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 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 (11.9.1) represents the integration of various model components, including fully 3D waveform tomographic results. We recommend use of the most recent version of CVM-H, in most cases.
Improvements in version 11.9 include a newly compiled Moho surface, opening up the offshore Santa Maria basin to the western model margin, a detailed representation of the San Bernardino basin, a much smoother transition between low resolution area and high resolution area at its southern border in the Los Angeles region and removal of various small near surface artifacts. The new Moho surface was compiled by Tape et al. from a large number of data sources, including global data sets, receiver functions and local studies. In replacing this surface care was taken that the depth interval around the Moho level both in the mantle and in the crustal portions of the model which were affected by this change, were assigned the correct domain, and consequently assigned velocities extrapolated from the underlying mantle model or from the crustal background model. In the offshore Santa Maria basin we extended the definition of the basement surface using reflection seismic data (McIntosh et al., 1991) to the very western margin of the model and to the north in order to remove an abrupt transition from the basin to background. We smoothly extrapolated sediment velocities from the onshore model into this new basinal area. Another basin, the relatively small San Bernardino basin, is now represented in the model. The basement surface is based on gravity data (Anderson, 2000) and seismic reflection data (Stephenson et al., 2004). To the west the basin is connected by a thin veneer of sediments to the Los Angeles basin whereas to the ESE the basin is represented as tapering out as is the case in other such basin representation. The ESE is the deepest part of the basin, and the data do not preclude a continuation of the basin in this direction. The Vp velocity structure in the basin is defined by stacking velocities (Stephenson et al., 2004) and a 1D velocity profile (Graves, 2004). Vs is derived from Vp using Brocher (2004). Finally, we removed a discontinuity in the velocity structure between the southern margin of the high resolution model in the Los Angeles area and the surrounding low resolution model. We modified the high resolution area by introducing a smooth N-S gradient in the delta between the low and high resolution models in a region at its southern margin.
The CVM-H 11.9 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 11.9 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.
SCEC CVM-H version 11.9.1 was released on Wednesday 5 December 2012.
Version 11.9.1 represents an improvement on 11.9.0 and it is recommended that all users upgrade to this new version. Specifically, the latest iteration includes the following changes to the high resolution (HR) data set:
- replaced about ten, seemingly random cells which were shallow in the basin and had a water tag with sediment and GTL tags (GTL tags are obsolete and can be considered equivalent to sediment tag)
- vp63: replaced water velocity in retagged cells with average from surrounding cells
- vs65: replaced all sediment tagged cells with values based on Vp using Brocher (2005). This resulted mostly in no change but fixed some cells (about 8) which were close to the southern edge and had no-data or negative values
- None at this time.
The following software is required to build and run CVM-H.
- UNIX operating system (tested on Linux and SunOS, untested on Solaris and 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/
User Guide Wiki (includes installation instructions):
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:
- The software can be installed in an account on a Linux computer with at least 600MB of disk storage and GNU C compiler and GNU compliant make.
- From the Linux computer, start a web browser and point to this download page. Alternatively, you can retrieve the files with SFTP or other retrieval software.
- Download the two CVM-H files (CVM-H source, CVM-H md5sum) into a directory and run the md5sum program to confirm you have an undamaged version of the distribution files.
- Uncompress the distribution (tar.gz) files into a local directory on your computer.
- Configure the installer by running the ./configure script.
- Build the executables by running the top level makefile ('make').
- Confirm the code is built correctly by running the unit/acceptance tests ('make check').
- Install the executables ('make install').
- Use CVM-H for research purposes.
|Linux||SCEC CVM-H 11.9.1 Source (550 Mb tar (tar.gz) file)||cvmh-11.9.1.tar.gz||Latest official release|
|Linux||SCEC CVM-H 11.9.1 md5 (small text file)||cvmh-11.9.1.tar.gz.md5||Latest official release|
These posters and presentations may contain information about earlier versions of CVM-H. This information may be useful to some users.
