Massive underwater avalanches deliver pollutants to deep sea

Research shows largest turbidity currents' can carry more sediment than the annual output of all the world's rivers combined over time

On 18 November 1929, a magnitude 7.2 earthquake shook the ocean floor off the coast of Newfoundland, Canada. Within minutes transatlantic telephone cables started sequentially snapping, with the furthest cable - 600km from the quake - breaking 13 hours and 17 minutes later.

At the time geologists hypothesised that the cables had been broken by a series of earthquakes, but we now know that the culprit was a massive underwater avalanche, known as a turbidity current".