| 词条 | 1929 Grand Banks earthquake |
| 释义 |
| timestamp = 1929-11-18 20:32:00 | anss-url = iscgem908394 | isc-event = 908394 | caption = | map2 = {{Location map+ | Canada | relief = 1 |places ={{Location map~|Canada|lat=44.54|long=-56.01|mark=Bullseye1.png|marksize=40}} | width = 250 | float = right | caption = }} | local-date = {{start-date|November 18, 1929|November 18, 1929}} | local-time = 17:02 | magnitude = 7.2 Mw {{Sfn|Fine; I.V.|2016}} | depth = {{convert|20|km|mi|0|abbr=on}} {{Sfn|Fine; I.V.|2016}} | location = {{coord|44.54|N|56.01|W}} {{Sfn|Engdahl|2016}} | intensity = (VI Strong tremor){{Sfn|RossiForel|2002}} (VIII Severe)(Natural Resources Canada 1929 earthquake revised){{Sfn|RossiForel|2002}} | tsunami = Yes | aftershocks = ~3 {{Sfn|RossiForel|2002}} | casualties = 27 or 28 killed | title = 1929 Grand Banks earthquake |damage = $400,000 {{Sfn|Fine; I.V.|2016}} ($5.6 million in 2017) | countries affected = Dominion of Newfoundland Canada French Republic Saint Pierre and Miquelon }} The 1929 Grand Banks earthquake (also called the Laurentian Slope earthquake and the South Shore Disaster) occurred on November 18. The shock had a moment magnitude of 7.2 and a maximum Rossi–Forel intensity of VI (Strong tremor) and was centered in the Atlantic Ocean off the south coast of Newfoundland in the Laurentian Slope Seismic Zone. EarthquakeThe earthquake was centred on the edge of the Grand Banks of Newfoundland, about {{convert|400|km|mi}} south of the island. It was felt as far away as New York City and Montreal. The quake, along two faults {{convert|250|km|mi}} south of the Burin Peninsula, triggered a large submarine landslide displacing ({{convert|200|km3|cumi|abbr=on|disp=or}}). It snapped 12 submarine transatlantic telegraph cables and led to a tsunami that arrived in three waves. Newfoundland, Canada and Saint Pierre and Miquelon had the largest impact, both from the snapped 12 submarine cables, and the tsunami. This was Canada's largest submarine landslide ever recorded, up to 500 times the size of 1894 Saint-Alban subaerial slide.{{Sfn|Fine; I.V.|2016}} In 2002 Natural Resources Canada and the United States Geological Survey, created an intensity map by using the Revised Modified Mercalli scale.{{Sfn|GBMMI|2016}} TsunamiThe tsunami waves had an amplitude of {{convert|3|-|8|m}}, and a runup of {{convert|13|m|ft}} along the Burin Peninsula.{{Sfn|Fine; I.V.|2016}} It destroyed many south coastal communities on the Peninsula, killing 27 or 28 people and leaving 1,000 or more homeless.{{Sfn|Ruffman;Hann|2016}} 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 was recorded as far away as Lagos, Portugal {{convert|4,060|km|mi|abbr=on}} away, 06:47 after the earthquake.{{Sfn|Fine; I.V.|2016}} It took 02:23 hrs to strike Burin, Newfoundland, {{convert|340|km|mi|abbr=on}} from the epicenter, and only two hours to be observed in Bermuda {{convert|1445|km|mi|abbr=on}}.{{Sfn|Fine; I.V.|2016}} This was Canada's largest submarine landslide ever recorded, up to 500 times the size of 1894 Saint-Alban landslide.{{Sfn|Fine; I.V.|2016}} {{Quote|text= {{As written}} Tsunami travel times demonstrate the strong anisotropy of the propagating waves. The waves reach open ocean islands such as Bermuda in about 2 h[hours] (mean speed ~700 km/h) and the Azores in about 4 h (~630 km/h). At the same time, tsunami wave speeds are much slower in the direction of the North America[n] coast: they require 2.7 h to reach Halifax (~230 km/h) and 4.2 h to reach Atlantic City (~380 km/h).|author=W.H Berninghausen|source={{Sfn|Fine; I.V.|2016}}}}Prince Edward IslandPrince Edward Island had felt the earthquake; the intensity was rated at the time at IV (Slight tremor) – VI (Strong tremor) on the Rossi-Forel scale.{{Sfn|RossiForel|2002}} In PEI it ranged from an intensity of III (Weak) – V (Moderate).{{Sfn|RossiForel|2002}} Saint Pierre and MiquelonIn the then named French Republic Overseas territory of Saint Pierre and Miquelon,{{Sfn|Ruffman, Alen|2016}} about {{Convert|18|km}} west of the Burin Peninsula, people were awakened around 16:30h by the earthquake that lasted approximately one minute. At 17:20, the tsunami reached the island of Saint-Pierre, submerging the docks. The worst damage was reported on the island then named Île-aux-Chiens (meaning Island of the Dogs; till 1931), now known as L'Île-aux-Marins (The Island of the Sailors). The tsunami hit from the south, rising above the height of the south bank that protects the south coast, flooding the lower part of the island. It damaged and moved some of the houses; there were no reported injuries or casualties from the islands.{{Sfn|Ruffman, Alen|2016}} The quake's intensity on the island was V (Moderate tremor) – VI (Strong tremor),{{Sfn|RossiForel|2002}} and on the revised Modified Mercalli Intensity scale IV (Light) – V (Moderate){{Sfn|GBMMI|2016}} Aftermath{{Refimprove section|date=March 2016|small=y}}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 totaled $250,000. 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.{{Sfn|Heezen;Ewing|2016}} 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.{{sfn|Heezen;Ewing|2016}} Scientists have examined other layers of sand believed to be deposited by other tsunamis in an effort to determine the occurrence rates of large earthquakes.{{citation needed|date=March 2016}} One sand layer, thought to be deposited by the 1929 tsunami, at Taylor's Bay was found {{convert|13|cm}} below the turf line.{{citation needed|date=March 2016}} 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.{{citation needed|date=March 2016}} See also
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Further reading
10 : Earthquakes in Newfoundland and Labrador|Natural disasters in Nova Scotia|Natural disasters in Prince Edward Island|1929 in Saint Pierre and Miquelon|1929 in Newfoundland|1929 in Nova Scotia|1929 in Prince Edward Island|1929 tsunamis|1929 earthquakes|November 1929 events |
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