The kinematics of rapid and slow moving landslides is commonly described by equations of motion, which in
case of a viscous component are based on the Navier-Stokes equation. They consist of inertial terms related to the
change in velocity in time (local acceleration) and space (convective acceleration) and terms related to respectively
the gravity, pressure and viscous forces. These viscous resistance forces in the mass balance can be accompanied
or replaced by other rheological (frictional and cohesive) terms depending on the liquid/solid ratio of the moving
mass