In‐situ measurements of velocity structure within turbidity currents

Xu, Jingping; Noble, Marlene A.; Rosenfeld, Leslie K.

doi:10.1029/2004gl019718

Cited by 244 publications

(283 citation statements)

References 15 publications

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“…B) Changes in flow frequency that span several orders of magnitude along the Monterey Canyon-Fan system, offshore California. Modified from Fildani and Normark (2004), Klaucke et al (2004), Xu et al (2004Xu et al ( , 2013 and Paull et al (2005Paull et al ( , 2010aPaull et al ( , 2010b. which is consistent with available field observations (Xu 2011;Talling 2013).…”

Section: (B) Supercritical-flow Dynamics and Depositssupporting

confidence: 64%

“…2; Xu et al 2004Xu et al , 2013Xu et al , 2014Xu 2010Xu , 2011. This is part of collaborative work by Paull and others at the Monterey Bay Aquarium Research Institute (MBARI), who are developing new sensors embedded in moving near-bed layers that record their acceleration and sense of rotation, and techniques for recovering data from such sensors through gliders.…”

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

“…2C), which are initially buried within the bed, could be transported by dilute flows travelling at speeds of up to 1 to 2.5 m/s thus far observed in these locations ( Fig. 2B; Xu et al 2004;Xu 2011;Hughes Clarke et al 2012, 2014.…”

Section: (B) Supercritical-flow Dynamics and Depositsmentioning

confidence: 99%

“…It is already the location of detailed and technologically sophisticated monitoring efforts (Paull et al 2010a), including the first velocity and density profiles through active flows ( Fig. 2; Xu et al 2004Xu et al , 2010Xu et al , 2013Xu et al , 2014Xu 2010). A major Monterey Bay Aquarium Research Institute (MBARI), US Geological Survey, and UK Natural Environment Research Council monitoring experiment is already funded from 2014-2017, which includes deployment of a seafloor observatory, event detectors along the flow path of the sandy floor of the canyon, and four sets of ADCP moorings at water depths of 300 m to 1850 m. An extensive set of cores (including vibracores taken with a remotely operated vehicle (ROV); Fig.…”

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

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Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

163

117

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Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than , 0.6u. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (, 0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces

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Section: (B) Supercritical-flow Dynamics and Depositssupporting

confidence: 64%

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

Section: (B) Supercritical-flow Dynamics and Depositsmentioning

confidence: 99%

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

See 2 more Smart Citations

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

163

117

View full text Add to dashboard Cite

show abstract

“…However, data are generally scarce and moorings are often either destroyed or too high above the seafloor to give true turbidity current velocities (e.g., Kripounoff et al 2003), or only minor turbidity currents are measured (e.g., Mitsuzawa et al 2004;Xu et al 2004). Unless equipments are designed to monitor deep stations in severe conditions, an effective way to get turbidity current velocities is to use cable break information.…”

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 99%

Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Hsu¹,

Kuo²,

Lo³

et al. 2008

Terr. Atmos. Ocean. Sci.

208

107

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Submarine landslides or slumps may generate turbidity currents consisting of mixture of sediment and water. Large and fast-moving turbidity currents can incise and erode continental margins and cause damage to artificial structures such as telecommunication cables on the seafloor. In this study, we report that eleven submarine cables across the Kaoping canyon and Manila trench were broken in sequence from 1500 to 4000 m deep, as a consequence of submarine landslides and turbidity currents associated with the 2006 Pingtung earthquakes offshore SW Taiwan. We have established a full-scale scenario and calculation of the turbidity currents along the Kaoping canyon channel from the middle continental slope to the adjacent deep ocean. Our results show that turbidity current velocities vary downstream ranging from 20 to 3.7 and 5.7 m s -1 , which demonstrates a positive relationship between turbidity current velocity and bathymetric slope. The violent cable failures happened in this case evidenced the destructive power of the turbidity current to seafloor or underwater facilities that should not be underestimated.

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Driven around the bend: Spatial evolution and controls on the orientation of helical bend flow in a natural submarine gravity current

et al. 2014

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Submarine channel systems transport vast amounts of terrestrial sediment into the deep sea.Understanding the dynamics of the gravity currents that create these systems, and in particular, how these flows interact with and form bends, is fundamental to predicting system architecture and evolution. Bend flow is characterized by a helical structure and in rivers typically comprises inwardly directed near-bed flow and outwardly directed near-surface flow. Following a decade of debate, it is now accepted that helical flow in submarine channel bends can exhibit a variety of structures including being opposed to that observed in rivers. The new challenge is to understand what controls the orientation of helical flow cells within submarine flows and determines the conditions for reversal. We present data from the Black Sea showing, for the first time, the three-dimensional velocity and density structure of an active submarine gravity current. By calculating the forces acting on the flow, we evaluate what controls the orientation of helical flow cells. We demonstrate that radial pressure gradients caused by across-channel stratification of the flow are more important than centrifugal acceleration in controlling the orientation of helical flow. We also demonstrate that nonlocal acceleration of the flow due to topographic forcing and downstream advection of the cross-stream flow are significant terms in the momentum balance. These findings have major implications for conceptual and numerical models of submarine channel dynamics, because they show that three-dimensional models that incorporate across-channel flow stratification are required to accurately represent curvature-induced helical flow in such systems.

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In‐situ measurements of velocity structure within turbidity currents

Cited by 244 publications

References 15 publications

Key Future Directions For Research On Turbidity Currents and Their Deposits

Key Future Directions For Research On Turbidity Currents and Their Deposits

Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Driven around the bend: Spatial evolution and controls on the orientation of helical bend flow in a natural submarine gravity current

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