Underwater rockfall kinematics: A preliminary analysis

Abstract

The marine environment presents various settings in which talus slopes are formed via a rock fall process similar to what exists on land. This is the case along fjords and submarine canyons in particular. Although many studies have been carried out on land, surprisingly very little is known for the submarine environment. We propose here the first kinematics analysis of underwater rockfall. It is postulated that the block have a diameter of more than one meter. As it can be expected, the main addition to the subaerial case is the consideration of the role of water (e.g. density or current). For submarine rockfall analysis, the effect of the ambient fluid cannot be neglected. Hydrodynamic constraints are controlled by the speed, shape, and size of the moving mass. Wind does not have a significant role in subaerial rockfall analysis, but currents must be considered in the subaqueous environment. In addition, coefficients of restitution are not only controlled by the elastic properties of the material, but also by impact Stokes number. This paper provides a summary of underwater rockfall kinematics in order to formulate underwater rockfall governing equations.