Video: "Trash-cano" Time!

Scientists at Carnegie’s Earth and Planets Laboratory use fieldwork, satellite monitoring, advanced computation, and laboratory experiments to uncover clues about the dynamic processes occurring deep beneath Earth’s surface, including the physics that power volcanic eruptions. 

Sometimes, they also MacGyver together a homespun volcano out of a garbage can, some bricks, a soda bottle, liquid nitrogen, and a whole mess of Ping-Pong balls. 

Dubbed the “Trash-cano” this demonstration illustrates the role of pressure build-up in volcanic eruptions. The root causes of eruptions vary, but the general story is similar for every volcano, explained Postdoc Andrea Goltz. 

Magma is supplied from about 20 kilometers below the planet’s surface. It’s full of so-called “volatiles,” which are compounds like water and carbon dioxide with low boiling points. The magma’s ability to contain these volatiles is aided by the high-pressure conditions found in Earth’s depths. But as the material moves into shallower reservoirs, the volatiles become less soluble. Eventually, they turn into bubbles—the scientific term is exsolving—driving a powerful upward pressure in a magma chamber beneath a volcano. 

Liquid nitrogen boils under ambient pressure and temperature conditions, which is why it’s always giving off clouds of vapor. By pouring it into an empty two-liter soda bottle and then sealing the lid, Goltz and EPL Staff Scientist Hélène Le Mével created an environment where pressure would build up with nowhere to go. Thanks to the aid of a few heavy bricks, the bottle was then submerged in a plastic garbage can filled with water and patriotic Ping-Pong balls.  

When the pressure built up enough to burst the soda bottle, kablooey! A huge splash and the feather-light balls are strewn everywhere, mimicking a volcanic eruption. 

The experiment is dramatic, Goltz said, and a great visual for the mechanics of eruptions, but strictly a professional operation. Do not try this at home; liquid nitrogen and pressurized blasts are for trained experts only.

Luckily, we recorded the whole thing, so you can watch the “Trash-cano” erupt whenever you want!