The Seafloor Does Not Collapse All at Once, Underwater Monitoring Shows

Researchers have directly monitored underwater landslides as they happened at the Homathko Delta in British Columbia, and the seafloor there did not give way all at once. It failed slowly, creeping back up the slope. Rebecca G. Englert of Durham University and colleagues report in a paper published Nov. 12, 2026, in Science that landslides taking place entirely underwater had never been directly monitored in nature before.

The authors say the finding matters for anything built on the seabed. Submarine landslides threaten seabed structures, and whether a failure drags on or happens in an instant bears on the stress those structures must be designed to withstand.

The paper describes what it recorded as breaching, a slow failure that migrates up the slope. Breaching in sandy parts of the seafloor was among the existing hypotheses for how submarine landslides fail, and those hypotheses had remained unvalidated for natural settings.

Prolonged landslides also start sustained flows of sediment, known as turbidity currents, which carry sediment, carbon and pollutants farther offshore. Submarine landslides move what the authors call globally important amounts of that material into the deep sea.

The paper lists 20 authors at universities, geological surveys and research institutes in Britain, Canada, the Netherlands, the United States and Turkey. The supporting data for the study are deposited openly on Zenodo.