Community Velocity Model (CVM) and Other Geophysical Data
The Utah Geological Survey (UGS) and U.S. Geological Survey (USGS) have a cooperative agreement to study earthquake hazards in Utah with an ultimate goal of producing detailed earthquake hazards maps. This goal includes large-scale ground-shaking maps along the densely populated Wasatch Front urban corridor.
An important component of the ground-shaking maps is developing a three-dimensional model of the subsurface, a Wasatch Front Community Velocity Model (CVM), that incorporates shallow shear-wave velocity (Vs), deep-basin structure, and other effects. To aid in producing these maps, the UGS has compiled well logs, databases of Vs, and deep-basin geophysical data.
Geophysical Data Donations
The UGS accepts geophysical data donations, including deep borehole logs, geophysical data, and shear-wave profiles, that may be included in our databases and used for future updates to site-conditions maps and the CVM. The data are made available to, and intended to benefit, the geotechnical community and the general public. For additional information or to submit data, contact Greg McDonald at 801-537-3383, email: firstname.lastname@example.org.
Community Velocity Model (CVM)
A three-dimensional Community Velocity Model (CVM) was developed to provide a framework for simulating ground motion expected during an earthquake on the highly urbanized part of the Wasatch fault zone. The CVM provides researchers a unified subsurface velocity model to simulate effects including strong motion, seismicity location, and tomographic velocity. Elements that populate the CVM include: soil classes, basin geometry, basin-sediment interfaces, crustal tomography, and the Moho.
The Wasatch Front CVM was developed by Harold Magistrale of San Diego State University and is based on earlier models developed by the Southern California Earthquake Center (SCEC). The CVM is periodically updated as more data become available and as additional analyses of existing data allow improvement to model elements. Important in refining the CVM are geophysical and borehole data that enhance our understanding of basin structure and velocities of various soil and rock types.
Presently, the CVM includes Cache, Weber/Davis, Salt Lake, and Utah basins. Future versions will expand the CVM to Tooele and Rush Valleys, Great Salt Lake Basin west of Antelope Island, and Wasatch Range back valleys.
The downloadable CVM version 3d includes Fortran 77 code with associated files that must be compiled (using a Fortran compiler on the users specific computer platform) and run locally. The CVM has been successfully compiled in Windows, using the g95 complier and MinGW. Input files must include latitude, longitude, and depth. The model returns Vp, Vs, and density for each input location.
While the Utah Geological Survey (UGS) provides the CVM to the public, the UGS does not provide support related to the CVM. Support related questions should be forwarded to Harold Magistrale, email email@example.com.
Magistrale, H, Olsen, KB, Pechmann, JC (2008) Construction and verification of a Wasatch front community velocity model. Technical report no. HQGR.060012, 14 pp. Reston, VA: US Geological Survey.