Seismic evidence for a lower-crustal detachment beneath San Francisco Bay, California

Thomas M. Brocher, Jill McCarthy, Patrick E. Hart, W. Steven Holbrook, Kevin P. Furlong, Thomas V. McEvilly, John A. Hole, Simon L. Klemperer

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Results from the San Francisco Bay area seismic imaging experiment (BASIX) reveal the presence of a prominent lower crustal reflector at a depth of ~ 15 kilometers beneath San Francisco and San Pablo bays. Velocity analyses indicate that this reflector marks the base of Franciscan assemblage rocks and the top of a mafic lower crust. Because this compositional contrast would imply a strong rheological contrast, this interface may correspond to a lower crustal detachment surface. If so, it may represent a subhorizontal segment of the North America and Pacific plate boundary proposed by earlier thermomechanical and geological models.

Original languageEnglish (US)
Pages (from-to)1436-1439
Number of pages4
Issue number5177
StatePublished - Sep 2 1994

All Science Journal Classification (ASJC) codes

  • General


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