Plenty of eerie sounds can be heard around Earth, including electrons that surround the planet, but it turns out we don't need go to space to get some natural beats.
Scientists have discovered that the Ecuadorian volcano Cotopaxi has become a sort of volcanic pipe organ, releasing sounds not unlike what we hear when pressurized air is forced through metal pipes.
"It's the largest organ pipe you've ever come across," Jeff Johnson, a volcanologist at Boise State University in Idaho, said in a statement.
Make your own kind of music
Cotopaxi was largely dormant for much of the 20th century, but it erupted multiple times in August 2015, pumping ash and gas into the air. While these eruptions were minor, a major eruption for Cotopaxi could melt its snowcap, which could lead to flooding and mudslides, a real danger to the people living within the vicinity.
One of the effects of the 2015 eruptions was that Cotopaxi's crater floor dropped completely out of sight due to an explosion. Once it was gone, Ecuadorian researchers noticed odd sounds coming from Cotopaxi's crater. They were too low for human hearing, but the monitoring instruments were picking up the sound waves just fine. Researchers were able to manipulate the sounds into something we could hear, and you can take a listen in the video below.
The frequency of the sound waves Cotopaxi generated looked like screw threads, so the researchers dubbed them tornillos, the Spanish word for screws. The waves would oscillate back and forth for around 90 seconds, growing smaller each time before finally fading out. And because of the crater's depth — it's more than 300 feet (100 meters) wide and around 1,000 feet (300 meters) deep — it takes a sound wave about five seconds to complete a single oscillation.
"It's like opening a bar door that goes back and forth for a minute and a half," Johnson said. "It's a beautiful signal and amazing that the natural world is able to produce this type of oscillation."
The tornillos continued about once a day until June 2016, which is when they finally stopped. Johnson and the other researchers aren't sure what caused the sounds, but they know that each instance of the sound was associated with gas coming out a vent.
Johnson and his team published their findings in the journal Geophysical Research Letters.
A wide-angle camera view captures the entire north portion of Kilauea's Overlook crater on May 6. The volcano's lava lake has drained significantly since eruptions began. (Photo: United States Geological Survey/Wikimedia Commons)
Since the interior of every volcano is unique, the sounds a volcano makes will also be unique. Understanding the geometry of a volcano's interior can help scientists understand a volcano's sounds, what those sounds might mean and what it means when those sounds change.
"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 continuing eruption of Hawaii's Kilauea could be a proving ground for the volcanic "music" monitoring approach. Since eruptions have drained Kilauea's lava lake at the summit, its tones should have changed as well. For instance, with magma levels at Kilauea's summit dropping, that magma could heat groundwater and cause eruptions that in turn would alter the sounds of Kilauea.