Large submarine slides on the Norwegian continental margin: Sediments, transport and timing

Jansen, Eystein; Befring, Stein; Bugge, Tom; Eidvin, Tor; Holtedahl, Hans; Sejrup, Hans Petter

doi:10.1016/0025-3227(87)90069-7

Cited by 145 publications

(56 citation statements)

References 23 publications

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“…Other sources of excess pore pressure reported in the literature are gas hydrates (Jansen et al 1987), and the decomposition of the organic matter that can result in the generation of free gas and thus excess pore pressure (Orange et al 2005). However, temperature and pressure conditions prevent the development of gas hydrates in the study area (Kvenvolden 2000).…”

Section: Discussionmentioning

confidence: 97%

Overpressure within upper continental slope sediments from CPTU data, Gulf of Lion, NW Mediterranean Sea

Lafuerza

Sultan

Canals

et al. 2008

Int J Earth Sci (Geol Rundsch)

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Data from in situ piezocone tests (CPTU) and laboratory analyses are utilized for the interpretation of the stress history of Quaternary sedimentary sequences in the upper continental slope of the Gulf of Lion, northwestern Mediterranean Sea. A CPTU based preconsolidation pressure profile referenced to the current effective stress indicates that the deposit is underconsolidated from 12 meters below the seafloor (mbsf) down to at least 150 mbsf. Excess pore pressure below 12 mbsf is further supported by results from oedometer and dissipation tests. Subseafloor pockmarks and indications of free gas in seismic reflection profiles reveal four main overpressure sources (SI-SIV) with overpressure ratios [0.3 at subseafloor depths coinciding with levels where the dominantly silty-clayey sediment contains increased proportions of sand. We relate the excess pore pressure related to free gas due to gas exsolution processes and sea level variations driven by Pleistocene sea level changes. Keywords Stress history Á Preconsolidation pressure Á Overpressure Á Continental slope Á Gulf of LionList of symbols Du excess pore pressure or overpressure, kPa Du CPTU overpressure determined by CPTU, kPa Du LOGS overpressure determined by downhole-logs, kPa Du e equilibrium pore pressure, Du e , kPa Du s excess pore pressure generated by sediment loading, kPa r vo total vertical stress, kPa r 0 vo vertical effective stress, kPa r 0 p preconsolidation pressure, kPa r 0 pa preconsolidation pressures r 0 p obtained following Casagrande's method, kPa r 0 pb preconsolidation pressures r 0 p obtained following Onitsuka's method, kPa k compression index k * adimensional ratio of the overpressure magnitude q w unit weight of the water, g cm -3 / porosity, % D h hydraulic diffusivity, m 2 s -1 e o reference void ratio f s sleeve friction, kPa g gravity, m s -2 N rt cone factor = (q t -r vo )/r 0 p

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Section: Discussionmentioning

confidence: 97%

Overpressure within upper continental slope sediments from CPTU data, Gulf of Lion, NW Mediterranean Sea

Lafuerza

Sultan

Canals

et al. 2008

Int J Earth Sci (Geol Rundsch)

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“…The genesis and distribution of Pleistocene sediments on the southwestern Norwegian margin strongly reflects environmental changes related to parameters as shelf edge glaciations, variability in ocean circulation, sea level changes and subsidence (e.g., Jansen et al, 1987;Henrich and Baumann, 1994;King et al, 1996;Dahlgren et al, 2002;Hjelstuen et al, 2004;Nygård et al, 2004, in press;Sejrup et al, 2004). The stratigraphical setting both inside and close to the Storegga Slide consists of sedimentary units characterised by clear seismostratigraphical cyclicity reflecting these environmental changes (Fig.…”

Section: Margin Sedimentary Sequencementioning

confidence: 97%

The Storegga Slide: architecture, geometry and slide development

et al. 2004

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“…These examples include surficial slides and slumps on the continental slope and rise of West Africa (59), slumps on the U.S. Atlantic continental slope (60), large submarine slides on the Norwegian continental margin (61,62), sediment blocks on the sea floor in fjords of British Columbia (63), and massive bedding-plane slides and rotational slumps on the Alaskan Beaufort Sea continental margin (64).…”

mentioning

confidence: 99%

Potential effects of gas hydrate on human welfare

Kvenvolden

1999

Proc. Natl. Acad. Sci. U.S.A.

498

282

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For almost 30 years. serious interest has been directed toward natural gas hydrate, a crystalline solid composed of water and methane, as a potential (i) energy resource, (ii) factor in global climate change, and (iii) submarine geohazard. Although each of these issues can affect human welfare, only (iii) is considered to be of immediate importance. Assessments of gas hydrate as an energy resource have often been overly optimistic, based in part on its very high methane content and on its worldwide occurrence in continental margins. Although these attributes are attractive, geologic settings, reservoir properties, and phase-equilibria considerations diminish the energy resource potential of natural gas hydrate. The possible role of gas hydrate in global climate change has been often overstated. Although methane is a ''greenhouse'' gas in the atmosphere, much methane from dissociated gas hydrate may never reach the atmosphere, but rather may be converted to carbon dioxide and sequestered by the hydrosphere/biosphere before reaching the atmosphere. Thus, methane from gas hydrate may have little opportunity to affect global climate change. However, submarine geohazards (such as sediment instabilities and slope failures on local and regional scales, leading to debris f lows, slumps, slides, and possible tsunamis) caused by gas-hydrate dissociation are of immediate and increasing importance as humankind moves to exploit seabed resources in ever-deepening waters of coastal oceans. The vulnerability of gas hydrate to temperature and sea level changes enhances the instability of deep-water oceanic sediments, and thus human activities and installations in this setting can be affected.

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Large submarine slides on the Norwegian continental margin: Sediments, transport and timing

Cited by 145 publications

References 23 publications

Overpressure within upper continental slope sediments from CPTU data, Gulf of Lion, NW Mediterranean Sea

Overpressure within upper continental slope sediments from CPTU data, Gulf of Lion, NW Mediterranean Sea

The Storegga Slide: architecture, geometry and slide development

Potential effects of gas hydrate on human welfare

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