A Burp or a Blast? Seismic Signals Reveal the Volcanic Eruption to Come

Last December, a gloopy ooze of lava began extruding out of the summit of La Soufrière, a volcano on the Caribbean island of St. Vincent. The effusion was slow at first; no one was threatened. Then in late March and early April, the volcano began to emit seismic waves associated with swiftly rising magma. Noxious fumes vigorously vented from the peak.

Fearing a magmatic bomb was imminent, scientists sounded the alarm, and the government ordered a full evacuation of the island’s north on April 8. The next day, the volcano began catastrophically exploding. The evacuation had come just in time: At the time of writing, no lives have been lost.

Perhaps monitoring from space will become the best way to see future phreatic eruptions coming. But so far, no successful long-term forecast of a phreatic eruption has taken place. “Phreatic eruptions are terrifying,” said Jackie Caplan-Auerbach, a volcanologist and seismologist at Western Washington University. “You really don’t know they’re coming.”