Skip Links

USGS - science for a changing world

Open-File Report 02-203

Borehole Velocity Measurements at Five Sites That Recorded the Cape Mendocino, California Earthquake of 25 April, 1992

By James F. Gibbs, John C. Tinsley, and David M. Boore

Thumbnail of and link to report PDF (5.1 MB)Introduction

The U.S. Geological Survey (USGS), as part of an ongoing program to acquire seismic velocity and geologic data at locations that recorded strong-ground motions during earthquakes, has investigated five sites in the Fortuna, California region (Figure 1). We selected drill sites at strong-motion stations that recorded high accelerations (Table 1) from the Cape Mendocino earthquake (M 7.0) of 25 April 1992 (Oppenheimer et al., 1993). The boreholes were drilled to a nominal depth of 95 meters (310 ft) and cased with schedule 80 pvc-casing grouted in place at each location. S-wave and P-wave data were acquired at each site using a surface source and a borehole three-component geophone. This report contains the velocity models interpreted from the borehole data and gives reference to locations and peak accelerations at the selected strong-motion stations.

First posted May 29, 2002

For additional information, contact:
Earthquake Science Center, Menlo Park
U.S. Geological Survey
345 Middlefield Road MS 977
Menlo Park, California 94025

Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Gibbs, James F., Tinsley, John C., Boore, David M., 2002, Borehole Velocity Measurements at Five Sites That Recorded the Cape Mendocino, California Earthquake of 25 April, 1992: U.S. Geological Survey Open-File Report 02-203, 48 pp., https://pubs.usgs.gov/of/2002/0203/.


Contents

Introduction

P- and S-Wave Travel-Time Data

Regional Map

Summary Velocity Profiles

Acknowledgments

References


Accessibility FOIA Privacy Policies and Notices

USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubs.usgs.gov/of/2002/0203/
Page Contact Information: Contact USGS
Page Last Modified: Wednesday, December 07, 2016, 07:22:15 PM