UCVM Users Guide

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Unified Community Velocity Model (UCVM) software framework is a collection of software tools designed to provide standard interface to multiple, alternative, California 3D velocity models. One important use of UCVM is in high resolution 3D wave propagation simulations for California. UCVM development is an interdisciplinary research collaboration involving geoscientists and computer scientists. UCVM geoscience research includes identification and assembly of existing California velocity models into a state-wide model and improvements to existing velocity models. UCVM computer science research includes definition of a easy-to-use CVM query interface, integration of regional 3D and geotechnical models, and automated CVM evaluation processing capabilities.

Coverage region for UCVM 2D maps (cyan) overlayed upon regions of various California 3D velocity models (CVM-S: red, CVM-H: blue, LinThurber: yellow, Thurber NoCal: green, USGS Bay Area: white)

Recent UCVM Software Distributions

Includes CVM-H 15.1, CCA05, CVM-S4.26, CVM-S4, and other California Velocity Models - Released October, 2015. This is the recommended version:

Includes CVM-H 14.3, and CVM-S4 California Velocity Models - Released March, 2014. This version is available as a reference only.

Current Detailed Seismic Velocity Models

  1. CCA - Latest Version: CCA05 - Preliminary Central California Area (CCA) Velocity Model (Min Vs 900m/s - No GTL)
  2. CVM-H - Latest Version: CVM-H 15.1 - Unified Structural Representation-based CVM with consistent Fault Geometries, Basins, and Velocity Model (no GTL)
  3. CVM-S5 - Latest Version: CVM-S4.26 - 500m tomographic results from 0.2Hz CVM-S4 iteration 26 (Min Vs 900m/s - No GTL)
  4. CVM-SI - Latest Version: CVM-S4.26.GTL - 500m tomographic results from 0.2Hz CVM-S4 iteration 26 with rules for adding GTL to top 350m
  5. CVM-S - Latest Version: CVM-S4 - Rule-based arbitrary precision southern California CVM with Geotechnical Layer
  6. Cencal CVM - USGS Bay Area Model
  7. Carl Tape's Great Central Valley Model
  8. Robert Graves' Cape Mendocino Region Model, Graves (1994)
  9. UCVM Utah Harold Magistrale's Wasatch Front Model (Utah)

Background Tomographic Models

  1. Moschetti Surface Wave Models
  2. Parkfield regional model, Thurber et al (2006)
  3. San Francisco area regional model, Thurber et al (2007)
  4. Northern California Regional 3D P-wave Velocity Model, Thurber et al (2009) USGS Thurber Report (pdf)
  5. Egill Hauksson regional southern CA model
  6. California Statewide 3D Velocity Model, Lin et al (2010). wiki: Lin Thurber CVM website: Guoqing Lin's website

Summary of Coverage Regions

Coverage regions of various California 3D velocity Models (Figure by Carl Tape )

CVM models typically provide Vp, Vs, rho, with constant attenuation above the basement surface (in the basins). The yellow dashed line is the target simulation goal for planned San Joaquin and Sierra model and simulations. The red box is CVMH 15.1.0. The inner red box is the high-res Los Angeles region of the CVM-H model.

Model List

CCA

This central California model is described at CCA

SCEC CVM-H

This southern California model is described at CVM-H.

SCEC CVM-S4.26-GTL1

This southern California model is described at CVM-SI.

SCEC CVM-S5

This southern California model is described at CVM-S5

SCEC CVM-S4

This southern California model is described at CVM-S.

USGS Bay Area (cencalvm)

This northern California model is described at USGS Bay Area Model cencalvm.

Northern California Regional 3D P-wave Velocity Model

Here is info on the first of four of our regional-scale 3D P-wave velocity models that I will provide. This is for our Northern California model, published in Thurber et al (2009).

Formally, the bounding rectangle is approximately given below however, the western edge realistically is the California coastline, and the northern edge is not quite to the Oregon border. 

