New modelling of submarine gravity flows: application to the Nice collapsein 1979.

We propose to apply in this note a simple mathematical model for the sedime ntation of gravity deposits in deep water. An inverse method has been devel oped in order to characterize the parameters associated with the submarine flow. This method also provides the initial conditions, which constitute a major uncertainty in geoscience modelling. Application of the inverse metho d to the 1979 Nice air-port collapse (southern France), constrained by cabl e breaks and/or deposit thicknesses, leads, for example, to the estimation of the initial volume and/or the physical parameters of the flow (friction coefficient, modified turbulent Schmidt number, etc.). The application of t he model to this real case shows that only the simultaneous inversion of dy namic (cable break times) and sedimentological (deposit) data allows a sati sfactory reconstruction of the flow. (C) 2001 Academie des sciences/Edition s scientifiques et medicales Elsevier SAS.