First assessment of the local seismic amplification susceptibility of the Isernia Province (Molise Region, Southern Italy) by the integration of geological and geomorphological studies related to the first level seismic microzonation project

Abstract

This paper presents the results of the geological and geomorphological investigation carried out during the first level seismic microzonation project in the Isernia Province territory. The study area falls in one of the most seismically active areas of the Apennine chain and it has been struck, in historical times, by destructive earthquakes that caused several causalities and diffuse damages to the buildings. The analysis points out the occurrence of geological features that can determine possible site amplification phenomena related to areas with extensive outcrops of thick continental deposits or to unstable areas (both covering about 48% of the investigated areas). The latter are sometimes combined with geomorphological features such as scarps, isolated peaks, and ridges that are also responsible for possible site amplification. In addition, a susceptibility to local seismic amplification index has been introduced which highlights that more than 64% of the investigated area, along with a significant percentage of buildings, fall within the highest categories of susceptibility to local seismic amplification.