Scientists reveal what triggered Santorini’s ‘earthquake swarm’

Scientists have discovered that tens of thousands of earthquakes near the Greek island of Santorini earlier this year were triggered by lava that passed through underground channels over a three-month period.

They used physics and artificial intelligence to pinpoint the exact cause of more than 25,000 earthquakes, which travel horizontally about 20 kilometers (12 miles) through the Earth’s crust.

They use each shock as a virtual sensor and then use artificial intelligence to analyze patterns associated with it.

Dr Stephen Hicks of University College London, one of the lead researchers, said combining physics and machine learning in this way could help predict volcanic eruptions.

In January 2025, seismic activity began beneath the Greek islands of Santorini, Amorgos and Anafi. The islands have experienced tens of thousands of earthquakes, many of which have magnitudes greater than 5.0 and can be felt.

Many tourists fled, and locals feared the nearby underwater volcano Kolumbo might be about to erupt, or that it was a precursor to a larger earthquake, like the devastating 7.7-magnitude quake that struck the same area in 1956.

The scientists published their findings in the journal Science and created a 3D map of the Earth around Santorini. They then mapped the evolving patterns of seismicity for each earthquake as well as the movement and stress in the Earth’s crust. This produced a detailed model of exactly what was driving this months-long swarm of earthquakes.

The team found that the event was driven by the horizontal movement of magma from beneath the Santorini and Colombo volcanoes through a 30-kilometer channel more than 10 kilometers below the seafloor.

Researchers estimate that the amount of magma that traveled through the Earth’s crust could fill 200,000 Olympic-sized swimming pools. These “magma intrusions” are known to shatter rock layers and trigger thousands of tremors.

Geophysicist Anthony Lomax, the study’s lead author, explained: “Earthquakes are like we have instruments deep in the Earth, and they are telling us something.

“[When we analyzed]the pattern these earthquakes created in a 3D model of the Earth, it matched very, very well with what we would expect for magma moving horizontally.”

Researchers say it appears all is over for now.

“The magma still lies deep within the crust, at a depth of more than 8 kilometers,” Dr Hicks explained. “We know that magma can rise and erupt at the surface within hours to days, but since activity has now ceased, we are almost certain that the melt will eventually get stuck deep in the crust and cool down.”

However, volcanoes can enter a prolonged turbulent and unpredictable phase that lasts for many years. Recent volcanic activity in southwestern Iceland proves this.

These researchers say using artificial intelligence, combined with the basic physics of how the Earth’s crust moves and responds to pressure, could transform the ability to monitor, understand and even predict volcanic activity. This could help keep people safe in seismically active areas of the world.

“Ultimately, this could be used as a predictive tool,” Dr. Hicks explained. Whenever we see a cluster of earthquakes, “the data can be used to figure out the most likely cause.”