Comparison of Deterministic and Probabilistic framework for Vs30 estimation in data scarce region: a case study for Southern Bihar, India.

Time-averaged shear-wave velocity in the topmost 30 meters of soil (V_s30) is a broadly accepted tool employed for site characterization. Adoption of V_s30 in the development of region-specific ground motion prediction equations and seismic design provisions marked it as a global parameter for local-site effect studies. Challenges arise in tectonically complex regions where an evaluation of V_s30 requires great exertion including mobility of equipment and manpower. Over the period, where researchers are still engaged in studying the effects and limitations of V_s30 at a location of interest, during the years various proxies have arrived for V_s30 estimation. Also, the selection of proxy depends upon the existing prior information about the region and its relationship with measured V_s30 values. Data scarce region requires interpolation techniques to address extensive geographical area with limited attainable datasets. Various deterministic (Inverse distance weighing, spline, etc.)  and probabilistic (kriging formats) interpolation techniques are widely used for robust estimation. In this study, an attempt has been made for a reliable region-specific selection of interpolation techniques. 35 V_s30 measurements are used as primary data and the topographic-slope proxy-based V_s30 model by U.S. Geological Survey is used as secondary data. Quantitative assessment acknowledges the existence, and validity which provides an understanding of the merits and flaws of interpolation techniques. The applicability of IDW, kriging and Bayesian scheme for sturdy estimation of Vs30 with focus on Southern Bihar region is examined for seismic response studies providing paramount importance to hazard and risk mitigation.

Keywords: V_s30, Topographic-slope Proxy, IDW, Kriging, Bayesian Scheme.