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Model Names and Abbreviations
CVM names and naming conventions within UCVM can be confusing, largely because the CVM model names and abbreviations have changed during UCVM development, and there is not consistent use throughout the software and documentation.
UCVM users need to know the velocity model of interest, and then the abbreviation that UCVM uses to refer to the CVM of interest. The following tables briefly describes the standard CVM models available through UCVM, and the abbreviation used by the UCVM software to refer to each model.
|Model Name||Description||UCVM Abbreviation|
|CVM-H||Southern California Velocity Model developed by Harvard Structural Geology Group with optional geotechnical layer||cvmh|
|CVM-S4||Southern California Velocity Model developed by SCEC, Caltech, USGS Group with geotechnical layer||cvms|
|CVM-S4.26||Tomography improved version of CVM-S4 with no geotechnical layer but has an optional Ely-Jordan GTL||cvms5|
|CVM-S4.26.M01||CVM-S4.26 with added geotechnical layer||cvmsi|
|USGS Bay Area||USGS developed San Francisco and Central California velocity model||cencal|
|CCA06||Central California Area Velocity Model at iteration 6 with added optional Ely-Jordan GTL (UCVMC18.5)||cca|
|CS17.3||CyberShake Study 17.3 Central California Velocity Model with added optional Ely-Jordan GTL (UCVMC18.5)||cs173|
|CS17.3-H||CyberShake Study 17.3 Central California Velocity Model integrated with Harvard group's Santa Maria and San Joaquin Basin Models with added optional Ely-Jordan GTL (UCVMC18.5)||cs173h|
|Modified Hadley Kanamori 1D||Southern California regional 1D model based on Hadley-Kanamori model||1d|
|Northridge Region 1D||Los Angeles Region 1D model used in SCEC Broadband Platform||bbp1d|
This table shows the standard scientific name for each model (on the left), and the model abbreviations used by UCVM in column 2. It is the abbreviation listed in column 2 that is used to specify the model of interest when calling UCVM. The sections below describe each of these registered 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)
We call the process of adding a CVM model (or other models, like topography models) registering a model in UCVM. Certain model information is required in order to register a model into UCVM. This includes, the geographical coverage region, the native projection, the material properties the model returns, and whether topography is supported in the model. In some cases, other information such as interpolation method is specified.
UCVMC defines a configuration file for each registered model. The model configuration files are collected in the installation directory in UCVMC/model/model_abbreviation/model_name.conf (e.g. UCVMC/model/1d/1d.conf)
Users can examine these .conf files to determine basic information about a model. In most cases, these model configuration files are static, and should not be modified by the user. In a few cases, such as bbp1d.conf file, there are user configuration options in the bbp1d.conf file (specifically a flag to specify whether the model should be delivered with interpolation).
Hadley-Kanamori 1D Model
The UCVM default background model is a modified Hadley-Kanamori 1d model. By default, ucvmc delivers this model using linear interpolation between layers. However, users can edit the 1d/1d.conf file and set the interpolation flag off, in which case the model will be delivered as a series of layers, with no interpolation of material property values between layers.
# 1D Velocity Model configuration # # Vp is interpolated between layer n to n+1. # Rho is derived from vp (./src/ucvm/ucvm_model_1d.c) # Vs is derived from Vp and Rho (./src/ucvm/ucvm_model_1d.c) # version=Hadley-Kanamori 1D (CVM-S) # Depth of model in layers num_z=9 # Depth to start of layer (km) depth_vals=1.0, 5.0, 6.0, 10.0, 15.5, 16.5, 22.0, 31.0, 33.0 # Vp at start of layer (km/s) vp_vals=5.0, 5.5, 6.3, 6.3, 6.4, 6.7, 6.75, 6.8, 7.8
This model definition only gives Vp values. Vs and rho are scaled from this Vp. The rules UCVMC uses to produce the Vs, and rho values are giving in the ../src/ucvm/ucvm_model_1d.c files mentioned in this configuration file.
