Kīlauea erupted in 2018, causing its summit to collapse. Prior to this eruption, the volcano exhibited other less dramatic eruptions, but there are still many unknowns about what happened in the volcanic system that led to these events.
New search Posted in Scientists progress looked to Kīlauea’s lava lake for answers. The lake provides a direct window into the magma, said Josh Crozierlead author of the new paper and a researcher at the US Geological Survey (USGS) California Volcano Observatory.
“A lava lake is like opening a manhole in the sewer system: we can see the pressure building up and how fast it’s flowing out,” Crozier said. “Once something physically disturbs the magma chamber or lava lake, it ripples, and we can measure that with seismometers.”
The researchers carefully examined the resonance signals collected by the Hawaii Volcano Observatory from 2008 to 2018, which allowed them to infer what was happening inside the volcano without directly probing the dangerous and extreme environment. Crozier and co-author Leif Karlstrom, an Earth scientist at the University of Oregon, focused on “very long period” (VLP) signals, at frequencies below 5 hertz. These “much softer and more resonant tremors” are produced by other seismic signals emitted by volcanoes, according to USGS. The authors found that the resonance characteristics encoded in seismic signals collected around Kīlauea are determined by the shape and properties of the volcano’s magma chamber, such as temperature and gas content.
The volcano’s “plumbing system,” which keeps magma cool in the lava lake, produces a seismic resonance somewhat analogous to the musical sound produced by a drum, Karlstrom said. “If you hit a drum, how long does it last before the sound stops? It’s determined by the shape of the drum and what’s inside,” Karlstrom said. , who is also a musician. “In the case of volcanoes, we use seismic displacement, not sound” to provide information about the internal dynamics and characteristics of the volcano.
The different types of seismic signals can be likened to various instruments in “singing” information from a volcano, Crozier said. “That’s the thing we’re still working on to figure out,” he said. “We have now received data on this – we can kind of see the score now, instead of just hearing nice noises.”
Although volcanologists have always predicted successful eruptions, such as the warning that was issued during the 2018 Kilauea eruption, there are big errors in the current models. The changing signals announcing the accumulation of gas or new magma from deep within the volcano could be seen as choruses in the song of seismic signals from the volcano.
Crozier said the hope is to one day be able to figure out when the next chorus is going to appear. “Some volcanoes are pop songs where there’s a predictable structure, and some might be more complicated,” he said.
Both Crozier and Karlstrom have explicitly stated that this study will not lead to new ways to predict volcanic eruptions overnight, but it could eventually help scientists make more informed interpretations of the volcano’s seismic signals.
Einat Leva volcanologist at Columbia University’s Lamont-Doherty Earth Observatory who was not involved in the article, agreed.
“I actually think the more we understand how magmatic systems change between eruptions, the better equipped we will be to predict eruptions,” she said. “While the specific model used in this paper is designed for lava lakes, information about the evolution of the system is likely more generally applicable to other volcanoes.”
—Andrew J. Wight (@ligaze), science writer