Charlotte Pearson, an associate professor in the Laboratory of Tree-Ring Research, is lead author of a new paper in PNAS Nexus that combines a mosaic of techniques to confirm the source of a volcanic eruption in 1628 B.C. While the eruption was previously thought to be Thera on the Greek island of Santorini, Pearson and her colleagues found instead that it was Alaskan volcano Aniakchak II. The finding helps researchers narrow down when the actual Thera eruption took place.