A Texas-specific $VS30$ map incorporating geology and $VS30$ observations Available to Purchase

A Texas-specific $VS30$ map that uses geostatistical kriging integrated with a region-specific geologic proxy, field measurements of $VS30$⁠, and P-wave seismogram estimates of $VS30$ is developed. The region-specific geologic proxy is used first to predict $VS30$ from the surface geologic conditions across the state, and then geostatistical kriging with an external drift is used to incorporate the local $VS30$ measurements/estimates into the map. Compared with the $VS30$ map of Texas developed from a topographic slope proxy, the Texas-specific $VS30$ map predicts larger $VS30$ values across much of Texas, except for the Gulf Coast region where the values are similar. The utilization of kriging brings the Texas-specific $VS30$ map into better agreement with the in situ measurements and estimates of $VS30$⁠. The sensitivity of predicted ground motions by ShakeMap to changes in $VS30$ values is evaluated with a scenario earthquake in the Dallas–Fort Worth area. The results suggest smaller predicted ground motions due to the generally larger values of $VS30$ in the Texas-specific $VS30$ map as compared to the $VS30$ from the topographic proxy.