A gis-based tool for reliability assessment of seismic microzonation studies according to italian instructions and criteria

Following the enactment of Italian Law 77, 2009, almost all the Italian regions have been funded to produce seismic microzonation studies, according to the three levels of detail provided by Instructions and Criteria for Seismic Microzonation, in municipalities where the PGA exceeds 0.125 g (recurrence time: 475 years). In order to allow homogeneity both in terms of representation of themes that in terms of content of the studies, the “Standards of representation and computer storage” have been developed by the Technical Committee on Seismic microzonation. The Civil Protection Department, in support to the Committee, predisposed special investigative controls on seismic microzonation studies carried out, in order to verify compliance and correct application of mentioned standards. It is not possible however, for obvious reasons, to enter into technical and scientific quality of all the submitted studies. Some indications on the reliability may instead come from an analysis of investigations and elaborations performed as part of the studies. By virtue of the uniformity that characterizes all studies produced by the regions, it has been possible to develop a semi-automated system that allows to evaluate the products in terms of reliability of the content. This document describes which indicators are taken into account for assessing the reliability of the submitted studies and proposes a quantitative procedure for their qualification. The method is based on a series of theoretical and GIS-based criteria for assessing the reliability of seismic microzonation depending on its content, through several indexes, returning a series of themes developed in GIS environment which allows an immediate perception of results.