NEHRP Clearinghouse

Title
Borehole Velocity Measurements at Five Sites That Recorded the Cape Mendocino, California Earthquake of 25 April, 1992.
File
PB2006105487.pdf
Author(s)
Gibbs, J. F.; Tinsley, J. C.; Boore, D. M.
Source
January 2002, 58 p.
Identifying Number(s)
USGS/OFR-02-203
Abstract
The U.S. Geological Survey (USGS), as part of an ongoing program to aquire seismic velocity and geologic data at locations that recorded strong-ground motion during earthquakes, has investigated five sites in the Fortuna, California region. We selected drill sites at strong-motion stations that recorded high accelerations from the Cape Mendocino earthquake (M7.0) of 25 April 1992 (Oppenheimer et al., 1993). The boreholes were drilled to a nominal depth of 95 meters (310 feet) 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.
Keywords
; Ground motion; Velocity measurement; Boreholes; Earthquakes; Geological surveys; Acceleration; California; Data sources; Seismometers; Travel time; Seismic waves