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

24.02.2012 2

Submarine landslides offshore Norway –

where and when?

24.02.2012 3

24.02.2012 4

Evans et al. (2005)

24.02.2012 5

Evans et al. (2005)

24.02.2012 6

Lee (2009)

24.02.2012 7

Evans et al. (2005)

Submarine landslides offshore Norway have a wide

geographic and stratigraphic distribution

24.02.2012 8

Which sediments failed?

24.02.2012 9

24.02.2012 10

Stratagem partners (2002)

24.02.2012 11

24.02.2012 12

24.02.2012 13

• 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

24.02.2012 14

Morphological characteristics of the

slide scar and the slide deposits

24.02.2012 15

24.02.2012 16

Sediment evacuation area

24.02.2012 17

Sediment evacuation area

24.02.2012 18

Sediment evacuation area

«Extentional»

«Compressional» Lindberg et al. (2004)

24.02.2012 19

Sediment evacuation area

«Extentional ridges»

«Compressional ridges» Lindberg et al. (2004)

24.02.2012 20

Sediment evacuation/bypass area

24.02.2012 21

Sediment evacuation/bypass area

24.02.2012 22

Area of sediment deposition

24.02.2012 23

Sediment evacuation area

24.02.2012 24

Area of sediment deposition

Johansen (2010)

Summary

24.02.2012 25

• 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

24.02.2012 26

Outlook

24.02.2012 27

24.02.2012 28

Lofoten

Vanneste et al. (2011)