Modern and recent sediment gravity flows offshore eastern Sicily, western Ionian Basin

Informations projet

MARGRAF

N° de convention de subvention: 101038070

DOI

10.3030/101038070

Projet clôturé

Date de signature de la CE 13 Avril 2021

Date de début 1 Juin 2021

Date de fin 31 Mai 2023

Financé au titre de

• SPREADING EXCELLENCE AND WIDENING PARTICIPATION

Coût total

€ 148 049,28

Contribution de l’UE

€ 148 049,28

Coordonné par

UNIVERSITA TA MALTA
Malta

Periodic Reporting for period 1 - MARGRAF (Modern and recent sediment gravity flows offshore eastern Sicily, western Ionian Basin)

Période du rapport: 2021-06-01 au 2023-05-31

Résumé du contexte et des objectifs généraux du projet

MARGRAF aimed to address key questions on submarine sediment gravity flows using a multidisciplinary approach and tested a novel application for monitoring these events. These sediment flows are among the most important sediment transport processes on earth. They can flow across the seafloor for 100s of kilometers down to the deep-sea basins and for hours after initiation. Sediment gravity flows pose a hazard to offshore infrastructure such as telecommunication cables and they may also contribute to tsunami generation. Despite their significance gravity flows are poorly understood (e.g. flow behavior and evolution). Their sporadic occurrence in remote areas makes it challenging to monitor these events directly. The gap in understanding submarine gravity flows is especially problematic for regions that are densely populated and of economic importance such as eastern Sicily. The Ionian Basin offshore eastern Sicily is known for its high seismicity, tsunamis and long history of gravity flows. The 1908 Messina earthquake, which caused >60,000 casualties and destroyed entire cities such as Reggio Calabria, triggered a tsunami and extensive turbidity current. Yet, this gravity flow remains poorly understood despite being one of the few recent events, and deposits (called turbidites) are easily accessible. The geohazard implication of gravity flows is poorly constrained for this region.

The objectives of MARGRAF are to: 1) reconstruct the behavior and evolution of the 1908 gravity flow; 2) evaluate the role of this gravity flow in the 1908 Messina tsunami; 3) test the effectiveness of using a submarine telecommunication cable to detect modern gravity flows; and 4) determine present-day probability of new gravity flows being generated along the eastern Sicilian margin. Addressing these objectives will help to understand key processes involved in submarine gravity flows.

MARGRAF successfully addressed its objectives, especially those concerning the past and current occurrence of gravity flows. These new findings provide important information on gravity flows in general and will help to better understand similar gravity flows in other regions. Results from MARGRAF can be used to test if the 1908 gravity flow was involved in the tsunami generation and is subject of an ongoing collaboration. The findings from testing a new application to monitor gravity flows will have a large impact on the scientific community, especially those studying submarine gravity flows. Some results from MARGRAF, however, need more time to be evaluated before they can be made available to the public.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

MARGRAF was carried out at the Department of Geosciences of the University of Malta from 1 June 2021 to 31 May 2023. The objectives of MARGRAF were addressed within four work packages, one for each objective, which included key tasks and training activities to ensure that work can be concluded within the MARGRAF time-frame. The tasks included the compilation and analysis of specific data sets needed to address each objective e.g. data from sediment cores and analysis of seafloor and sub-seafloor images. MARGRAF further included research stays in Kiel (Germany), Brest (France) and Turin (Italy), which were important to exchange data and training of relevant skills. In summary, various data sets of multiple scale were analyzed and interpreted and key training activities (e.g. how to analyze laser interferometry data) were fulfilled. Results of MARGRAF were disseminated to target audiences via different measures such as a publication, attending various conferences, setting up a project website and participation in outreach events such as the “Tiny teen cafe”, where the researcher visited a Primary School to talk to students and their parents and teachers.

The main findings archived during the project time frame of MARGRAF are:
• Reconstruction the 1908 Messina gravity flow (flow direction and evolution, erosional and depositional behavior, potential source regions). These results will be used to test if the gravity flow was involved in the 1908 tsunami generation.
• Identification of depositional behaviors of gravity flows offshore eastern Sicily and the presence of various canyon-channel systems along the western Ionian Basin associated with different source areas and depositional centers of gravity flows.
• Initiation and testing of a novel application to monitor gravity flows. The data show a variety of signals, which are being evaluated to identify if they include a gravity flow.
• Evaluation of the slope stability for different areas along the Malta Escarpment. Preliminary findings seem to agree with previous studies, suggesting potential sediment movement and failure of the upper sediment column in case of strong earthquake (but are rare) or in areas that show a high slope inclination. A paper covering the findings from MARGRAF on the slope stability along the Malta Escarpment is currently being prepared.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

MARGRAF aimed to address key questions on submarine gravity flows by: i) integrating multi-scale and different data sets and techniques; and ii) focusing on one of the best monitored sections of the Mediterranean seafloor. The available data from the western Ionian Basin have a better spatial coverage than those used in previous studies. MARGRAF was focused on investigating recent events, as their signature is easily visible in geophysical and sedimentological data. By attempting to identify the origin of the 1908 tsunami we address a long-standing question in marine geosciences and improve geohazard assessment in the central Mediterranean region. An important novel aspect of MARGRAF is the testing of the use of telecommunication cables to detect gravity flows, which has not been carried out so far. If successful, and in view of the presence of such cables along all continental margins, the application of our results will be widespread.

Preparation of water tank to show how a turbidty current may look like

Example of an experimental turbidity current in a tank experiment (with blue food colour)