High-resolution seismic characterization of postglacial subaqueous mass movements in the Beagle Channel (Tierra del Fuego, Argentina): dynamics and tsunami hazard implications

BRAN, M.; PALMA, F.I.; PRINCIPI, S.; LODOLO, E.; LOZANO, J.G.; TASSONE, A.A.

NATURAL HAZARDS (DORDRECHT)

SPRINGER

Lugar: Berlin; Año: 2023

0921-030X

Analysis of high-resolution seismic profiles from the central Beagle Channel enabled the recognition and characterization of several postglacial subaqueous mass transport deposits in the subsurface of Bahía Ushuaia, offshore the city of Ushuaia (Argentina). These deposits are located at different stratigraphic levels and are embedded in the stratified sedimentary sequence within a deep trough, suggesting a recurrent occurrence. Up to eleven deposits have been identified, with four major events with estimated sediment volumes ranging from 12 to 57 million m3. The latter are associated with megaturbidite deposits up to 10 m thick. Two of the largest events date to the early Holocene unconformity of marine transgression. The seismic data suggest a different dynamic behaviour of these four main events, with erosional, strongly disintegrating and longer-lasting older mass transport events compared to the post-early Holocene deposits. Several of the deposits appear to have a common origin due to earthquake-induced collapses of submerged glaciofluvial deposits or from tributary deltas. In addition, a preliminary analysis of the potential generation of tsunami waves associated with the largest submarine collapses was carried out using numerical models. The results show that at least three of them would have the potential to generate dangerous waves with maximum heights of up to 1.5 m in the port of Ushuaia and estimated run-up heights between 2 and 8 m. Although further detailed analysis is recommended, particularly with regard to a more sophisticated modelling approach and refinement of the resolution of bathymetric and topographic data for strategic areas.