Analysis of P and S wave vertical seismic profile data from the Salton Sea Scientific Drilling Project
As part of the Salton Sea Scientific Drilling Project at California State well 2--14, vertical seismic profile (VSP) data were collected from P and S wave sources at two distances from the well. Use of a three-component geophone, along with rotation of the recorded data traces into a wave front-based coordinate system, allows analysis of many aspects of seismic wave propagation properties around the well. Standard VSP analysis techniques were used to measure interval P and S wave velocities and to identify reflecting horizons both within and below the survey interval (from 455 to 1735 m). A reflection from below the survey interval, seen with both P and S sources, seems to be associated with a fractured reservoir near 2100 m. Indications of fracturing were observed, including vertical scattering of P waves from a zone near 915 m. Orthogonally polarized shear waves were generated at each offset to study anisotropy by travel time measurement and particle motion analysis of the shear wave arrivals. Three component particle motion analysis of shear wave arrivals was found to be effective for characterizing the subtleties in the S wave splitting throughout the various zones in the well. The SH/sub t/ source (horizontal and transverse to the well) produced complicated, elliptical particle motion while the SV source (in-line with the well) produced linear particle motion. The difference in linearity of particle motion from orthogonally polarized shear wave sources was unexpected and may be related to regional tectonics. Anomalous zones may be related to transition depths in the Salton Sea geothermal field. Travel time difference between SV and SH waves, while clearly observable, indicates only about 1% average anisotropy.
- Research Organization:
- Center for Computational Seismology, Lawrence Berkeley Laboratory, University of California, Berkeley
- OSTI ID:
- 6569798
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 93:B11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
SALTON SEA
DRILLING
SEISMIC P WAVES
SEISMIC S WAVES
ANISOTROPY
FRACTURES
RESEARCH PROGRAMS
ROCKS
SALTON SEA GEOTHERMAL FIELD
TECTONICS
VELOCITY
WAVE PROPAGATION
FAILURES
GEOTHERMAL FIELDS
LAKES
SEISMIC WAVES
SURFACE WATERS
150201* - Geology & Hydrology of Geothermal Systems- USA- (-1989)
580201 - Geophysics- Seismology & Tectonics- (1980-1989)