LINKS BETWEEN MORPHOLOGY AND GEOTECHNICAL CHARACTERISTICS OF LARGE DEBRIS FLOW DEPOSITS IN THE ALBATROSS AREA ON THE SCOTIAN SLOPE (SE CANADA)

A succession of debris flow deposits are recognized in the Albatross a rea of the Scotian Slope (SE Canada). A geotechnical study has been co nducted on samples recovered in 28 piston cores. Results show that sed iment of the area can be separated into four geotechnical groups accor ding to consolidation state. These groups are strongly related to the nature of the deposits. All the cores sampled in the proximal part of the debris flow deposits show overconsolidated blocks included in a no rmally consolidated matrix. The thickness of initial failures is estim ated as 30-56 m based on the peak value of undrained shear strength me asured on debris flow deposits. Simple viscous analysis of the most re cent debris flow allows an estimate of postdepositional erosion at the location where debris flows have been channeled. The calculated maxim um value of 80 m is consistent with results from seismic reflection pr ofiling, but the relationship of this erosion with the debris flow mot ion remains uncertain. Stratigraphically equivalent debris flows 50 km west in the Verrill Canyon area transformed into turbidity currents. Whether such a transformation is due to the initial pore pressure cond itions related to shallow gas or to earthquake accelerations, high por e pressure is generated and leads to grain buoyancy and a high entrain ment rate. Ignitive turbidity currents generated on low slope are prob ably earthquake triggered and associated with shallow gas.