Ground Zoning Map of the Piedmont Region (NW Italy): methodology and preliminary results

This paper briefly describes the methodology and preliminary results of a study aimed at the realization of a Ground Zoning Map of the Piedmont region, characterized by low-to-moderate seismic hazard. In this study, two thematic maps were produced, namely a Lithotechnical map and a Ground Zoning Map of the Piedmont region at 1:250,000 scale. In the Lithotechnical map, the geological units were grouped, on the basis of their strength properties, grain-size, density and weathering of rocks, into 24 categories qualitatively characterized by a homogeneous seismic response. In the Ground Zoning Map, the regional territory was subdivided into three main sectors characterized by homogeneous mechanical behaviour during seismic shaking. These areas were further subdivided into several zones characterized by homogenous lithostratigraphy and/or geo-structural conditions. These maps should constitute the basis for the realization of an updated Vs30 map of the Piedmont region, which is currently lacking.