18 November 1929, Mw 7.2, Newfoundland, Canada
| Seismic and Geodetic |
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| Data and Information Sites |
- The Magnitude 7.2 1929 "Grand Banks" earthquake and tsunami (Natural Resources Canada) (Website)
- 1929 Grand Banks Tsunami
(The University of Washingtion) (Website)
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1929 Grand Banks Earthquake & Tsunami
Click here to download the Event Article (PDF, 3.0 MB)
An unexpected tsunami in the far North Atlantic foretells the importance of education, early warning, evacuation, and communications – and gives birth to the science of turbidity currents.
On the island of Newfoundland in mid-November 1929, a blustery storm knocked down the telegraph wires connecting it to neighboring areas. Newfoundlanders – not yet part of the Canadian Confederation of 1949 – were accustomed to harsh subarctic conditions and isolation from the mainland. For many it was a near-subsistence livelihood built around cod fishing, where townspeople depended largely on themselves and their neighbors. They were used to whatever the sea and weather threw at them, sometimes with deadly force. But at 5 pm on November 18 something different was about to happen.
420 km away on the steep slope where the 100 m deep coastal plateau drops sharply to 2000 m, tension had been building up in the submarine rock 20 km below the seafloor. At 5:02 pm local time the ground in Newfoundland shook. Dishes rattled and lamps swayed. A 100 km long fault had ruptured.
The earthquake did not damage any structures in Newfoundland and residents went about their business at the end of the day, but two and a half hours later everything changed. A Mr. Bartlett witnessed the incoming wave:
“Mr. Bartlett was on board the S.S. Daisy after tea on Monday night when the steamer was lying at the government wharf. Someone on the wharf made an outcry, and he rushed onto the wharf. He saw the water recede first and then come in with a bore. The bore collapsed and the Daisy struck bottom. He immediately went around the harbour to his own premises where he found that his buildings were submerged. His shop measuring 30 by 60 feet, was lifted bodily and deposited 200 feet away.” – The Free Press, St. John’s, Newfoundland, 26 November 1929.
The wave arrived trough first, after traveling approximately 265 km at a speed of 140 km/hr on the open ocean, slowing to 40 km/hr near the coast. Along open coastline it reached a height of 3-7 meters, but towered to 13-27 meters in some of the narrow bays and inlets common in the area. Three successive waves arrived and receded within just 30 minutes.
The first contact from the outside occurred as a ship sailed into Burin and noticed nine buildings floating along the coast. The rest of the country did not learn the magnitude of the tsunami until two and a half days later, on the morning of November 21, when a wireless message was sent via
the S.S. Portia to the capitol in St. John’s. “As a bolt from the blue the news of the disaster which overtook the towns and settlements on the east side of the Burin Peninsula reached the city Thursday morning,” reported the Free Press. 
“There was nothing to indicate that it was of such terrific force as to cause such loss of life and property as has now been reported.”
A report to the government printed in the paper reported these details: “Burin experienced very severe earth tremors at 5:05 p.m. Monday, followed by an immense 15 foot tidal wave which swept away practically everything along the waterfront from Port au Bras to Great Burin. There is scarcely a waterside premises left standing. … Four houses at Kelly’s Cove and Stepaside disappeared to sea in an instant with a loss of two lives. … There were many hair-breadth escapes and many people are suffering from shock and privation. The loss of property is terrible and hundreds of people will be destitute. As yet can get no particulars from St. Lawrence to Garnish inclusive. A severe S.E. gale and rain storm is raging.”
In addition to the previously storm-severed telegraph lines, the tsunami inflicted further communication challenges. “St. Lawrence telegraph office is anchored in middle of St. Lawrence Hr., and Lord’s Cove telegraph office totally destroyed. – Cox, operator.”
