Professor: Earthquake caused mysterious U.P. crack

BIRCH CREEK, Mich. - One expert says a large crack in Michigan’s Upper Peninsula is the result of a small earthquake.

The crack is about eight miles north of Menominee, near Birch Creek. It is about 120 yards long and measures about five feet deep in parts. The crevice was first noticed a week ago after neighbors felt a rumble and heard a loud noise.

Over the weekend, Prof. Wayne Pennington, a geologist from Michigan Technological University, went out to the site. He says the ridge that formed around the crack suggests an earthquake that was simply too small for seismographs in the area to detect.

"Twenty feet or so on top of hard limestone. The limestone must have a fault in it and that fault must have moved,” Pennington said. “It moved, it was a little earthquake, magnitude one or two. And that's what the people in the neighborhood felt.”

Pennington says the earthquake would be one of the first ever in the Upper Peninsula.

• Click here to see Pennington's sketch of the earthquake process.