Tag: volcanoes

Earth is slowly peeling its continents from below, fueling ocean volcanoes

New research challenges long-held ideas about how volcanic islands form and how Earth’s interior stays dynamic.

Source:University of Southampton

Summary:Researchers discovered that continents don’t just split at the surface—they also peel from below, feeding volcanic activity in the oceans. Simulations reveal that slow mantle waves strip continental roots and push them deep into the oceanic mantle. Data from the Indian Ocean confirms this hidden recycling process, which can last tens of millions of years.Share:

    

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Hidden Forces Fuel Ocean Volcanoes
Continents slowly peel away from below, sending slivers deep into the oceanic mantle that fuel volcanic activity far from tectonic edges. This newfound process, traced through the Indian Ocean, reshapes how scientists understand Earth’s hidden geological engine. Credit: Shutterstock

Earth scientists have uncovered a slow and surprising process beneath our planet’s surface that helps fuel volcanic activity in the oceans.

Researchers from the University of Southampton found that fragments of continents are gradually stripped away from below and drawn into the oceanic mantle — the hot, mostly solid layer beneath the sea floor that slowly circulates. Once there, this continental material can power volcanic eruptions for tens of millions of years.

This discovery resolves a long-standing geological puzzle: why certain ocean islands located far from tectonic plate boundaries contain chemical signatures that look distinctly continental, even though they lie in the middle of vast oceans.

The study, published in Nature Geoscience, was conducted by an international team from the University of Southampton, GFZ Helmholtz Centre for Geosciences in Potsdam, the University of Potsdam, Queen’s University (Canada), and Swansea University.

Ancient chemical clues deep within the mantle

Ocean islands such as Christmas Island in the northeast Indian Ocean often contain unusually high concentrations of certain “enriched” elements that typically come from continents. Scientists have compared this mixing process to the motion of a cake mixer folding in older, recycled ingredients from deep within the Earth.

For years, geologists assumed these enriched elements came from ocean sediments pulled into the mantle when tectonic plates sink, or from columns of rising hot rock known as mantle plumes.

However, those explanations have limits. Some volcanic regions lack evidence of recycled crust, while others seem too shallow and cool to be driven by deep mantle plumes.

“We’ve known for decades that parts of the mantle beneath the oceans look strangely contaminated, as if pieces of ancient continents somehow ended up in there,” said Thomas Gernon, Professor of Earth Science at the University of Southampton and the study’s lead author. “But we haven’t been able to adequately explain how all that continental material got there.”

Continents are peeling from below

The researchers propose a new mechanism: continents not only split apart at the surface but also peel away from below, and across far greater distances than scientists once believed possible.

To test this, the team built computer simulations that recreated how the mantle and continental crust behave when stretched by tectonic forces.

Their results show that when continents begin to break apart, powerful stresses deep within the Earth trigger a slow-moving “mantle wave.” This rolling motion travels along the base of the continents at depths of 150 to 200 kilometers, disturbing and gradually stripping material from their deep roots.

The process happens at an incredibly slow rate — roughly a millionth the speed of a snail. Over time, these detached fragments are carried sideways for more than 1,000 kilometers into the oceanic mantle, where they feed volcanic activity for tens of millions of years.

Study co-author Professor Sascha Brune of GFZ in Potsdam explained, “We found that the mantle is still feeling the effects of continental breakup long after the continents themselves have separated. The system doesn’t switch off when a new ocean basin forms — the mantle keeps moving, reorganizing, and transporting enriched material far from where it originated.”

Clues from the Indian Ocean

To support their model, the team analyzed chemical and geological data from regions such as the Indian Ocean Seamount Province — a chain of volcanic formations that appeared after the breakup of the supercontinent Gondwana over 100 million years ago.

Their findings show that soon after Gondwana split apart, a pulse of magma unusually rich in continental material erupted to the surface. Over time, this chemical signature gradually faded as the flow of material from beneath the continents diminished. Notably, this happened without the presence of a deep mantle plume, challenging long-held assumptions about the source of such volcanism.

Professor Gernon added: “We’re not ruling out mantle plumes, but this discovery points to a completely new mechanism that also shapes the composition of the Earth’s mantle. Mantle waves can carry blobs of continental material far into the oceanic mantle, leaving behind a chemical signature that endures long after the continents have broken apart.”