An table from the original Hadley Kanamori paper, giving the original HK 1D model definition is posted on a SCEC website: Hadley Kanamori 1D model description
BBP1D LA Basin 1D Model
The BBP1D model was originally constructed by R. Graves as a 1d model for the Northridge Region. It was developed by averaging velocity profiles from a series of site around the Los Angeles basin. The resulting model is used in the SCEC Broadband Platform when simulating regional Los Angeles area earthquakes. This model configuration file provides a user specified flag specifying whether linear interpolation is used for material properties between layers. By default, linear interpolation is used.
# Northridge Region 1D Velocity Model Configuration # # This 1D model was defined by Graves and Pitrarka # in Table 3 of their paper: doi: 10.1785/0120100057 # It is used in the SCEC Broadband Platform format # for Los Angeles area simulations. # # Name of model. version=Northridge Region 1D Velocity Profile # Number of layers. num_z=18 # Interpolation method. # Set interpolation=linear to turn on interpolation # Set interpolation=none to turn off interpolation interpolation=linear # Columns # Thickness (km) Vp (km/s) Vs(km/s) Density (gm/cm3) Qp Qs # Start of model. # --MODEL-- 0.0020 1.7000 0.4500 2.0000 45.0000 22.5000 0.0040 1.8000 0.6500 2.1000 65.0000 32.5000 0.0060 1.8000 0.8500 2.1000 85.0000 42.5000 0.0080 1.9000 0.9500 2.1000 95.0000 47.5000 0.0100 2.0000 1.1500 2.2000 115.0000 57.5000 0.0700 2.4000 1.2000 2.2000 120.0000 60.0000 0.2000 2.8000 1.4000 2.3000 140.0000 70.0000 0.2000 3.1000 1.6000 2.4000 160.0000 80.0000 0.2000 3.4000 1.8000 2.4500 180.0000 90.0000 0.3000 3.7000 2.1000 2.5000 210.0000 105.0000 2.0000 4.4000 2.4000 2.6000 240.0000 120.0000 2.0000 5.1000 2.8000 2.7000 280.0000 140.0000 1.0000 5.6000 3.1500 2.7500 315.0000 157.5000 5.0000 6.1500 3.6000 2.8250 360.0000 180.0000 5.0000 6.3200 3.6500 2.8500 365.0000 182.5000 5.0000 6.5500 3.7000 2.9000 370.0000 185.0000 10.0000 6.8000 3.8000 2.9500 380.0000 190.0000 999.0000 7.8000 4.5000 3.2000 450.0000 225.0000
The following SCEC website provides more information about this model. https://scec.usc.edu/scecpedia/BBP_1D_LA_Basin_Model BBP1D LA Basin 1D Model
This is the most recent version of a southern California velocity model developed by the Harvard structural geology group.
More information about the CVM-H velocity model is available on a SCEC Website: SCEC Community Velocity Model - Harvard Website
This is the best available version of the rule-based SCEC southern California velocity model. SCEC produced several iteration of this model from about 1995-2004. The later version are considered improvements on previous versions of the SCEC CVM models, so this replaces earlier version. The version available through UCVMC contains all available code fixes that have been added to the model since its release in 2004.
This models provides two regions that define a geotechnical layer (GTL), the return low Vs values, in the top 350m. These are polygon regions, as shown in the coverage maps, that provide GTL information Los Angeles region and in the Salton Sea area.
More information about the SCEC CVM-S4 is available on a SCEC Website at: SCEC CVM-S4 Website
This is a tomography improved model of the CVM-S4 model. The tomography was performed on a 500m x 500m x 500m resolution mesh for the full region. The results are delivered on this fairly low resolution mesh, with linear interpolation used to determine material properties between mesh points. The tomography used a minimum Vs value for the region at about 900m/s, so this model does not deliver any low (or realistic) Vs values, when the GTL flag is set gtl = off. When the flag is set gtl = on, UCVM will add the Ely-Jordan Vs30-based GTL into the top 350 meters which provide velocities down to 200m/s in some areas.
