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 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 Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the population ...

in the Laurentian Slope seismic zone.

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 (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

and

Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...

. The quake, which occurred along two faults south of the

Burin Peninsula The Burin Peninsula ( ) is a peninsula located on the south coast of the island of Newfoundland (island), Newfoundland in the province of Newfoundland and Labrador. Marystown is the largest population centre on the peninsula.Statistics Canada. 201 ...

, 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 stres ...

displacing (). It snapped 12 submarine

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

s and led to a

tsunami A tsunami ( ; from , ) 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 underwater explosions (including detonations, ...

that arrived in three waves.

, Canada and

Saint Pierre and Miquelon Saint Pierre and Miquelon ( ), officially the Territorial Collectivity of Saint Pierre and Miquelon (), is a self-governing territorial overseas collectivity of France in the northwestern Atlantic Ocean, located near the Canada, Canadian prov ...

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; ; )Natural Resources Canada is the applied title under the Federal Identity Program; the legal title is Department of Natural Resources (). is the department of the Government of Canada responsible for natural r ...

and the

United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

created an intensity map by using the Revised Modified Mercalli scale.

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 Lagos (; ) is a city and concelho, municipality at the mouth of Bensafrim River and along the Atlantic Ocean, in the Barlavento region of the Algarve, in southern Portugal. The population of the municipality in 2011 was 31,049, in an area of 212.99 ...

away, 06:47 after the earthquake. It took 2 hours and 23 minutes to strike Burin,

, from the epicentre, and only two hours to be observed in

Bermuda Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

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 the province, it ranged from an intensity of III (Weak) – V (Moderate).

Saint Pierre and Miquelon

In the French

Overseas territory A territory is an area of land, sea, or space, belonging or connected to a particular country, person, or animal. In international politics, a territory is usually a geographic area which has not been granted the powers of self-government, ...

, about west of the

, residents were startled around 16:30h by an earthquake lasting approximately one minute. At 17:20, the subsequent tsunami reached the island of Saint-Pierre, submerging the docks. The most destruction was reported on the island formerly known as Île-aux-Chiens (''The Island of the Dogs'', until 1931–now known as L'Île-aux-Marins, ''The Island of the Sailors''); the tsunami approached from the south, rising above the height of the south bank that protects the south coast, and flooding the lower part of the island upon impact. The waves destroyed (and moved) several residences and structures, but 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

In the immediate aftermath of the tsunami, electricity, radio and telegram communications were unavailable for several days. It took three days for the S.S. ''Meigle'' to respond to a distress signal, sending supplies, aid workers, doctors, nurses, blankets, and food. Donations from across Newfoundland, the United States and the United Kingdom totaled around $250k (about CA$4.3 million in 2023). There was never an accurate or official list of victims produced, by any individual or branch of the Newfoundland or Canadian government. In a report entitled "Loss of Life", the Dr. Harris Munden Mosdell (chairman of the board of Health Burin West) reported that "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, scientists from

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

put together the pieces of the sequentially-broken cables, leading to the discovery of the landslide and the first documentation of a

turbidity current A turbidity current is most typically an Ocean current, 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 ...

. Scientists have examined layers of sand, believed to be deposited by other tsunamis, in an effort to determine the regional frequency 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 frequency of large tsunamis varies according to the deposition of sediments offshore, as it was the submarine landslide's power that triggered the wave.

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 Library and Archives Canada (LAC; ) is the federal institution tasked with acquiring, preserving, and providing accessibility to the documentary heritage of Canada. The national archive and library is the 16th largest library in the world. T ...

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, Geochemistry, geochemical, Sedimentology, sedimentological and paleontological investigations of the ocean floor and ...

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 e ...

and

Geophysics Geophysics () is a subject of natural science concerned with the physical processes and Physical property, properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct i ...

(2004) *