Assessment of the 1783 Scilla landslide–tsunami's effects on the Calabrian and Sicilian coasts through numerical modeling

Abstract

Abstract. The 1783 Scilla landslide–tsunami (Calabria, southern Italy) is a well-studied event that caused more than 1500 fatalities on the beaches close to the town. This paper complements a previous work that was based on numerical simulations and was focused on the very local effects of the tsunami in Scilla. In this study we extend the computational domain to cover a wider portion of western Calabria and northeastern Sicily, including the western side of the Straits of Messina. This investigation focuses on Capo Peloro area (the easternmost cape of Sicily), where the highest tsunami effects outside Scilla were reported. Important tsunami observations, such as the wave height reaching 6 m at Torre degli Inglesi and flooding that reached over 600 m inland, have been successfully modeled but only by means of a high-resolution (10 m) topo-bathymetric grid, since coarser grids were inadequate for the purpose. Interestingly, the inundation of the small lake of Pantano Piccolo could not be reproduced by using today's coastal morphology, since a coastal dune now acts as a barrier against tsunamis. Historical analysis suggests that this dune was not in place at the time of the tsunami occurred and that a ground depression extending from the lake to the northern coast is a remnant of an ancient channel that was used as a pathway in Roman times. The removal of such an obstacle and the remodeling of the coeval morphology allows the simulations to reproduce the tsunami penetration up to the lake, thus supporting the hypothesis that the 1783 tsunami entered the lake following the Roman channel track. A further result of this study is that the computed regional tsunami propagation pattern provides a useful hint for assessing tsunami hazards in the Straits of Messina area, which is one of the most exposed areas to tsunami threats in Italy and in the Mediterranean Sea overall.

Tsunamis From Submarine Collapses Along the Eastern Slope of the Gela Basin (Strait of Sicily)

“…The study of the tsunamis associated with submarine mass movements along the GBES is performed through a well-tested numerical procedure that has been developed in-house and applied to several cases of landslide-generated tsunamis (Zaniboni et al, 2014b;Ceramicola et al, 2014;Zaniboni et al, 2016;Zaniboni et al, 2019;Gallotti et al, 2020;Triantafyllou et al, 2020). Under the assumption that the submarine slope will fail, the simulation sequence covers the whole process including 1) the dynamics of the sliding motion, 2) the tsunamigenic impulse caused by the movement of the mass along the sea bottom, and 3) the propagation of the tsunami over the computational domain.…”

Something Still Remains: Factors Affecting Tsunami Risk Perception on the Coasts Hit by the Reggio Calabria-Messina 1908 Event (Italy)

“…Italy, throughout history, has been hit by several major tsunamis. Among these are the tsunamis that affected the coasts of Puglia in 1627, the eastern coasts of Sicily in 1693, the coasts of Calabria and Sicily in 1783, again the Calabrian coasts in 1905 and then the Calabrian and Sicilian coasts in 1908 [33][34][35][36].…”

“…Moreover, tsunamis impacts are extremely variable, due to the non-linear combination of physical phenomena related to the characteristics of the source, bathymetry and the coastal profile that can affect both the propagation of waves in the open sea and impacts near the coast [55,56]. As an example, an earthquake or a volcanic eruption can compromise the stability of a landslide by triggering a tsunami wave, as occurred in Scilla, 1783 [33]. It is worth also mentioning that tsunamis are generally preceded by unusual and ambiguous premonitory signals (ground shaking, loud noise, sea level anomalies) thus making it particularly difficult for them to be identified and recognized by people unfamiliar with this type of event, and hampering proper response (e.g., self-evacuation and other mitigation measures).…”

Tsunami risk management for crustal earthquakes and non-seismic sources in Italy

“…Examples are the events that occurred in 1184 (M w 6.8), 1638 (M w 7.1), 1783 (a long sequence with three M w > 6.7 earthquakes in two months, M w 7.1 being the largest), 1905 (M w 7.0), and 1908 (M w 7.1). For some of them (mainly 1783, but also 1908), a significant contribution may be ascribed to seismically induced landslides (for the 1783 event see [338][339][340][341]; for the 1905 event see [342]).…”

“…Campallà, entering the sea and generating a tsunami which impacted the nearby village of Scilla with waves up to 9 m high, killing around 1500 people. The simulation of the rockslide dynamics and of the ensuing tsunami has been addressed by several authors [338][339][340][341].…”