# UTM Zone utm_zone = 11 # Model directory model_dir = s5 # GTL on or off? gtl = off # Number of cells in x, y, and z. nx = 1536 ny = 992 nz = 100 # Depth, in meters depth = 50000 depth_interval = 500 # Density scaling parameters p5 = -0.0024189659303912917 p4 = 0.015600987888334450 p3 = 0.051962399479341816 p2 = -0.51231936640441489 p1 = 1.2550758337054457 p0 = 1.2948318548300342 # Corners, in UTM projection. bottom_right_corner_e = 596013.92402056302 bottom_right_corner_n = 3368878.9393477398 bottom_left_corner_e = 10616.346941343043 bottom_left_corner_n = 3863137.9139448642 top_right_corner_e = 915108.80599173578 top_right_corner_n = 3746813.1405760832 top_left_corner_e = 329711.22891251586 top_left_corner_n = 4241072.1151732076
This is a version of the CVM-S4.26 model that combines the tomography improved CVM-S4.26 model with some elements of the CVM-S rule-based geotechnical layer in the top 350m. This provides more realistic low Vs values often wanted in 3D ground motion simulations in the Los Angeles Region. The algorithm used to combine the tomography mesh, and the geotechnical layer are defined the UCVM site.
Cencal is The USGS 3-D Geologic and Seismic Velocity Models of the San Francisco Bay region. This model provide a three-dimensional view of the geologic structure and physical properties of the region down to a depth of 45 km (28 miles). Construction of this 3D Bay Area model was a joint effort of the USGS Earthquake Hazards Program and the USGS National Cooperative Geologic Mapping Program.
Computational research has shown that the 3-D structure of the earth has a significant impact on how strongly an earthquake is felt at different locations and on the duration of the shaking. Because seismic waves propagate through different rock types with differing speeds that depend on the rock properties, the waves can be reflected and refracted as they travel through various rock types. These effects need to be understood in order to predict the shaking in future large earthquakes.
The Cencal 3-D models combine 100 years of surface geologic mapping by the USGS, the California Geological Survey, and many other institutions together with decades of research into the seismic properties of the rocks in the Bay Area. Traditional two-dimensional geologic maps show only the distribution of rock units at Earth's surface.
The Cencal Seismic Velocity Model is defined in two files, formatted as etrees.
Detailed model USGSBayAreaVM-08.3.0.etree.gz (1.6 GB) This is an Etree database file for inner, fine resolution model covering the San Francisco Bay area
Regional model USGSBayAreaVMExt-08.3.0.etree.gz(1.1 GB) This is an Etree database file for outer, coarser resolution model. The model fits around the detailed model and extends the region covered by the model. If you are only interested in the volume covered by the detailed model, you do not need to download this model.
Cencal Coverage Region
Detailed Regional (Extended) Approx. Dimensions 290km 140km 650km 330km SE corner (lon,lat) -120.644051 37.050062 -118.944514 36.702176 SW corner (lon,lat) -121.922036 36.320331 -121.930857 35.009018 NW corner (lon,lat) -123.858493 38.424179 -126.353173 39.680558 NE corner (lon,lat) -122.562365 39.174505 -123.273199 41.484869
Native Model Resolution
Detailed model Elevation1 Horiz. Resolution Vertical Resolution z > -400m 100m 25m -400m > z > -3200m 200m 50m -3200m > z > -6400m 400m 100m -6400m > z > -45000m 800m 200m
Transition from detailed model to extended model. This is a region 3.2km in width surrounding the detailed model. It is part of the extended model.
Elevation Horiz. Resolution Vertical Resolution (see elevation note) z > -3200m 200m 50m -3200m > z > -6400m 400m 100m -6400m > z > -45000m 800m 200m Extended model Elevation Horiz. Resolution Vertical Resolution (see elevation model) z > -6400m 400m 100m -6400m > z > -45000m 800m 200m Elevation is given with respect to mean sea level, so -400m corresponds to 400m below mean sea level.
- Native Projection: The detailed and regional velocity models are rectangular volumes in a Transverse Mercator (TM) projection with the following parameters:
Scale factor for central meridian: 0.99960000 Longitude of central meridian: -123.00000 Latitude of origin: 35.00000 False easting: 0.00000 False northing: 0.00000 Azimuths of sides: 53.638, 323.638
- Model External Website https://earthquake.usgs.gov/data/3dgeologic/
This is a trilinearly interpolated version of the 6th iteration of Po Chen and En-Jui Lee's full 3D tomographic inversions of the central California region. The inversions were done on a 500m coarse mesh, however the trilinearly interpolation allows this model to be queried at arbitrary precision. The GTL flag is default to off. When the flag is set gtl = on, UCVM will add the Ely-Jordan Vs30-based GTL into the top 500??350 meters.
