There’s a general rule in volcanology: the longer it takes for a volcano to erupt, the more destructive it will be, and the less precisely we’ll be able to forecast when it will erupt. So it almost goes without saying that not knowing even roughly when dangerous stratovolcanoes like Mount Fuji or supervolcanic calderas like Yellowstone will erupt is an enormous pain in the backside.
Volcanologists have spent at least two millennia working on this most frustrating of conundrums, and they have certainly found a few warning signs of impending eruptions. As a new study in Science Advances has revealed, volcanoes may also be letting out “whispers” that indicate when they’re about to erupt.
When magma moves through their plumbing system, when rocky conduits crack apart, or when gases begin to bubble out of the mix, noise is created. Previously, scientists have only heard these noises as one massive cacophony, like an orchestra tuning up their instruments before the show begins – which in this case, is the eruption itself.
Researchers from the University of Cambridge wondered if they could isolate one of the instruments in this orchestra; specifically, they wanted to know if they could pick up on sounds that indicate increases in internal pressure.
Heading to Kilauea, the world’s most active volcano, they set up an array of sonic sensors to try and identify all the various instruments. Importantly, they set up detectors along the volcano’s flanks rather than in just one spot, so they could see if see sound migrating to and from anywhere.
They were thrilled to discover that there was indeed a movement of sound throughout the volcano – and when these whispers picked up speed, the part of the volcano they were coming from began to swell and bulge slightly.
After scouring through their four-year data set, they found that there was a rather strong correlation between the appearance of these whispers and the size of the bulge. The team concluded that both coincide with pressure increase in the volcano – and when pressure reaches a particular peak, the volcano erupts.
This means that the speeds of these whispers can potentially tell us when the volcanic orchestra is about to hit an especially violent, lava-filled crescendo.
Unlike massive movements of magma which tends to create small earthquakes, these whispers are quiet enough to be lost in the noise of seismographs. This new technique is the first time that anyone has been able to isolate them.
Will this predictive tool be a useful addition to volcanologists’ forecasting repertoire, or will it be something more – a veritable game-changer? There’s only one way to find out: we need to set up camp near one of the world’s most dangerous volcanoes and, well, let the orchestra play.