RT Journal Article
T1 Shallow seismic stratigraphy of the southwestern Algarve shelf (Portugal) and characteristics of offshore tsunami deposits
A1 Feist, Lisa
A1 Costa, Pedro J.M.
A1 Santisteban Navarro, Juan Ignacio
A1 Albers, Stijn
A1 Bellanova, Piero
A1 Bosnic, Ivana
A1 De Batist, Marc
A1 Duarte, João F.
A1 Rodrigues, Aurora
A1 Reicherter, Klaus
AB Understanding the sedimentary dynamics of continental shelves is crucial for decoding past high-energy events like tsunamis. Based on data from HSV FISÁLIA cruise of the Portuguese Navy, this study investigates the geomorphological features of the southwestern Algarve shelf and the seismo-stratigraphic characteristics of sedimentary units attributed to two tsunamis that occurred in 1755 CE (Lisbon earthquake) and ca. 3600 cal yr BP. Using high-resolution geoacoustic profiling in combination with sedimentological analyses and radiocarbon dating from prior studies, this study is the first to identify an Infralittoral Prograding Wedge on the shallow southwestern Algarve shelf. Furthermore, remnants of an older transgressive prograding wedge-shaped sediment body have been detected on the mid to outer shelf off Portimão. A crucial finding of this study is a high-amplitude reflector which has been associated with the ca. 3600 cal yr BP tsunami deposit. This reflector is particularly strong based on the corresponding deposit's stark compositional contrast with the surrounding sediment. In its distribution, this reflector is restricted to the base of the Infralittoral Prograding Wedge indicating this wedge as the most likely sediment source for the ca. 3600 cal yr BP deposit. On the other hand, the 1755 CE Lisbon tsunami deposit has no clear geophysical signature on the southwestern Algarve shelf due to its vestigial thicknesses and scarce compositional contrast with the surrounding sediment. This divergence raises significant questions about the different triggering mechanisms and transport processes that define both offshore tsunami deposits. Our findings highlight the significance of local bathymetric conditions, sediment sources, as well as triggering mechanisms and transport pathways in shaping offshore tsunami deposits.
PB Elsevier
SN 0025-3227
YR 2025
FD 2025-02
LK https://hdl.handle.net/20.500.14352/118309
UL https://hdl.handle.net/20.500.14352/118309
LA eng
NO Feist, L., Costa, P. J. M., Santisteban, J. I., Albers, S., Bellanova, P., Bosnic, I., De Batist, M., Duarte, J. F., Rodrigues, A., & Reicherter, K. (2025). Shallow seismic stratigraphy of the southwestern Algarve shelf (Portugal) and characteristics of offshore tsunami deposits. Marine Geology, 480, 107463
NO FCT (Portugal)
NO German Research Foundation
DS Docta Complutense
RD 10 abr 2025