A seismologist with Earthquakes Canada says aftershocks are likely after Thursday night's earthquake deep below Amherstburg, but they will not be powerful.
"The typical pattern of aftershocks is that as time goes on, they get smaller and smaller and fewer and fewer," says Nick Acklerley. "It's extremely rare for an aftershock to be stronger than the main shock."
Data is still being compiled and interpreted at the agency, an arm of Natural Resources Canada, but Ackerley can say the earthquake that rattled residents at 8:03pm Wednesday was one of the stronger ones we have felt in Windsor-Essex.
"For this area, yeah. It was strong," says Ackerley. "In very nearly the same location we had an earthquake in 1980 that was 3.3."
Earthquake intensity map for Amherstburg earthquake. (Photo courtesy of the USGS)
On the south shore of Lake Erie, near Cleveland, stronger quakes have been recorded in the past, but the probability of getting one as strong as what they feel on the west coast is unlikely because we are located in the middle of the tectonic plate.
"The de-glaciation of 10,000 years ago is still to this day resulting in slow uplift of the earth," speculates Ackerley, who says the cause of these earthquakes is still very mysterious. "That may be one source of stresses and strains that produce earthquakes."
Some on Facebook have speculated the earthquake may have been caused by work at the Amherstburg quarry, and Ackerley says that is very unlikely, but not as crazy as you might think.
"I personally doubt it because of the sense I have of the depth of this earthquake," he says. "It is not unheard of for mines and quarries to induce earthquakes, but they tend to be closer both in terms of distance to the surface and in terms of depth."
While Windsor-Essex escaped harm, it is possible to see damage, even with an earthquake of a magnitude of just 4.1.
"Magnitude 4 is the threshold where you could start seeing damage, but it typically needs to be a very shallow earthquake," says Ackerley.
Ackerley urges anyone who felt the earthquake to take part in an online survey. The information is used for research into future events.