30 at Six Strong-Motion Recording Stations in Southern California using Multichannel Analysis of Surface Waves and Refraction Tomography

Open-File Report 2024-1016
By: , , , , and 
https://doi.org/10.3133/ofr20241016

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Abstract

To better understand the potential for amplified ground shaking at sites that house critical infrastructure, the U.S. Geological Survey (USGS) evaluated shear-wave velocities (VS) at six strong-motion recording stations in Southern California Edison facilities in southern California. We calculated VS30 (time-averaged shear-wave velocity in the upper 30 meters [m]), which is a parameter used in ground-motion prediction equations (GMPEs) to account for site amplification (Building Safety Seismic Council, 2003; Holtzer and others, 2005; Baltay and Boatwright, 2015). Previous site-characterization studies using multiple methods in Alameda, Napa, and Sonoma Counties, Calif., and in British Columbia (Catchings and others, 2017, 2019; Chan and others, 2018a, 2018b) show that some sites have significant lateral variability; thus, a single measurement of VS30 nearest to the strong-motion recording station may not accurately account for the actual subsurface velocity variations. In the summer of 2017, we recorded body and surface waves along linear profiles (118–174 m long) using active-source seismic methods (226-kilogram [kg] accelerated weight-drop and 3.5-kg sledgehammer impacts) near strong-motion recording stations. We used S-wave refraction tomography and a multichannel analysis of surface waves (MASW) method (using common midpoint cross-correlation; CMPCC) to evaluate two-dimensional (2-D) VS from body and surface waves, respectively. We evaluated VS from both Rayleigh- and Love-waves.

Suggested Citation

Chan, J.H., Catchings, R.D., Goldman, M.R., Criley, C.J., and Sickler, R.R., 2024, Evaluation of 2-D shear-wave velocity models and VS30 at six strong-motion recording stations in southern California using multichannel analysis of surface waves and refraction tomography: U.S. Geological Survey Open-File Report 2024–1016, 58 p., https://doi.org/10.3133/ofr20241016.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Seismic Survey
  • Seismic-Imaging Methods
  • VS30 Calculations
  • Velocity Models and Dispersion Curves
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Evaluation of 2-D shear-wave velocity models and VS30at six strong-motion recording stations in southern California using multichannel analysis of surface waves and refraction tomography
Series title Open-File Report
Series number 2024-1016
DOI 10.3133/ofr20241016
Publication Date April 18, 2024
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description Report: vii, 58 p.; Data Release
Country United States
State California
Online Only (Y/N) Y
Additional publication details