Active tectonics along the submarine slope of south-eastern Sicily and the source of the 11 January 1693 earthquake and tsunami

Abstract

South-eastern Sicily has been affected by large historical earthquakes, including the 11 January 1693 earthquake, considered the largest magnitude earthquake in the history of Italy (<i>M</i><sub>w</sub> = 7.4). This earthquake was accompanied by a large tsunami (tsunami magnitude 2.3 in the Murty-Loomis scale adopted in the Italian tsunami catalogue by Tinti et al., 2004), suggesting a source in the near offshore. The fault system of the eastern Sicily slope is characterised by NNW–SSE-trending east-dipping extensional faults active in the Quaternary. The geometry of a fault that appears currently active has been derived from the interpretation of seismic data, and has been used for modelling the tsunamigenic source. Synthetic tide-gauge records from modelling this fault source indicate that the first tsunami wave polarity is negative (sea retreat) in almost all the coastal nodes of eastern Sicily, in agreement with historical observations. The outcomes of the numerical simulations also indicate that the coastal stretch running from Catania to Siracusa suffered the strongest tsunami impact, and that the highest tsunami waves occurred in Augusta, aslo in agreement with the historical accounts. A large-size submarine slide (almost 5 km<sup>3</sup>) has also been identified along the slope, affecting the footwall of the active fault. Modelling indicates that this slide gives non-negligible tsunami signals along the coast; though not enough to match the historical observations for the 1693 tsunami event. The earthquake alone or a combination of earthquake faulting and slide can possibly account for the large run up waves reported for the 11 January 1693 event

Applicability of the Decision Matrix of North Eastern Atlantic, Mediterranean and connected seas Tsunami Warning System to the Italian tsunamis

“…Both tsunamis have been the object of intense research in recent years and hypotheses have been advanced that their source was not exclusively the earthquake, but also some landslides in the Hyblean-Malta escarpment, and in the Messina Straits or on the Mt. Etna offshore complex, respectively (Tinti et al, 1999(Tinti et al, , 2001Gutscher et al, 2006;Favalli et al, 2009;Billi et al, 2010;Argnani et al, 2012). Such debate has no relevance in this context, since, whatever the real cause, there is no doubt that the DM predictions are adequate.…”

First report of live deep-water cnidarian assemblages from the Malta Escarpment

“…The Malta Escarpment is the expression of a passive margin separating the continental crust of the Malta Plateau from the oceanic crust of the Ionian Basin (Argnani & Bonazzi 2005). The age of the Malta Escarpment remains controversial, with estimates ranging from Late Triassic to Early Cretaceous (Argnani et al 2012). Triassic-Neogene shallow-water to basinal carbonate sequences outcrop along the escarpment (Scandone et al 1981;Casero et al 1984).…”

Calibration of a real-time tsunami detection algorithm for sites with no instrumental tsunami records: application to coastal tide-gauge stations in eastern Sicily, Italy

“…According to the Italian tsunami catalogue , most of these tsunamis are associated with large local earthquakes (e.g. 1693,1783,1908), but recently their purely tectonic origin was questioned and a debate was opened on the possible parallel or prevalent contribution provided by submarine landslides triggered by seismic shaking (see tsunami studies and tsunami source analyses in Piatanesi and Tinti, 1998;Graziani et al, 2006;Gutscher et al, 2006;Tinti et al, 2007;Papadopoulos et al, 2007;Billi et al, 2008;Gerardi et al, 2008;Favalli et al, 2009;Argnani et al, 2009Argnani et al, , 2012. Indeed, because of the morphology and steep bathymetry of the Messina Strait and of the Hyblean-Malta escarpment bordering eastern Sicily offshore, landslide excitation by earthquakes and even by simple gravitational loading cannot be ruled out, which means that landslides can be considered a further source of tsunami.…”