Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers

Bailey, Lewis; Clare, Michael; Rosenberger, Kurt J.; Cartigny, Matthieu; Talling, Peter J.; Paull, C. K.; Gwiazda, R.; Parsons, D.; Simmons, S.; Xu, Jingping; Haigh, Ivan D.; Maier, K. L.; McGann, Mary; Lundsten, E. M.

doi:10.1016/j.epsl.2021.116845

Cited by 42 publications

(29 citation statements)

References 69 publications

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“…For instance, the Congo Canyon (W Africa) extends into the estuary to provide direct connection to the high-discharge Congo River across all sea-level stands 23 , 24 . The head of Monterey Canyon (California) lies only a few metres from shore, intersecting two littoral cells that directly funnel sediment into the canyon head 25 , 26 . In contrast, land-detached canyons that do not, or barely, incise into the continental shelf are generally considered to be inactive during sea level highstands, only switching on during lowstands 11 , 23 .…”

Section: Introductionmentioning

confidence: 99%

Challenging the highstand-dormant paradigm for land-detached submarine canyons

et al. 2022

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Sediment, nutrients, organic carbon and pollutants are funnelled down submarine canyons from continental shelves by sediment-laden flows called turbidity currents, which dominate particulate transfer to the deep sea. Post-glacial sea-level rise disconnected more than three quarters of the >9000 submarine canyons worldwide from their former river or long-shore drift sediment inputs. Existing models therefore assume that land-detached submarine canyons are dormant in the present-day; however, monitoring has focused on land-attached canyons and this paradigm remains untested. Here we present the most detailed field measurements yet of turbidity currents within a land-detached submarine canyon, documenting a remarkably similar frequency (6 yr−1) and speed (up to 5–8 ms−1) to those in large land-attached submarine canyons. Major triggers such as storms or earthquakes are not required; instead, seasonal variations in cross-shelf sediment transport explain temporal-clustering of flows, and why the storm season is surprisingly absent of turbidity currents. As >1000 other canyons have a similar configuration, we propose that contemporary deep-sea particulate transport via such land-detached canyons may have been dramatically under-estimated.

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Section: Introductionmentioning

confidence: 99%

Challenging the highstand-dormant paradigm for land-detached submarine canyons

et al. 2022

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“…Peters et al (1978) also showed that much greater bedload discharge occurred towards the canyon lip during ebb tides, which is likely to be accentuated during the strongest spring tides. It is thus highly plausible that river floods and spring tides combine to produce unusually rapid progradation of the submarine canyon's lip, thereby triggering turbidity currents via slope failure, as in other systems 35,36 .…”

Section: Physical Processes That Generate Turbidity Currents In the River-mouth Estuarymentioning

confidence: 99%

Novel sensor array helps to understand submarine cable faults off West Africa

Talling¹,

Baker²,

Pope³

et al. 2021

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Seabed telecommunication cables can be damaged or broken by powerful seafloor flows of sediment (called turbidity currents), which may runout for hundreds of kilometres into the deep ocean. These flows have the potential to affect multiple cables near-simultaneously over very large areas, so it is more challenging to reroute traffic or repair the cables. However, cable-breaking turbidity currents that runout into the deep ocean were poorly understood, and thus hard to predict, as there were no detailed measurements from these flows in action. Here we present the first detailed measurements from such cable-breaking flows, using moored-sensors along the Congo Submarine Canyon offshore West Africa. These turbidity currents include the furthest travelled sediment flow (of any type) yet measured in action on Earth. The SAT-3 (South Atlantic 3) and WACs (West Africa Cable System) cables were broken on 14-16 th January 2020 by a turbidity current that accelerated from 5 to 8 m/s, as it travelled for > 1,130 km from river estuary to deep-sea, although a branch of the WACs cable located closer to shore survived. The SAT-3 cable was broken again on 9 th March 2020 due to a second turbidity current, this time slowing data transfer during regional coronavirus (COVID-2019) lockdown. These cables had not experienced faults due to natural causes in the previous 19 years. The two cable-breaking flows are associated with a major flood along the Congo River, which produced the highest discharge (72,000m 3 ) recorded at Kinshasa since the early 1960s, and this flood peak reached the river mouth on ~30 th December 2019. However, the cable-breaking turbidity currents occurred 2-10 weeks

