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Several California seismic velocity models are accessible through the UCVM software. The CVMs in UCVM are distributed in their original storage format, and they are accessible through the standardized UCVM query interface.

The IRIS Earth Model Collaboration uses NetCDF as a standardized format and SCEC has formated selected CVMS in netCDF format for users.

NetCDF resolution

The current SCEC netCDF file are discritized on a regular lat lon grid (0.01 degree increments) which is approximately 1km resolution in the horizontal (N-S) and 500m spacing in the vertical. The NetCDF format includes metadata describing the model.

CVM-H v15.1.1

This version of the CVM-H model uses UCVM utilities to create a version in which the model properties (Vp, Vs, rho) are defined relative to ground level (+ are depth below earth surface). CVM-H also provides optional geotechnical layers, either as a GTL by the model developers, and as an optional Ely-Jordon GTL which is based on Vs30 values. This CVM-H model uses the default "no background model" and "no GTL" configuration.


The CVM-S4.26 is a tomographically improved CVM, based on the SCEC CVM-S4 starting model. In UCVM, this model is called CVM-S5. The tomographic processing imposed a min Vs of 900m/s in the starting model, which removed low Vs values from the model. In some cases, the tomography lower the resulting Vs values below 900m/s, but the model has few low Vs velocity areas. UCVM has options for adding low Vs values back into the model, but these methods are not used to create this NetCDF file.

CVM-S4.16 is defined within a simulation volume that was rotated to be largely parallel to the strike of the San Andrea Fault. To define properties outsite the region where CVM-S4.26 is defined, this CVM-S4.26 netCDF file add properties from a 1D California background model, based on Hadley-Kanamori model

A description of the algorithms used to estimate Qp and Qs for this model are described in this CVM-S4.26 entry.

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