The 1929 Grand Banks earthquake (also called the Laurentian Slope earthquake and the South Shore Disaster) occurred on November 18, 1929. The shock had a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

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 The Laurentian Slope Seismic Zone is a seismically active area in Atlantic Canada located on the Grand Banks of Newfoundland. It was the epicenter of the magnitude 7.2 1929 Grand Banks earthquake The 1929 Grand Banks earthquake (also called the ...

Earthquake

The earthquake was centred on the edge of the

Grand Banks of Newfoundland The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordf ...

, about south of the island. It was felt as far away as

New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...

and

Montreal Montreal ( ; officially Montréal, ) is the second-most populous city in Canada and most populous city in the Canadian province of Quebec. Founded in 1642 as '' Ville-Marie'', or "City of Mary", it is named after Mount Royal, the triple ...

. The quake, along two faults south of the

Burin Peninsula The Burin Peninsula ( ) is a peninsula located on the south coast of the island of Newfoundland in the province of Newfoundland and Labrador. Marystown is the largest population centre on the peninsula.Statistics Canada. 2017. Marystown, T ensu ...

, triggered a large

submarine landslide Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress (gravity and other factors) exceeds the resisting str ...

displacing (). It snapped 12 submarine

transatlantic telegraph cable Transatlantic telegraph cables were undersea cables running under the Atlantic Ocean for telegraph communications. Telegraphy is now an obsolete form of communication, and the cables have long since been decommissioned, but telephone and data a ...

s and led to a

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

that arrived in three waves. Newfoundland, Canada and

Saint Pierre and Miquelon Saint Pierre and Miquelon (), officially the Territorial Collectivity of Saint-Pierre and Miquelon (french: link=no, Collectivité territoriale de Saint-Pierre et Miquelon ), is a self-governing territorial overseas collectivity of France in t ...

had the largest impact, both from the snapped 12 submarine cables, and the tsunami. This was Canada's largest

ever recorded, up to 500 times the size of 1894 Saint-Alban subaerial slide. In 2002

Natural Resources Canada Natural Resources Canada (NRCan; french: Ressources naturelles Canada; french: RNCan, label=none)Natural Resources Canada is the applied title under the Federal Identity Program; the legal title is Department of Natural Resources (). is the dep ...

and the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

, created an intensity map by using the Revised

Modified Mercalli scale The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...

Tsunami

The tsunami waves had an

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

of , and a runup of along the

. It destroyed many south coastal communities on the Peninsula, killing 27 or 28 people and leaving 1,000 or 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 was recorded as far away as Lagos, Portugal away, 06:47 after the earthquake. It took 2 hours and 23 minutes to strike Burin, Newfoundland, from the epicentre, and only two hours to be observed in

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Prince Edward Island

Prince Edward Island felt the earthquake; at the time the intensity was rated at IV (Slight tremor) – VI (Strong tremor) on the Rossi-Forel scale. In PEI it ranged from an intensity of III (Weak) – V (Moderate).

Saint Pierre and Miquelon

In the then named French Republic

Overseas territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...

, about 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. The quake's intensity on the island was V (Moderate tremor) – VI (Strong tremor), and on the revised Modified Mercalli Intensity scale IV (Light) – V (Moderate)

Aftermath

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. 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 A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. T ...

. 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. One sand layer, thought to be deposited by the 1929 tsunami, at Taylor's Bay was found 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. It will take a while before there is a large enough deposition of sediments to form an underwater landslide of a size similar as that of 1929.

References

Citations

Sources

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External links

Archival moment: Tsunami hits Burin Peninsula
- CBC
The Magnitude 7.2 1929 "Grand Banks" earthquake and tsunami
–

The South Shore disaster: Newfoundland's tsunamiNot Too Long Ago (first hand accounts of the tsunami, pp. 51–60)
– Library and Archives Canada
Marine Geology Volume 215, Issues 1–2
International Journal of

Marine geology Marine geology or geological oceanography is the study of the history and structure of the ocean floor. It involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal zone. Marine geolog ...

Geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the ...

and

Geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...

(2004) *