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“…Similar to rivers, but perhaps to a much larger degree, sediment transport along submarine canyons can be highly episodic, hence analogies between the two types of systems could be of interest. Sediment gravity flows in submarine canyons are triggered by a variety of factors that include: slope failures at the head of the canyon due to storms, wave action or tidal forcing (Ayranci et al., 2012; Bailey et al., 2021; Hughes Clarke, 2016), seawater density contrasts (Canals et al., 2006; Palanques et al., 2006), canyon‐lip failure of rapidly accumulating sediment (Bailey et al., 2021; Carter et al., 2012; Flemings et al., 2008; Smith et al., 2007), direct hyperpycnal river discharge (Johnson et al., 2001; Liu et al., 2016; Parsons et al., 2001), and by submarine landslides due to earthquakes (Gavey et al., 2017; Heezen & Ewing, 1952; Mountjoy et al., 2018; Piper & Aksu, 1987). The scale of sediment gravity flows can vary greatly, but the largest events can carry exceptional volumes of sediment that may exceed the annual sediment flux from all of the world's rivers (Mountjoy et al., 2018; Talling, 2014; Talling et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, over the last 10 years, instrumental monitoring of sediment gravity flows has been accomplished successfully in a number of locations (Azpiroz‐Zabala et al., 2017; Khripounoff et al., 2003; Hughes Clarke, 2016; Hughes Clarke et al., 2012; Zhang et al., 2018). One of these monitoring efforts was the Coordinated Canyon Experiment (Bailey et al., 2021; Heerema et al., 2020; Maier, Gales, et al., 2019; Maier, Rosenberger, et al., 2019; Paull et al., 2018; Wang et al., 2020) conducted in Monterey Canyon. This project monitored sediment gravity flows over a distance of ∼50 km, from 285 to 1,850 m water depths, using an array of instrumented moorings and sensors on the seafloor.…”

Section: Introductionmentioning

confidence: 99%

“…Sediment sources include the Salinas River, smaller coastal rivers draining into and to the north of Monterey Bay, and cliff retreat. Littoral currents then carry this sediment, which may become trapped at the head of Monterey Canyon, where it accumulates until transported further down canyon (Bailey et al., 2021; Smith et al., 2007). Monitoring of Monterey Canyon prior to the CCE has shown that sediment gravity flows occur on a sub‐annual basis and are very powerful (1.9 m s −1 velocity; Paull et al., 2002; Xu, 2010; Xu et al., 2004), having the capacity to destroy heavy instrument packages and carry very heavy objects over long distances (Paull et al., 2002, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Near‐Bed Structure of Sediment Gravity Flows Measured by Motion‐Sensing “Boulder‐Like” Benthic Event Detectors (BEDs) in Monterey Canyon

et al. 2022

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Submarine canyons are an important link in the long-term global cycling of material on Earth. Sediment eroded on land is transported by rivers to the sea, where a large fraction is then carried into the deep ocean by near-seafloor sediment laden flows (called turbidity currents), which are routed through submarine canyons incised in continental slopes (Shepard, 1981). In addition, turbidity currents carry significant amounts of organic carbon that supports deep sea communities (Fernandez-Arcaya et al., 2017) and it is ultimately buried in deep sea fans (Galy et al., 2007;Mountjoy et al., 2018). Turbidity currents are also important from an economic perspective. Seabed cable networks that carry over 95% of global data traffic, as well as pipelines and other seabed

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Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers

Cited by 42 publications

References 69 publications

Challenging the highstand-dormant paradigm for land-detached submarine canyons

Challenging the highstand-dormant paradigm for land-detached submarine canyons

Novel sensor array helps to understand submarine cable faults off West Africa

Near‐Bed Structure of Sediment Gravity Flows Measured by Motion‐Sensing “Boulder‐Like” Benthic Event Detectors (BEDs) in Monterey Canyon

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