SW4 Mesh Development

Goal: Create NorCal CyberShake Mesh for SW4

Mesh Region

Region should match the SFBR model https://www.usgs.gov/programs/earthquake-hazards/science/3-d-geologic-and-seismic-velocity-models-san-francisco-bay

• ne_coord (-122.562365, 39.174505)
• nw_coord (-123.858493, 38.424179)
• sw_coord (-121.922036, 36.320331)
• se_coord (-120.644051, 37.050062)
• spacing=25.0

Config Script

• input 4 corners (and projection) and spacing
• calc rotation angle
• distance between points
• calculate nx, ny, nz based on spacing

Define Region

• origin
• rotation angle
• distance x
• distance y
• distance z
• spacing

Low Res UCVM2Mesh Configuration for SFBR Model

To test our mesh formats for SW4, we will test with a low resolution

1. rot=-53.9
2. x0=-123.858493
3. y0=38.424179
4. z0=0.0
5. spacing=500.0
6. Dist x = 140,000
7. Dist y = 290,000
8. Dist z = 40,000
9. nx=280
10. ny=580
11. nz=80

Full Res UCVM2Mesh Configuration for SFBR Model

1. rot=-53.9
2. x0=-123.858493
3. y0=38.424179
4. z0=0.0
5. spacing=25.0
6. Dist x = 140,000
7. Dist y = 290,000
8. Dist z = 60,000
9. nx=
10. ny=
11. nz=

Example from CyberShake

We don't actually generate a ucvm2mesh config file as part of the process of creating CyberShake meshes, but I've created what I think is the correct ucvm2mesh file for USC. The rotation angle is -55 degrees, and the 4 corners should be about:

   -122.46716     34.52173 (x=      0.000 y=      0.000)
   -119.66138     37.97316 (x=    460.000 y=      0.000)
   -113.59525     34.44267 (x=    460.000 y=    672.000)
   -116.52591     31.13175 (x=      0.000 y=    672.000)

Rob might use a different projection system, so I'd only expect the corners to agree to 3 or so decimal places.

Related Entries

• UCVM