S-wave measurements and seismic site classification in the Hispaniola Island

A proper dynamic characterization of soils is essential for an effective seismic site response evaluation. A typical approach consists in the determination of dynamic properties at low strain levels by means of in-situ shear wave velocity measurements. In-hole (e.g. Cross-hole and Down-Hole) and surface (e.g. SASW and MASW) methods are the most common techniques used worldwide. For the evaluation of seismic site effects in “regular” subsoil conditions, a simplified approach is based on a soil classification, according to an average shear wave velocities (e.g. VS,30). Here two case-histories of geotechnical characterization of two different areas in Hispaniola Island are illustrated, where proper dynamic in-situ tests allowed to individuate complex subsoil conditions. Then, according to national codes, subsoil categories and related seismic site responses are evaluated: the shortcomings of such code approaches are highlighted, and suggestions for more effective seismic action evaluation are suggested.