S33C-2800
UCVM: An Open Source Software Package for Querying and Visualizing 3D Velocity Models

Wednesday, 16 December 2015
Poster Hall (Moscone South)
David Gill1, Patrick Small2, Philip J Maechling1, Thomas H Jordan1, John H Shaw3, Andreas Plesch3, Po Chen4, En-Jui Lee1, Ricardo Taborda5, Kim Bak Olsen6 and Scott Callaghan2, (1)Southern California Earthquake Center, Los Angeles, CA, United States, (2)University of Southern California, Los Angeles, CA, United States, (3)Harvard University, Cambridge, MA, United States, (4)University of Wyoming, Laramie, WY, United States, (5)Center for Earthquake Research and Information, Memphis, TN, United States, (6)San Diego State Univ, San Diego, CA, United States
Abstract:
Three-dimensional (3D) seismic velocity models provide foundational data for ground motion simulations that calculate the propagation of earthquake waves through the Earth. The Southern California Earthquake Center (SCEC) has developed the Unified Community Velocity Model (UCVM) package for both Linux and OS X. This unique framework provides a cohesive way for querying and visualizing 3D models. UCVM v14.3.0, supports many Southern California velocity models including CVM-S4, CVM-H 11.9.1, and CVM-S4.26. The last model was derived from 26 full-3D tomographic iterations on CVM-S4. Recently, UCVM has been used to deliver a prototype of a new 3D model of central California (CCA) also based on full-3D tomographic inversions. UCVM was used to provide initial plots of this model and will be used to deliver CCA to users when the model is publicly released.

Visualizing models is also possible with UCVM. Integrated within the platform are plotting utilities that can generate 2D cross-sections, horizontal slices, and basin depth maps. UCVM can also export models in NetCDF format for easy import into IDV and ParaView. UCVM has also been prototyped to export models that are compatible with IRIS’ new Earth Model Collaboration (EMC) visualization utility. This capability allows for user-specified horizontal slices and cross-sections to be plotted in the same 3D Earth space.

UCVM was designed to help a wide variety of researchers. It is currently being use to generate velocity meshes for many SCEC wave propagation codes, including AWP-ODC-SGT and Hercules. It is also used to provide the initial input to SCEC’s CyberShake platform. For those interested in specific data points, the software framework makes it easy to extract P and S wave propagation speeds and other material properties from 3D velocity models by providing a common interface through which researchers can query earth models for a given location and depth.

Also included in the last release was the ability to add small-scale stochastic heterogeneities to extracted Cartesian meshes for use in high-frequency ground motion simulations. This tool was built using the C language open-source FFT library, FFTW. The stochastic parameters (Hurst exponent, correlation length, and the horizontal/vertical aspect ratio) are all adjustable by the user.

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