Province’s regular earthquakes often go unnoticed
Offshore quakes usually larger, but N.L. has numerous smaller land-based earthquakes
There may not be a whole lotta shakin’ goin’ on, but that doesn’t mean Newfoundland and Labrador doesn’t have its share of seismic activity.
When most people think of earthquakes associated with the province, they likely think of the tsunami disaster that struck the Burin Peninsula on Nov. 18, 1929.
In that terrible incident, 28 people died and many more were left homeless after a tidal wave — generated by a subsea landslide triggered by a 7.2-magnitude earthquake on the southern edge of the Grand Banks — walloped the peninsula.
While there was no warning of the impending tsunami, the 1929 quake was felt far and wide. It was felt by the unsuspecting people on the Burin Peninsula a few hours before the waves struck, but it was also felt along eastern North America and as far east as Portugal.
RECENT EARTHQUAKES
While there has not been another quake of that seriousness in the province, minor earthquakes on land and at sea in and around Newfoundland and Labrador do happen quite regularly.
There was a 3.0-magnitude quake 143 kilometres south of Trepassey on the Avalon Peninsula on April 6, 2024, and another that measured 3.2 on the Richter scale 133 kilometres southsouthwest of Grand Bank on the Burin Peninsula on April 1, 2024.
Allison Bent, a research scientist and seismologist with the Canadian Hazards Information Service division of Natural Resources Canada, a quake in the 2.5 to 3.0 range would likely need to be close to a community — within tens of kilometres — for someone to feel it.
‘THEY DO HAPPEN’
Earthquakes Canada maintains an earthquake database on the Natural Resources Canada website.
A narrowed-down search of the island of Newfoundland shows numerous quakes have occurred on the island since 2000, but none have reached 4.0 in magnitude and they don’t wind up being reported in the news because they’re likely not felt by anyone.
“They do happen, and some people might feel them, but the bigger ones that have affected Newfoundland were all offshore,” explained Bent.
THE STEPHENVILLE ‘SWARM’
Most of Atlantic Canada, including the Labrador region, is similar when it comes to being able to feel the earthquakes that regularly occur beneath the region.
New Brunswick is an exception, as it does have regions that occasionally produce quakes significant enough to be noticed.
Bent said it’s hard to learn much from the small earthquakes that happen in Newfoundland and Labrador, other than record where and when they happened.
Even when there are several that happen close together in the same area, it’s hard to know what is setting them off.
For example, between June 20 and July 10, 2020, there was a cluster of 13 minor earthquakes near Stephenville that ranged from 1.6 to 3.3, with seven of them being between 2.3 to 2.5, one registering at 2.9 and two reaching 3.3.
“Something funny was going on there,” said Bent. “I wouldn’t be able to tell you exactly what, just that we do see it from time to time in other places as well.”
On average, the Stephenviile area isn’t more active than other parts of the province or Atlantic Canada, she noted.
“Swarm activity has been observed elsewhere in eastern Canada and we don’t really know what triggers it,” said Bent.
‘THINGS ARE JUST REORGANIZING’
Despite such activity, Newfoundland and Labrador – and, in fact, Eastern Canada – are considered to be on relatively stable ground, especially when compared to the west coast of the country.
While British Columbia sits on a major tectonic plate boundary, making it more susceptible to significant earth movement, the closest major plate boundary to the east coast is the mid-atlantic ridge — far out at sea.
There are still faults throughout eastern Canada, but most are considered inactive, especially those found in most of Atlantic Canada.
RIPPLE EFFECT?
Alison Malcolm, a geophysics professor at Memorial University, says the two quakes recorded off Newfoundland earlier this month are on par with the province’s geophysical history and the underground pressures constantly
panrt dof at play are a ripple effect that could have had faraway origins.
“It’s normal that we get a few and then nothing for a while and then a few more,” Malcolm said.
“When you have an earthquake, things are just reorganizing. When they reorganize in one place, it changes the forces in another place and may cause a bit of earthquake activity in another place.”
‘CAN ABSOLUTELY HAPPEN AGAIN’
While hazard maps of Canada show the land masses of Newfoundland and Labrador are at a low risk, the Grand Banks area to the south of the island is considered to be a high risk.
Quakes like the big one in 1929 may be evidence that major earthquakes can happen close by and affect the coastlines, but they remain difficult to predict.
“It can absolutely happen again, but it’s kind of clearly not something that happens frequently and, as a result, it’s very hard to predict these very rare events,” said Malcolm.
‘REGION DOES EXTEND QUITE FAR’
The fracture zone south of the Burin Peninsula extends beyond the epicentre of the 1929 earthquake.
“That region does extend quite far, so … quite a bit further north or south could be equal probability (of a future major earthquake),” said Malcolm.
Bent agreed that given one major earthquake has happened off Newfoundland, there is always a chance of another.
The question becomes when that might happen.
She said it could be hundreds, if not thousands, of years before there is another one.
“The magnitude-7 may not happen again during the lifetime of any of us who are around now,” she said.
“It’s never safe to say it won’t happen, but, usually, the larger they are, the longer the time between the next one.”
TSUNAMI
The fact it was the subsequent landslide that caused the fateful tsunami of 1929 is also an event that may not happen with the next big one under the Grand Banks.
Tsunamis come with their own variables and level of unpredictability and, Malcolm says, how damaging one will be depends on where it strikes.
“If you have a very narrow inlet, you could have a higher wave because it squeezes the water together. It can’t go left or right and can only go up,” she explained.
“A flatter coastline could spread it out more and the water doesn’t have to go up as high.”
BEING PREPARED
Being prepared for earthquakes and tsunamis isn’t much different from being ready for any sort of emergency, noted Malcolm, including having supplies on hand to last for a few days.
While earthquakes happen without warning, public alerts and warning signs — such as a suddenly retreating shoreline — can help give people time to get away from the ocean and to higher ground before the dangerous waves hit.