Macroseismic re-appraisal of the 1783 Calabria seismic sequence

Among the natural disasters that occurred in Europe in modern times, the earthquakes of February and March 1783 are certainly the most well-known and studied. This is due to their vast European resonance, the wealth of documentary material produced about the event, and the complexity and audacity of the recovery plan for the province developed by the Neapolitan government authorities. The seismic sequence is currently reported in seismic catalogs with five main shocks occurring between February 5 and March 28, 1783, with magnitudes ranging between 5.1 and 7.1. Despite the wealth of documentary evidence and the extensive scholarly literature that has emerged, significant gaps remain in our understanding of this seismic sequence. These limitations arise primarily from the inherent challenge of distinguishing between the effects of individual earthquakes and assessing the cumulative impact of successive shocks (Stucchi and Rovida, 2008; Guidoboni and Valensise, 2015; Tertulliani et al., 2018). Therefore, a long-term study was undertaken to re-examine what was already known, starting from existing sources, and to enrich the documentary heritage through new basic research, with the aim of increasing the number of macroseismic observations. This work presents the analysis of information relating to approximately 565 localities, based on a hypothetical chronological reconstruction of the sequence's shocks, which takes into account the impact of cumulative damage caused by multiple shocks when assigning macroseismic intensity. Through this approach, the shocks already present in the catalogs were reconstructed as faithfully as possible, using a richer knowledge framework compared to the past. The assignment of macroseismic intensities, according to the MCS and EMS-98 scales, has allowed for the construction of a new and broader macroseismic dataset and the proposal of a new interpretation of the sequence, highlighting the problems connected to the assignment of intensities.