Late Holocene co-seismic uplifts along the coasts of the Calabrian Arc: an appraisal based on raised paleoshorelines
Deformazioni co-sismiche tardo Oloceniche lungo le coste dell’Arco Calabro: una sintesi sulla base di antiche linee di riva sollevate
1 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, L.go San Marcellino 10, 80138, Napoli, Italy. E-mail: email@example.com
* CRUST, Centro inteRUniversitario per l’analisi Sismotettonica Tridimensionale con applicazioni territoriali.
2 ENEA, UTMEA, Casaccia, Roma, via Anguillarese 301. I-00123 Roma, Italy.
3 Dipartimento di Scienze Biologiche, Geologiche ed Ambientali, Università di Catania, Corso Italia 57, 95129 Catania, Italy.
4Studio Geologi Associati T.S.T., Misterbianco (Ct), Italy.
5PortableLab Geology & Engineering s.r.l. Academic spin-off University of Catania, Italy .
Ital. J. Geosci., 136 (3), 454-470
Late Holocene (~6 ka) shorelines represented by tidal notches, beach deposits, wave-cut terraces and intertidal organic rims are raised from few 0.1 m up to 5.5 m above the present sea level in the southern part of the Calabrian Arc. At five locales (Capo Vaticano and Scilla in southern Calabria and Taormina, Schisò, Capo Milazzo in north-eastern Sicily), the uplifted paleo-shorelines form a distinct vertical sequence where the older shorelines rest invariably above the younger ones. Such arrangement documents the occurrence of abrupt uplift events that are attributed to ancient earthquakes. A comprehensive appraisal of published studies has allowed to draw an inventory with a total of thirteen (and possibly sixteen) earthquakes which, based on the length of the coastal section involved in uplift, were likely of strong to major size (M~6.5-7). The amount of uplift per event ranges between ~0.5-2 m, with one event peaking at ~2.5 m. It appears that the amount of uplift decreased with time during the Late Holocene at all sites but Capo Vaticano, where it remained almost stationary. The co-seismic events appear grouped within four temporal clusters, during which uplift occurred at most of the five coastal sectors investigated here. These clusters spanned time intervals whose length, although difficult to bracket with precision, is of few hundred years, and are separated by longer (~0.5-1.5 ka) periods of apparent tectonic quiescence. The sources of co-seismic uplifts are still undefined, and must be searched between normal faults in the stretched Calabrian upper crust, or lower crustal thrust faults related to the Ionian subduction.
Keywords: Raised paleoshorelines, co-seismic uplift, earthquake clusters, Late Holocene, southern Calabrian Arc.