Looking for missing earthquake traces in the Ferrara-Modena plain: an update on historical seismicity

According to the latest issue of the Italian seismic catalogue [Rovida et al. 2011], the area most affected by the May-June 2012 Emilia sequence [for an overview, vide Galli et al. 2012; Tertulliani et al. 2012, this volume] has a centuries-old seismic history of comparatively low magnitude events. These have been on a par with those that have occurred in the nearby Reggiano-Parmense area (where M 4.5 to M 5.5 earthquakes were comparatively frequent in the last century), although less significant than those on record in the portion of the northern Apennines that forms the southern boundary of the Pia-nura Padana (Figure 1), and a lot lower than in the most seismically active zones of the Italian peninsula. Magnitude ca. 5.5 earthquakes are known to have occurred near Ferrara (in 1346, 1561) and in the areas of Finale Emilia-Bondeno (1574, 1908, 1986), Mantua (1901) and Cento (1922). However, this picture might be incomplete, as suggested by the recent discovery of a previously unknown earthquake that occurred in 1639, whose maximum intensity was assessed as 7-8 Mercalli–Cancani–Sieberg (MCS) in Finale Emilia by Camassi et al. [2011a]. [...