Experts have figured out what rocked several central Alberta communities on Jan. 1, 2018.

University of Alberta researchers said it was an ice quake caused by a unique combination of weather and buckling lake ice.

Many residents in Alberta Beach said they woke up to shaking and loud crashing and cracking noises.  When daylight arrived, they found large cracks in the ice.

Crack in ice

There were also large cracks in the ground.

Crack in ground

Even homes were damaged, leading many to think an earthquake had hit.

House damaged

“Central Alberta is a pretty seismically quiet place, and so the fact that these tremors were felt in several communities across the region, and with this much power, is quite noteworthy,” said Jeffrey Kavanaugh, associate professor in the Department of Earth and Atmospheric Sciences.

Experts say the quakes happened on Lac Ste. Anne, Pigeon Lake and Gull Lake. They had a magnitude of 2.0 on the Richter scale which was recorded on the Albertan regional seismic network.

"Unlike most seismic activity, which is caused by tectonic stresses, these were caused by thermal stresses related to Alberta’s cold climate,” Kavanaugh said.

According to researchers, anyone who has been on a frozen lake has felt pops and groans as it adjusts itself during the day.

“These are tiny little ice quakes,” said Ryan Schultz, geophysical research scientist and seismologist at the Alberta Geological Survey.   “Usually this process happens slowly and as a series of smaller events, since snow cover can insulate some of the temperature changes.”

Schultz said the lack of snow on the lake and dramatic rise in temperature cause the temperature of the lake ice to rise.

“This caused a rapid thermal expansion of the ice, up to four metres towards the shoreline.”

“With nowhere for the expanding icefront to go, it eventually buckled and broke suddenly—resulting in the ice quake shaking and the spectacular ice-ridges forming near lakefront,”he added.

Mirko van der Baan, a department of physics professor, says  a large ice quake like the one that hit New Year’s Day is very rare.  “The last time this happened on the Albertan lakes was probably several decades ago.”