McAdam, New Brunswick hit by rare ‘earthquake swarm’

Nothing earth-shaking normally happens in McAdam, a village of about 1,400 in southwestern New Brunswick near the border with Maine.

But that's changed quite literally in the last few weeks as the normally quiet community has been rattled by dozens of small earthquakes.

"You'll be out and about and people will say, 'Did you feel the one last night, or did you feel the one this morning?" retired science teacher David Blair told the National Post.

"Some people will say yes, others might say no. It really depends on what you are doing.

"If you are quiet at home and there is not a lot of noise you are probably going to feel or hear it. But if you are banging around, or if the grandkids are banging around, you sometimes won't know if it's the kids — or if it was an earthquake — they are about the same magnitude, I guess."

The first quake, measured at magnitude 2.4, woke people up at 1:40 a.m., on March 10. A 1.4-magnitude aftershock hit three minutes later.

People said it sounded like an explosion, rattling windowpanes and knocking pictures off the wall.

Since then, there have been almost 40 additional quakes, though never very strong.

"What is happening in McAdam is something called an earthquake swarm," Stephen Halchuk, a seismologist with Natural Resources Canada, told the Post.

"It is a series of earthquakes, which is rare. But what is particularly unusual about what is happening in McAdam is that it is basically happening directly beneath the village — and at a depth of less than one kilometre.

"When these earthquake swarms occur they are typically in a remote area where nobody feels them."

Halchuk could not predict when the quakes would stop or if a more serious one is possible.

"I wouldn't rule out a very large event occurring but, typically, in situations like this, the magnitude of the earthquakes is modest and doesn't increase," he said.

About 100 McAdam residents attended a public meeting Tuesday with two earthquake experts, CBC News reported.

Geophysicist Ken Burke told the group the seismic activity is fairly close to the surface.

"What we've found is the swarm appears to be concentrated directly under the village here, particularly under the north end of the village," Burke said.

The number and shallow depth of the quakes suggests they probably don't stem from a major fault, and the likelihood of a major quake is very low, residents were told.

Natural Resources Canada and the University of New Brunswick have installed three seismographs in the village, with plans for a fourth.

Residents describe the noise the quakes make as a loud bang or thud, like someone falling out of bed.

Connie Klein, the village clerk, said it sounds as though someone was upstairs and had dropped an encyclopedia.

"You might jump for a second," she told the Post.