On June 3, 2018, Guatemala’s Volcán de Fuego erupted with extraordinary violence, setting off one of the most lethal volcanic events in the nation’s history. A massive column of ash punched more than 15 kilometers (about 50,000 feet) into the air, drifting across nearby communities and dusting Guatemala City, roughly 35 kilometers away. The ash fall was alarming, but the true catastrophe came from the pyroclastic flows—blistering surges of gas, ash, and shattered rock—that barreled down the slop