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TitleA massive slump on the St. Pierre Slope, a new perspective on the 1929 Grand Banks submarine landslide
 
AuthorSchulten, I; Mosher, D CORCID logo; Piper, D J WORCID logo; Krastel, S
SourceJournal of Geophysical Research, Solid Earth vol. 124, 2019 p. 1-24, https://doi.org/10.1029/2018JB017066
Image
Year2019
Alt SeriesNatural Resources Canada, Contribution Series 20190010
PublisherAmerican Geophysical Union (AGU)
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
ProvinceNewfoundland and Labrador; Nova Scotia; Eastern offshore region
NTS1; 10; 11
AreaSt. Pierre Slope; Grand Banks of Newfoundland; Atlantic Ocean
Lat/Long WENS -58.0000 -54.0000 45.3333 43.2500
Subjectsmarine geology; surficial geology/geomorphology; stratigraphy; structural geology; geophysics; Nature and Environment; Science and Technology; landslides; slumps; slope failures; mass wasting; continental margins; continental slope; marine sediments; tsunami; geophysical surveys; seismic surveys, marine; seismic reflection surveys; acoustic surveys, marine; side-scan sonar; bathymetry; seafloor topography; submarine features; escarpments; submarine fans; channels; bedrock geology; structural features; faults; tectonic history; earthquakes; epicentres; earthquake risk; decollement; displacement; crustal movements; depositional history; stratigraphic analyses; 1929 Grand Banks Submarine Landslide; St. Pierre Slump; Laurentian Fan; Halibut Canyon; Grnad Banks Valley; Western Valley; Eastern Valley; St. Pierre Valley; translational landslides; Infrastructures; sediment transport directions; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; tables; seismic profiles; 3-D images; block diagrams; schematic cross-sections
ProgramPublic Safety Geoscience Marine Geohazards
Released2019 06 28
AbstractThe 1929 Grand Banks submarine landslide on the southwestern Grand Banks of Newfoundland was triggered by a Mw 7.2 strike-slip earthquake. It is the first studied example of a submarine mass movement known to have caused a turbidity current and tsunami. The event resulted in 28 casualties and caused severe economic damage. The St. Pierre Slope is the main source area for the sediment failure. It contains translational and probable retrogressive surficial failures (<25 m); the majority of which lie in >1,700-m water depth. These observations contradict what might be expected for a tsunamigenic event; thus, the objective of this study is to look for other potential causal mechanisms. A comprehensive analysis of 2-D seismic reflection data of various resolutions and multibeam bathymetry allowed mapping of new stratigraphic and structural features. Numerous, low-angle (~17°) faults are present throughout the Quaternary section of the St. Pierre Slope that are associated with seafloor escarpments (750- to 2,000-m water depth). These faults have up to 100-m high displacement and are interpreted as part of a massive (~560 km3), complex slump. There are multiple décollements (250- and 400- to 550-m below seafloor) within this slump and there is indication for slumping in at least two directions. Evidence suggests slumping as a result of the 1929 earthquake occurred along these faults, with ~100-m seafloor displacement in places. The 1929 submarine landslide therefore involved two failure mechanisms: massive slumping (~500-m thick) and consequent widespread, surficial (<25 m) sediment failure. Both failure mechanisms likely contributed to tsunami generation.
Summary(Plain Language Summary, not published)
An underwater landslide occurred south of Newfoundland in November 1929, as a result of a strong earthquake. It triggered a tsunami that killed 28 people. This study shows that the submarine landslide occurred as a ~500 m-thick rotational slump that had a vertical displacement of nearly 100 m.
GEOSCAN ID314602

 
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