# UTM Zone utm_zone = 10 # Model directory model_dir = i06 # GTL on or off? gtl = off # Number of cells in x, y, and z. nx = 1024 ny = 896 nz = 100 # Depth, in meters depth = 50000 depth_interval = 500 # Density scaling parameters p5 = -0.0024189659303912917 p4 = 0.015600987888334450 p3 = 0.051962399479341816 p2 = -0.51231936640441489 p1 = 1.2550758337054457 p0 = 1.2948318548300342 # Corners, in UTM projection. top_left_corner_e = 503240.523120 top_left_corner_n = 4051863.829470 bottom_left_corner_e = 779032.901477 bottom_left_corner_n = 3699450.983449 top_right_corner_e = 906054.312483 top_right_corner_n = 4367099.140150 bottom_right_corner_e = 1181846.690839 bottom_right_corner_n = 4014686.294129 # Data Layout Parameters seek_axis = fast-X seek_direction = bottom-up
CyperShake Study 17.3 Central California Velocity Model. This is a 175m resolution mesh tiled from CCA06, CenCal, CVM-S4.26-M01 with 10km smoothing on each horizontal interface used in the CyberShake Study 17.3, a Central California Seismic Hazard Model. The GTL flag is default to off. When the flag is set, gtl = on, UCVM will add the Ely-Jordan Vs30-based GTL into the top 175 meters.
# UTM Zone utm_zone = 11 # Model directory model_dir = cs173 # GTL on or off? gtl = off # Number of cells in x, y, and z. nx = 3200 ny = 6960 nz = 288 # Depth, in meters depth = 50400 depth_interval = 175 bottom_left_corner_e = 548969.079292 bottom_left_corner_n = 3459243.769232 top_left_corner_e = -448610.671359 top_left_corner_n = 4157755.975881 bottom_right_corner_e = 870071.761707 bottom_right_corner_n = 3917825.705794 top_right_corner_e = -127508.133290 top_right_corner_n = 4616338.305196 # Seek method, fast-X or fast-Y seek_axis = fast-Y seek_direction = top-down
CyperShake Study 17.3 Central California Velocity Model integrated with Harvard group's Santa Maria and San Joaquin Basin Models. The GTL flag is default to off. When the flag is set, gtl = on, UCVM will add the Ely-Jordan Vs30-based GTL into the top 175 meters.
# UTM Zone utm_zone = 11 # Model directory model_dir = cs173h # GTL on or off? gtl = off # Number of cells in x, y, and z. nx = 3200 ny = 6960 nz = 288 # Depth, in meters depth = 50400 depth_interval = 175 bottom_left_corner_e = 548969.079292 bottom_left_corner_n = 3459243.769232 top_left_corner_e = -448610.671359 top_left_corner_n = 4157755.975881 bottom_right_corner_e = 870071.761707 bottom_right_corner_n = 3917825.705794 top_right_corner_e = -127508.133290 top_right_corner_n = 4616338.305196 # Seek method, fast-X or fast-Y seek_axis = fast-Y seek_direction = top-down
State-wide Topography and Vs30 Model
To provide query by depth and query by elevation and Vs30 values for all models, UCVMC provides a statewide topography and Vs30 model. This is constructed as an etree data structure that stores the topography and vs30 values. The topography data is provided by USGS DEM. The Vs30 data is provide by converting Wills-Wald california site classifications to Vs30 values where ever the Wills-Wald map is defined. For regions outside of California, the Vs30 values were derived from the Wald vs30 topography relationship. The regional specification for the UCVMC topography and Vs30 etree are:
# UCVM model config file # Projection parameters for reference proj_str=+proj=aeqd +lat_0=36.0 +lon_0=-120.0 +x_0=0.0 +y_0=0.0 proj_origin=-129.75,40.75 proj_rot=55.0 proj_size=1800000.0,900000.0