The sounds of lava slapping are music to the ears of a volcanologist. Reverberating belches and burps can help reveal what’s going on deep within a volcano’s belly.
Putting an ear to the Kīlauea volcano in Hawaii has allowed researchers to track the temperature of magma and the migration of volcanic gases as they bubble to the surface.
The findings revealed something unexpected about the volcano’s famous eruption in 2018.
“It’s a new vision of the dynamics of a very popular volcano”, said Earth scientist Leif Karlstrom of the University of Oregon.
“People could stand near the edge of the lava lake and see the lava flows coming out of it. But below the surface there was a lot more going on.”
For 10 years, between 2008 and 2018, the Kilauea Volcano experienced gentle lava eruptions on a near continuous basis.
Then, suddenly, two dozen vents above the eastern fault zone exploded, sending fountains of molten rock into the air.
The eruption was followed by several years of silence, until September 2021when the seepage of lava started again.
It is often said that Kīlauea is the most active volcano in the world, and much of this unrest comes from within Halema’uma’u Crater. This crater sits at the top of the volcano and is filled with a lava lake.
It is believed that the lava lake is constantly being filled by an underground chamber of magma. But how these deeper dynamics work is still largely unknown.
By positioning seismic sensors around the crater, researchers hope to penetrate the boiling abyss.
The technique they use is similar to listening to the tone emitted by a half-filled bottle when you tap it. As with the bottle, the vibrations that resonate in the volcano depend on its contents.
“Once something physically disturbs the magma chamber or lava lake, it laps, and we can measure that with seismometers,” Explain geophysicist Josh Crozier, also from the University of Oregon.
“During this decade-long eruption, we have detected tens of thousands of such events. We are combining this data with a physics-based model of the processes that create these signals.”
Researchers don’t yet really know what the noises mean, but they hope to learn Kīlauea’s “melody” so they can better predict when the volcano will erupt explosively again.
Without taking direct measurements of the lava lake itself, the team was able to track bubbling gas and temperature changes over eight active years.
Curiously, just before the 2018 eruption, the authors noticed no signs of magma influx into the lava lake.
The temperature and chemistry of the lava lake were largely constant in 2018. Nothing changed drastically before the eruption.
This means that an influx of magma is probably not what triggered the explosion, as scientists once thought.
Instead of the underground magma chamber feeding the lava lake until a high enough pressure is reached, it appears that the explosion occurred from the opposite process.
The lava appears to have flowed out of the main system and flowed east through a 10 kilometer long underground tunnel. This is probably what triggered the major eastern rift eruption, which finally destroyed 700 houses and displaced more than 2,000 people.
Above: Simplified model of the Kīlauea magma system powering the 2018 Lower East Rift Zone eruption.
Kīlauea may be one of the best-studied volcanoes in the world, but its plumbing remains a mystery.
Researchers do not yet fully understand the true nature of the volcano’s lava lake, its fault zone or its underground sources of magma.
The deep reverberating sounds of lava could one day help us hear what we can’t see.
The study was published in Scientists progress.