SCEC Community Velocity Model (CVM-H)

© Harvard University

Who is working on this?
Andreas Plesch, Carl Tape, Peter Suess, Carlos Rivero, John Shaw

In collaboration with:
SCEC, USGS, CGS

Fig. 1: Perspective view of CVM-H 6.2 looking from the Salton Sea to the NW, which includes basin structures embedded in underlying tomographic and teleseismic surface wave models that extends to a depth of 300km. Vp is shown. See Fig. 2 for location.

Summary



The CVM-H is a velocity model of crust and upper mantle structure in southern California developed by the SCEC community for use in fault systems analysis, strong ground motion prediction, and earthquake hazards assessment. The model describes seismic P- and S-wave velocities and densities, and is comprised of basin structures embedded in tomographic and teleseismic crust and upper mantle models.

This latest release of the CVM-H (6.2) is an important milestone for SCEC, as it represents the integration of various model components, including fully 3D waveform tomographic results. The CVM-H 6.2 consists of basin structures defined using high-quality industry seismic reflection profiles and tens of thousands of direct velocity measurements from boreholes (Plesch et al., 2009; Süss and Shaw, 2003). The basin structures are also compatible with the locations and displacements of major faults represented in the SCEC Community Fault Model (CFM) (Plesch et al., 2007). These basin structures were used to develop travel time tomographic models of the crust (after Hauksson, 2000) extending to a depth of 35 km, and upper mantle teleseismic and surface wave models extending to a depth of 300 km (Prindle and Tanimoto, 2006). These various model components were integrated and used to perform a series of 3D adjoint tomographic inversions that highlight areas of the model that were responsible for mismatches between observed and synthetic waveforms (Tape et al, 2009). Sixteen tomographic iterations, requiring 6800 wavefield simulations, yielded perturbations to the starting model that have been incorporated in the latest model release. CVM-H 6.2 also incorporates a new Moho surface (Yan and Clayton, 2007) and a series of other upgrades to the geotechnical layer (GTL), the Vp-density scaling relationship, and the code that delivers the model.

Download: To download, right click on the file, and choose "save link as..."

The latest available model including query code and data files can be found tarred and zipped as vx62.tar.bz2 (~500MB)

For details refer to the included manual file here: cvmh_manual.pdf

Poster describing latest advances: scec2009poster.pdf

© Harvard University

Referencing

Use of this model should reference:
Suess, M. P., and J. H. Shaw, 2003, P-wave seismic velocity structure derived from sonic logs and industry reflection data in the Los Angeles basin, California, Journal of Geophysical Research, 108/B3.
and

Plesch, A., C. Tape, J. H. Shaw, and members of the USR working group, 2009, CVM-H 6.0: Inversion integration, the San Joaquin Valley and other advances in the community velocity model, in 2009 Southern California Earthquake Center Annual Meeting, Proceedings and Abstracts, vol. 19, pp. 260–261.

The waveform tomographic model is described in:
Tape, C., Q. Liu, A. Maggi, and J. Tromp, 2009, Adjoint tomography of the southern California crust, Science, v. 325, p. 988-992.

Additional references and descriptions of various model components, along with instructions on how to access the model, are available in the manual.

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Structural Geology and Earth Resources Group