CAMBRIDGE, MASSACHUSETTS—Volcanic particles discovered in an ice core taken in 2013 from the Colle Gnifetti glacier in the Alps have been chemically matched to the 1875 Askja eruption in Iceland by Matthew Luongo, a junior at Harvard University. This information helped researchers to align the data from the ice core with written records, including information about famine conditions in Europe in the years leading up to the arrival of the Black Death in 1347. “The evidence indicates that the famine was a broader phenomenon, geographically and chronologically,” Alexander More of Harvard’s History Department told The Harvard Gazette. If the famine had lasted decades, the population would have been weak and could explain the Black Death’s high mortality rate—between one-third and one-half of the European population are thought to have died over a period of five years.