Gas bubbles reveal two distinct eruption styles at Mount Etna
By reconstructing two ancient eruptions at Mount Etna, researchers found that magma either lingered near the surface for weeks or rose from nearly 30 kilometers deep in just hours. The difference was traced to volcanic gases like carbon dioxide and water. This insight could improve models for anticipating explosive eruptions.
The research team applied Raman spectroscopy to examine crystals formed within magma, measuring carbon dioxide trapped in bubbles roughly one-tenth the width of a human hair. By converting gas density readings into pressure estimates, they could calculate the depth of magma storage with unusual precision. Mount Etna's 122 B.C. eruption was both mafic—meaning low-viscosity magma rich in magnesium and iron—and Plinian, the most explosive category of volcanic activity, named for Pliny the Elder's account of Vesuvius in 79 A.D. The work builds on earlier findings from 2023 that identified carbon dioxide as a potential trigger for explosive eruptions, challenging the long-held assumption that water alone drives volcanic violence.
Improved eruption forecasting could directly benefit communities living near active volcanoes, particularly those in Italy's densely populated regions surrounding Etna. If gas signatures reliably distinguish slow-building eruptions from rapid deep-seated blasts, monitoring agencies may gain earlier warning windows for evacuation planning. This could reduce casualties and economic disruption from future explosive events, though the technique's practical application to real-time monitoring remains uncertain and would require substantial infrastructure investment.