Tracking Earthquakes in Documentary Sources of the Sixteenth–Eighteenth Centuries: Examples from Calabria (Southern Italy)

Abstract

Though the Calabrian arc is the most seismic area of the Italian peninsula, the overwhelming majority of M >6:5 earthquakes have occurred during the last four centuries. Conversely, the Italian seismic catalog exhibits an almost total absence of earthquakes— even moderate-magnitude earthquakes—between the eleventh and sixteenth centuries. The reason for this anomalous distribution of seismicity can be partially accounted for by the lack of historical sources caused by a paucity of local archives and by the enduring isolation of local administrations. We focused our research on moderate-magnitude earthquakes of centralnorthern Calabria between the sixteenth and eighteenth centuries and performed systematic research in many repositories, including in the Archivio Segreto Vaticano, in the state Archives of Naples, Catanzaro, Cosenza, and Potenza, and in several historic libraries. We found 15 previously unknown earthquakes for which we provide the level of shaking and the indication of the epicentral area for the first time. Also, we could definitively categorize one further event as a landslide rather than an earthquake. Finally, we found new evidence and information about four seismic events already known in the seismological literature; in particular, we provide a new intensity map and an increased magnitude (M 6.0) of the 14 July 1767 earthquake. Besides the new data on the earthquakes, we provide general clues and hints for searching useful documents to study earthquakes in the historical context of the sixteenth–nineteenth centuries.