Dam Safety Technology Development Project: Evaluation of Various Approaches to Obtaining Vs30 Values

The report presents an overview and evaluation of all relevant techniques currently available to Reclamation for assessing site-specific Vs30 values. The main objective of the study is to compare and evaluate all indirect Vs30 estimation techniques and all direct Vs30 measurement techniques (surfacebased and borehole seismic techniques), in order to better understand the various accuracies, advantages, and limitations of each technique. The study is based upon the quantitative and qualitative comparisons of various co-located seismic surveys and Vs30 estimates conducted at various field sites from 2016 through 2018 at several Reclamation and non-Reclamation embankment dams. Results of these various surveys and corresponding new or otherwise updated Vs30 values are also presented, where applicable. Finally, these results are utilized to inform and develop a set of practical Vs30 technique selection guidelines that can be used by project managers and engineers in order to optimize the tradeoffs between value of information and cost for future Dam Safety seismic risk analysis planning efforts.