How frequently do submarine fans avulse? Insights from a new analytical model and global datasets

Submarine channel avulsions, i.e., abrupt shifts in channel pathways, are fundamental to the construction and evolution of submarine fans. Constraining the frequency of these events is critical for understanding sediment dispersal, organic carbon sequestration, and pollutant transport in deep-marine environments, as well as for assessing geohazard risks to seafloor infrastructure. Yet, a mechanistic framework capable of quantitatively predicting avulsion frequency in submarine environments has remained elusive.

Here, we introduce a new analytical model on the basis of sediment mass balance that estimates the characteristic avulsion frequency of submarine channels, informed by and validated against five modern to late Quaternary submarine fan systems. Our results reveal that avulsion frequency is predominantly determined by the interaction between avulsion length (or channel distance from canyon head), superelevation thresholds, channel–floodplain coupling, and intrinsic flow properties, including flow velocity, sediment concentration, and flow intermittency. External forcings such as sea-level changes, climate changes or tectonics might exert a control on the avulsion frequency of submarine channels through influencing volume and recurrence of the sediment delivery into the deep sea. These findings establish a predictive basis for improving the design and routing of seafloor infrastructure to reduce geohazards, forecasting sediment routing pathways, and decoding the stratigraphic architecture of submarine fans.