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U.S. Geological Survey
Open-File Report 2005-1365
Version 1.0

Shear Wave Velocity of the Ground Near Southern California TRINET Sites Using the Spectral Analysis of Surface Waves Method (SASW) and Parallel-Arrayed Harmonic-Wave Sources

By Robert Kayen, Brad Carkin, Diane Minasian, and John Tinsley


Photograph of seismometer, coil of data cable, and very long measuring tape.  The seismometer is a calendar and accessories about half a meter tall

The seismic network for Southern California administered through the TRINET project (the name implies the synthesis of three networks) is a collaborative effort of the administers of the US Geological Survey Southern California Seismic Network (SCSN), California Institute of Technology network, and California Geological Survey network (CSMIP). Many of these sites have little or no quantitative characterization for site amplification effects or natural period characterization. In this study, we investigate thirteen TRINET sites using an active-source approach that employs ultra-low frequency controlled harmonic waves to measure the dispersive nature of surface waves in the ground. We use a new spectral analysis of surface waves (SASW) approach by arraying multiple harmonic wave sources that are driven in-phase to excite the ground. An inversion algorithm employing a non-linear least-squares best fit is used to invert shear wave velocities for the upper 40-to-100 meters of the soil column.

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For questions about the content of this report, contact Rob Kayen

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Maintained by: Michael Diggles
Date created: January 23, 2006
Date last modified: January 23, 2006 (mfd)