Cyclic Steps at the Head of Channelized Features Along the Calabrian Margin (Southern Tyrrhenian Sea, Italy)
High-resolution multibeam bathymetry have revealed coaxial trains of crescent-shaped bedforms within the heads of channelized features lying in shallow-water sectors along the tectonically-controlled Calabrian Margin. These bedforms have wavelengths of tens or a few hundreds of metres and wave heights of a few metres, and their crest-lines trend perpendicular to the maximum slope gradients. Repeated multibeam surveys carried out in 2007, 2008, 2012 and 2013 showed a rapid and significant morphological evolution of the channel’s floors, with the generation or upslope migration of the bedforms. Based on their size, upslope migration and similarities to crescent-shaped bedforms recognized in other active canyon heads, these features can be interpreted as cyclic steps. The bedforms are, in fact, formed or modified by frequent slope failures and related sedimentary flows, whose occurrence is favoured by the concurrent presence of several predisposing and triggering mechanisms, such as a high sedimentation rate due to a steep coastal creek, severe storms and seismic events.
KeywordsCrescent-shaped bedforms Seafloor mapping Repeated multibeam bathymetry Geohazard
This research was funded by the Italian MaGIC (Marine Geohazards along the Italian Coasts) Project and carried out in the framework of the RITMARE (Ricerca ITaliana per il MARE) Project. Crews of R/Vs Urania, Universitatis and Thetis are gratefully acknowledged along with the fellow researchers and students who took part in the sea surveys. We also thank Alan Lounds for the English revision.
- Antonioli F, Ferranti L, Lambeck K et al (2006). Late Pleistocene to Holocene record of changing uplift rates in southern Calabria and northeastern Sicily (southern Italy, Central Mediterranean Sea). Tectonophysics 422: 23–40.Google Scholar
- Bosman A, Casalbore D, Romagnoli C, Chiocci FL (2014). Formation of an ‘a’ā lava delta: insights from time-lapse multibeam bathymetry and direct observations during the Stromboli 2007 eruption. Bulletin of Volcanology, 76(7): 1–12.Google Scholar
- Casalbore D, Chiocci FL, Scarascia Mugnozza G et al (2011). Flash-flood hyperpycnal flows generating shallow-water landslides at Fiumara mouths in Western Messina Straits (Italy). Mar. Geophys. Res. 32: 257–271.Google Scholar
- Casalbore D, Bosman A, Ridente D, Chiocci FL (2014). Coastal and submarine landslides in the tectonically-active Tyrrhenian Calabrian Margin (Southern Italy): examples and geohazard implications. In: Krastel, S., et al. (Eds.), Submarine Mass Movements and Their Consequences. Advances in Natural and Technological Hazards Research, 37: 261–269.Google Scholar
- Hughes Clarke JE, Marques CR, Pratomo D (2014). Imaging active mass-wasting and sediment flows on a Fjord Delta, Squamish, British Columbia. In: Krastel, S., et al. (Eds.), Submarine Mass Movements and Their Consequences, Advances in Natural and Technological Hazards Research, 37: 249–260. doi: 10.1007/978-3-319-00972-8.
- Kostic S (2011). Modeling of submarine cyclic steps: controls on their formation, migration and architecture. Geosphere 7: 294–304.Google Scholar
- Paull CK, Ussler W, Caress DW, Lundsten E, Covault JA, Maier KL, Xu J, Augenstein S (2010). Origins of large crescent-shaped bedforms within the axial channel of Monterey canyon, offshore California. Geosphere 6: 1–20.Google Scholar