Sketches of observations at the study site on consecutive days
Observations at the study site on consecutive days. The lower panel shows the mechanism of generating a turbidity current from a dilute plume. Turbidity maximum induced on the upper part of the slope generates weak downslope motion, which is amplified by erosion and produces a strong turbidity current. Credit: Hage et al. [2019], Figure 6a, top two panels
Source: Geophysical Research Letters

Marine turbidity currents can be generated by submarine landslides or by sediment load from rivers, both of which act to increase the density of water. This high-density water then propagates along the sea floor, powered by its own density anomaly.

The standard theory for river-induced turbidity currents is that a large sediment input from the river is required. Hage et al. [2019] turn that theory on its head. They demonstrate that turbidity currents can, in fact, be generated from rivers with a very small sediment load. The case is made with an incredibly detailed set of measurements which catch a short (6 minute) turbidity current in the act of forming and dissipating – even showing the change in sea floor bathymetry after the event. These results will lead to a re-evaluation of how and when turbidity currents form.

Citation: Hage, S., Cartigny, M. J. B., Sumner, E. J., Clare, M. A., Hughes Clarke, J. E., Talling, P. J., et al [2019]. Direct Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes. Geophysical Research Letters, 46.

—Andrew M. Hogg, Editor, Geophysical Research Letters

Text © 2019. The authors. CC BY-NC-ND 3.0
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