CVM-H

From SCECpedia
Jump to navigationJump to search

The SCEC Community Velocity Model - Harvard (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 latest version of the SCEC Community Velocity Model (CVM-H 11.2) includes basin structures embedded in the 3D waveform inversion model of Tape et al. (2009), and an explicit representation of the Moho (after Yan and Clayton, 2007; Chulick and Mooney, 2002), and an optional arbitrary-precision Vs30-derived geotechnical layer for the top 350m (Ely et al 2011).

Overview

The SCEC CVM-H velocity 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 (11.2.0) represents the integration of various model components, including fully 3D waveform tomographic results. The CVM-H 11.2.0 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 11.2.0 also incorporates a new Moho surface (Yan and Clayton, 2007) and an upgraded geotechnical layer (GTL) based on a Vs30 map (Ely 2010), the Vp-density scaling relationship, and the code that delivers the model. The CVM-H version 11.2 provides three significant new capabilities:

  • Vs30-based arbitrary precision GTL
  • Extended Region using 1D background model
  • Standardized interface for removing topography

Current Release

SCEC CVM-H version 11.2.0 is scheduled to be released on Friday 25 February 2011.

Dependencies

The following software is required to build and run CVM-H.

  • UNIX operating system (Linux, Solaris, MacOS)
  • GNU make
  • tar for opening the compressed files
  • GNU C compiler for building the executable program.
  • Optionally GTS (GNU Triangulated Surface Library) for cvmdist http://gts.sourceforge.net
  • Optionally GMT (Generic Mapping Tools) to generate plots from vx_slice http://www.soest.hawaii.edu/gmt/

Documentation

User Guide Wiki (includes installation instructions):

Downloads

To install and use the CVM-H, you need to download and build the CVM-H software distribution. There are detailed installation instructions on the CVM-H User Guide. The main steps involved in installing CVM-H include:

  1. The software can be installed in an account on a Linux computer with at least 600G of disk storage and C compilers.
  2. From this Linux computer, start a web browser and point to this download page. Alternatively, you can download the files to a different machine and use FTP or SFTP to copy them over.
  3. Download the following two files (source, source md5sum) into a directory and run the md5sum program to confirm you have an undamaged version of the distribution files.
  4. Uncompress the distribution (tgz) files into a local directory on your computer.
  5. Build the executables by running the top level makefile.
  6. Confirm the code is built correctly by running UnitTests.
  7. Confirm the code runs correctly on your system by running AcceptanceTests.
  8. Use CVM-H for research purposes.


Supporting Materials

These posters and presentations may contain information about earlier versions of CVM-H. This information may be useful to some users.

Help

For assistance with the SCEC CVM-H, you may:

  • Browse and submit new tickets at CVM-H Trac
  • Email software (at) scec.org with specific questions
  • Subscribe to email list cvmh-all (at) intensity.usc.edu to receive announcements about new version of the software.

Software License

The CVM-H software is released under the Apache 2.0 license as posted:

Release History

  • 11.2 - February 2011 - This is the first release of CVM-H that includes the Vs30-based geotechnical layer and the vx_lite user interface. This version also introduces a date-based version numbering scheme (Year.Month.Revision).
  • 6.3capi - November 2010 - This is an interim version of CVM-H for use in testing and evaluation. This version includes an initial version of the vx_lite interface but does not provide the Vs30-based geotechnical layer. This version is distributed for completeness and we do not recommended its use by researchers.
  • 6.3 - August 2010 - This version CVM-H, released by the Harvard Structural Geology Group, removes all CVM-S geotechnical information and restores the original CVM-H material properties to all regions of the model.
  • 6.2 - August 2009 - This version of CVM-H includes modifications to top 300m material properties based on geotechnical information extracted from CVM-S as an interim approach to providing near surface geotechnical information into CVM-H material properties database.
  • 6.1 - January 2009 - This version of CVM-H incorporates tomographic inversion results from Carl Tape et al.
  • 5.3 - August 2008 - This is a version of CVM-H prior to integration of tomographic inversion results.

Collaborators

CVM Evaluation

We have introduced CVM Evaluation tests as part of the CVM-H release process. In our CVM Evaluation system, we use the latest version of CVM-H to build a velocity mesh for use in a 1Hz wave propagation simulation. We then run a wave propagation simulation using the each CVM mesh under evaluation, and we run goodness-of-fit measures that compare the simulation result against observation data (seismograms). The SCEC CVM Evaluation system is designed to compare simulation results for alternative CVM models.

Alternative SCEC CVM's

As a part of the CVM-H release procedure, we are posting software version used to make the velocity meshes in our CVM evaluations. We are posting these version of the software so users can get the "as tested" version of the code.

For the CVM-H 11.2 release, our CVM evaluation system to evaluate three different CVM's for southern California, the current release and two alternative, or earlier, SCEC CVM's.

  • CVM-H 11.2 - This is the latest CVM-H and we tested it using a newly implemented Vs30-based geotechnical layer. CVM-H 11.2 is based on CVM-H 6.3 with the following differences:
    • Vs30-based geotechnical layer added. GTL is arbitrary precision and optional.
    • 1D background model added to extend model region
    • New query interface supports query by depth in addition to query by elevation.
  • CVM-H v6.3capi (CVM-H v63 model w/ vx_lite and C API, w/o any GTL): cvmh_v63.tgz
    • This is the previous version of CVM-H. The material properties in this CVM-H 6.3 version are equivalent to the material properties in CVM-H 11.2, except for the geotechnical layer. In CVM-H 11.2, the geotechnical layer is optional, and without GTL, CVM-H 11.2 should produce material properties equivalent to this CVM-H 6.3 version. We believe CVM-H 6.3 version we are distributing is equivalent to the CVM-H 6.3 released through the Harvard Structural Geology Web site. We are posting this distribution because it contains software we developed to implement query by depth. All capabilities in CFM-H 6.3 have been implemented in CVM-H 11.2 and we recommend all users use CVM-H 11.2 or later.
  • CVM-S (CVM-4 with Geoff Ely bug fixes): cvm4_gely_20101209.tar
    • This version of CVM-S4 includes fixes to all known software bugs in the 2005 distribution released through the SCEC data center. This is, to our knowledge, the best available version of CVM-S4.

Development version

If you're interested in working with the latest development version of the platform, you can check it out from: 

svn co https://source.usc.edu/svn/cvmh/trunk

Details about working with the development version are provided in the User Guide.

Related Entries

See Also

References

  1. 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.
  2. 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.
  3. Tape, C., Q. Liu, A. Maggi, and J. Tromp, 2009: Adjoint tomography of the southern California crust, Science, v. 325, p. 988-992.
  4. Ely, G., 2010: Vs30 Derived GTL
Retrieved from "https://strike.scec.org/scecwiki/index.php?title=CVM-H&oldid=2001"