GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 Shakemaps for Historical Earthquakes in Italy I. Oliveti 1 , L. Faenza 2 , A. Rovida 3 , A. Antonucci 3 , M. Locati 3 , A. Michelini 1 1 Istituto Nazionale di Geofisica e Vulcanologia, sezione ONT, Roma, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, sezione di Bologna, Italy 3 Istituto Nazionale di Geofisica e Vulcanologia, sezione di Milano, Italy Introduction When evaluating earthquake consequences, macroseismic intensity distributions of past events are of the foremost relevance for several scopes, including source characterization of pre-instrumental earthquakes and risk analysis. For instance, in the absence of instrumental ground-motion data, the spatial distribution of macroseismic data points (MDPs) can be useful for the description of earthquake sources, i.e., estimates of epicentral location and magnitude (e.g., Bakun and Wentworth, 1997; Gasperini et al., 1999; 2010; Provost and Scotti, 2020; amongst others). This makes macroseismic intensity distributions fundamental for building historical earthquake catalogues covering multiple centuries. On a national and worldwide level, efforts are currently being made to compile homogenous historical earthquake catalogues, such as the global synthesis of the pre-20th century earthquake history of the world (Albini et al., 2014) and the European PreInstrumental Earthquake Catalogue, EPICA (Rovida and Antonucci, 2021; Rovida et al., 2022a). Mapping of the intensities of historical earthquakes can be important for reconstructing the distribution of the ground shaking in the pre-instrumental era. An atlas of peak ground motions and intensity maps for recent and historical global earthquakes has been developed by Allen et al. (2008). At the same time, several efforts have been made to estimate the ground shaking for historical events at the local scale (e.g., Schwarz et al., 2008; Faenza et al., 2013). In this study, we adopted the ShakeMap service provided by Istituto Nazionale di Geofisica e Vulcanologia (INGV; http://shakemap.ingv.it/shake4/) to accurately generate historical earthquake shaking maps. For this purpose, we used the configuration developed for the Italian seismological settings, as detailed in Michelini et al. (2020), with (i) an updated map of VS30 for the local site effects and (ii) the ad hoc formulation of ground-motion to intensity conversion equations (GMICEs) and intensity prediction equations (IPEs). From the Italian Macroseismic Database (DBMI15), we selected more than 12,000 intensity data points (DBMI15, https://emidius.mi.ingv.it/CPTI15-DBMI15 here considered in its version 4.0, Locati et al., 2022). These observed data are related to 78 earthquakes with a magnitude greater than or equal to 6.0 that occurred before 1972 and that are contained in the last version of the Italian Parametric Earthquake Catalogue, CPTI15 (Rovida et al., 2020; 2022b).