- Overview of CVM-H 11.2 (1Mb powerpoint file)
- Andreas Plesch Overview of CVM-H (2008) (7.4Mb powerpoint file)
- CVM-H Poster SCEC Annual Meeting (2008) (1.8Mb pdf file)
- Overview of SCEC Unified Structure Representation (USR) Developments (4.2Mb powerpoint file)
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 cvm-h-all (at) intensity.usc.edu to receive announcements about new version of the software.
CVM-H software distributions are released under an Apache 2.0 open-source license as described here CVM-H License.
The CVM-H releases contain cumulative improvements to the geological models and software interfaces. We recommend using the most recent version of the software, in most cases.
- CVM-H 11.9.1 - December 2012
- tag: replaced about ten, seemingly random cells which were shallow in the basin and had a water tag with sediment and GTL tags (GTL tags are obsolete and can be considered equivalent to sediment tag).
- vp63: replaced water velocity in retagged cells with average from surrounding cells
- vs65: replaced all sediment tagged cells with values based on Vp using Brocher (2005). This resulted mostly in no change but fixed some cells (about 8) which were close to the southern edge and had no-data or negative values.
- CVM-H 11.9.0 - September 2011
- This release included the Santa Maria and San Bernardino basins, and changes to the Moho.
- CVM-H 11.2.0 - February 2011
- This is the prior release, and the first release of CVM-H that includes the Vs30-based geotechnical layer, the Hadley-Kanamori 1D background model, and the vx_lite depth-based query user interface. This version also introduces a date-based version numbering scheme (Year.Month.Revision).
- CVM-H 11.2.0 contains a small code error. Only exceptionally advanced users, users that write their own C language software to query CVM-H through the vx_api interface, might encounter this bug. For nearly all standard usages, the code works as designed. Details about this known issue are described at the end of this entry. A workaround for this bug is available and is described in the users manual. This issue will be fixed in the next release. See a description below, and the the online user guide CVM-H User Guide for an example that employs the work-around.
- CVM-H 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.
- CVM-H 6.3 - September 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.
- CVM-H 6.2 - January 2010
- 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.
- CVM-H 6.0 - September 2009
- This version of CVM-H incorporates tomographic inversion results from Carl Tape et al.
- CVM-H 5.5 - September 2008
- This is the last version of CVM-H prior to integration of tomographic inversion results.
The CVM-H User Guide contains a comprehensive version history for CVM-H that is more complete than this summary including scientific references for each version.
|Linux||SCEC CVM-H 11.9.0 Source (529 Mb tar (tgz) file)||cvmh-11.9.0.tar.gz||cvmh-11.9.0.tar.gz||Prior release|
|Linux||SCEC CVM-H 11.9.0 md5 (small text file)||cvmh-11.9.0.tar.gz.md5||cvmh-11.9.0.tar.gz.md5||Prior release|
|Linux||SCEC CVM-H 11.2.0 Source (529 Mb tar (tgz) file)||cvmh_11.2.0.tgz||cvmh_11.2.0.tgz||Prior release|
|Linux||SCEC CVM-H 11.2.0 md5 (small text file)||cvmh_11.2.0.tgz.md5||cvmh_11.2.0.tgz.md5||Prior release|
- Harvard Structural Geology and Earth Resources Group Home Page
- San Diego State University Dept of Geological Sciences
- Po Chen Tomography
- Geoff Ely Geotechnical Layer Implementation
- Carl Tape Tomography
- USGS CVM Web Site
- USGS Pasadena
- SCEC/CME Project
We have introduced CVM Evaluation tests as part of the CVM-H release process. In our CVM Evaluation system, we evaluate CVM's using earthquake wave propagation simulations. For each CVM, we build a velocity mesh for use in a 1Hz wave propagation simulation. We then run a wave propagation simulation using the 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 the software versions used to make the velocity meshes in our CVM evaluations. We are posting these version of the software so users can get most recent, and best available, versions of SCEC CVM codes.
For the CVM-H 11.9.0 release, our CVM evaluation system was used to evaluate it in comparison with CVM-H 11.2.0.
