Ice quake shakes things up at Madge Lake, Sask.

Saskatchewan is home tosundogs, dust devils and other weird weather, but now people are talking about "ice quakes."

According to a post on the Saskatchewan provincial parks Facebook page, an ice quake, complete with a loud boom, happened on Madge Lake on the east side of the province on Dec. 18 around 9:45 p.m. CST.

After a week of temperatures below -25 C, there was a rapid warming up that day to about -14 C.

"With the ice securely frozen to the shore, the sudden warming caused the lake ice to expand, resulting in a terrific pressure buildup," the Facebook page says.

A fissure opened up in the ice and ran about two kilometres parallel to the shore.

"The fissure resulted in a loud boom and ice shift that was felt for several blocks back from the shore," the page says.

According to Environment Canada, ice quakes, also known as frost quakes or cryoseisms, happen when the sudden expansion of the water in frozen soil or rocks puts stress on the ground, resulting in cracking, vibrating and booming noises.

What caused the quake?

David Barber, the Canada research chair in Arctic systems science at the University of Manitoba, said there are a couple ofthings which could have caused the quake.

Barber first emphasized that "quake" is a very generic term which in this case means a rapid change in the structure of the ice itself.

Sudden warming can cause an ice quake, he said, and that very well may be the cause.

"The complicating factor is the snow cover on the lake," he said, which acts as a very good insulator.

The rapid change in weather might not be felt by the ice for several days because of the snow, he said. Barber added that very little snow cover is needed tocause a quake.

Ice quakes are not uncommon and occur in all types of ice environments. The one at MadgeLake was particularly big, he added.

"What's unusual about itis the magnitude of this one and really, the abrupt nature of it."

What about the boom?

Broken bonds shearing apart in the ice contributed to the loud boom, Barber said. In other words, it was the ice breaking.

"Ice fisherman hear these kinds of things all the time, you know, smaller ones," he said.

"Because the ice had grown so rapidly under the cold temperatures, you're adjusting a lot of those crystals so it makes a loud noise."

When lake ice is formed quickly, it will be interspersed with air bubbles, Barber said. In weak areas of ice, there will be a "preferential alignment" where the thermal change in the ice causes it to break.