Modeling of non-hydroplaning mudflows on continental slopes

An analytical model is proposed for two-dimensional, laminar, non-hydroplaning mudflows resulting from submarine slides that occur in deep waters, have substantial runout distances, and can be approximated as Bingham fluids. Length-scale analysis indicates that the dynamics of the mudflows can be treated in two regions: the outer region away from the flow front and the inner region near the flow front. The model, obtained by a matched-asymptotic method, can predict the asymptotic runout characteristics of submarine, non-hydroplaning mudflows as well as subaerial mudflows. A critical condition for hydroplaning to occur is found with the help of the model. The model can be used to predict the evolution of submarine slides such as velocities and time scales, and to interpret the deposits generated by them. As an example, a hypothetical submarine slide on a slope of 2 degrees is considered. The initial sediment mass has a maximum thickness of 7.25 m, a maximum length of 207.6 m, and a volume of 752.6 m(3)/m. For a bulk density of 2.0 t/m(3), a kinematic Viscosity of 0.005 m(2)/s, and a yield stress of 200 N/m(2), the propagating velocity of the flow front is predicted to be 2.3 mis after about 30 s, and then to decrease along the flow path, producing a deposit 0.58 m thick and 1.3 lan long. The final stage of the slide is similar to a creeping motion. (C) 1999 Published by Elsevier Science B.V. All rights reserved.