William Park
It was a little after 17:00 on 18 November 1929 when the ground began to shake. Just off the coast of Burin Peninsula, a finger-like protrusion on the south of Newfoundland, Canada, a 7.2 magnitude earthquake disturbed the evening's peace. Residents noticed only a little damage at first – a few toppled chimney pots.
But out at sea, an unseen force was moving. By around 19:30, a 13m-high (43ft) tsunami made landfall on the Burin Peninsula. In total, 28 people lost their lives as a result of drowning or injuries caused by the wave.
The earthquake was devastating for the local communities, but it also had a long-lasting effect further out at sea. It had triggered a submarine landslide. People did not realise this at the time, historical records suggest, because no one knew such underwater landslides existed. When sediment is disturbed by earthquakes and other geological activity it makes the water denser, causing it to flow downwards like an avalanche of snow down a mountain. The submarine landslide – called a turbidity current – flowed more than 1,000km (621 miles) away from the earthquake's epicentre on the Laurentian Continental Slope at speeds between 50 and 70 knots (57-80mph).
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