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Wikinews has related news: Search for survivors of Canadian helicopter crash ends, recovery mission focuses on victims |
The 1929 Grand Banks earthquake, also called the Laurentian Slope earthquake and the South Shore Disaster, was a magnitude 7.2 earthquake that occurred on November 18, 1929 in the Atlantic Ocean off the south coast of Newfoundland in the Laurentian Slope Seismic Zone.
The earthquake was centered on the edge of the Grand Banks of Newfoundland, about 400 kilometres (250 mi) south of the island. It was felt as far away as New York and Montreal. The quake, along two faults 250 kilometres (160 mi) south of the Burin Peninsula, triggered a large submarine landslide (200 km3/48 cu mi). It snapped 12 submarine transatlantic telegraph cables and led to a tsunami that arrived in three waves, each 3 to 4 meters high[1], that struck the coast at 105 km/h (65 mph) about three hours after the earthquake occurred. The waves travelled at speeds up to 129 km/h (80 mph) at the epicentre; they were recorded as far away as Portugal.
The tsunami destroyed many south coastal communities on the Burin Peninsula, killing 28 people and leaving 10,000 more homeless. All means of communication were cut off by the destruction, and relief efforts were further hampered by a blizzard that struck the day after. It took more than three days before the SS Meigle responded to an SOS signal with doctors, nurses, blankets, and food. Donations from across Newfoundland, Canada, the United States and United Kingdom totalled $250,000.
As of 2009 it is the only recorded tsunami to have struck Canada's east coast.
In 1952 American scientists from Columbia University put together the pieces of the sequentially broken cables that led to discovery of the landslide and the first documentation of a turbidity current. Scientists are looking at layers of sand believed to be deposited by other tsunamis in an effort to determine the occurrence rates of large earthquakes. One sand layer, thought to be deposited by the 1929 tsunami, at Taylor's Bay was found 13 cm below the turf line. The occurrences of large tsunamis, such as the one in 1929, are dependent upon deposition of sediments offshore because it was the landslide, which made the tsunami so powerful. The deposition of such a large volume of sediments will take a while before there is enough to for an underwater landslide of size as in 1929.