Tracing the subducted oceanic crust beneath the central California continental margin: Results from ocean bottom seismometers deployed during the 1986 Pacific Gas and Electric EDGE experiment

Journal Article · Wed Apr 10 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JB00494· OSTI ID:5316631

Trehu, A ^[1]

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1. Oregon State Univ., Corvallis (USA)

Large aperture seismic data were collected on several ocean bottom seismometers (OBS) deployed along a deep crustal seismic profile that was shot across the central California continental margin. The line of shots extends from the oceanic crust seaward of the Santa Lucia Escarpment to the California coast near Morro Bay and crosses the Santa Lucia Basin, Santa Lucia Bank, Santa Maria Basin, and Hosgri fault zone. The OBS data permits one to trace the subducted oceanic crust from seaward of the Santa Lucia Escarpment to beneath the central part of the Santa Maria Basin. Just seaward of the Santa Lucia Escarpment, the oceanic crust is subhorizontal and covered by a thin layer of low-velocity sediment. The velocity (4.5 km/s) and gradient (1.20-1.25 km/s/km) of the upper oceanic crust in this region are well determined and agree with earlier determinations of the crustal structure of the eastern Pacific. Beneath the Santa Lucia Escarpment and Santa Lucia Basin, the oceanic crust dips approximately 16{degrees} to the east. It is overlain by material with a velocity that increases from 4.8 to 6.4 km/s at a depth of 1.7-5.5 km below the seafloor beneath the Santa Lucia Basin. A low-velocity zone may be sandwiched between the subducted crust and this shallow high-velocity material, which the authors interpret to represent obducted oceanic crustal material. Beneath the eastern edge of Santa Lucia Basin, the dip of the subducted oceanic crust decreases to less that 2{degrees}. The configuration of the subducted crust in this region is consistent with imbrication of the subducted crust. Beneath the central Santa Maria Basin, the top of the subducted oceanic crust is at a depth of about 14-16 km and the Moho is at 19-21 km.

• OSTI ID: 5316631
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:B4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CALIFORNIA
CONTINENTAL MARGIN
DEPTH
DETECTION
DEVELOPED COUNTRIES
DIMENSIONS
EARTH CRUST
FEDERAL REGION IX
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
INCLINED STRATA
MAPPING
NORTH AMERICA
OCEANIC CRUST
OFFSHORE SITES
ONSHORE SITES
SEDIMENTS
SEISMIC DETECTION
SEISMIC SURVEYS
SEISMIC WAVES
SUBDUCTION ZONES
SURVEYS
USA
WAVE PROPAGATION