42.60, -122.32
40.34, -126.27
37.74, -117.88
35.62, -121.71
  • The bottom nodes of the model are at 36 km.
  • Node spacing is mostly 10 or 15 km in the NE-SW direction and is uniformly 20 km in the NW-SE direction. Actual model resolution based on checkerboard tests is nominally ~twice the node spacing.
  • Vp model provided.

Cape Mendocino Region Model

This manuscript describes some 3D modeling of the Eel River basin which is in the Cape Mendocino region at the northern end of the San Andreas. Robert Graves did this work as part of the development of the 3D FD methodology and published as a USGS external grant report in Graves (1994).

Parkfield Regional Model

Parkfield regional model, published in Thurber et al. (2006). Bounding box corners: 

TOP:
35.918339 -121.412085
36.6838908 -120.320581

BOTTOM:
35.0996582 -120.542912
35.86521 -119.45284

The model is fully documented in the supplementary information for the paper Thurber et al (2006).

San Francisco Regional Model

A higher-resolution model for the San Francisco Bay area, published in Thurber et al (2007). It covers a smaller region than our northern California model.

Wasatch Front Model (Utah)

UCVM Utah This is a Utah Geological Survey velocity model for NE Utah, developed by Harold Magistrale and described at wfcvm.

Overview of CVM Models

These posters and presentations may contain information about earlier versions of CVM-H. This information may be useful to some users.

UCVM Software

A software framework has been developed to support a state-wide model. The framework contains a command-line query tool and a C API for querying any supported velocity model.

Coverage Region and Projection

Projection for 2D Maps

The following is the coverage region and projection for the included 2D elevation and Vs30 maps. The entire state of California is included, along with portions of Oregon, Nevada, Arizona, and northern Mexico.

Coverage region for UCVM 2D maps (cyan) overlayed upon regions of various California 3D velocity models (CVM-S: red, CVM-H: blue, LinThurber: yellow, Thurber NoCal: green, USGS Bay Area: white)
Origin: -129.75 DD, 40.75 DD
Projection: Azimuthal Equidistant (Proj.4 projection string "+proj=aeqd +lat_0=36.0 +lon_0=-120.0 +x_0=0.0 +y_0=0.0")
Rotation Angle: 55.0 D
Dimensions: 1800km x 900km

Statewide Data Sets

DEM

A statewide DEM for the proposed coverage region is included within UCVM. Elevation data has been sampled from USGS NED 1 arcsec dataset (~30 m), and bathymetric data from the NOAA ETOPO1 1' dataset (~1.5 km). This DEM is currently sampled at a resolution of approximately 220m but this may be increased. The elevation data is stored as a fixed resolution Etree for the entire 1800 x 900 km region. The elevation at a particular point is smoothed using bilinear interpolation of the surrounding four elevation octants.

UCVM Digital Elevation Model, with elevation set to 0.0 m outside of coverage region. The distortion is caused by differences in the DEM projection (Az-equi) and the plot projection (cylindrical).

Vs30 Maps

Two statewide Vs30 maps for the proposed coverage region are included within UCVM:

  • Wills-Wald Vs30 map (default): Vs30 data for the California landmass has been sampled from the Wills (2006) dataset at approx 0.0002197 D resolution, and out-of-state/ocean areas have been sampled from the Wald (2007) dataset at 0.0083333 D resolution.
  • Yong-Wald Vs30 map (optional): Vs30 data for the California landmass has been sampled from the Yong (2011) dataset at approx 0.013 D resolution, and out-of-state/ocean areas have been sampled from the Wald (2007) dataset at 0.0083333 D resolution.

These maps are currently sampled at a resolution of approximately 220m but this may be increased. The Vs30 data is stored as a fixed resolution Etree for the entire 1800 x 900 km region. The Vs30 value at a particular point is smoothed using bilinear interpolation of the surrounding four map octants.

UCVM Wills-Wald Vs30 map, with Vs30 set to 0.0 km/s outside of coverage region.

Geotechnical Layer

A statewide GTL for the proposed coverage region is included within UCVM. This is based on the Vs30-derived GTL method developed by Ely (2010). Interpolation between this GTL and the underlying crustal models is accomplished with the interpolation method described in that same publication. The z range over which interpolation is performed is configurable, as is the interpolation method used. The Ely method takes its input Vs30 value from the Vs30 map included within UCVM (described in the previous section).

