New infrasound recordings of Cotopaxi volcano in central Ecuador witnessed eruptions in 2015 and its crater changed shape. Now the deep narrow crater makes air to reverberate against the crater walls when the volcano rumbled, producing sound waves like those of a pipe organ.
“It’s the largest organ pipe you’ve ever come across,” said Jeff Johnson, a volcanologist at Boise State University in Idaho and lead author of a new study detailing the findings in Geophysical Research Letters, a journal of the American Geophysical Union.
The new findings show that each volcano’s unique “voiceprint” can help scientists better monitor these natural hazards and alert scientists to understand what’s going on inside the volcano before realizing its impending eruption, said the study authors.
“Understanding how each volcano speaks is vital to understanding what’s going on,” Johnson said. “Once you realize how a volcano sounds, if there are changes to that sound, that leads us to think there are changes going on in the crater, and that causes us to pay attention.”
The ongoing eruption of Kilauea in Hawaii could be a proving ground for studying how changes to a crater’s shape influence the sounds it makes, according to Johnson.
The lava lake at Kilauea’s summit drained as the magma supplying it flowed downward, which should change the tones of the infrasounds emitted by the crater.
Listening to Kilauea’s infrasound could help scientists monitor the magma depth from afar and forecast its potential eruptive hazards, according to David Fee, a volcanologist at the University of Alaska Fairbanks who was not connected to the new study.
When magma levels at Kilauea’s summit drop, the magma can heat groundwater and cause explosive eruptions, which is believed to have happened at Kilauea over the past several weeks. This can change the infrasound emitted by the volcano.
“It’s really important for scientists to know how deep crater is, if the magma level is at the same depth and if it’s interacting with the water table, which can create a significant hazard,” Fee said.