Frequency and triggering of small-scale submarine landslides on decadal timescales: Analysis of 4D bathymetric data from the continental slope offshore Nice (France)

Time-series bathymetric data acquired from 1967 to 2011 are used to evaluate the morphological evolution of the continental shelf and upper continental slope off the city of Nice (SE France, Ligurian Sea). Mapping in water depths of 0–300m was undertaken to identify the changing morphology of landsl...

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Bibliographic Details
Published in:Marine geology 2016-09, Vol.379, p.281-297
Main Authors: Kelner, Maëlle, Migeon, Sébastien, Tric, Emmanuel, Couboulex, Françoise, Dano, Alexandre, Lebourg, Thomas, Taboada, Alfredo
Format: Article
Language:English
Subjects:
Bathymetry
Brackish
Continental shelves
Continental slope
Deposition
Earth Sciences
Failure
Geohazards
Geomorphology
Landslides
Ligurian Sea
Marine
Mathematical models
Nice
Offshore
Sciences of the Universe
Sediments
Slopes
Submarine landslides
Triggering mechanism
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Summary:Time-series bathymetric data acquired from 1967 to 2011 are used to evaluate the morphological evolution of the continental shelf and upper continental slope off the city of Nice (SE France, Ligurian Sea). Mapping in water depths of 0–300m was undertaken to identify the changing morphology of landslide scars and their erosive chutes. Quantitative Digital Terrain Model (DTM) comparisons reveal areas of erosion and deposition over intervals of 5–8years. Sediment remobilization events on the upper slope (above depths of 200m) are frequent and significant; landslide scars with volumes>25,000m3 can occur with frequencies of 200m). Periods of quiescence (1980–1990 and 2006–2011) are seen to alternate with periods when rapid retrogressive failure increase sediment volumes eroded from the upper slope-shelf transition by an order of magnitude (1999–2006). Temporal variations in landslide activity were correlated to several potential triggering factors that individually would not induce failures, including earthquake activity, rapid deposition of fine-grained sediments on a steep slope, and rainfall leading to fresh groundwater circulation below the shelf. This 4D bathymetric study suggests that over the last 50years the most important factor triggering landslides offshore Nice is overpressure due to freshwater outflows. •Repetitive bathymetries show that landslides are active over periods
ISSN:0025-3227
1872-6151
DOI:10.1016/j.margeo.2016.06.009