Morphological Variability of Submarine Mass Movements in the Tectonically–Controlled Calabro–Tyrrhenian Continental Margin (Southern Italy)

Daniele Casalbore,Domenico Ridente,Alessandro Bosman,Francesco Chiocci,Eleonora Martorelli,David Casas

doi:10.3390/geosciences9010043

Abstract

The analysis of high resolution morpho–bathymetric data on the Calabro Tyrrhenian continental margin (Southern Italy) enabled us to identify several morphological features originated by mass–wasting processes, including shallow gullies, shelf–indenting canyons and landslides. Specifically, we focus our attention on submarine landslides occurring from the coast down to −1700 m and affecting variable areas from thousands of square meters up to few tens of square kilometers. These landslides also show a large variability of geomorphic features which seems strictly related to the physiographic/morphological domains where the landslide formed. Tectonically–controlled scarps and canyon flanks are typically characterized by several coalescent and nested landslides, with diameters ranging from hundreds to a few thousands of meters. Canyon headwalls are commonly characterized by a cauliflower shape due to an array of small (diameters of tens of meters) and coalescent scars. In all these sectors, disintegrative–like landslides dominate and are generally characterized by a marked retrogressive evolution, as demonstrated by their morphology and comparison of repeated bathymetric surveys at the canyon headwall. Only in the lower part of tectonically–controlled scarps, a few cohesive–like and isolated landslides are present, indicating the main role of slope gradients and height drop in controlling the post–failure behavior of the mobilized material. Open slopes are generally characterized by large–scale (diameters of thousands of meters) and isolated scars, with associated landslide deposits. A peculiar case is represented by the Capo Vaticano Scar Complex that affected an area of about 18 km2 and is characterized by an impressive variability of landslide morphologies, varying also at short distance. The large extent and variability of such scar complex are thought to be associated with the occurrence of a mixed contouritic–turbidite system. By integrating the high–resolution morpho–bathymetric dataset with the results of previous studies, we discuss the main factors controlling the variability in size and morphology of submarine landslides developed in a tectonically–controlled setting and provide preliminary considerations on their potential geohazard in a densely populated coastal area.

Highlights

Geomorphic features associated with submarine mass movements are ubiquitous in all marine settings at very different depths and slope steepness [1,2,3]
Landslide scars occurring along the canyon flanks generally have a larger size
The previous section evidenced the widespread distribution and variability of landforms associated with submarine mass movements in the sector of the Calabro–Tyrrhenian margin comprised between the Cape Vaticano and the Messina Strait, where semi–circular to elongated landslides scars, with variable size and morphology are present

Summary

Introduction

Geomorphic features associated with submarine mass movements are ubiquitous in all marine settings at very different depths and slope steepness [1,2,3]. Their study has significantly increased in the last two decades in relation to the technological advances both in seafloor imagery system and seismic techniques as well as to the growing interest for their hazard potential [4,5]. These events can directly impact offshore or coastal infrastructures [6,7] or cause local but destructive tsunami waves, as for instance observed at Nice in 1979 [8] and Stromboli in 2002 [9]. They typically occur more frequently than the larger events and can generate local but destructive tsunamis [7] if they occur in shallow–water sectors

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