Dynamic and instability of submarine avalanches

TL;DR

This study investigates the dynamics and instabilities of submarine avalanches through laboratory experiments, revealing a progression from straight to fingering instability in sediment flows on inclined planes.

Contribution

It introduces a detailed analysis of the instability mechanisms and wavelength selection in submarine avalanches, expanding understanding of their complex behaviors.

Findings

Identification of a transition from straight to transverse and fingering instabilities.

Observation of rivulet-like patterns in submarine sediment flows.

Discussion of mechanisms and wavelength selection for the observed instabilities.

Abstract

We perform a laboratory-scale experiment of submarine avalanches on a rough inclined plane. A sediment layer is prepared and thereafter tilted up to an angle lower than the spontaneous avalanche angle. The sediment is scrapped until an avalanche is triggered. Based on the stability diagram of the sediment layer, we investigate different structures for the avalanche front dynamics. First we see a straight front descending the slope, and then a transverse instability occurs. Eventually, a fingering instability shows up similar to rivulets appearing for a viscous fluid flowing down an incline. The mechanisms leading to this new instability and the wavelength selection are discussed.