A Texas-specific V-S30 map incorporating geology and V-S30 observations

A Texas-specific V-S30 map that uses geostatistical kriging integrated with a regionspecific geologic proxy, field measurements of V-S30, and P-wave seismogram estimates of V-S30 is developed. The region-specific geologic proxy is used first to predict V-S30 from the surface geologic conditions across the state, and then geostatistical kriging with an external drift is used to incorporate the local V-S30 measurements/estimates into the map. Compared with the V-S30 map of Texas developed from a topographic slope proxy, the Texas-specific V-S30 map predicts larger V-S30 values across much of Texas, except for the Gulf Coast region where the values are similar. The utilization of kriging brings the Texas-specific V-S30 map into better agreement with the in situ measurements and estimates of V-S30. The sensitivity of predicted ground motions by ShakeMap to changes in V-S30 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 V-S30 in the Texas-specific V-S30 map as compared to the V-S30 from the topographic proxy.