When a Volcano Screams

Methods to the madness of monitoring volcanoes

- By Bill Gourgey

On Jan. 15, 2022, the Earth belched. It was a soda-gulping kind of burp-violent, loud, and sudden. But this event was not the usual carbonated beverage variety. It happened when bubbles of gas inside the Earth suddenly broke free.

"We know that volcanoes erupt because of bubbles," says Leif Karlstrom. He's a volcanologist and associate professor of Earth science at the University of Oregon. "It's like shaking up a bottle of soda."

When the mostly underwater volcano Hunga Tonga-Hunga Ha'apai erupted in the South Pacific, the plume shot up so high it reached the edge of space. Shockwaves from the explosive event circled the Earth four times in six days. An umbrella cloud of ash blanketed nearby Tongan islands. Tsunami waves stretched the breadth of the Pacific Ocean. And one shortlived island that had emerged during a different eruption in 2014 exploded into smithereens in the blast. The eruption was the Earth's biggest belch so far this century.

Using Technology and Staying Safe

But the planet-shaking belch wasn't a total surprise. Even though scientists couldn't predict the exact moment of this major eruption, they had had their eyes and ears on Hunga Tonga-Hunga Ha'apai for years. They had noticed when it started to hiccup weeks earlier, in late December 2021. Volcanologists-scientists who study volcanoes-are like detectives, gathering and analyzing clues to piece together a volcano's story. They monitor and study tiny crystals spit up by eruptions, the tremors that shake the Earth, the gases that explode into the atmosphere, and even the sounds of subterranean distress.