On Sunday, there was a 2.5 magnitude earthquake in Crandon just after 7 am.
Earthquakes are very unusual for Wisconsin.
Wisconsin is likely not the first state you think of when I say “earthquake”.
Regardless, at 7:05am on Sunday, January 7th, Crandon, Wisconsin experienced a 2.5 magnitude earthquake.
Susan Hough is a seismologist with the U.S. Geological Survey.
She said that we have data on a total of six recorded earthquakes in the state.
This doesn’t happen everyday.
“Wisconsin is a very old and stable part of North America. And Wisconsin is one of the least quake prone states in the country, even less than Illinois, Iowa, or Minnesota, for example,” she explained.
Wisconsin’s biggest earthquake was an estimated 3.8 magnitude near Milwaukee in 1947.
“It's an unusual event. It's not a huge shock that an earthquake that small, we know that can happen pretty much anywhere on Earth,” explained Hough.
Hough said that all over the country, there are old faults.
“There's a zone in the crust that goes up through northern Wisconsin. And it's a zone where there were old faults, and that zone in Wisconsin isn't associated with earthquake activity. So it's not like we expect significant earthquakes to happen. But because there are these old faults, and there's a low level of stress in the crust, you get infrequent, very small earthquakes,” said Hough.
There’s also a theory that lake level fluctuations of the Great Lakes could be contributing to seismic activity.
“There's one theory that lake level fluctuations actually stressed the crust, water going up and down is kind of bending the crust around the edges. And that may cause some of the earthquakes we see in places like Milwaukee and new Cleveland, for example,” said Hough.
Earthquakes are followed by aftershocks, but as a rule of thumb, those aftershocks are smaller in magnitude than the original quake, which in our case was pretty small to begin with.
Hough says that it’s unlikely people in the area would even feel these aftershocks.
“In California, we emphasize preparing, obviously that people need to be aware that earthquakes can happen. I'm not sure day to day preparedness is that critical for folks in Wisconsin,” said Hough.
That said, general emergency preparedness is never a bad idea; food, water, and a supply of medication can come in handy in an earthquake scenario or a blizzard.
