VS30 at three strong-motion recording stations in Napa and Napa County, California—Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane—Calculations determined from s-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love)

Open-File Report 2018-1161
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  • Related Work: Open-File Report 2018-1162 - VS30 at three strong-motion recording stations in Napa and Solano Counties, California—Lovall Valley Road, Broadway Street and Sereno Drive in Vallejo, and Vallejo Fire Station—Calculations determined from S-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love)
  • Data Release: USGS data release - 2015 high resolution seismic data recorded at six strong motion seismograph sites in Napa and Solano counties, California
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Abstract

The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa County where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report, we present results from three sites—Main Street in Downtown Napa (Northern California Seismic Network station, NCSN N016), Napa Fire Station Number 3 (National Strong Motion Project station, NSMP 1765), and Kreuzer Lane (station KRE, temporary deployment). To characterize the recording sites in terms of shallow-depth shear-wave velocities (VS), we used both surface waves (Rayleigh and Love) and body waves (S-wave) to evaluate the time-averaged VS in the upper 30 meters of the subsurface (VS30). We used two-dimensional multichannel analysis of surface waves (MASW) to evaluate VS from the surface waves, and a refraction tomography inversion algorithm, developed by Hole in 1992, to evaluate VS from the body waves. As determined by the various methods, we found VS30 near the strong-motion recording stations on Main Street in Downtown Napa, Napa Fire Station Number 3, and on Kreuzer Lane to be from 281 meters per second (m/s) to 286 m/s, 297 to 371 m/s, and 885 to 916 m/s, respectively. The VS30 calculated from Love waves were slightly lower (10 m/s) than those calculated from Rayleigh waves at the Downtown Napa location and at Napa Fire Station Number 3 (4 m/s); however, VS30 calculated from Love waves was higher (190 m/s) than those calculated from Rayleigh waves at Kreuzer Lane. We also found that VS30 determined from MASW for both Love and Rayleigh waves varied depending on the number of shots along the profiles, and VS30 was not systematic based on the number of shots used in the analysis. Furthermore, VS30 calculated from S-wave refraction tomography are closer to those determined from MASW calculated from Love waves than from using Rayleigh waves.

Suggested Citation

Chan, J.H., Catchings, R.D., Goldman, M.R., and Criley, C.J., 2018, VS30 at three strong-motion recording stations in Napa and Napa County, California—Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane—Calculations determined from s-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love): U.S. Geological Survey Open-File Report 2018–1161, 47 p., https://doi.org/10.3133/ofr20181161.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Tectonic and Geological Setting
  • August 24, 2014, Mw 6.0 South Napa Earthquake
  • Seismic Survey
  • Seismic-Imaging Methods
  • VS30 Calculations
  • Results
  • Summary
  • Conclusion
  • References Cited
  • Appendixes

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title VS30 at three strong-motion recording stations in Napa and Napa County, California—Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane—Calculations determined from s-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love)
Series title Open-File Report
Series number 2018-1161
DOI 10.3133/ofr20181161
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description Report: vii, 47 p.; Data release
Country United States
State California
County Napa County
City Napa
Online Only (Y/N) Y