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Philip Maechling edited this page Apr 22, 2022 · 11 revisions

Geotechnical Layers

The geotechnical characteristics of soils are an important aspect of the construction of buildings and structures such as tunnels, bridges, etc. These low velocity upper surface regions have significant effect on ground motion simulations, particularly at higher frequencies, above 0.5Hz and higher. For that reason, ground motion simulation modelers often want material properties from CVMs to contain accurate Vs values in the top 300-500 meters.

Ely-Jordan GTL method

UCVM provides a method for integrating low surface Vs values into the top 0-350m (user defined) of existing velocity models. This is useful because in some cases, existing velocity models do not provide detailed near surface velocity values. The UCVM supported optional GTL is based on the Ely-Jordan method that uses the surface site characteristics as an observation that can be used to provide an estimated near surface Vs value. The method then smoothly merges this surface-based Vs estimate into the underlying model Vs using a interpolation scheme developed by Ely.

Using the ucvm_query GTL option

The basic ucvm_query method provides a command line (and API) option to add GTL values to returned material properties. The effect of this option is to modify the native velocity model material properties in the top 350m (user defined) using information about the near surface geology. The end effect is to return lower Vs values in many areas which better reflect actual Vs values in many areas of California.

ucvm_query returns both the original model Vs values, and the modified Vs values when this option is used. The modified values are returned in the "combined" data columns of the ucvm_query return string.

In this example, the native material properties are returned in columns 6,7,8 and the modified (or combined) values are returned in columns 14,15,16. In nearly all cases, the GTL modifications are made for material properties in top 300-500m, and do not effect properties below that.

ucvm_query return values are:

Col 0: lon - Input lon in decimal degrees
Col 1: lat - Input latitude in decimal degree
Col 2: Z  - Input depth (or elevation) in meters
Col 3: elevation - Returned elevation (m) from UCVMC Digital Elevation Map
Col 4: vs30_from_Map - Returned Vs30 (m/s) from a Wills-Wald site type to Vs30 relationship (for points in California), or from Wald topography relation (outside of California)
Col 5: cvm_name - Input name of user specified CVM that was queried
Col 6: cvm_vp(m/s) - Returned Vp (m/s) from specified CVM
Col 7: cvm_vs(m/s) - Returned Vs (m/s) from specified CVM
Col 8: cvm_rho(kg/m3) - Returned density (kg/m3) from specified CVM
Col 9: gtl_name - Geotechnical used to modify values in top 350m
Col 10: gtl_vp - Geotechnical layer Vp
Col 11: gtl_vs - Geotechnical Layer Vs
Col 12: gtl_rho - Geotechincal layer rho
Col 13: combining_algorithm_name - Name of algorigthm used to combine base model and GTL
Col 14: combined_vp - Returned Vp based on base model and GTL
Col 15: combined_vs - Returned Vs based on base model and GTL
Col 16: combined_rho - Returned rho based on base model and GTL

 -118.0000    34.0000      0.000    280.896    390.000         1d   5000.000   2886.751   2654.500     elygtl      0.000    390.000      0.000        ely    824.177    195.000   1084.062

./ucvm_query -f ../conf/ucvm.conf -m 1d,elygtl:ely -z 0,350
Using Geo Depth coordinates as default mode.
-118 34 0
-118 34 100
-118 34 200
-118 34 300
-118 34 400
-118 34 500
 -118.0000    34.0000      0.000    280.896    390.000         1d   5000.000   2886.751   2654.500     elygtl      0.000    390.000      0.000        ely    824.177    195.000   1084.062
 -118.0000    34.0000    100.000    280.896    390.000         1d   5000.000   2886.751   2654.500     elygtl      0.000    390.000      0.000        ely   3423.315   1528.545   2305.443
 -118.0000    34.0000    200.000    280.896    390.000         1d   5000.000   2886.751   2654.500     elygtl      0.000    390.000      0.000        ely   4333.536   2277.050   2439.286
 -118.0000    34.0000    300.000    280.896    390.000         1d   5000.000   2886.751   2654.500     elygtl      0.000    390.000      0.000        ely   4848.471   2746.588   2511.898
 -118.0000    34.0000    400.000    280.896    390.000         1d   5000.000   2886.751   2654.500       none      0.000      0.000      0.000      crust   5000.000   2886.751   2654.500
 -118.0000    34.0000    500.000    280.896    390.000         1d   5000.000   2886.751   2654.500       none      0.000      0.000      0.000      crust   5000.000   2886.751   2654.500

The GTL is calculated small surface velocities and gradually increasing them by depth using the “ely” interpolation function and after 350m the interpolation and GTL are no longer used.

