How depositional processes in turbidite deposits affect the self-acceleration of turbidity currents

This study investigates the conditions required for self-acceleration in laboratory-scale turbidity currents using a numerical model validated against experimental measurements. A series of simulations were conducted to isolate the main hydro-sedimentary factors potentially controlling the onset and sustenance of flow self-acceleration. Specific depositional processes, namely the vertical and lateral grain size composition of the turbidites formed by antecedent turbidity currents were found to affect the dynamics of subsequent flow events. Results show that simplified bed representations fail to reproduce self-accelerating regimes, demonstrating that an erodible bed is a necessary but not sufficient condition for a current to self-accelerate. In contrast, when the modelled bed exhibits realistic sedimentary features, such as bed slope increase due to cumulative deposition, downstream sediment fining, and vertical stratification, flows accelerate due to enhanced sediment entrainment. These findings underscore the critical role of past flow deposits in actively preconditioning the nature of future events.