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 cvms5 model. We used cvms5 in default mode, which includes the addition of a Vs30-based geotechnical layer. We queried the cvms5 model for material properties starting at the surface, and at 200m steps. This UCVM model will return low Vs values in some regions, based on geotechnical information derived from Vs30 information about the region. The GTL implementation defines low Vs value (less than 200m/s in some areas), and smoothly tapers those values in the top 300 meters to meet the Vs values provided by the tomography-defined velocity model.

Details about the Ely-based GTL is posted here.

• Common CVM Name: CVM-S4.26
• UCVM Name for CVM: cvms5
• Description: This is a CVM produced by Po Chen and En-Jui Lee. The starting model was a slightly modified version of CVM-S4. One of the modifications made to create the starting model was to put a min Vs of 1000 m/s floor into their starting model because their simulations were at low frequencies. During the tomography iterations which improved the velocity models, they allowed the tomography to lower those min Vs, but the lowest values in the cvms tomography model are Min Vp: 1250.00, Min Vs: 825.00, Min Rho: 2000.00. 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. UCVM adds a Vs30-based GTL using the Ely method. You must turn off this GTL to access the actual tomography-derived model.

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

• Ely GTL Method
• SCEC-ERI_Workshop_2014
• UCVM