Poás Volcano in Costa Rica is undergoing intense and unprecedented activity, marked by persistent tremors, high gas emissions, and structural deformation, according to the Volcanological and Seismological Observatory (OVSICORI). Experts say this behavior is unlike anything seen in recent records. “We can’t predict exactly what will happen because this is a new situation for Poás. We lack data from past events for comparison,” said OVSICORI volcanologist Geoffroy Avard.
Throughout 2024, the volcano’s crater lake has been drying up, triggering ash-producing eruptions and releasing increased gas levels. Small explosions ejecting rocks have also occurred, and the drying process continues. Researchers are studying signs of deep-seated fluids, heat, and possible magma intrusion driving the unrest.
Despite these signals, Avard cautioned that predicting an eruption remains elusive. “Most eruptions lack additional precursors beyond what we’re already seeing—rumbling, high gas flow, and seismicity. We won’t get clear warnings of an imminent event hours or days ahead,” he said. The greatest risk is concentrated within Poás Volcano National Park, particularly at the viewpoint. “Visitors and SINAC officials face significant danger from volcanic gases and potential eruptions hurling ash or stones,” Avard warned.
Last week, OVSICORI elevated the alert level from “Warning” to “Precautionary” due to the escalating activity. “We’re detecting magmatic fluids nearing the surface, altering the volcanic system. This uncertainty justifies our heightened stance,” Avard explained.
