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

Abstract

The acquisition of high resolution morpho-bathymetric data on the Calabro Tyrrhenian continental margin (Southern Italy) enabled us to identify several mass-wasting processes, including shallow gullies, shelf-indenting canyons and landslides. In particular, we focus our attention on submarine landslides occurring from the coast down to -1700 m, with mobilized volumes ranging from some hundreds up to tens of millions of cubic meters. These landslides also show a large variability of geomorphic features in the headwall, translational and toe domain. Based on their morphology and distribution, four main classes of coastal/submarine landslides have been recognized: a) rocky coastal/shallow-water failures characterized by large hummocky deposits offshore; b) large-size and isolated scars with associated landslide deposits, mostly occurring on open slope environment and lower part of tectonically-controlled escarpments; c) a linear array of coalescent and nested landslide scars occurring in the upper part of tectonically-controlled escarpments and canyon flanks; d) a cauliflower array of small and coalescent scars occurring in canyon headwall.  The latter two classes of landslides are also characterized by a marked retrogressive evolution and their landslide deposits are generally not recognizable on the morpho-bathymetric data. By integrating the morpho-bathymetric dataset with the results of previous studies, we also discuss the main factors controlling the variability in size and morphology of these submarine landslides to provide insights on their failure and post-failure behavior.

Coarse‐grained deltas approaching shallow‐water canyon heads: A case study from the Lower Pleistocene Messina Strait, Southern Italy

“…2B to D). Although these features have no direct sediment supply, it is interesting to note how they also contain supercritical bedforms migrating upstream with dynamics extremely similar to those of river-fed canyon heads (Casalbore et al, 2014(Casalbore et al, , 2019. Arguably, deposits within these canyons may derive from longshore-transported sediments (Fig.…”

“…Recent observations suggest that the dominant process regime in the sublittoral zone of the strait derives from a combination of river-derived, gravity-driven event flows, related to occasional river floods and gradient-dependent instability of the margins (e.g. Casalbore et al, 2017Casalbore et al, , 2018Casalbore et al, , 2019. The modern Messina Strait lies near the subduction zone separating the African and European plates (Malinverno & Ryan, 1986;Patacca et al, 1990;Doglioni, 1991;Doglioni et al, 2001;Fig.…”

“…Scouring of chutes within the canyon is associated with canyon-head receding, whereas episodic accretion of trains of large supercritical-flow bedforms migrating upstream (e.g. Casalbore et al, 2011Casalbore et al, , 2019Tubau et al, 2015) is facilitated by the tendency of density currents to rapidly attain high densimetric Froude numbers along steep bathymetric gradients (Komar, 1971;Sequeiros, 2012). These processes are common in deep-water slope and channel/canyon settings, and are particularly known for channel-lobe transitions at the base of continental slopes (e.g.…”

“…This paper presents an outcrop-based study of a Lower Pleistocene succession exposed along the north-eastern margin of the modern Messina Nearshore subaqueous canyon along the south-western portion of the strait documented after the high-magnitude, flash flood event occurred on 1 October 2009. Scouring features and up-slope migrating bedforms resulted from supercritical flows violently entering the basin in the course of few hours after an intense and localized rainfall [the satellite image in (A) is from Google Earth©; multibeam data in (A) are modified, after Chiocci et al,2008; images in (B), (C) and (D) are modified, after Casalbore et al,2019; bathymetric data in (E) are modified, after Casalbore et al,2011).…”

“…Canyons promote sediment transfer to the deep basin and contribute to the scarce development of a subaerial plain (Fig. 2B to D; Cocco et al, 1988;Casalbore et al, 2014Casalbore et al, , 2019. Modern canyon heads correspond to river valleys in the emerged coastal areas, as they reflect the expression of ancient incised valleys transgressed after the Last Glacial Maximum (e.g.…”