The sounds of sloshing lava are music to a volcanologist’s ears. The echoing belch and belch can help reveal what goes on deep inside a volcano’s belly.
By listening to the Kīlauea volcano in Hawaii, researchers were able to monitor the temperature of magma and the migration of volcanic gases as they bubble to the surface.
The findings have revealed something unexpected about the volcano’s famous 2018 eruption.
“It’s a new look at the dynamics of a really popular volcano,” say Earth scientist Leif Karlstrom of the University of Oregon.
“People could stand at the edge of the lava lake and visit the lava flows that came out. But below the surface, there was a lot more going on.”
For 10 years, between 2008 and 2018, the Kīlauea volcano experience gentle eruptions of lava on an almost continuous basis.
Then suddenly two dozen vents exploded above the eastern fissure zone, sending fountains of molten rock into the sky.
The eruption was followed by several years of silence, until September 2021when lava seeping started again.
Kīlauea is often said to be the most active volcano in the world, and much of that crowds come from Halema’uma’u Crater. This crater is located on top of the volcano and is filled with a lake of lava.
The lava lake is thought to be constantly replenished by an underground chamber of magma. But how those deeper dynamics work is still largely unknown.
By placing seismic sensors around the crater, researchers hope to penetrate the boiling hot abyss.
The technique they use is similar to listening to the tone a half-filled bottle makes when you tap it. As with the bottle, the vibrations that ring through the volcano depend on its contents.
“As soon as something physically disrupts the magma chamber or the lava lake, it sloshes around, and we can measure that with seismometers,” explains geophysicist Josh Crozier, also of 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 processes that create these signals.”
The researchers don’t yet know exactly what the sounds mean, but they hope to learn Kīlauea’s “tune” so they can better predict when the volcano will explode again.
Without taking any direct measurements of the lava lake itself, the team has been able to track bubbling gas and changing temperatures for eight active years.
Curiously, just before the 2018 eruption, the authors noticed no signs of magma influx into the lava lake.
The lava lake temperature and chemistry were largely consistent in 2018. Before the eruption, nothing dramatically changed.
This means that an influx of magma probably didn’t cause the eruption, as scientists once believed.
Rather than the subterranean magma chamber feeding the lava lake until a high enough pressure is reached, it appears that the explosion actually occurred from the opposite process.
Lava appears to have drained from the main system and has spread eastward via a 10 km underground tunnel. This was probably the cause of the great eastern fissure eruption, which eventually destroyed 700 homes and more than 2,000 people displaced.
Above: Simplified model of the Kīlauea magma system fueling the 2018 lower east fissure zone eruption.
Kīlauea may be one of the most studied volcanoes in the world, but the plumbing is still a great mystery†
Researchers don’t yet fully understand the true nature of the volcano’s lava lake, fissure zone, or underground magma sources.
The deep reverberating sounds of lava could one day help us hear what we can’t see.
The study is published in scientific progress†
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