submarine landslides offshore norway a summary of … · 2019-08-20 · submarine landslides...
TRANSCRIPT
Submarine landslides offshore Norway – a
summary of observations and implications for
initial deformation and flow dynamics
Jan Sverre Laberg
Dept. of Geology, University of Tromsø, Tromsø, Norway
Outline
• Submarine landslides offshore Norway – where and
when?
• Which sediments failed?
• Morphological characteristics of the slide scar and the
slide deposits
• Summary
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Submarine landslides offshore Norway –
where and when?
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Evans et al. (2005)
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Evans et al. (2005)
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Lee (2009)
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Evans et al. (2005)
Submarine landslides offshore Norway have a wide
geographic and stratigraphic distribution
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Which sediments failed?
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Stratagem partners (2002)
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• In most cases both glacigenic and contouritic sediments
affected
• The contourites were the weak layers that originally failed
(strain softening behaviour)
• The properties of the contourites that controlls the stability
of the continental slope – these layers may be located ~10
- ~100 m below the sea floor
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Morphological characteristics of the
slide scar and the slide deposits
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Sediment evacuation area
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Sediment evacuation area
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Sediment evacuation area
«Extentional»
«Compressional» Lindberg et al. (2004)
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Sediment evacuation area
«Extentional ridges»
«Compressional ridges» Lindberg et al. (2004)
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Sediment evacuation/bypass area
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Sediment evacuation/bypass area
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Area of sediment deposition
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Sediment evacuation area
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Area of sediment deposition
Johansen (2010)
Summary
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• A very complex slide scar morphology that relates to the
variations in sediment composition and physical properties
• The run-out, even on slopes of low gradient is extremely
long
• In areas of buried slide scars as well as slide deposits;
large variations in sediment composition and properties is
to be expected over very short distances
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Outlook
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Lofoten
Vanneste et al. (2011)