Greek Volcano Thought Dormant for Millennia Is Actually Accumulating Magma
Scientists have made a startling discovery about the Methana volcano in Greece, which was previously thought to have been dormant for more than 100,000 years. New research reveals that this volcano, located just 50 kilometres southwest of Athens, has been steadily accumulating enormous amounts of magma deep within its chambers, prompting a major rethink of how dormant volcanoes are assessed for potential threats.
Reevaluating Dormant Volcanoes
For over a century of millennia, the Methana volcano has appeared completely inactive, with no lava flows, explosions, or ash clouds. However, a study published in the journal Science Advances indicates that this prolonged silence does not mean the volcano is extinct. Instead, it may be quietly building up a large and potentially more dangerous magma system.
"This highlights the importance of monitoring dormant volcanoes, even in the absence of recent eruptions," the researchers write. The findings have significant implications for volcanic risk assessment in regions like Greece, Italy, Indonesia, the Philippines, Japan, and the Americas, where many volcanoes have been quiet for tens of thousands of years but show periodic signs of magmatic unrest.
Zircon Crystals as Natural Time Capsules
To uncover the volcano's hidden activity, scientists analysed tiny zircon crystals that form inside magma reservoirs as they cool. These crystals act like natural time capsules, preserving detailed information about when and under what conditions they grew.
"We can think of zircon crystals as tiny flight recorders," explains volcanologist Olivier Bachmann from ETH Zurich. "By dating more than 1,250 of them across 700,000 years of volcanic history, we've reconstructed the volcano's inner life with precision."
The analysis showed that magma was produced almost continuously beneath Methana during its exceptionally long quiet period. "What we learned is that volcanoes can 'breathe' underground for millennia without ever breaking the surface," Dr Bachmann said.
Water-Rich Magma and Its Implications
During the 100,000-year timeline, zircon growth peaked underneath the volcano, providing clear evidence of intense magma activity. The magma supplying Methana's upper chamber was found to be exceptionally water-rich, far more than researchers anticipated.
Scientists believe this could be due to the mantle beneath Methana being strongly influenced by ocean-floor sediments and substantial amounts of water. This process "hydrates" the mantle, triggers crystallisation, and makes magma production more efficient.
Such rapid crystallisation of water-rich magma may lead to fewer eruptions, but researchers caution that more cases need to be studied. "We actually believe that many subduction zone volcanoes might be periodically fed by particularly wet primitive magma, something that the scientific community has not yet fully recognised," said Răzvan-Gabriel Popa, another author of the study.
Major Implications for Hazard Assessment
The findings indicate that a prolonged period of volcanic silence does not equate to extinction. On the contrary, it could signal the buildup of a large and potentially more hazardous magma system. Such seemingly dormant volcanoes can remain quiet for millennia while quietly storing energy, eventually transitioning into highly dangerous systems.
This research underscores the need for continuous monitoring and reevaluation of volcanoes worldwide, even those that have shown no activity for thousands of years. The discovery at Methana serves as a critical reminder that volcanic threats can lurk beneath the surface, unseen but steadily growing.