“No fear of disaster from this direction”
Newfoundland measures approximately 800 km across, but with its many bays, inlets and small islands the perimeter totals nearly 10,000 km of coastline, scattered with tiny fishing towns. On the nearby Grand Banks – a large, shallow, submarine plateau – the northerly flowing warm Gulf Stream passes the cold Labrador current
and brings to the surface abundant nutrients that have fueled one of the largest cod fisheries in the world. Newfoundland’s economy was rooted in seasonal cod fishing, with salt cod exports of 53,000 metric tons in 1925. The mainstay of the economy was cod fishing, mostly family operations with small rowing boats launched daily into the inshore waters near the coast and some larger schooners ferrying rowed dories to the outer banks. The catch was salted, dried, then stored for used over the long winters along with root crops and hay grown at home.
The effect of the tsunami on the local economy was devastating. Magistrate Hollett reported from Burin: “Port au Bras was swept clean of all fishery premises and boats and schooners. Fourteen boats were lost or badly damaged. All is desolation in Port au Bras. … All the people had their winter’s provisions, fuel, traps, and gear of every description in their stores. Everything is gone. I visited them to-day. There is great distress. There are not 5 barrels flour in the place and no coal.” To make matters worse, the world economy
had just entered the start of the Great Depression.
Fishing villages that had been able to withstand fierce sub-arctic storms for generations were crushed by the unexpected threat from the deep ocean, which hit hardest in the normally protected bays. “The tidal wave struck with greatest force on the west side of Placentia Bay. Sweeping in from the Atlantic, when it reached the comparatively narrow entrance of Placentia bay, it rose to a great height, dashed with relentless fury against the lower end of the Burin Peninsula and then rushed along the coast until its force was spent, leaving death and disaster in its wake, wrote the Free Press. “For many years the sea had dashed the rocks without danger to their houses, but the hardy fishermen and their families had no fear of disaster overtaking them from this direction.”
Unsuspecting families were trapped in their houses when the tsunami struck. The town of Lamaline sent this accounting to the Free Press:
“Mrs. Henry Hillier and four grandchildren were swept away in her house. At Taylor’s Bay, Mrs. Robert Bonnell and her children were drowned, also two children of Bertram Bonnell. At Lord’s Cove, Mrs. Patrick Rennie and three children were drowned in the house. At Allan’s Island, James Lockyer, age 81, was crushed by the sea and died in a few hours.” Conditions were similar in Port au Bras: “Mrs. Bennett, widow of Captain Samuel Bennett who, a few years ago, was lost from his schooner outside St. John’s harbour, left her house to visit her brother, Mr. Henry Dibbin. Both were carried out to sea. Six houses built on breakwater were carried out to sea en masse.” In total, 25 people were killed immediately and another 3 in the days after. Hundreds more were rendered homeless, or destitute from lack of provisions, just as the harsh winter approached.
Most immediate aid and rescue had to be supplied by local boats and ships that were not damaged by the tsunami, such as the S.S. Daisy, directed by Captain Hollett. Even houses were retrieved this way. Steven Henry Isaacs found his house floating 1-2 km offshore of the mouth of Port au Bras inlet. He and his father tied it to the fishing schooner Marian Belle Wolfe and towed it back into the harbor.
More telegraph problems
The St. John’s Evening Standard on November 21contained a small item with the headline “Upheaval in Ocean Floor Reported” which stated that far offshore the earthquake had disrupted a large area where telegraph cables cross. “Cable ships belonging to the Anglo and Commercial Companies are now engaged locating their broken cables.” Another small item explains that about half of the 20 transatlantic cables were damaged for the first time ever by an earthquake, although scientists debated for years how the damage actually occurred. Oddly, instead of breaking at the same time, they broke in a particular sequence, one after the other, traveling down the steep continental slope and all the way out onto the deep ocean floor hundreds of kilometers from the earthquake’s epicenter. This unusual behavior eventually led to the discovery by Bruce Heezen and Maurice Ewing that shaking and upheaval were not the cause of the damage:
“Following the 1929 Grand Banks earthquake which shook the continental slope south of Newfoundland, all the submarine telegraph cables lying downslope (south) of the epicentral area were broken in sequence from north to south. All previously published explanations of these breaks are considered and rejected because they do not adequately explain this sequence. A new explanation is offered according to which each successive cable was broken by a turbidity current originating as a slump on the continental slope in the epicentral area and traveling downward across the continental slope, continental rise, and ocean basin floor and continuing far out on the abyssal plain.” – Heezen & Ewing, 1952
Two years later they had evidence
from sediment on the seafloor itself that this was the case. The earthquake had caused a submarine landslide in which sediments deposited from glaciation tens of thousands of years ago slumped off the continental slope near the epicenter, forming what is now known as a turbidity current – an avalanche of liquified sediment moving with tremendous power. The Grand Banks flow is estimated to have been 200-300 meters thick, moving at a speed of 60-70 km/hr, and depositing 175 cubic kilometers of mud, silt and gravel in a layer 1 meter thick over a large area of the abyssal plain below the slope. In the slumping area – about 100 km wide – the transatlantic cable broke instantaneously. But as the flow raced down the slope and onto the plain below, cables snapped in succession over a period of about 13 hours.
