The lava bubbled after the record rain: study results suggest that unusually heavy rainfall influenced the timing of the eruption of the Kīlauea in Hawaii in 2018. The liquid could have “softened” the rock to great depths, making it easier for the magma to break through. The researchers suspect that local precipitation in other volcanoes could also influence the temporal pattern of the eruptions.
In 2018, the infamous Kīlauea in Hawaii once again caused a hellish inferno: the volcano spat glowing lava more than 60 meters (in the PM there are 200 feet) into the air and devastated from May 3 to September 2018 an area of 33 square kilometers through boiling embers. The violent eruption destroyed hundreds of homes on the east coast of the main Hawaiian island and led to the collapse of the Kīlauea summit caldera.
The magma that had previously been dammed up under pressure in the Feuerberg underground was obviously discharged. “An eruption occurs when the pressure in the magma chamber is high enough to break the surrounding rock, which allows the magma to surface,” said co-author Falk Amelung of the University of Miami Rosenstiel School of Marine and Atmospheric Science. “This pressure usually causes the soil to inflate by dozens of centimeters before the eruption. “But in this case there was no such significant increase before the eruption,” reports the scientist. Therefore, there was a suspicion that in addition to the pressure, another factor may have played a role in the timing of the eruption of the Kīlauea.
Was Kīlauea “softened”?
This focused on the extreme rains that had hit the region in the months before the eruption. “It is known that changes in the water content in the underground can trigger earthquakes and landslides,” says Amelung. Together with his colleague Jamie Farquharson, he investigated whether the eruption of the Kīlauea could also have been linked to the unusually high rainfall in Hawaii.
They evaluated information about the rock features in the area of the Kīlauea and satellite data: “This study was possible thanks to a number of earth observation satellites,” says Amelung. “We received precipitation information from NASA and soil deformation observations from a mission of the European Space Agency,” says the scientist. On the basis of the data, Amelung and Farquharson developed a model of the possible processes in the volcanic underground after the precipitation.
As they report, the rock in the area is very permeable, which allowed rainwater to penetrate for miles. According to the models, this increased the pore pressure in a critical rock area immediately before and during the eruption to the highest level in almost 50 years. The scientists suspect that this weakened the structure in the underground of the volcano, which allowed magma to penetrate – which ultimately triggered the eruption. “Under the pressure of magma, wet rock breaks more easily than dry rock – it’s that easy,” says Amelung. While small steam explosions and volcanic earthquakes have been linked to rainfall infiltration in other volcanoes in the past, this is the first time that this mechanism has been used to explain deeper magmatic processes, the scientists explain.
Wet volcanoes could be dangerous
They also supported their thesis of the role of rain by looking at the history of the Kīlauea eruptions: “Interestingly, when we examine the historical eruption records of Kīlauea, we see that early eruptions of the volcano are almost twice as common in the wettest times of the year have occurred, ”says Farquharson.
As the scientists emphasize, the phenomenon may not just be a peculiarity of the Kīlauea: “After the evidence of the role of rainfall in the eruption of this volcano, our eyes are now turning to others,” says Farquharson. “If we can identify regions on the globe where there is such a link between rainfall and volcanism, it could be a big step in the direction of warning of the associated volcanic hazards,” says the researcher.
As Amelung and Farquharson conclude, even climate change could ultimately change the timing of eruptions: “It has been shown that the melting of the ice caps in Iceland has led to changes in volcanism there,” says Farquharson. “Against the background of our results, the changes in precipitation distributions in the course of climate change could thus influence the pattern of volcanic activities,” said the scientist.
Source: University of Miami Rosenstiel School of Marine and Atmospheric Science, professional article: Nature, doi: 10.1038 / s41586-020-2172-5