ADVANCES IN THE NUMERICAL MODELING OF SEDIMENT FAILURE DURING THE DEVELOPMENT OF A CONTINENTAL MARGIN

Abstract

The SedFlux model is modified to more realistically simulate the distributions of seafloor geotechnical parameters during the growth of a seismically active continental margin. Alternative methods are provided for the prediction of the coefficient of consolidation, remolded shear strength, internal friction angle, sediment cohesion, dynamic viscosity and excess pore pressure. The new methods improve simulations of the architecture of basin deposits through the dynamics within the slope stability and debris flow modules. The new formulation shows sediment failures to be more frequent but smaller in size, and to occur at larger water depths. However, the overall architecture is not significantly different. SedFlux is then used to examine the role of global sea level fluctuations on the location and dimensions of sediment failure, and the subsequent transport of sediment to the deep ocean. More sediment failures are predicted to occur during periods of falling or low sea level conditions, and to be confined to the upper continental slope (500+/-250 m water depth). The shallower failures are more characteristic of the period represented by the last two episodes of low sea level (i.e. during the Late Pleistocene), affected by the magnitude of the sea level fluctuation. Most of the predicted failures have thickness <10 m. Larger failures occur during periods of rising or high sea level stand.