Earthquake-triggered landslides along the Hyblean-Malta Escarpment (off Augusta, eastern Sicily, Italy) – assessment of the related tsunamigenic potential

Abstract

Abstract. Eastern Sicily is affected by earthquakes and tsunamis of local and remote origin, which is known through numerous historical chronicles. Recent studies have put emphasis on the role of submarine landslides as the direct cause of the main local tsunamis, envisaging that earthquakes (in 1693 and 1908) did produce a tsunami, but also that they triggered mass failures that were able to generate an even larger tsunami. The debate is still open, and though no general consensus has been found among scientists so far, this research had the merit to attract attention on possible generation of tsunamis by landslides off Sicily. In this paper we investigate the tsunami potential of mass failures along one sector of the Hyblean-Malta Escarpment (HME). facing Augusta. The HME is the main offshore geological structure of the region running almost parallel to the coast, off eastern Sicily. Here, bottom morphology and slope steepness favour soil failures. In our work we study slope stability under seismic load along a number of HME transects by using the Minimun Lithostatic Deviation (MLD) method, which is based on the limit-equilibrium theory. The main goal is to identify sectors of the HME that could be unstable under the effect of realistic earthquakes. We estimate the possible landslide volume and use it as input for numerical codes to simulate the landslide motion and the consequent tsunami. This is an important step for the assessment of the tsunami hazard in eastern Sicily and for local tsunami mitigation policies. It is also important in view of tsunami warning system since it can help to identify the minimum earthquake magnitude capable of triggering destructive tsunamis induced by landslides, and therefore to set up appropriate knowledge-based criteria to launch alert to the population.

The enigmatic 1693 AD tsunami in the eastern Mediterranean Sea: new insights on the triggering mechanisms and propagation dynamics

“…According to Tonini et al 30 and Argnani et al 28 , a tsunami due only to submarine slide may not have determined a flooding surface as reported in historical records. However, the geophysical surveys showed the presence of a submarine landslide of significant volume that, as also suggested by Paparo et al 29 , can generate a high tsunami wave in deep water. Therefore, the dual mechanism of fault displacement and submarine landslide could represent a step-forward in resolving the source of tsunami of 1693 AD.…”

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

“…More recently, Paparo et al [361] studied the slope stability of the HME under seismic loading on a number of transects, trying to identify those sectors that may move under the effect of seismic shaking. One of the results of the study was the estimation of landslide volumes that might be set in motion by seismic shaking, representing a fundamental step toward quantitative tsunami hazard assessment for the nearby coastal areas.…”

3D Flooding Maps as Response to Tsunami Events: Applications in the Central Sicilian Channel (Southern Italy)

“…Refs. [9][10][11][12] show the fragility of the Ionian coast of Sicily (Italy) that is a densely populated area highly exposed to the tsunami hazard, and, in such parts, the flooding effects related to tsunami waves can be significant. Ref.…”