Explosive eruption columns of ash rising

Explosive eruption columns of ash rising from Halema‘uma‘u at 11:15 a.m. on May 18, 1924 (top) and at 11:05 a.m. on May 15, 2018 (bottom) look similar. Researchers are re-evaluating early assumptions about the role groundwater played in triggering these explosive eruptions at the summit of Kīlauea Volcano and are now looking at the build-up of gases from retreating magma as a likely trigger.