- CVM-H 11.9.0 - This is the current CVM-H. This version of CVM-H is posted in the download section of this web page.
- CVM-H 11.2.0 - This is the prior CVM-H and we tested it using a newly implemented Vs30-based geotechnical layer. This version of CVM-H is posted in the download section of this web page. CVM-H 11.2 is based on CVM-H 6.3 with the following differences (1) Arbitrary precision and optional Vs30-based geotechnical layer added, (2) a 1D Hadley-Kanamori background model added to extend model region, and (3) New query interface supports query by depth in addition to query by elevation.
For the CVM-H 11.2.0 release, our CVM evaluation system was used 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 prior CVM-H and we tested it using a newly implemented Vs30-based geotechnical layer. This version of CVM-H is posted in the download section of this web page. CVM-H 11.2 is based on CVM-H 6.3 with the following differences (1) Arbitrary precision and optional Vs30-based geotechnical layer added, (2) a 1D Hadley-Kanamori background model added to extend model region, and (3) 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):
- 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 v4.1 (CVM-4 with Ely/Graves/Small mods):
- This version of CVM-S4 includes fixes to all known software bugs in the 2005 distribution released through the SCEC data center, with additional modifications by Ely/Graves/Small to support querying with binary input files, and inclusion of an MPI query utility for large point sets, as well as a static library that allows the model to be queried programmatically. This is, to our knowledge, the best available version of CVM-S4.
- CVM-S 4-gely (CVM-4 with Geoff Ely bug fixes):
- This version of CVM-S4 includes fixes known bugs, such as un-initialized variables, in the original CVM-S distribution distributed through the SCEC Data Center. This is the version of CVM-S used in the CVM-H 11.2.0 CVM_Evaluation. If you want to work with CVM-S, we recommend you use version CVM-S v4.1, posted above, as it contains additional changes and capabilities not in this version.
These distributions are available for download from the table below:
|CVM-H v6.3capi Source Code File (527 Mb tar (tgz) file)||cvmh_v63.tgz||cvmh_v63.tgz|
|CVM-H v6.3capi Source Code md5sum File (small text file)||cvmh_v63.tgz.md5||cvmh_v63.tgz.md5|
|CVM-S v4.1 Source Code File (6.5 Mb tar (tgz) file)||cvms_v41.tgz||cvms_v41.tgz|
|CVM-S v4.1 Source Code md5sum File (small text file)||cvms_v41.tgz.md5||cvms_v41.tgz.md5|
|CVM-S 4-gely Source Code File (6.5 Mb tar (tgz) file)||cvm4_gely_20101209.tar||cvm4_gely_20101209.tar|
|CVM-S 4-gely Source Code md5sum (small text file)||cvm4_gely_20101209.tar.md5||cvm4_gely_20101209.tar.md5|
Known Issue Description
- CVM-H 11.2.0 is known to contain a small code error. Only advanced users might encounter this bug. For nearly all standard usages, the code works as designed.
The vx_api library has a bug in query by depth mode. The structure member vx_entry_t.coord (z value) gets altered during a vx_getcoord() call from depth to elevation when querying below the GTL. This value should not be changed during the call. The work-around for this issue is to make a copy of the depth value before the call to vx_getcoord() if you wish to use that depth later. The vx_lite command line tool does not exhibit this bug. This issue will be fixed in the next release. See the online user guide CVM-H User Guide for an example that employs the work-around.
If you're interested in working with the latest development version of the platform, you can check it out from:
Details about working with the development version are provided in the User Guide.
- Harvard Structural Geology and Earth Resources Web Page
- Harvard Community Velocity Model
- Goodness of Fit
- CVM-H v6.3capi
- CVM Toolkit
- CVM Evaluation
- Community Velocity Model
- CVM-H User Guide
- CVM Toolkit
- Geotechnical Layer
- 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.
- 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.
- Tape, C., Q. Liu, A. Maggi, and J. Tromp, 2009: Adjoint tomography of the southern California crust, Science, v. 325, p. 988-992.
- Ely, G., 2010: Vs30 Derived GTL