Submarine Landslides in the Central Mediterranean: Causes and Recurrences

Gauchery, Tugdual Tristan Nicolas Marie (2021) Submarine Landslides in the Central Mediterranean: Causes and Recurrences, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Ingegneria civile, chimica, ambientale e dei materiali, 33 Ciclo. DOI 10.48676/unibo/amsdottorato/9902.
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This thesis (SLATE-project, is concentrated on submarine landslides in the central Mediterranean Sea. Commonly found in marine and lacustrine environments, submarine landslides represent one of the main mechanisms of sediment transport along continental margins, their volumes can be far larger than any terrestrial landslides and have potential to produce far-reaching tsunamis that can rival those produced by earthquakes. However, many uncertainties remain concerning their preconditioning factors, triggering mechanisms, return frequencies and relationship with climate change as well as their geohazard potential, which vary depending on their location. Newly identified submarine landslides emplaced in the Gela Basin (GB; south of Sicily, central Mediterranean Sea) were investigated where the particular geodynamic and oceanographic context and the limited extent basin is ideal for submarine landslides research. The investigation through multiple data types including deep boreholes, multi-channel and subbottom seismic profiles, sediment cores and swath bathymetry revealed the emplacement of multiple submarine landslides during the margin outbuilding in the Pliocene-Quaternary with a drastic transition in their volumes and emplacement location at the Middle-Pleistocene Transition (MPT). This change, accompanied by an accelerated margin outbuilding from 150 to 900 m/kyr and growth of the contourite deposits, has been related to the decreasing tectonic activity at the southern front of the Maghrebian fold-and-thrust belt and the climatic changes linked to the switch to the 100-kyr Milankovitch cyclicity. Numerical in-house codes used for the reconstruction of two small-size MTDs located at the ends of the GB show similar potential of generating high-wave tsunamis that can impact the coasts of Malta and Sicily but different triggering mechanisms based on the stability analysis. A multiproxy approach made on the sediment cores revealed that strong bottom currents and very-high sedimentation rate fluctuations, associated with sea-level changes, affected the stability of contourite deposits and contributed to the recurrent emplacement of MTDs.

Tipologia del documento
Tesi di dottorato
Gauchery, Tugdual Tristan Nicolas Marie
Dottorato di ricerca
Settore disciplinare
Settore concorsuale
Parole chiave
Submarine landslides, preconditioning factors, triggering mechanisms, return frequencies, Gela Basin, Middle Pleistocene Transition, Milankovitch cyclicity, contourite deposits, very-high sedimentation rate
Data di discussione
22 Ottobre 2021

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