A lava lake in Hawaii’s Kilauea caldera spent 10 years sloshing and churning before the volcano released a bigger eruption, researchers report.
Kilauea broke out dramatically in 2018. Earthquakes, ash plumes and lava flows destroyed more than 700 homes on the Big Island of Hawaii and altered the volcano’s topography. But Kilauea had been erupting softer for a decade before its big eruption.
A notable feature of this slow-moving eruption: a persistent lake of lava that formed in the Halema’uma’u crater on Kilauea’s summit.
The study is a “new look at the dynamics of a truly popular volcano.”
New research reveals how the dynamics of the lava lake, along with the deformation of the soil around it, encodes the signature of migrating volcanic gases and changing magma temperature in the shallows plumbing system from the volcano.
“It’s a new look at the dynamics of a very popular volcano,” said Leif Karlstrom, an Earth scientist at the University of Oregon who led the work. “People could stand near the edge of the lava lake and visit the lava flows that come out of it. But beneath the surface there was much more going on.”
The findings appear in the journal scientific progress†
Kilauea’s lava lake was fed by an underground magma chamber, which was connected to the surface by a passageway. Since lava cools and solidifies quite quickly, maintaining a consistent lava lake requires a remarkable balance: a steady influx of new lava from the depths, with enough lava remaining to prevent too much pressure from building up.
To learn more about the volcano’s deeper dynamics, researchers analyzed data collected by the Hawaiian Volcano Observatory from 2008 to 2018. A series of sensors placed around the volcano record vibrations and other disturbances.
“As soon as something physically disrupts the magma chamber or the lava lake, it sloshes around, and we can measure that with seismometers,” said Josh Crozier, a former doctoral student now affiliated with the US Geological Survey’s California Volcano Observatory.
“During this decade-long eruption, we have discovered tens of thousands of such events. We’re combining this data with a physics-based model of processes that create these signals,” said Crozier.
Just as the sound of a fork tapping on a drinking glass changes based on the amount of liquid in the glass, or the sound of a drum changes based on its shape, the seismic signals observed around Kilauea’s summit encode the resonance of magma sloshing in the glass. and from the shallow magma chamber.
The characteristics of that resonance, in contrast to simpler musical instruments, are determined by both the shape and the properties of the magma, such as temperature and gas content. By carefully examining resonating signals throughout the eruption, the researchers were able to deduce what was happening inside the volcano without directly investigating the dangerous and extreme environment.
“We can see gas build up over time and change the temperature without direct measurements,” Crozier says.
A simple model for exuberant volcanic eruptions like Kilauea says that magma is pushed up from the depths and spouts out of the volcano, like toothpaste squeezed from a tube. But in the case of Kilauea’s 2018 eruption, “we don’t see any signs that there was a major influx of magma leading up to the eruption,” Crozier says.
Instead, the new analysis supports the idea that shallow processes associated with the tapping of the summit magma chamber in the volcano’s eastern fissure zone helped shape the big eruption†
It’s too early to use that information to predict future eruption behavior, Karlstrom points out. Ultimately, though, it could help scientists make more informed interpretations of the volcano’s seismic signals.
“That’s the next step, identifying implications of these variations that we found for the volcano’s dynamics and human hazards,” he says.
Source: Laurel Hamers for the University of Oregon
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