UCVM VS30 etree map (Wills 2015) UCVM's interpolation
From SCECpedia
vs30 etree map in UCVM
After UCVM v22.7, vs30 tree map, ucvm.e, was updated to a new release by Thompson's latest ver. 2.0
- Thompson, E.M. (2018), An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022): U.S. Geological Survey data release, doi:10.5066/F7JQ108S.
>>> Below is for version before UCVM v22.7 using Wills 2015 <<<
vs30 etree map
In UCVM, the extraction of vs30 & surface values from vs30 etree map(ucvm.e) base on Wills 2015 is in src/ucvm/ucvm_map.c
UCVM's method:
A Latlng is converted from geo to xy offset and then calculate the matching gridpoint into the etree map 4 corners of interpolation grid plane points are extracted from etree Interpolate_bilinear are called to arrive at the final surf and final vs30 values
Rob's method:
Figure out the closest vs30 etree grid point and then use it
There are 2 big discrepancies in vs30 returned from UCVM and vs30 from Rob
lon lat ucvm Rob -117.95682 33.84007 293.500 294 -117.81793 33.85332 351.900 352 -117.88693 33.88911 312.445 294 <--- A -117.95898 33.86630 228.200 228 -117.93108 33.90853 386.600 387 -117.95576 33.93152 386.600 387 -117.80333 33.92733 385.100 385 -117.85709 33.85299 228.200 228 -118.04687 33.88925 228.200 228 -118.05753 33.92822 386.600 387 -117.86562 34.02098 419.818 352 <--- B -117.98124 33.80772 228.200 228 -117.92242 33.87170 293.500 294 -117.92371 33.94536 385.411 385 -117.95081 34.00950 293.500 294
Adding debug statements to UCVM to output the surf and vs30 from multiple grid points that were used
A: ucvm_query -m cvms5 -l 33.88911,-117.88693,0
>>> grid location: x0 5648 y0 1702 >>> corners -> 0 0 >>> corners -> 1 0 >>> corners -> 0 1 >>> corners -> 1 1 >>> 4 sets of grid point values.. >>>...surf 84.540581 78.770798 79.989998 81.523117 >>>...vs30 386.600006 293.500000 385.100006 293.500000 >>>...FINAL surf 80.292620 vs30 312.445426 -117.8869 33.8891 0.000 80.293 312.445 cvms5 1621.082 854.413 2032.805 none 0.000 0.000 0.000 crust 1621.082 854.413 2032.805
B:ucvm_query -m cvms5 -l 34.02098,-117.86562,0
>>> grid location: x0 5598 y0 1746 >>> corners -> 0 0 >>> corners -> 1 0 >>> corners -> 0 1 >>> corners -> 1 1 >>> 4 sets of grid point values.. >>>...surf 207.701019 182.753067 176.160889 172.366409 >>>...vs30 468.399994 385.100006 468.399994 351.899994 >>>...FINAL surf 179.832657 vs30 419.817623 -117.8656 34.0210 0.000 179.833 419.818 cvms5 1714.918 943.196 2076.987 none 0.000 0.000 0.000 crust 1714.918 943.196 2076.987
For a matching location,
ucvm_query -m cvms5 -l 33.84007,-117.95682,0
>>> grid location: x0 5652 y0 1664 >>> corners -> 0 0 >>> corners -> 1 0 >>> corners -> 0 1 >>> corners -> 1 1 >>> 4 sets of grid point values.. >>>...surf 34.806599 34.438507 37.543068 34.159943 >>>...vs30 293.500000 293.500000 293.500000 293.500000 >>>...FINAL surf 34.435791 vs30 293.500000 -117.9568 33.8401 0.000 34.436 293.500 cvms5 1626.430 833.127 2021.462 none 0.000 0.000 0.000 crust 1626.430 833.127 2021.462
