Turbidity currents, sometimes triggered by underwater landslides, are destructive avalanche-like flows that carve deep channels in the seafloor – think of a snow avalanche powerful enough to run up the base of a slope in a mountain valley. These events are hazardous to seafloor infrastructure, and the landslides, in some cases, have generated tsunamis. Canada’s west coast has many turbidite channel systems, but they are difficult to study and poorly understood.
In 1986, the Geological Survey of Canada deployed instruments in British Columbia’s Bute Inlet to measure past turbidity current events. Some were found to be thicker than 30 metres and travelled 26 kilometres underwater on slopes less than 1°.
In 2012, the Survey, in collaboration with Ocean Networks Canada, installed a cabled observatory on the Fraser Delta to observe turbidity currents, as they occur, to better understand these events. The observatory has successfully detected events every spring since it was installed – but not without a few close calls. In 2012 a powerful turbidity current rolled the 1000-kilogram observatory down the delta front. The platform continued taking measurements, and the data provide a valuable insight to the natural behaviour of turbidity currents.
Category: Science Advances
Lintern, D.G., Hill, P.R., and Stacey, C.D., 2016. Powerful unconfined turbidity current captured by cabled observatory on the Fraser delta slope, British Columbia, Canada; Sedimentology, v. 63, p. 1041–1064. doi:10.1111/sed.12262