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