How an Atlantic island narrowly escaped 'stealthy' eruption

A new study suggests the Atlantic island of São Jorge in Portugal's Azores narrowly escaped eruption in 2022 after magma rose quickly beneath the island and then stalled before reaching the surface.

The peer-reviewed paper, published in Nature Communications on April 23, says the crisis was driven by magma moving from more than 20 km deep to about 1.6 km below the island. Researchers describe it as a failed eruption because the magma never broke through to the surface.

The March 2022 unrest brought thousands of earthquakes and measurable ground deformation. UCL says satellite observations showed the island's surface rose by about 6 cm during the episode.

Scientists say the magma appears to have followed the Pico do Carvão fault system, which helped guide its ascent and also triggered seismicity. That makes the event important not just as a local near-miss, but as a case study in how faults can shape volcanic behavior.

The findings sharpen a bigger forecasting problem for island volcanoes: the magma gave few obvious signs until after it had already moved and stalled, a pattern that helps explain why eruptions can be hard to anticipate.

Researchers and institutional summaries do not indicate any immediate change to official hazard status, but the study is likely to feed future monitoring and risk-assessment work in the Azores and beyond.