Materiali per una storia sismica del territorio di Gubbio: terremoti noti e ignoti, riscoperti e rivalutati

Abstract

Gubbio (Umbria) is the chief locality in a moderately seismic area and also a landmark in Italy’s network of tourist destinations; this makes Gubbio a significant economic resource and the mitigation of seismic risk in the Gubbio area a strategic objective. To achieve this objective it is required – inter alia – to have a comprehensive and reliable picture of local historical seismicity; until now, however, no critical study of historical earthquakes of the Gubbio area had ever been made. From 2013 to early 2015 this area has been affected by constant seismic activity, with mostly low energy events interspersed with a few significant ones, though none comparable with the last major local earthquake, occurred in 1984 (Mw 5.6). As the sequence went on, a few INGV researchers teamed up with local scholars with the intent of producing a systematic, up-to-date study of Gubbio historical seismicity. The study, carried out on a voluntary basis and totally unfunded, has had excellent results: the total number of macroseismic observations available for Gubbio has risen to 159 from 56 observations that were collected in the Italian Macroseismic Database 2011 (DBMI11) [Locati et al., 2011]; evidence of damage has been collected for some earthquakes thatì were previously believed not to have caused any damage; finally we discovered about twenty hitherto ‘unknown’, earthquakes, some of which caused damage in Gubbio and/or the surrounding area.