A Regional View of Urban Sedimentary Basins in Northern California Based on Oil Industry Compressional-Wave Velocity and Density Logs

Brocher, Thomas M.

doi:10.1785/0120050025

Cited by 33 publications

(51 citation statements)

References 49 publications

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“…For Plio-Quaternary deposits at depths between 0.5 and 2 km, I used a linear velocity gradient derived from a regression of oil industry sonic log data for Tertiary sedimentary rocks (Brocher, 2005c):…”

Section: Plio-quaternary Sedimentary Depositsmentioning

confidence: 99%

“…These basins have been described in a number of articles recently summarized by Brocher (2005c). Apart from the Great Valley, many of these basins record relative subsidence primarily during the Miocene.…”

Section: Older Cenozoic Sedimentary Rocksmentioning

confidence: 99%

“…The Paleocene to Pliocene sedimentary rocks in these basins are exclusively clastic and consist primarily of sandstones, silts, and shales: evaporates and carbonates are rare. Regional differences in the sonic velocities and densities in these basins largely reflect variations in the lithology, depth of burial, grain size, and porosity, but are not necessarily the stratigraphic age of the deposits (Brocher, 2005c). Older Cenozoic sedimentary rocks contribute to the amplification of low frequency strong ground motions in these basins (e.g., Dolenc et al, 2005;Aagaard, 2006;Graves, 2006;Hartzell et al, 2006;Rodgers et al, 2006;Aagaard, Brocher, Dolenc, Dreger, Graves, Harmsen, Hartzell, Larsen, McCandless, et al, 2008;Rodgers et al, 2008).…”

Section: Older Cenozoic Sedimentary Rocksmentioning

confidence: 99%

“…Another motivation for this approach was that available sonic log data in northern California are more limited than in other parts of California such as in the Los Angeles basin (Magistrale et al, 1996;Brocher et al, 1998;Suess and Shaw, 2003), and stratigraphic and lithologic variations are simply not well sampled in much of northern California. As noted in Figure 1, there are a number of Cenozoic sedimentary basins in northern California, but they tend to be smaller and have a thinner sedimentary cover than basins elsewhere in California, particularly in the Los Angeles area (Suess and Shaw, 2003;Brocher, 2005c).…”

Section: Introductionmentioning

confidence: 99%

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Compressional and Shear-Wave Velocity versus Depth Relations for Common Rock Types in Northern California

Brocher

2008

Bulletin of the Seismological Society of America

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100

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This article presents new empirical compressional and shear-wave velocity (Vp and Vs) versus depth relationships for the most common rock types in northern California. Vp versus depth relations were developed from borehole, laboratory, seismic refraction and tomography, and density measurements, and were converted to Vs versus depth relations using new empirical relations between Vp and Vs. The relations proposed here account for increasing overburden pressure but not for variations in other factors that can influence velocity over short distance scales, such as lithology, consolidation, induration, porosity, and stratigraphic age. Standard deviations of the misfits predicted by these relations thus provide a measure of the importance of the variability in Vp and Vs caused by these other factors. Because gabbros, greenstones, basalts, and other mafic rocks have a different Vp and Vs relationship than sedimentary and granitic rocks, the differences in Vs between these rock types at depths below 6 or 7 km are generally small. The new relations were used to derive the 2005 U.S. Geological Survey seismic velocity model for northern California employed in the broadband strong motion simulations of the 1989 Loma Prieta and 1906 San Francisco earthquakes; initial tests of the model indicate that the Vp model generally compares favorably to regional seismic tomography models but that the Vp and Vs values proposed for the Franciscan Complex may be about 5% too high.

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Section: Plio-quaternary Sedimentary Depositsmentioning

confidence: 99%

Section: Older Cenozoic Sedimentary Rocksmentioning

confidence: 99%