Scientists studying suspected Lake Superior meteotsunami that left residents 'in awe'

Alan Auld of Shuniah, Ont., said he stepped out to look at Lake Superior on Saturday and was among people who saw the waters receding — something he compared to the draining of a bathtub. 

"At first we joked to everyone saying, 'Who pulled the plug?'" said Auld. 

"To see Lake Superior, the largest freshwater lake in the world, can do something like that, that's quite powerful. So we were in awe."

On the east border of Thunder Bay, Shuniah is a municipal township along Lake Superior's northern shoreline.

The massive fluctuations in water levels have also intrigued multiple scientists, who think the area experienced a meteotsunami — a type of tsunami wave that can cause water levels near shorelines to rise and fall rapidly. 

While traditional tsunamis are caused by seafloor movement like earthquakes, meteotsunamis are linked to fast-moving weather conditions such as thunderstorms. 

A big change in air pressure accompanied with high wind speeds can play into generating a meteotsunami wave, said Eric Anderson, an associate professor at the Colorado School of Mines who has been studying meteotsunamis for over a decade. 

Anderson said researchers are analyzing atmospheric conditions and water-level data to figure out what happened last weekend. 

"We have enough evidence to say that this was a meteotsunami-like event," he said. 

In order to officially confirm it was a meteotsunami, Anderson said, researchers need to create a computer model that simulates how the waves move around inside the lake, which will take some time.  

Auld and others who saw the water-level fluctuations thought it was a seiche. 

Anderson said a seiche is a standing wave that oscillates, like water sloshing back and forth in a bathtub. In Lake Superior, a seiche period would last about eight hours, he said.

Anderson said the event Saturday occurred too fast to be a seiche and was more consistent with a meteotsunami. 

He said meteotsunamis are propagating waves that move through the water — like a wave that starts at one end of the lake and ends at another — and have a much quicker timeframe, lasting minutes to an hour or two.