In UCVM, geotechnical layer (GTL) refers to the near-surface region of the velocity models. These regions have significant impact on ground motion simulations.

How to enable/disable GTL from models

Both CVM-S4 and CVM-S4.26.M01 have builtin GTL that can not be disabled. For other models with GTL, there are two different methods for enable and disable GTL depending on the models.

CVM-H

The default GTL setting for CVM-H is off and the flag can be found in installdir/conf/ucvm.conf file.

# CVM-H model flags. The model defaults are:
# No 1D background model
# No GTL added
#
cvmh_param=USE_1D_BKG,False
cvmh_param=USE_GTL,False
#

To enable GTL, update the last line to be,

cvmh_param=USE_GTL,True

CVM-S4.26, CCA06, CS17.3, CS17.3-H

The default GTL setting for CVM-S4.26, CCA06, CS17.3 and CS17.3-H are off. The GTL setting can be set in each model's config file located at installdir/model/cvms5/data/config, installdir/model/cca/data/config, installdir/model/cs173/data/config and installdir/model/cs173h/data/config

# GTL on or off?
gtl = off

To enable GTL, change the line to

gtl = on

UCVM can add the Ely Jordan GTL to velocity models using a command line parameters. The following three queries are for the same cvm-h points, without GTL, with elygtl:ely and elygtl:linear.

When addin the elygtl, a -z parameter is required to indicate the start and end values.

CVM-H, UCVM.conf CVM-H GTL,false

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   1946.508    505.610   1880.905       none      0.000      0.000      0.000      crust   1946.508    505.610   1880.905
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   3994.835   2271.410   2392.620       none      0.000      0.000      0.000      crust   3994.835   2271.410   2392.620
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   5087.308   2795.410   2548.363       none      0.000      0.000      0.000      crust   5087.308   2795.410   2548.363
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   4855.963   2866.868   2513.006       none      0.000      0.000      0.000      crust   4855.963   2866.868   2513.006
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   4730.289   2751.258   2494.663       none      0.000      0.000      0.000      crust   4730.289   2751.258   2494.663

CVM-H UCVM.conf CVM-H GTL,false, elygtl:ely -z 0,350

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh,elygtl:ely -z 0,350 < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   2139.914    672.340   1965.082     elygtl      0.000    397.973      0.000        ely   2226.984    600.934   1999.243
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   4398.315   2524.129   2448.169     elygtl      0.000    527.718      0.000        ely   3334.547   1485.425   2289.937
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   5074.826   2788.256   2546.395     elygtl      0.000    518.900      0.000        ely   3609.738   1589.793   2335.911
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   4860.199   2866.500   2513.634     elygtl      0.000    394.017      0.000        ely   3369.378   1523.207   2296.108
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   4713.636   2738.400   2492.270     elygtl      0.000    293.500      0.000        ely   3177.536   1389.021   2260.583

CVM-H UCVM.conf CVM-H GTL,false, elygtl:linear -z 0,350

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh,elygtl:linear -z 0,350 < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   2139.914    672.340   1965.082     elygtl      0.000    397.973      0.000     linear      0.000      0.000      0.000
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   4398.315   2524.129   2448.169     elygtl      0.000    527.718      0.000     linear      0.000      0.000      0.000
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   5074.826   2788.256   2546.395     elygtl      0.000    518.900      0.000     linear      0.000      0.000      0.000
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   4860.199   2866.500   2513.634     elygtl      0.000    394.017      0.000     linear      0.000      0.000      0.000
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   4713.636   2738.400   2492.270     elygtl      0.000    293.500      0.000     linear      0.000      0.000      0.000

CVM-H, UCVM.conf CVM-H GTL,true

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   2164.931    561.880   1975.122       none      0.000      0.000      0.000      crust   2164.931    561.880   1975.122
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   3571.999   1661.088   2329.946       none      0.000      0.000      0.000      crust   3571.999   1661.088   2329.946
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   3633.909   1606.619   2339.684       none      0.000      0.000      0.000      crust   3633.909   1606.619   2339.684
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   3221.180   1432.285   2269.012       none      0.000      0.000      0.000      crust   3221.180   1432.285   2269.012
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   3256.877   1437.267   2275.747       none      0.000      0.000      0.000      crust   3256.877   1437.267   2275.747

