Scientists from the University of St Andrews have found that ash from an eruption of the Newberry volcano in the United States travelled more than 5,000 kilometres and settled in Greenland ice cores. This proves that even moderate eruptions are capable of disrupting aviation and infrastructure on the other side of the continent.
The study, published in Quaternary Science Reviews, precisely dated the event. Using geochemical analysis of microscopic ash particles — just 0.02 mm in size — specialists matched them to rock samples from the Newberry caldera in Oregon. The match was exact, allowing the eruption to be dated to within two years: it occurred around 686 CE. Previously, the estimated time window had spanned 140 years.
Newberry is part of the Cascade Range — the same volcanic chain as the famous Mount St Helens. The eruption was assigned a Volcanic Explosivity Index (VEI) of 4. For comparison, St Helens in 1980 was one step more powerful (VEI 5), while Iceland’s Eyjafjallajökull, which paralysed air travel across Europe in 2010, rated VEI 3–4. Yet it was the Newberry ash that travelled an exceptional distance — across the entire North American continent and the Atlantic to Greenland.
Lead author Dr Helen Innes notes that the discovery changes our understanding of impact zones. Volcanoes of this size typically erupt several times per decade and their effects have generally been considered local. It is now clear that even a modest but ash-rich eruption in a densely populated region or along busy flight routes can cause enormous disruption. The North Atlantic is one of the world’s most heavily trafficked aviation corridors, and volcanic ash settling on Greenland’s glaciers serves as a stark warning.
Co-author Dr William Hutchison emphasises that beyond Iceland there are numerous volcanoes in North America, Russia, and Japan capable of spreading ash across the entire Northern Hemisphere. And since Newberry is still classified by the United States Geological Survey as a “very high threat” volcano, this risk cannot be ignored.
Professor Andrea Burke, who led the ice core analysis, admits the find was unexpected. “We would never have thought we’d find so much ash so far from a moderate eruption. It clearly shows how important it is to study past disasters in order to prepare for future ones,” she concludes.
Scientists are calling on governments and international agencies to develop coordinated response plans for such long-range ash dispersal events — because the size of a volcano is not the only factor determining the threat it poses.
Source: phys.org
Image: Michael Sigl
