02234nas a2200325   4500000000100000008004100001260001500042100001800057700002200075700001200097700001600109700001800125700002000143700001600163700001600179700001800195700001800213700002000231700001700251700001600268700001600284700002000300700002000320245007500340856004700415300001200462490000600474520141400480020001401894       2023                            d  c2023/09/011 aPeter Talling1 aMatthieu Cartigny1 aEd Pope1 aMegan Baker1 aMichael Clare1 aMaarten Heijnen1 aSophie Hage1 aDan Parsons1 aSteve Simmons1 aCharlie Paull1 aRoberto Gwiazda1 aGwyn Lintern1 aJohn Clarke1 aJingping Xu1 aRicardo Jacinto1 aKatherine Maier00aDetailed monitoring reveals the nature of submarine turbidity currents  uhttps://doi.org/10.1038/s43017-023-00458-1  a642-6580 v43 aSeafloor sediment flows, called turbidity currents, form the largest sediment accumulations, deepest canyons and longest channels on Earth. It was once thought that turbidity currents were impractical to measure in action, especially given their ability to damage sensors in their path, but direct monitoring since the mid-2010s has measured them in detail. In this Review, we summarize knowledge of turbidity currents gleaned from this direct monitoring. Monitoring identifies triggering mechanisms from dilute river plumes, and shows how rapid sediment accumulation can precondition slope failure, but the final triggers can be delayed and subtle. Turbidity currents are consistently more frequent than predicted by past sequence-stratigraphic models, including at sites >300 km from any coast. Faster flows (more than ~1.5 m s\textendash1) are driven by a dense near-bed layer at their front, whereas slower flows are entirely dilute. This frontal layer sometimes erodes large (>2.5 km3) volumes of sediment, yet maintains a near-uniform speed, leading to a travelling-wave model. Monitoring shows that flows sculpt canyons and channels through fast-moving knickpoints, and shows how deposits originate. Emerging technologies with reduced cost and risk can lead to widespread monitoring of turbidity currents, so their sediment and carbon fluxes can be compared with other major global transport processes.  a2662-138X