Paleoseismology along the Cittanova fault: Implications for seismotectonics and earthquake recurrence in Calabria (southern Italy)

Abstract

This paper focuses on the seismogenic structure responsible for the 5 February 1783 earthquake ( M > 7, Calabria, southern Italy), in particular the slip rate and recurrence time along the Cittanova fault, thus giving new insights on the seismic hazards and seismotectonics of the region. The 1783 earthquake, one of the strongest earthquake of the Mediterranean area, caused more than 30,000 casualties and radically changed the physiography of the local landscape. Until now, the Cittanova fault (or Aspromonte fault) has been generally identified as the surficial expression of the seismogenetic structure, even though its youthful activity has never been demonstrated. Recently, the shortage of geologic evidence of middle‐upper Pleistocene activity on this fault led some authors to locate the 1783 fault elsewhere. In our study we used a multidisciplinary approach (paleoseismology, geomorphology, historical seismology, archaeoseismology); our analysis of contemporary literary sources strengthened our interpretation of the coseismic origin of many geological features and, sometimes, oriented our field research toward specific areas. In particular, we excavated trenches and pits at three different sites along the trace of the Cittanova fault for paleoseismological analysis and 14 C dating. Our data document the Holocene and present activity of the Cittanova fault, providing a minimum vertical slip rate of 0.44 mm/yr and a possible return time of 1350–1800 years for earthquakes similar to 1783. The penultimate event has been dated to the 4th century A.D., a time when southern Calabria and eastern Sicily were devastated by an earthquake documented by archaeoseismic analyses.