MARQUETTE, Mich. (AP) — A little bit of liquid nitrogen and some imagination can go a long way into making a physical geography class interesting.

Hans Lechner, assistant professor in the Northern Michigan University Department of Earth, Environment and Geographical Sciences, created a simulation/model of a volcanic eruption for his Wednesday class between the Hedgcock Building and Jamrich Hall.

The demonstration involved a 55-gallon trash can, water, liquid nitrogen and small balls of different size, density and color.

Lechner said his class is doing a unit on volcanoes and volcanic eruptions, and the students are learning about the different variables that go into a volcanic eruption and how gases over-pressurize and will eventually explode. They also are learning about how the viscosity of magma modifies the eruption style and shape of the volcano, The Mining Journal reported.

One of Lechner's research specialties is working with populations in the Americas who live in volcanically active regions, and Wednesday's demo dealt with that aspect as well. He assesses the hazards and risks involved and how the physical geography and society affect one another.

Following the two "eruptions," students looked at what spewed from the makeshift volcano, which pretty much shredded the trash can on the second try.

"They're mapping the different products that came from the eruption," Lechner said. "Then they're going to place it on a grid on their sheet, and then the index cards represent communities, and ideally, they're supposed to be thinking about how, if they were volcano scientists, how they'd be communicating the hazards to people who lived in those communities."

Sophomore Marty Spring learned when you put liquid nitrogen, water and pingpong balls in a trash can, "it blows up."

However, he did get more out of the demonstration than simply watching the explosion.

"We were basically mapping it out by making little fake cities with the notecards," Spring said, "and then the pingpong balls were supposed to represent projectiles from the volcanoes going up and out."

The students used chalk to map out the blast radius to see how many of the cities would get wiped out, he said.

There were no big surprises for him.

"Basically, I expected a huge boom, and I got a huge boom, so I'm pretty happy," Spring said. "It was like Fourth of July during the middle of October."


Information from: The Mining Journal,

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