The research also builds on the team’s earlier work showing that these slow, rolling mantle waves can have dramatic effects deep inside continents. Their previous studies suggest that such waves may help trigger diamond eruptions and even reshape landscapes thousands of kilometers away from tectonic boundaries.

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https://www.sciencedaily.com/releases/2025/11/251112011806.htm

Melting glaciers are awakening Earth’s most dangerous volcanoes

Scientists have discovered that melting glaciers could unleash powerful volcanic eruptions by removing the weight that keeps magma trapped deep underground. Antarctica may hold hundreds of these explosive time bombs. Credit: Shutterstock

Melting glaciers may be silently setting the stage for more explosive and frequent volcanic eruptions in the future, according to research on six volcanoes in the Chilean Andes.

Presented today (July 8) at the Goldschmidt Conference in Prague, the study suggests that hundreds of dormant subglacial volcanoes worldwide – particularly in Antarctica – could become more active as climate change accelerates glacier retreat.

The link between retreating glaciers and increased volcanic activity has been known in Iceland since the 1970s, but this is one of the first studies to explore the phenomenon in continental volcanic systems. The findings could help scientists better understand and predict volcanic activity in glacier-covered regions.

Researchers from the University of Wisconsin-Madison, USA, used argon dating and crystal analysis across six volcanoes in southern Chile, including the now dormant Mocho-Choshuenco volcano, to investigate how the Patagonian Ice Sheet’s advance and retreat influenced past volcanic behaviour. The work is in collaboration with researchers from Lehigh University, University of California Los Angeles, and Dickinson College.

By precisely dating previous eruptions and analysing crystals in erupted rocks, the team tracked how the weight and pressure of glacial ice alter the characteristics of magma underground.

They found that during the peak of the last ice age (around 26,000-18,000 years ago), thick ice cover suppressed the volume of eruptions and allowed a large reservoir of silica-rich magma to accumulate 10-15 km below the surface.

As the ice sheet melted rapidly at the end of the last ice age, the sudden loss of weight caused the crust to relax and gasses in the magma to expand. This buildup of pressure triggered explosive volcanic eruptions from the deep reservoir, causing the volcano to form.

Pablo Moreno-Yaeger from the University of Wisconsin-Madison, USA, is presenting the research at the Goldschmidt Conference. He said: “Glaciers tend to suppress the volume of eruptions from the volcanoes beneath them. But as glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively. The key requirement for increased explosivity is initially having a very thick glacial coverage over a magma chamber, and the trigger point is when these glaciers start to retreat, releasing pressure – which is currently happening in places like Antarctica.

“Our study suggests this phenomenon isn’t limited to Iceland, where increased volcanicity has been observed, but could also occur in Antarctica. Other continental regions, like parts of North America, New Zealand and Russia, also now warrant closer scientific attention.”

While the volcanic response to glacial melting is almost instant in geological terms, the process of changes in the magma system is gradual and occurs over centuries, giving some time for monitoring and early warning.

The researchers also note that increased volcanic activity could have global climate impacts. In the short term, eruptions release aerosol (tiny particles in gases) that can temporarily cool the planet. This was seen after the 1991 eruption of Mount Pinatubo in the Philippines, which reduced global temperatures by approximately 0.5 degrees C. But with multiple eruptions, the effects reverse.

“Over time the cumulative effect of multiple eruptions can contribute to long-term global warming because of a buildup of greenhouse gases,” said Moreno-Yaeger. “This creates a positive feedback loop, where melting glaciers trigger eruptions, and the eruptions in turn could contribute to further warming and melting.”

The research was funded by the National Science Foundation as part of a grant led by Professor Brad Singer at UW-Madison, and is due to be published in a peer-reviewed journal later this year.

The Goldschmidt Conference is the world’s foremost geochemistry conference. It is a joint congress of the European Association of Geochemistry and the Geochemical Society (US), and over 4000 delegates attend. It takes place in Prague, Czech Republic, from July 6-11 2025.

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https://www.sciencedaily.com/releases/2025/07/250708045654.htm