1929 Grand Banks earthquake

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1929 Grand Banks earthquake
1929 Grand Banks earthquake is located in Canada
1929 Grand Banks earthquake
Date November 18, 1929 (1929-11-18)
Origin time 20:32 UTC [1]
Magnitude 7.2 Mw [2]
Depth 20 km (12 mi) [2]
Epicenter 44°32′N 56°01′W / 44.54°N 56.01°W / 44.54; -56.01 [1]
Countries or regions Newfoundland
Canada
Saint Pierre and Miquelon
Total damage $400,000 [2]
Max. intensity VI (Strong)
Tsunami Yes
Casualties 27 or 28 killed

The 1929 Grand Banks earthquake (also called the Laurentian Slope earthquake and the South Shore Disaster) occurred with a moment magnitude of 7.2 on November 18. The shock was centered in the Atlantic Ocean off the south coast of Newfoundland in the Laurentian Slope Seismic Zone.

Earthquake[edit]

The earthquake was centred 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 or 48 cu mi). It snapped 12 submarine transatlantic telegraph cables and led to a tsunami that arrived in three waves, each 3 to 4 metres high,[3] 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.

Tsunami[edit]

The tsunami destroyed many south coastal communities on the Burin Peninsula, killing 27 or 28 people[4] 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.

Aftermath[edit]

There was never an accurate official list of the victims produced by any branch of the Newfoundland government. In the report entitled "Loss of Life," the Honourable Dr. Harris Munden Mosdell, Chairman of the Board of Health Burin West, reported: "The loss of life through the tidal wave totals twenty-seven. Twenty-five deaths were due directly to the upheaval. Two other deaths occurred subsequently and were due to shock and exposure." Later research attributed an additional death to the earthquake.[4]

In 1952, American scientists from Columbia University put together the pieces of the sequentially broken cables that led to the 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 that made the tsunami so powerful. The deposition of such a large volume of sediments will take a while before there is enough to form an underwater landslide the same size as that in 1929.

References[edit]

  1. ^ a b Engdahl, E. R.; Vallaseñor, A. (2002). "Global seismicity: 1900-1999". International Handbook of Earthquake & Engineering Seismology. Part A, Volume 81A (First ed.). Academic Press. p. 675. ISBN 978-0124406520. 
  2. ^ a b c Fine, I. V.; Rabinovich, A. B.; Bornhold, B. D.; Thomson, R. E.; Kulikov, E. A. (2005). "The Grand Banks landslide-generated tsunami of November 18, 1929: preliminary analysis and numerical modeling". Marine Geology (Elsevier) 215 (1–2): 45–47. doi:10.1016/j.margeo.2004.11.007. 
  3. ^ "Ancient tsunami 'hit New York'". BBC News. May 3, 2009. Retrieved April 20, 2010. 
  4. ^ a b Ruffman, A.; Hann, V. (2001). "The Newfoundland Tsunami of November 18, 1929: An Examination of the Twenty-eight Deaths of the "South Coast Disaster"". Newfoundland and Labrador Studies. 

External links[edit]