Agents of geomorphic change in submarine canyons

ended

Submarine canyons are dynamic systems that are ubiquitous across continental margins and play a key role in the transport of material into the deep ocean. This transport is primarily facilitated through submarine landslides and turbidity currents, which can mobilise large volumes of sediment at high speeds across great distances. While some submarine canyons are flushed by low volume turbidity currents multiple times each year, others in similar tectonic settings remain inactive for multiple decades between higher-magnitude canyon flushing events. Nonetheless, such rapid change can dwarf the effect of other geomorphic processes, such as biological erosion or bedform migration, whose action over decades or centuries can bring about significant change in canyon morphology and also precondition slopes for failure. SubCAN will make use of a suite of acoustic (multibeam echosounder, subbottom and seismic) data and sediment cores, as well as numerical modelling, to investigate the agents that bring about change in submarine canyons over a variety of spatial and temporal scales. This work has implications for understanding and predicting margin evolution, and will provide important constraints on margin stability and hazards. In particular, SubCAN will (i) Use repeat mapping and monitoring to quantify fine-scale geomorphic changes and processes over up to 25 years in two end-member submarine canyons: one low-event-magnitude, high-event-frequency system, and one high-event-magnitude, low-event-frequency system; (ii) Implement hierarchical reduced-order numerical modelling to model canyon evolution and stratigraphic change in response to the action of geomorphic processes on a margin-scale using those two systems as end members; and (iii) Reconstruct geomorphic processes and evolution of a canyon where high resolution and repeat data are not available to reveal the universality of the key processes that bring about change in submarine canyons.