Pipe Organ-Like Volcano Music Could Help Scientists Forecast Impending Eruptions

Scientists have recorded pipe organ-like sounds from a volcano in Ecuador and believe the strange rumblings, which were too hard to detect in the first place, could be key to improve the understanding of volcanic activity and predict impending eruptions.

The Cotopaxi volcano in the Andes is one of the highest volcanoes in the world. It has mostly been quiet, but in 2015, a series of eruptions spewed ash and gas into the air, threatening the population living in the vicinity.

Though the eruptions were minor and ended in few months, there was an explosion which forced the floor of its deep cylindrical crater to drop out of sight. As a result, the team monitoring the activity of the volcano heard the low-frequency sound waves from the formation for the first time.

The volcano produced the sounds at least once a day till it went quiet in the first half of 2016, while the research team, led by professor Jeff Johnson of Boise State University in Idaho, analyzed the infrared recordings. They dubbed the sounds as tornillos — Spanish for screws — because the sound waves produced in the process looked like screw threads and oscillated back and forth for more than a minute before fading away.

"It's like opening a bar door that goes back and forth for a minute and a half," Johnson said in a statement. "It's a beautiful signal and amazing that the natural world is able to produce this type of oscillation."

According to their initial observation and analysis, when the explosion occurred in 2015, the 1,000-feet deep crater of the volcano forced air to reverberate against its walls and produced the sounds. This, as the researchers described, is same as the effect created by pipe organ players who use a keyboard to force pressurized air through metal pipes.

"It's the largest organ pipe you've ever come across," Johnson added in the statement. But, the group believes there is more to these sounds than just reverberation of the air.

At present, they don’t exactly know what processes trigger these sounds, but there are two plausible theories. First could be the effect of a collapsing part of crater floor due to the movement of magma under the volcano, while the other could an explosion at the bottom of the crater, something which is very common open-vent volcanoes like Cotopaxi.

Either way, the findings indicate the geometry of a volcano contributes a lot to the sounds it produces and understanding this so-called “voiceprint” of volcanoes could be the key to monitor them more effectively — even from afar — and warn scientists of an impending eruption.

"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 group believes listening to the sounds emitted from the ongoing eruption of Kilauea in Hawaii could improve the understanding of these sounds and how they change.

The study titled, “Infrasound Tornillos Produced by Volcán Cotopaxi's Deep Crater,” was published June 13 in the journal American Geophysical Union.