UCVM ucvm with sw4 using cvmsi
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Question
Question from Rie to Scott,
..conducting SW4 simulations within the LA Basin for both small and large magnitude earthquake events (please see the attached slides for reference where we are interested in). While validating the ground motions, we have come across several features in the velocity model—built from the SCEC model—that we were hoping to better understand with your insight.
Blocky structure north of LA (highlighted in red in the slides):
We observed a blocky structure characterized by elevated Vs compared to the surrounding region. This structure appears to disappear at 50 m depth and then re-emerges below. Is there a specific reason why this structure is not present at the 50 m depth level?
Vp–Vs relationship of the blocky structure (green color):
The structure shows higher Vs values, with Vp appearing higher at the surface (Z = 0 m) but becoming lower at 250 m depth. We also noted that the density is relatively low at the surface.
Vp–density relationship west of the blocky structure:
In this nearby region, the density is higher than that of the surrounding material, but Vp appears to be lower. (I expect Vp correlates with density)
Would you know of any literature or documentation that describe these characteristics?
Background of the posted question
Accessing UCVM velocity model via SW4's UCVM reader branch and then run the SW4 simulation.
CVM-S4.26.M01 (cvmsi), the velocity values are extracted using UCVM "withSCPBR" branch
internal query parameters were:
ucvm_query -f conf/ucvm.conf -m cvmsi,elygtl:taper -L 200,700,1500
Is this version of velocity model, recommended for ground motion simulation ? (another question)
Plots from explorer with the posted parameters
Base cvm
looking at basin,
