MINNEAPOLIS (WCCO) — Forty-four years ago to the day, Minnesota had its strongest recorded earthquake. It happened just outside Morris, and registered a 4.6 magnitude.
According to the July 10, 1975 edition of the West Central Tribune, the quake “rattled dishes and windows, shook buildings and startled residents of the area.”
So, after seeing more powerful earthquakes in California, and in Cleveland in June, WCCO-TV viewer Emily from South St. Paul who wanted to know: How common are earthquakes in Minnesota? Good Question.
“We’re bush league, maybe little league,” says Val Chandler, a geophysicist with the Minnesota Geological Survey.
In 2014, he wrote a paper called “Earthquakes in Minnesota: Are we getting a fair shake?” In it, he wrote Minnesota has recorded 20 earthquakes since 1860, some as measuring as small as 0.1 — Rush City, 1979 — up to the 4.6 magnitude quake in Morris in 1975.
Most earthquakes occur because one rock mass moves past another on a fracture called a fault. Minnesota is more than 1,500 miles from those faults, as it sits in the middle of the North American tectonic plate.
“We’re in the middle of a plate that’s fairly cold and old,” Chandler said. “That bears up pretty well under the modern stresses.”
Chandler says it’s not entirely understood why places like Minnesota would have earthquakes, but he says there is a prevailing idea. He says there are stresses on the ancient fault lines in Minnesota due to happenings at either end of the tectonic plate.
“If there’s ancient faults that are aligned in an opportunistic way, they can be jostled,” he said.
And, as for the chance of the “Big One” coming to the “Land of 10,000 Lakes”?
“Not likely,” Chandler said.
He says he can’t put the risk at zero, but says Minnesota should focus their priorities on other natural disasters, like tornadoes and flooding.