Ice volcano! An eruption of ice on frigid Lake Michigan

An ice volcano on Lake Michigan Photo by Ernie Ostuno, National Weather Service Grand Rapids

Have you ever seen an ice volcano?

One of the pleasures of our Great Lakes is that they rarely look the same from one day to the next. Once frozen, however, we generally endure a sameness until the ice breaks and we’re again treated to the variations of big water.

Occasionally, however, winter on the Great Lakes yields surprises. Thing is, often we’re not there to witness them. Case in point: ice volcanoes.

Ice volcanoes form when the surface temperature of the lake water is near freezing. Add lake-effect snow, which creates a sort of slush on the surface, and winds, which create waves. This combination of water and slush gets heavy enough that it sinks, and when the water is shallow, such as on a sandbar, it creates these conical mounds, says Ernie Ostuno, a meteorologist and severe weather historian with The Weather Network’s Grand Rapids, Mich., outlet.

Posted by US National Weather Service Grand Rapids Michigan on Sunday, February 16, 2020

As icy waves rush into shore, water gushes out of the hole in the top of the conical structures and then freezes around the rim, adding to the volcanic shape and giving its name: ice volcano.

The ice volcanoes recently spotted on Lake Michigan are roughly 1.5 to two metres high, but these formations can get as high as five to six metres.

Despite the dire warnings on some sites, Ostuno says it’s highly unlikely that you’ll fall into one, and, he says that if you do, chances are it’s not very deep, given that these frequently form on shallow sandbars. However, he doesn’t advise climbing on one. Sometimes the sandbars beneath an ice volcano might be eroded and, therefore, be deeper than expected.

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You’ll find ice volcanoes on all five of the Great Lakes, though topography plays a role. Those that form along the rocky shores of Lake Superior and northern Lake Michigan are slightly different than those in southern Michigan or on Lakes Erie and Ontario.

“Every winter you’ll see an internet headline that says extremely rare ice balls or ice volcanoes,” says Ostuno. “But the face of the matter is that they form every year. It’s just that people don’t see them because they’re not at the beach in the middle of January.”

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