Vertical CVM Profiles

We are preparing a series of vertical velocity model profiles plots to support the SCEC summer school activities.

CVM Request

1. Lat/Long of locations
   1. 34.829 , -116.335
   2. 33.998 , -117.680
   3. 34.093 , -117.316
   4. 35.305 , -188.488
2. Velocity models to create profiles for
   1. CVM S4.26 if possible
3. Step resolution in depth (meters between data points in depth)
   1. 200m depth resolution, mainly to capture the shallow layers and the main discontinuities.
4. Smooth plots by using interpolation between steps
   1. no
5. How deep the profiles should go.
   1. The surface until 40km.

CVM

The names of SCEC CVMs can be confusing to users. One reason is that the CVM names used by SCEC scientists often do not match the names used by the UCVM software. The two groups may refer to the same velocity model using different names. For this reason, we often describe a CVM Common Name: (name often used by SCEC Scientists) and the CVM UCVM Name: (the name used by the UCVM software).

The profiles below were extracted from a model registered into UCVM that we call CVM-S4.26. In UCVM terms, the user queries this model using model name cvms5.

For the profiles below, we configured UCVM cvmsi model, and we queried the points at 200m steps. This UCVM model will return low Vs values in some reasons, based on geotechnical information encoded into the original CVM-S4 model. This model will provide Vs values down to Vs 200 m/s in some areas.

The UCVM software also provides an optional Vs30-based GTL. However, that Vs30-based GTL is not used for these plots.

• Common Name: CVM-S4.26-M01
• Model Name: cvmsi
• UCVM Name: cvmsi
• Description: cvmsi is a model that combines Po Chen and En-Jui Lee’s tomography-based improvements to CVM-S4, and uses an SCEC developed algorithm to preserve some of the rule-based GTL that was in the original CVM-S4. This model has been used to run wave propagation simulations at higher frequencies, because it will return some low GTL velocities when queried for material properties in the top 300 meters. This model is delivered on a coarse 3D grid of 1536 x 992 x 100 cells with a grid spacing of 500 m. UCVM returns values from this mesh using trilinear interpolation to provide intermediate values between mesh points below 350 meters. Above 350 meters, UCVM will call the original CVM-S4 to get material properties, in some cases. The rules for the GTL layer in this model were defined by SCEC research group, and are documented in the UCVM software source code, and with some entries on a SCEC wiki.

The results below show evidence of low Vs values, below 500 m/s. This indicates that this CVM provides the low velocities associated with a geotechnical layer. In this case, the GTL is based on the rule-based Magistrale GTL, not on the Ely-based Vs30 GTL that can be added to CVMs using the UCVM software.

Results Table

Southern California Velocity Profiles

34.829 , -116.335	33.998 , -117.680	34.093 , -117.316	35.305 , -118.488
Google Maps Site 1	Google Maps Site 2	Google Maps Site 3	Google Maps Site 4
Vp	Vp	Vp	Vp
Vs	Vs	Vs	Vs
rho	rho	rho	rho
Txt Data	Txt Data	Txt Data	Txt Data

Related Entries

• UCVM
• SCEC-ERI_Workshop_2014