Researchers Pinpoint Newberry Volcanic Eruption to 686 AD — Volcanic Eruption
Researchers have pinpointed a Newberry volcanic eruption in Oregon to within two years of 686 AD after finding its ash in a Greenland ice core. The volcanic eruption sent tiny fragments more than 5000 km across the United States and the Atlantic.
Dr Helen Innes said the ash pieces were only 0.02 mm across, which made the source hard to trace until geochemical fingerprinting produced an exact match with Newberry Pumice deposits. The finding narrows a date that had previously sat inside a 140-year window around the turn of the 7th Century AD.
Greenland Ice Core Match
The University of St Andrews team identified ash from the Newberry Pumice eruption in the Greenland ice core and linked it to the volcano’s most recent eruptive period. The ash particles matched volcanic deposits from Newberry Volcano in Oregon, USA, giving researchers a precise anchor for the timing of the event.
Dr Innes said: "When we find tiny (0.02 mm) ash fragments in the ice core, it can be really challenging to trace them to their precise volcanic source. So, it was an exciting moment when we compared the geochemical fingerprint to Newberry, and it was an exact match. Discoveries like this can unlock so much critical information about past eruptions, their precise timings and importantly, their hazards on a very large scale. Finding such an abundance of ash particles from Newberry thousands of kilometres from the eruption site is key for improving our understanding of how far Cascades volcanoes can send very fine ash particles and what risks they pose in the future to the North Atlantic region."
North Atlantic Flight Route
The study says the eruption was a VEI 4 event, around 10 times smaller than the 1980 Mount St Helens eruption, which ranked as VEI 5. It was also about 10 times bigger than the VEI 3-4 Eyjafjallajökull eruption in 2010, which caused mass disruption in European airspace with far travelled ash.
Dr William Hutchison said: "Iceland usually grabs the headlines as our restless volcanic neighbour, but this study is an important reminder that there are huge numbers of volcanoes across North America, Russia and Japan that can spread vast quantities of ash across the Northern hemisphere." He added: "The North Atlantic is one of the busiest flight routes on Earth, and the discovery of such large quantities of ash in Greenland is a striking example of the global reach of even relatively minor eruptions. It shows that size isn’t everything when it comes to volcanic eruptions; a small but very ash rich eruption in a busy place could cause huge amounts of upheaval. It’s difficult to forecast when and where the next globally disruptive eruption is going to ta"
Oregon Eruption Timing
The Newberry Pumice eruption had already been known from volcanic deposits, but its timing remained uncertain before the Greenland ice core evidence narrowed it to within two years of 686 AD. That makes the eruption one of the more precisely dated examples of far-travelled ash from the North American west reaching the North Atlantic region.
For researchers studying ash hazards, the practical takeaway is direct: even a VEI 4 eruption can spread fine material far beyond the volcano’s immediate region, and the ice-core record now ties Newberry to a date that can be used when comparing other large eruptions across the Northern hemisphere.
