Seismic hazard and land management policies in Italy: the role of seismic investigation

Italy is a highly populated country with an important cultural heritage and is characterized by high seismicity. It is therefore of paramount importance to define clear and feasible policies for land management and to adopt consistent procedures for seismic risk assessment. In this context, seismic surveys aimed at providing S-wave velocity models are applied at a different degree of detail and com¬plexity. We provide a description of the regulatory frame¬work for seismic microzonation and an overview of the use of seismic measurements, with particular regard to surface wave analysis, for different levels of microzoning with some examples of recent applications in Italy. The definition of cost-effective strategies for seismic risk reduction requires a detailed knowledge of seismic hazard. Seismic microzonation can help in orienting the limited available funds for retrofitting to most the critical situations, developing city-planning activities aiming at reducing expo¬sure to earthquakes and exploitation of the most hazardous areas. In general, central authorities provide reference seismic hazard estimates at a national scale (e.g., for Italy, see Stucchi et al., 2011). However, local evaluations are required to account for the effects of seismo-stratigraphic and geomor¬phological site conditions on the expected seismic ground motion. These effects may play a dramatic role in enhancing local damages, as for example the local instabilities induced by ground shaking (liquefaction, induced landslides), or those resulting from interference of seismic waves induced by the presence of heterogeneities in the subsoil (e.g., Tertulliani et al., 2012).