Large underwater experiment in Monterey Canyon shows turbidity currents involve seafloor movement

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Large underwater experiment in California’s Monterey Canyon shows that “turbidity currents” are not just currents, but involve movement of the seafloor itself

Men stand on a boat wearing safety gear and they are deploying instrumentation into the water using cables and ropes.

On October 6, 2016, scientists lower an instrument package on a taut-wire mooring into the canyon. The sediment trap (long funnel-shaped device) is designed to capture mud and sand carried in turbidity flows; the other sensors measure currents and suspended sediment. Credit: Katie Maier, USGS, MBARI. Public domain

Turbidity currents have historically been described as fast-moving currents that sweep down submarine canyons, carrying sand and mud into the deep sea. But a new paper in Nature Communications shows that, rather than just consisting of sediment-laden seawater flowing over the seafloor, turbidity currents also involve large-scale sediment movements within the seafloor. This discovery emerged from an 18-month-long, multi-institutional study of Monterey Canyon. USGS researchers and marine technicians were collaborators in the project, which monitored a 50-kilometer-long stretch of the canyon in unprecedented detail. The findings could help ocean engineers avoid damage to pipelines, communications cables, and other seafloor structures. Read a news release from the Monterey Bay Aquarium Research Institute and the scientific paper in Nature.

Paull, C.K., Talling, P.J., Maier, K.L., Parsons, D., Xu, J., Caress, D.W., Gwiazda, R., Lundsten, E.M., Anderson, K., Barry, J.P., Chaffey, M., O’Reilly, T., Rosenberger, K.J., Gales, J.A., Kieft, B., McGann, M., Simmons, S.M., McCann, M., Sumner, E.J., Clare, M.A., and Cartigny, M.J., 2018, Powerful turbidity currents driven by dense basal layers: Nature Communications, v. 9 no. 1, 9 pages, doi: 10.1038/s41467-018-06254-6.

Men stand on a boat wearing safety gear and they are recovering damaged instrumentation from the water using cables and ropes.

On March 21, 2017, the sediment trap from this instrument package (deployed the previous October into Monterey Canyon) is gone and the mounting frame is mangled, having been exposed to several significant turbidity currents in one deployment. 

Credit: Katie Maier, USGS, MBARI. Public domain