Recent research is challenging the traditional understanding of extinct volcanoes, suggesting that some dormant volcanoes may still pose a significant eruption risk.

Reassessing Volcanic Dormancy

For years, scientists have generally classified smaller volcanoes as extinct if they haven’t erupted in the last 10,000 years. Larger volcanoes were considered potentially active for much longer periods, given the time needed to accumulate sufficient magma. However, a new study led by volcanologist Razvan-Gabriel Popa at ETH Zurich indicates that volcanic activity can continue deep beneath the surface even when a volcano appears inactive.

Methana Volcano: A 700,000-Year Timeline

The research team focused on Methana, an active volcano located near Athens, Greece. They analyzed over 1,250 rock samples, examining zircon crystals formed within the magma chambers. This analysis revealed a detailed 700,000-year eruption timeline for Methana, identifying two major eruptive periods separated by a prolonged period of dormancy.

Hidden Activity During Dormancy

Surprisingly, the highest concentration of zircon crystal formation occurred during the volcano’s dormant phase. This suggests that significant magma activity was ongoing beneath the surface, even without visible eruptions. Researchers believe water-saturated magma plays a crucial role in these volcanic cycles.

The Role of Water in Magma Dynamics

The study proposes that water keeps magma molten at the high pressures found deep underground. As the magma rises and pressure decreases, the water escapes as vapor. This process causes the magma to crystallize and potentially stall before reaching the surface. This behavior could explain why some volcanoes erupt after extended periods of inactivity.

Expert Insights

Kari Cooper, a geochemist at the University of California, Davis, noted that most magmas do not erupt and that water content may significantly influence eruption timing. Adam Kent, a volcanologist at Oregon State University, emphasized the importance of reevaluating the timeframe of a volcano’s last eruption when assessing its potential threat.

Implications for Hazard Forecasting

These findings have important implications for volcanic hazard forecasting. Many potentially dangerous volcanoes may be incorrectly classified as extinct due to their long periods of dormancy. The study suggests that water content in magma and evidence of ongoing underground activity should be key factors in determining a volcano’s future eruption potential.