The Global Vs30 Server allows a user to select from a map or input a rectangular region of interest. It then provides (optionally) a Vs30 grid in ASCII or GMT grid format, and a JPEG Vs30 map. Wald et al. (2004) first, and Wald and Allen (BSSA, 2007, in press), more fully, describe a methodology for deriving maps of seismic site conditions using topographic slope as a proxy. Vs30 measurements (the average shear-velocity down to 30 m) are correlated against topographic slope to develop two sets of coefficients for deriving Vs30: one for active tectonic regions that possess dynamic topographic relief, and one for stable continental regions where changes in topography are more subdued.
Summary
The Global Vs30 Server allows a user to select from a map or input a rectangular region of interest. It then provides (optionally) a Vs30 grid in ASCII or GMT grid format, and a JPEG Vs30 map. Wald et al. (2004) first, and Wald and Allen (BSSA, 2007, in press), more fully, describe a methodology for deriving maps of seismic site conditions using topographic slope as a proxy. Vs30 measurements (the average shear-velocity down to 30 m) are correlated against topographic slope to develop two sets of coefficients for deriving Vs30: one for active tectonic regions that possess dynamic topographic relief, and one for stable continental regions where changes in topography are more subdued.
Having a first-order assessment of seismic site conditions anywhere in the world provides a valuable tool in the prediction of ground-motions following a global earthquake, the primary motivation for this research.
