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TitleReconstructing the sediment concentration of a giant submarine gravity flow
AuthorStevenson, C J; Feldens, P; Georgiopoulou, A; Schönke, M; Krastel, S; Piper, D J WORCID logo; Lindhorst, K; Mosher, DORCID logo
SourceNature Communications vol. 9, 2616, 2018 p. 1-7, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20170341
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNewfoundland and Labrador; Eastern offshore region
AreaGrand Banks
Lat/Long WENS -59.0000 -52.0000 45.0000 40.0000
Lat/Long WENS -56.3667 -53.4167 45.1667 41.0333
Subjectsmarine geology; surficial geology/geomorphology; geophysics; stratigraphy; marine sediments; landslides; landslide deposits; tsunami; flow regimes; flow structures; flow velocities; computer simulations; earthquakes; bathymetry; geophysical surveys; acoustic surveys, marine; continental margins; continental slope; marine sediment cores; 1929 Grand Banks Submarine Landslide; 1929 Grand Banks Earthquake; Infrastructures
Illustrationslocation maps; geoscientific sketch maps; geophysical images; profiles; plots; cross-sections
ProgramOffshore Geoscience
Released2018 07 05
AbstractSubmarine gravity flows are responsible for the largest sediment accumulations on the planet, but are notoriously difficult to measure in action. Giant flows transport 100s of km3 of sediment with run-out distances over 2000 km. Sediment concentration is a first order control on flow dynamics and deposit character. It has never been measured directly nor convincingly estimated in large submarine flows. Here we reconstruct the sediment concentration of a historic giant submarine flow, the 1929 'Grand Banks' event, using two independent approaches, each validated by estimates of flow speed from cable breaks. The calculated average bulk sediment concentration of the flow was 2.7-5.4% by volume. This is orders of magnitude higher than directly-measured smaller-volume flows in river deltas and submarine canyons. The new concentration estimate provides a test case for scaled experiments and numerical simulations, and a major step towards a quantitative understanding of these prodigious flows.
Summary(Plain Language Summary, not published)
The first determination of the bulk sediment concentrations in a giant underwater turbidity current. Important for modelling the consequences of this type of geohazard.

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