Mass Transport Deposits and geo-hazard assessment in the Bradano Foredeep (Southern Apennines, Ionian Sea)

• Published in: Marine geology 2019-01, Vol.407, p.275-298
• Main Authors: Artoni, Andrea, Polonia, Alina, Carlini, Mirko, Torelli, Luigi, Mussoni, Paola, Gasperini, Luca
• Format: Article
• Language: English
• Subjects: Foredeep basin; Geo-hazards; Mass Transport Deposits; Quantitative mapping; Southern Apennines
• ISSN: 0025-3227; 1872-6151
• DOI: 10.1016/j.margeo.2018.11.008

Seafloor bathymetry, combined with multi-scale seismic reflection profiles, were used to describe the morphostructural setting of the Bradano Foredeep (Gulf of Taranto, northern Ionian Sea), where a submerged portion of the Southern Apennines is facing the Apulia Platform in the Calabrian Arc convergent margin. In this complex area, marine geophysical data highlight the presence of two mega-slide deposits at the shelf-slope transition, which are most likely the largest ever described in the region. These slid masses, named the Bradano Basento MegaSlide (BBMS) and Bradano Basento MegaSlide 1 (BBMS1), form a Mass Transport Deposit Complex (MTDC) affecting and eroding the topmost portion of the outer Apennines deformation front and the Apulian Foreland Ramp. It was emplaced in late Pleistocene times inside the narrow (about 10 km wide) Bradano Foredeep basin, a Plio-Pleistocene submarine trough developing at the chain front. The youngest of these deposits (BBMS1) likely predates the Last Glacial Maximum. Location of the MTDC within the subduction complex suggests that active tectonics and seismic shaking might represent the main triggering mechanisms for gravitative instability in this area, although gravitational tectonics and sediment creeping mechanisms cannot be excluded. On the other hand, size and distribution of the MTDC in the sedimentary record of the Bradano Foredeep suggest the need of re-evaluating the potential for large earthquakes/tsunamis, and more in general geological hazard related to submarine sliding masses, along the coast of this highly populated area. •Sea floor bathymetry, multichannel seismic profiles allow to discover and map a new Mass Transport Deposits Complex (MTDC).•The new MTDC is a composite megaslide: Bradano Basento MegaSlide (BBMS) and Bradano Basento MegaSlide1 (BBMS1).•The MTDC erodes the outermost, offshore front of the Southern Apennines and infills the narrow Bradano Foredeep.•Pre- LGM active tectonics and seismic shaking are considered the main triggering mechanisms of the BBMS-BBMS1.•This new and biggest MTDC in the Gulf of Taranto calls for re-evaluating the tsunami hazard along this coastal populated area.