In 2022, São Jorge Island in the Azores was rocked by thousands of earthquakes in a matter of weeks. Scientists now know why: a massive surge of magma was silently pushing upward from more than 20 kilometers underground.
This «stealth» magma intrusion was unlike anything seismologists had seen. The magma didn’t erupt — it stalled, spreading horizontally through deep rock layers like a hydraulic fracture, triggering more than 30,000 earthquakes.
The invisible eruption
Using data from seismic stations deployed across the island, researchers mapped the magma’s journey in 3D. They discovered:
- The magma rose from the mantle-crust boundary at 20+ km depth
- It spread horizontally over an area of several square kilometers
- It never breached the surface, but permanently altered the island’s geology
«This is a new type of volcanic behavior we’re only beginning to understand. The magma can intrude without erupting and still cause massive disruption,» said the lead geophysicist.
The discovery has profound implications for volcanic hazard assessment worldwide — especially for island nations where «failed eruptions» can still be devastating.
Based on research published May 14, 2026.