This led to another question however: what caused the tsunami – ocean water displaced by the movement on the fault during the earthquake, or ocean water displaced by the movement of the sediment in the turbidity current? Was there even an earthquake at all, or was the shaking the result of the massive submarine landslide? For assessing future tsunami risk, it is important to recognize the mechanism responsible. If it is solely an earthquake, one can look to the frequency of earthquakes in the area
historically. If a submarine landslide is responsible for most or all of the tsunami, the interval can be much longer because it depends on the slow accumulation of seafloor sediments to create the volume necessary.
Research and modeling of the seismic characteristics of the Grand Banks event point to an earthquake from a strike-slip rupture, with two smaller ruptures following. The seafloor displacement that would have been generated by this mechanism indicate that the tsunami must have been generated by the submarine landslide, not the earthquake itself.
References & Further Reading
Higgins, Jenny. The Tsunami of 1929. Newfoundland & Labrador Heritage, Memorial University of Newfoundland. https://www.heritage.nf.ca/articles/politics/tsunami-1929.php
The Evening Telegram, St. John’s Newfoundland, 1929-11-21. Memorial University of Newfoundland, Digital Archives. https://collections.mun.ca/digital/collection/telegram20/id/48105/rec/17
The Free Press, St. John’s Newfoundland 1929-11-26. Earthquakes Canada/Natural Resources Canada.
https://www.earthquakescanada.nrcan.gc.ca/historic-historique/events/images/19291118_1929StJohnsFreePress1126.png
Ruffman, Alan, and Hann, V. The Newfoundland Tsunami of November 18, 1929: An Examination of the Twenty-eight Deaths of the "South Coast Disaster. https://journals.lib.unb.ca/index.php/nflds/article/view/5887/6897
Heezen, Bruce C., and Ewing, M., 1952, Turbidity currents and submarine slumps, and the 1929 Grand Banks earthquake, American Journal of Science, Vol. 250(12): 849-873. https://doi.org/10.2475/ajs.250.12.849
Heezen, Bruce, and Ewing, M. 1954. Further evidence for a turbidity current following the 1929 Grand banks earthquake. Deep Sea Research, Vol. 1(4): 193-202.
https://doi.org/10.1016/0146-6313(54)90001-5
Undersea Avalanches. Bureau of Economic Geology, Earthdate.org Fact Sheet ED 246. https://www.earthdate.org/files/000/002/524/EarthDate_246_C.pdf
Piper, David. J., Shor, A.N. and Clarke, J.E. 1988. The 1929 “Grand Banks” earthquake, slump, and turbidity currents. In Sedimentologic Consequences of Convulsive Geologic Events, ed. H. Edward Clifton. https://doi.org/10.1130/SPE229-p77
Bent, Allison, 1995. A Complex Double-Couple Source Mechanism for the Ms 7.2 1929 Grand Banks Earthquake. Bull. Seismological Society of America 85(4): 1003-1020.
https://www.seismescanada.rncan.gc.ca/historic-historique/events/1995BSSA_Bent_1929mechanism.pdf
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