Investigation of gas migration as a triggering mechanism for submarine landslides on continental slopes (TRISCO)

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Submarine landslides are common along continental slopes worldwide. Fast-moving, large volume landslides can potentially trigger destructive tsunamis. The flows that landslides generate damage and disrupt global communication links and other critical marine infrastructure. While the importance of submarine landslides for society and economy is evident, our understanding of the mechanisms leading to submarine slope failure is limited. Geophysical investigations often provide evidence for the existence of free gas below failure planes. Laboratory experiments have shown that both the presence of gas bubbles and gas driven excess pore pressure may reduce the sediment’s shear strength. It has therefore been suggested that free gas may play an important role for submarine slope stability. We therefore propose to test whether the vertical or lateral migration of gas could be responsible for causing submarine landslides on continental slopes by means of geophysical and geotechnical analyses, thereby aiming to ensure a direct and continuous integration of laboratory and numerical experiments with field data. Advanced analysis of 3D seismic data from two case studies (Storegga and Ana slides) will provide a detailed spatial and quantitative relationship of landsliding and free gas occurrence. Laboratory experiments on gassy sediments and numerical modeling of their constitutive behavior will form the basis for stability analyses of gas-charged submarine slopes. The integration of all results will allow identifying the conditions under which gas-charged continental slopes may fail, which will provide important constraints on future offshore developments and hazard assessments.