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Introduction

The SCEC Unified Community Velocity Model (UCVM) software is used to access information, including estimated Vp and Vs seismic wave velocities and density, about the earth's crust. This is the software repository for the C language version of the software.

UCVM provides seismic velocity information for several California regions. Seismic velocities of rocks and sediments at shallow depths determine how strongly an area will shake. By assigning velocities to rock types in the 3-D geologic model, geologists can gain an understanding of the extent of areas of low shear velocity that are most likely to experience localized strong shaking and future earthquake damage. An important application for the models accessible through UCVM is for use in computer simulations of California earthquakes.

The map below shows the coverage regions for currently supported California velocity models that are accessible through UCVMC. Each of the models shown is considered a regional velocity model. Typically the models return values down to about 50km or 100km, but most models are undefined below 100km. For earth material properties below 100km, global seismic velocity models, such as the Preliminary Earth Reference Model (PREM), are possible alternative models.

Map shows coverage region for California CVMs registered into UCVMC. Coverage region for UCVM 2D maps (cyan) overlayed upon regions of various California 3D velocity models (CVM-S4: red, CVM-S4 geotechnical regions: Red Polygons, CVM-H high resolution: small blue, CVM-H low resolution: larger blue, USGS High Resolution Bay Area: small white, USGS Low Resolution Bay Area: larger white)

UCVM v17.1.0 builds on Linux systems with GNU software stack including automake tools, C and Fortran compilers, and Python 2.7 distribution.

UCVM was developed with support from National Science Foundation (NSF), US Geological Survey (USGS), and other sources. UCVM software and documentation are available on the SCEC github wiki at UCVM Github Wiki.

Preferred Reference

If you use the UCVM software in your research, please include a reference our UCVM publication in your research papers. References help us obtain continued financial support for the development of this software. The preferred reference for the UCVM software is:

Small, P., Gill, D., Maechling, P. J., Taborda, R., Callaghan, S., Jordan, T. H., Ely, G. P., Olsen, K. B., and Goulet, C. A. (2017). The SCEC Unified Community Velocity Model Software Framework. Seismological Research Letters, 88(5). https://doi.org/doi:10.1785/0220170082

Additional Information on Previous Versions

Additional documentation on previous versions of the UCVMC software is posted on a SCEC website at SCEC UCVM Documentation

Software Support

For software support, please email [email protected]