Minor earthquake detected off Cape Breton coast

SYDNEY — If you felt any shaking on Saturday night, you may not have been alone.

That’s because an earthquake had struck just off the coast of Cape Breton.

On April 13 at 11:13 p.m., Earthquakes Canada detected a quake in the Atlantic Ocean 53 kilometres southeast of Louisbourg. The epicentre was located 18 km below the surface.

It’s possible some may have felt it. But a seismologist with the Canadian Hazards Information Service branch of Natural Resources Canada told the Cape Breton Post she usually wouldn’t expect a tremor of that size and distance offshore to be noticed.

“Had it occurred on land and close to a community, it is likely that it would have been lightly felt by some people,” said Allison Bent in an email. She added that as of late Wednesday morning, no reports were received by anyone who felt it through Earthquakes Canada’s reporting tool.

Bent said all of Earthquakes Canada’s seismological instruments in Atlantic Canada detected the quake. Even a few in eastern Quebec — almost 800 km away from the epicentre — picked up the motion.

The closest seismograph station to Saturday’s quake was the one in Cheticamp, 159 km from the epicentre.

QUAKES RARE, NOTICEABLE ONES RARER

Within the last 10 years, 11 earthquakes have occurred within 100 km of the April 13 quake’s epicentre. Most of them have been further offshore in the area of the Grand Banks south of Newfoundland.

One of those earthquakes was felt in Cape Breton in 2022. A 4.7-magnitude quake in the Grand Bank was detected on July 19 of that year. The Post reported that two people in the Sydney area felt it and reported minimal impacts to Earthquakes Canada.

Neither Cape Breton nor the Atlantic coast of North America are known for their earthquakes compared to other parts of the world but local tremors aren’t all that uncommon — just not noticeable.

According to Earthquake Canada’s database, five earthquakes have occurred under Cape Breton Island in the past 30 years (including one in the Bras d’or Lake). None have been larger than 2.8 in magnitude. Several more have been recorded just offshore or in the eastern mainland.

Quakes from offshore have usually had more noticeable impacts. That includes the infamous 7.1-magnitude Nov. 18, 1929, shaking from south of Newfoundland. It triggered an underwater landslide and tsunami that sent seawater crashing into Sydney and other parts of Cape Breton.

It badly flooded and damaged the area, according to accounts of the event, along with personal property such as chimneys and dishes.

That tsunami also hit the south coast of Newfoundland and killed 28 people.