| Summary: | 8th International Symposium on Submarine Mass Movements and Their Consequences (ISSMMTC), 7-9 May 2018, Victoria, British Columbia, Canada Using a combination of geophysical and geotechnical data from the Storfjorden Trough Mouth Fan, off southern Svalbard, we investigate the role of glacial advances and retreats over the continental shelf on the hydrogeology of the continental margin. The results of compressibility and permeability tests are used together with margin stratigraphic models from seismic data, as input for numerical finite element models to understand focusing of interstitial fluids in glaciated continental margins. The modeled evolution of the Storfjorden TMF from 2.7 to 0.2 Ma shows that onset of glacial sedimentation (~1.5 Ma) had a significant role in developing aquicludes (tills) on the shelf that decreased the vertical fluid flow towards the sea floor and diverted it towards the slope. This model shows that prior to 220 ka, high overpressure (~0.6) develops below the shelf edge and in the middle slope. A more detailed, high resolution model for the last 220 kyrs accounting for ice loading during Glacial Maxima shows that the less permeable glacigenic debris flows deposited during glacial maxima on the slope hinder fluid evacuation from the plumites. This effect in combination with the fluid flow focusing from the shelf allows high overpressures (~0.7) to develop in the shallower-most plumite layers. These high overpressures likely persist to the Present and are critical in determining the onset of submarine slope failure. The safety factor of the upper continental slope is reduced by60% due to the combination of high sedimentation rates, ice loading and focusing of fluids during Glacial Maxima with values of the factor of safety reaching 1.2 during the LGM and beginning of the last deglaciation Peer Reviewed
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