Frost Quake
© Aileen Andrews/Action Reporter MediaDennis Olsen of Waupun measures a giant crack, maybe an inch wide and 8 to 10-inches deep, apparently caused by a frost quake. The giant crack ran across the driveway and the length of the driveway.
It was dark and cold, as if hell were freezing over.

Then came the booming sounds that shook the earth and sent area residents running to their windows.

The cracking sound, like an explosion, was heard about 6 p.m. Jan. 7 around Waupun, Fairwater, Brandon, Markesan, Oakfield and Campbellsport.

Dennis Olsen of Waupun thought perhaps his garage had blown up as he peered out into the winter night.

Nope. Everything was quiet.

Then he went to the basement to see if any of his walls had split open.

"Things looked fine. Strange, because it was so loud," he said.

But the next morning, Olsen's grandson was coming up the gravel driveway to visit and came upon a strange sight.

"First time I've ever seen something like this. It was a giant crack, maybe an inch wide and a good eight to 10 inches deep when I stuck a ruler down," Olsen said.

The giant crack ran across the driveway and, when they looked again, they realized it also ran the length of the drive.

"We didn't follow it all the way but it's a good hundred feet long or better," Olsen said.

His home on Whooley Road is out in the country on what used to be a farmstead. The old gravel driveway measures about 1,500 feet long.

They thought about it for awhile, he and his wife Mabel Olsen, and then Mabel said maybe they should call someone. The next day they contacted the Fond du Lac County Sheriff's Office.

"When I told them what I saw, they were kind of excited," Olsen said. "Within 15 minutes there was a sheriff here."

Officer Jeffry Belsma told Olsen he'd seen it before - there are some cracks like this on The Ledge east of town.

"They call it a frost quake," Olsen said.

University of Wisconsin-Milwaukee seismologist Brett Ketter said the sound may have been a cryoseism, commonly known as a frost quake or ice quake. He said the phenomenon results from water freezing and expanding in the soil and bedrock. The expansion builds pressure that eventually leads to a popping sound that can resemble an earthquake.

"We might hear more of that in the next couple of days as it gets warmer, as that frozen water down there starts to melt," Ketter said. "Things might go back to where they were and it might create another pop."

Similar actions occur on lakes and with houses as water freezes, expands and cracks.

Olsen said the giant crack didn't harm anything.

"It's only an inch wide, so we've just been driving over it," he said.