CVM-H UCVM.conf CVM-H GTL,true elygtl:ely -z 0,350

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh,elygtl:ely -z 0,350 < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   2139.914    672.340   1965.082     elygtl      0.000    397.973      0.000        ely   2226.984    600.934   1999.243
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   4398.315   2524.129   2448.169     elygtl      0.000    527.718      0.000        ely   3334.547   1485.425   2289.937
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   5074.826   2788.256   2546.395     elygtl      0.000    518.900      0.000        ely   3609.738   1589.793   2335.911
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   4860.199   2866.500   2513.634     elygtl      0.000    394.017      0.000        ely   3369.378   1523.207   2296.108
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   4713.636   2738.400   2492.270     elygtl      0.000    293.500      0.000        ely   3177.536   1389.021   2260.583

CVM-H UCVM.conf CVM-H GTL,true elygtl:linear -z 0,350

[ucvm@ac3e0e643150 target]$ ucvm_query -f /app/ucvm/conf/ucvm.conf -m cvmh,elygtl:linear -z 0,350 < querypts.txt
Using Geo Depth coordinates as default mode.
 -118.4810    34.3120    100.000    386.051    397.973       cvmh   2139.914    672.340   1965.082     elygtl      0.000    397.973      0.000     linear      0.000      0.000      0.000
 -118.5000    34.5000    100.000    573.044    527.718       cvmh   4398.315   2524.129   2448.169     elygtl      0.000    527.718      0.000     linear      0.000      0.000      0.000
 -117.5000    33.5500    100.000    381.905    518.900       cvmh   5074.826   2788.256   2546.395     elygtl      0.000    518.900      0.000     linear      0.000      0.000      0.000
 -117.5000    35.5000    100.000    721.905    394.017       cvmh   4860.199   2866.500   2513.634     elygtl      0.000    394.017      0.000     linear      0.000      0.000      0.000
 -116.5000    34.4000    100.000    791.036    293.500       cvmh   4713.636   2738.400   2492.270     elygtl      0.000    293.500      0.000     linear      0.000      0.000      0.000

Examples Effect of Ely/Jordan GTL in vs30queries

[ucvm@28d7188735e6 target]$ vs30_query -f /app/ucvm/conf/ucvm.conf -m cvms5 < vs30pts.txt
 -118.4810    34.3120    479.035
 -118.5000    34.5000    542.880
 -117.5000    33.5500   1488.633
 -117.5000    35.5000   1301.073
 -116.5000    34.4000   1297.697
[ucvm@28d7188735e6 target]$ vs30_query -f /app/ucvm/conf/ucvm.conf -m cvms5,elygtl:ely -z 0,350 < vs30pts.txt
 -118.4810    34.3120    209.404
 -118.5000    34.5000    276.783
 -117.5000    33.5500    313.116
 -117.5000    35.5000    246.636
 -116.5000    34.4000    200.306
[ucvm@28d7188735e6 target]$ vs30_query -f /app/ucvm/conf/ucvm.conf -m cvms5,elygtl:linear -z 0,350 < vs30pts.txt
 -118.4810    34.3120      0.000
 -118.5000    34.5000      0.000
 -117.5000    33.5500      0.000
 -117.5000    35.5000      0.000
 -116.5000    34.4000      0.000

Shield: CC BY 4.0

This work is licensed under a Creative Commons Attribution 4.0 International License.

CC BY 4.0

UCVM Documentation

  1. Overview and Introduction
  2. Installation
  3. Registered CVMs
    1. Model-Specific-Notes
  4. UCVM Configuration File
  5. Setting the UCVM Environment
  6. Basic UCVM Commands
    1. Query by Elevation or Depth
    2. Ely/Jordan GTL
    3. Plotting Scripts
  7. List of Commands
    1. Manual Pages
    2. Executables
    3. Scripts
    4. Examples
  8. Tutorials
    1. ucvm_query
    2. makegrid.sh
    3. Make-Grid
    4. Adding GTL
    5. Basin-Query
    6. ucvm2mesh
    7. vs30_query
  9. UCVM-Docker
    1. Using-UCVM-Docker
  10. References
  11. UCVM Query Parameters
  12. Model Specific Query Behavior
  13. Model Specific GTLs
  14. System-specific Builds
  15. Model References
  16. Concepts
    1. GitHub Branches
    2. Vs30 Info
    3. UCVM Plotting
    4. C-API
    5. FORTRAN-API
    6. Projections
  17. Test Cases
    1. GTL-Testing
      1. CVM-H GTLs
      2. CVM-S5 GTLs
      3. CVM-S4 GTLs
      4. CVMSI GTLs
      5. CCA GTLs
      6. 1D GTLs
      7. BBP1D GTLs
    2. Other CVM-H-Tests
  18. Earlier Documentation

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