Site effects associated with near-surface geological conditions constitute an important part of any seismic hazard assessment. In situ measurements of shear-wave velocity (VS) are commonly used to evaluate the seismic response of sites under investigation. Traditional invasive approaches “directly” measure VS; however, these methods are often costly and (or) environmentally prohibitive. In comparison, non-invasive methods (using body- and surface-waves) are generally more cost-effective and by nature, considered environmentally friendly. Thus, the appeal and use of non-invasive methods has significantly increased in recent years. Non-invasive methods, however, do not directly measure VS and have inherent uncertainties. The purpose of this session is to facilitate discussions about the state-of-practice in the application of non-invasive approaches for characterizing seismic site conditions and disseminate recent advances. Topics of interest include, but are not limited to: evaluation of forward algorithms, in particular, for cases of velocity inversions; the effects of lateral velocity variation; non-uniform impedance contrasts (e.g., dipping or undulating bedrock subsurface, etc.); uncertainty analyses including effect(s) of data quality, and, the quantification and (or) propagation of data uncertainty; model parameterization; effective- and multi-mode analyses; non-uniqueness of inversions; advanced inversion methods (joint, 2- and 3-D, nonlinear, Monte Carlo, etc.). Presentations on applying passive seismic interferometry, and, on comparing different techniques on data from the same site and those integrating a variety of datasets are encouraged.

The session conveners are members of an International Facilitation Committee supported by the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) to develop international guidelines for applying non-invasive geophysical techniques to characterize seismic site conditions. This special session was developed by the COSMOS Committee in coordination with conveners of recent and upcoming special sessions (same title) at the 2016 Seismological Society of America to be held from 20–22 April 2016 in Reno, Nevada, U.S.A., and the 2017 16th World Conference on Earthquake Engineering to be held from 9–13 January 2017 in Santiago, Chile. The COSMOS Committee includes: Yong, Alan (Chair, U.S.A.); Steidl, Jamison (U.S.A.); Nigbor, Robert (U.S.A.); Stephenson, William (U.S.A.); Asten, Michael (Australia); Molnar, Sheri (Canada); Cassidy, John (Canada); Crow, Heather (Canada); Lawrence, Martin (Canada); Xia, Jianghai (China); Bard, Pierre-Yves (France); Cornou, Cécile (France); Hollender, Fabrice (France); Parolai, Stefano (Germany); Bindi, Dino (Germany); Mucciarelli, Marco (Italy); Albarello, Dario (Italy); Foti, Sebastiano (Italy); Socco, Laura (Italy); Matsushima, Shinichi (Japan); Yamanaka, Hiroaki (Japan); Wotherspoon, Liam (New Zealand); Askan, Aysegul (Turkey); Yilmaz, Özdogan (Turkey).