Thousands of earthquakes affecting Portugal’s São Jorge Island in the Azores in March 2022 were triggered by a vast sheet of magma (molten rock) rising from more than 20km below Earth’s surface and stalling just 1.6km beneath the island, finds a new study led by UCL researchers. Much of this ascent occurred with little seismic activity, with most earthquakes occurring after the magma stopped ascending. The magma rose over just a few days – there was enough of it to fill 32,000 Olympic-sized