For years, the Methana volcano located in Greece has been classified as a dormant volcano because of its proximity to the Saronic Gulf around Athens, it has always appeared peaceful and inactive. It has always been believed that it has not displayed any signs of volcanic activity for hundreds of years, but current findings by scientists have proven that this was just a misconception. Geological studies show that there were periods when volcanoes remained quiescent on the surface for decades, during which time magma accumulated beneath the Earth’s surface.
Greece’s Methana volcano reawakens after 100,000 years of hidden magma activity
The last recorded volcanic eruption of Methana occurred around 250 BC. It was mentioned in several ancient Greek texts, and since then, there has been no activity on the surface of the Methana volcano. Thus, its relative peace has led to the belief that it poses no threat to humans.According to the study published in Science Advances, titled ‘A volcano reawakens after more than 100,000 years of “quiet” magma reservoir growth’, modern scientists claim this assumption is wrong. Scientists at ETH Zurich took a deep dive into the geology of Methana and found something unexpected. Over the past 700,000 years, Methana Volcano has gone through several phases of volcanic activity, separated from each other by long quiet periods.One of the most interesting discoveries was the period when Methana displayed no activity on the surface for approximately 100,000 years, but inside the Earth there was nothing but calm.
What zircon crystals reveal about methane’s hidden underground activity
To understand the history of methane, a study was conducted on more than 1,250 zircon crystals obtained from ancient volcanic rock flows. Such crystals grow in magma and can retain information about geological processes over long periods of time. Studying the process of radioactive uranium decay allows to estimate the time of the explosion.It turned out that even at a time when there were no volcanic eruptions, zircon formation was active. This indicates that there was movement of magma beneath the volcano. Scientists believe that during that period methane was not dormant but went into a state where underground magma was accumulating, but it did not come to the surface.
Why might magma remain trapped underground?
Metahana lies on top of a subduction zone, causing one plate to move beneath another. Melting of parts of the ocean floor creates magma, which then rises toward the surface. Unlike other magmas, this particular magma is exceptionally full of water.When highly watery magma moves upward, gases begin to form due to reduced pressure. In many ways, magma resembles soda because the gases will form bubbles, making it very thick. Magma does not rise to the Earth’s surface; Instead, it becomes trapped within the Earth. As a result, magma chambers are formed deep within the volcano.
Methana study suggests some “extinct” volcanoes may still be active underground.
Generally, extinct volcanoes are defined as volcanoes that have not erupted within the last 10,000 years. The history of Methana poses a challenge to this definition. It takes up to 100,000 years for a volcano to enter a period of quiescence, which indicates that a period of dormancy does not necessarily mean that the volcano is extinct.It has been speculated that there is a possibility that volcanoes that are defined as extinct may actually have active magma chambers beneath their surfaces. Such a magma chamber can only exist in a dormant state and requires certain conditions to erupt.