A global hybridVS30map with a topographic slope-based default and regional map insets

Time-averaged shear wave velocity over the upper 30 m of the earth's surface (V-S30) is a key parameter for estimating ground motion amplification as both a predictive and a diagnostic tool for earthquake hazards. The first-order approximation ofV(S30)is commonly obtained through a topographic slope-based or terrain proxy due to the widely available nature of digital elevation models. However, better-constrainedV(S30)maps have been developed in many regions. Such maps preferentially employ various combinations ofV(S30)measurements, higher-resolution elevation models, lithologic, geologic, geomorphic, and other proxies and often utilize refined interpolation schemes. We develop a new hybrid globalV(S30)map database that defaults to the global slope-basedV(S30)map, but smoothly inserts regionalV(S30)maps where available. In addition, we present comparisons of the default slope-based proxy maps against the new hybrid version in terms ofV(S30)and amplification ratio maps, and uncertainties in assignedV(S30)values.