If you’ve ever been caught in a heavy downpour without an umbrella, hood or awning to duck under, you know that the force of heavy, sometimes wind-driven drops can be painful … especially when the showers last for a long time. But can they carry enough power to trigger a volcano? That’s the premise of a new study which proposes that an extreme and extended heavy rain period triggered the 2018 extreme eruption of Kīlauea in Hawaii, burying a portion of the Big Island with a four-month-long flow of lava. Is it time for weather reporters to start giving “chance of volcano” forecasts?
“The May 2018 rift intrusion and eruption of Kīlauea Volcano, Hawai‘i, represented one of its most extraordinary eruptive sequences in at least 200 years, yet the trigger mechanism remains elusive.”
Kīlauea is one of Hawaii's most active volcanoes and has actually been in a period the eruption on , entered an extraordinary new phase on May 3, 2018, throwing incandescent lava nearly two hundred feet in the air and spewing lava over 13 square miles across the well-populated east coast of Hawaii's Big Island. The unprecedented eruption, which destroyed hundreds of homes, involved the collapse of the summit caldera before it ceased four months later in September 2018. Kīlauea is heavily monitored and has been under especially close scrutiny since 1983 when the latest activities began.
"An eruption happens when the pressure in the magma chamber is high enough to break the surrounding rock and the magma travels to the surface. This pressurization causes inflation of the ground by tens of centimeters. As we did not see any significant inflation in the year prior to the eruption we started to think about alternative explanations."
In their new study, published in the journal Nature, UM Rosenstiel School scientists Jamie Farquharson and Falk Amelung describe how they were surprised by the extreme May 2018 eruption which launched lava two hundred feet in the air, covering over 13 square miles and destroying hundreds of homes, before the summit caldera collapsed and it quit erupting in September 2018. With the usual warning signs missing, Farquharson and Amelung went looking for others and noticed a sustained period of rain right before it. Could the rain have penetrated the volcano’s edifice and changed the pressure, causing the ground to crack enough to allow an eruption?
“Here we show that immediately before and during the eruption, infiltration of rainfall into Kīlauea Volcano’s subsurface increased pore pressure at depths of 1 to 3 kilometres by 0.1 to 1 kilopascals, to its highest pressure in almost 50 years. We propose that weakening and mechanical failure of the edifice was driven by changes in pore pressure within the rift zone, prompting opportunistic dyke intrusion and ultimately facilitating the eruption.”
Going back through meteorological records in the Kilauea area, they found that "magmatic intrusions and recorded eruptions are almost twice as likely to occur during the wettest parts of the year. Based on that, the team plans to investigate other volcanoes and their rainfall patterns, giving people living in the area another thing to worry about during heavy downpours – something an umbrella won’t help. And it gets worse, as Farquharson describes in a press release.
"It has been shown that the melting of ice caps in Iceland led to changes of volcanic productivity. As ongoing climate change is predicted to bring about changes in rainfall patterns, we expect that this may similarly influence patterns of volcanic activity."
Climate change contributing to volcanic activity? Is it time to do something about it or move farther away from Yellowstone?