Probabilistic procedure to estimate the macroseismic intensity attenuation in the Italian volcanic districts

Abstract

In this work we apply a probabilistic procedure to estimate the macroseismic intensity attenuation in the volcanic areas of Italy which allows to exploit additional information on historical earthquakes following the Bayesianapproach. The method starts from the intensity data points of the selected earthquakes and arrives at theassessment of the probability distribution for the intensity at a site given the epicentral intensity and thesite-epicenter distance. The CMTE local earthquake catalogue has been used for the Etna region while for theother Italian volcanic districts (Aeolian Islands, Ischia, Vesuvius and Albani Hills) the CPTI04 Italian seismic catalogue and the DBMI04 associated database have been considered. For the analysis, subsets of earthquakeswith epicentral intensity I0 ≥ VII MCS and I0 ≥ VI MCS were used for the Etna region and for the other Italian volcanic districts, respectively. Only earthquakes with more than 10 felt observations have been considered. The results show a specific attenuation trend for the Etna region compared with the other Italian volcanic areas.