Volcanic risk update from Yellowstone

New USGS findings on Yellowstone show a fragmented magma system and a global risk that demands preparation.

Yellowstone magma pockets reshape eruption risk analysis

A 2025 USGS study uses electromagnetic imaging to map pockets of melt under the Yellowstone caldera. Researchers report the magma is not a single connected reservoir but several melt pockets, with 2% to 30% melt fractions, concentrated in the northeast area where 400–500 km3 of rhyolitic magma sits. The system is warmed by basaltic intrusion from the mantle, which continues to heat and potentially enlarge these pockets. No sign of a connected magma body currently, but gradual connectivity could raise eruption risk in the long term.

Climatologist Markus Stoffel and other risk researchers estimate about a 16% chance of a VEI 7 or higher eruption somewhere on Earth before 2100. Yellowstone is the primary concern, but other large systems such as Campi Flegrei in Italy and Toba in Indonesia show elevated activity. A Yellowstone super-eruption would likely start with smaller precursors, then accelerate once melt zones connect, producing a plinian ash column that could reach the stratosphere. Ash could fall far from the source and collapse infrastructure; climate effects could cool the planet for years, with impacts on agriculture and water cycles.

The study reframes risk as a long tail rather than an imminent threat. It shows the gravity of an event that is not predictable in timing, but has outsized consequences for climate, food, and cities.

Policy and science communication must balance seriousness with accuracy. The call for international cooperation, better monitoring, and resilient infrastructure is not about fear but about preparedness.

Highlights

Science should guide policy with calm realism, not sensational headlines.