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Finite-frequency traveltime tomography of San Francisco Bay region crustal velocity structure

Geophysical Journal International

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DOI: 10.1111/j.1365-246X.2007.03532.x

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Abstract

Seismic velocity structure of the San Francisco Bay region crust is derived using measurements of finite-frequency traveltimes. A total of 57 801 relative traveltimes are measured by cross-correlation over the frequency range 0.5-1.5 Hz. From these are derived 4862 'summary' traveltimes, which are used to derive 3-D P-wave velocity structure over a 341 ?? 140 km2 area from the surface to 25 km depth. The seismic tomography is based on sensitivity kernels calculated on a spherically symmetric reference model. Robust elements of the derived P-wave velocity structure are: a pronounced velocity contrast across the San Andreas fault in the south Bay region (west side faster); a moderate velocity contrast across the Hayward fault (west side faster); moderately low velocity crust around the Quien Sabe volcanic field and the Sacramento River delta; very low velocity crust around Lake Berryessa. These features are generally explicable with surface rock types being extrapolated to depth ???10 km in the upper crust. Generally high mid-lower crust velocity and high inferred Poisson's ratio suggest a mafic lower crust. ?? Journal compilation ?? 2007 RAS.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Finite-frequency traveltime tomography of San Francisco Bay region crustal velocity structure
Series title:
Geophysical Journal International
DOI:
10.1111/j.1365-246X.2007.03532.x
Volume
171
Issue:
2
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
630
Last page:
656
Number of Pages:
27