Researchers have precisely dated a volcanic eruption from Oregon’s Newberry Volcano after tracing its ash more than 5,000 km across the globe and into a Greenland ice core. The study, published in Quaternary Science Reviews, pins the Newberry Pumice eruption to within two years of 686 AD.
The find matters because the eruption had previously only been narrowed to an approximate 140-year window around the turn of the 7th Century AD. By matching ash particles in the ice core to volcanic deposits from Newberry’s most recent eruptive period through geochemical fingerprinting, researchers tied a distant layer of fallout to a specific moment in time.
Dr Helen Innes said the work began with ash fragments so small, at about 0.02 mm, that tracing them to their source was exceptionally difficult. She said the geochemical fingerprint to Newberry was an exact match, and that discoveries like this can unlock crucial information about past eruptions, their timing and the hazards they posed on a large scale. The ash had crossed the United States and the Atlantic before settling in Greenland, making it one of the clearest examples yet of how far fine volcanic material can travel.
The eruption itself was a VEI 4 event, roughly 10 times smaller than the 1980 Mount St Helens eruption, which was VEI 5, but about 10 times bigger than the VEI 3-4 Eyjafjallajökull eruption in Iceland in 2010. That Iceland eruption caused mass disruption in European airspace, underscoring how even smaller events can upend travel when ash drifts into busy skies. Researchers said the Newberry case is another warning that relatively minor eruptions can still pose hazards across the North Atlantic.
Dr William Hutchison said the finding is a reminder that volcanoes across North America, Russia and Japan can send vast quantities of ash across the Northern Hemisphere, not just Iceland. He said the North Atlantic is one of the busiest flight routes on Earth, and the Greenland ash layer is a striking example of the global reach of even relatively minor eruptions. Greenland ice cores carry especially precise age models, which is what allowed the team to narrow the date so sharply.
The bigger concern is not the size of the Newberry eruption on paper, but where and how it spread. A small but ash-rich eruption in the wrong place could still disrupt aviation over a heavily trafficked ocean corridor, and the study makes clear that the next globally disruptive volcanic episode does not have to come from a giant eruption to cause serious problems.
