This research is to continue the recording and analysis of a triaxial set of 10 Hz geophones placed at a depth of 2.5 km in the Cajon Pass deep drill hole near the San Andreas fault in southern California. To date, the instrumentation has recorded several hundred earthquakes at frequencies up to 400 Hz. Most larger events were recorded simultaneously by a 2 Hz triaxial surface seismometer. Results suggest that surface seismograms are severely depleted in high frequency wave amplitudes and downhole seismograms have high corner frequencies and high frequency power law amplitude decays. Additional wide-band seismic sensors will be installed at 2.0 and 3.5 km depths in order to give an improved measure of natural seismicity and record microearthquake scaling in a volume of seismically active crust. This research is a component of the National Earthquake Hazard Reduction Program.

Agency
National Science Foundation (NSF)
Institute
Division of Earth Sciences (EAR)
Application #
9219856
Program Officer
James H. Whitcomb
Project Start
Project End
Budget Start
1993-05-01
Budget End
1995-10-31
Support Year
Fiscal Year
1992
Total Cost
$121,734
Indirect Cost
Name
University of Southern California
Department
Type
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90089