Publication Date:
2023-11-17
Description:
Submarine landslides can destroy seafloor infrastructures and generate devastating tsunamis. In spite of decades of research into the functioning of submarine landslides there are still numerous open questions, in particular how different phases of sliding influence each other. Here, we re‐analyze Ana Slide—a relatively small (〈1 km3) landslide offshore the Balearic Islands, which is unique in the published literature because it is completely imaged by high‐resolution 3D reflection seismic data. Ana Slide comprises three domains: (a) a source area that is almost completely evacuated with evidence of headscarp retrogression, (b) an adjacent downslope translational domain representing a by‐pass zone for the material that was mobilized in the source area, and (c) the deposit formed by the mobilized material, which accumulated downslope in a sink area and deformed slope sediment. Isochron maps show deep chaotic seismic units underneath the thickest deposits. We infer that the rapid deposition of the landslide material deformed the underlying sediments. A thin stratified sediment unit between three lobes suggests that Ana Slide evolved in two failure stages separated by several tens of thousands of years. This illustrates the problem of over‐estimating the volume of mobilized material and under‐estimating the complexity even of relatively simple slope failures without high‐quality 3D reflection seismic data.
Description:
Plain Language Summary:
We investigate a submarine landslide in the Balearic Islands off Spain. The aim is to find out how such landslides work. This study is special because it can draw on a unique data set: the complete imaging of this landslide with high quality reflection seismic data. We find that previous studies have over‐estimated the volume of the mobilized material because deformed sediments below the landslide were also counted, and that the slide actually consisted of two individual slope failures that occurred at the same place but in distinct episodes separated by some tends of thousands of years. Together these results show that there is a large risk of overestimating landslide‐related tsunami hazards when this kind of reflection seismic data is not available.
Description:
Key Points:
Ana Slide is completely covered by 3D reflection seismic data and its kinematic development is addressed.
Large parts of the volume previously interpreted as landslide material was deformed in‐situ.
Ana Slide developed during two separate phases that involved likely significantly smaller volumes of material than previously proposed.
Description:
Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659
Description:
GRC Geociències Marines
Description:
https://doi.pangaea.de/10.1594/PANGAEA.943506
Description:
https://doi.pangaea.de/10.1594/PANGAEA.943523
Keywords:
ddc:622.1592
;
submarine landslide
;
kinematic analysis
;
substrate deformation processes
;
Mediterranean Sea
;
emplacement mechanism
Language:
English
Type:
doc-type:article
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