UCVM Vs map at depth 0.0 m, showing the Ely GTL overlayed on the 1D background.

Additionally, UCVM is able to support any number of other user-defined GTLs. It will combine them in a manner analogous to how the crustal models are combined. Each GTL may also have its own user-defined interpolation function that is used to blend it with the underlying crustal models. If no interpolation method is specified, linear interpolation is assumed.

These shows how velocity model material properties delivered by a 3D velocity model depend on how the velocity model is queried and whether the model considers elevation, or whether the earth is modeled as a flat region.

Hydrology Map

A statewide hydrology map for the proposed coverage region will be included within UCVM. This map will provide the surface elevations of bodies of water such as oceans, lakes, and seas. No source dataset has been identified as of yet. This map will allow water information to be returned when UCVM is queried by elevation.

Documention

The user guide is available at UCVM User Guide.

UCVM Issue Tracking System

Users can report issues, bugs, and request features using the UCVM Trac system. Requires a SCEC login.

UCVM Beyond California

The UCVM code base has no specific dependencies upon the state of California. UCVM may be quickly configured for a new region given digital elevation data, Vs30 data, and one or more velocity models. As a proof of concept, this was done for northern Utah (see UCVM Utah) using the Utah Geological Survery Wasatch Front velocity model.

Future Models to be Integrated

Related Entries

See Also

References

  1. Ely, G., T. H. Jordan, P. Small, P. J. Maechling (2010), A Vs30-derived Near-surface Seismic Velocity Model Abstract S51A-1907, presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13-17 Dec. [Ely2010-AGU.pdf]
  2. Graves, R. (1994), Rupture History and Strong Motion Modeling of the 1992 Cape Mendocino Earthquake, USGS External Grant Report Cape mendocino-19941027.pdf
  3. Lin, G., C. H. Thurber, H. Zhang, E. Hauksson, P. Shearer, F. Waldhauser, T. M. Brocher, and J. Hardebeck (2010), A California statewide three-dimensional seismic velocity model from both absolute and differential Times, Bull. Seism. Soc. Am., 100, in press. supplemental
  4. Taborda R., López J., O'Hallaron D., Tu T. and Bielak J. (2007), A review of the current approach to CVM-Etrees, SCEC Annual Meeting, Palm Springs, CA, USA, September 8–12. [1]
  5. Thurber, C., H. Zhang, F. Waldhauser, J. Hardebeck, A. Michael, and D. Eberhart-Phillips (2006), Three-dimensional compressional wavespeed model, earthquake relocations, and focal mechanisms for the Parkfield, California, region, Bull. Seism. Soc. Am., 96, S38-S49, 2006. supplemental
  6. Thurber, C., T. Brocher, H. Zhang, and V. Langenheim (2007), Three-dimensional P-wave velocity model for the San Francisco Bay region, California, J. Geophys. Res., 112, B07313, doi:10.1029/ 2006JB004682, 2007.
  7. Thurber, C., H. Zhang, T. Brocher, and V. Langenheim (2009), Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California, J.Geophys. Res., 114, B01304, doi:10.1029/2008JB005766, 2009.
  8. Wald, D. J., and T. I. Allen (2007), Topographic slope as a proxy for seismic site conditions and amplification, Bull. Seism. Soc. Am., 97 (5), 1379-1395, doi:10.1785/0120060267.
  9. Wills, C. J., and K. B. Clahan (2006), Developing a map of geologically defined site-condition categories for California, Bull. Seism. Soc. Am., 96 (4A), 1483-1501, doi:10.1785/0120050179.
  10. Yong, A., Hough, S.E., Iwahashi, J., and A. Braverman (2012), A terrain-based site conditions map of California with implications for the contiguous United States, Bull. Seism. Soc. Am., Vol. 102, No. 1, pp. 114–128, February 2012, doi: 10.1785/0120100262.
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