Underwater Santorini volcano eruption 520,000 years ago was 15 times bigger than record-breaking Tonga eruption

An illustration of the Santorini archipelago as the submarine volcano erupts.
An illustration of the islands of the Greek archipelago of Santorini with the submarine volcano erupting. (Image credit: mikroman6 via Getty Images)

Deep beneath the Mediterranean seabed circling the Greek island of Santorini, scientists have discovered the remnants of one of the most explosive volcanic eruptions Europe has ever seen.

A giant layer of pumice and ash, which is up to 500 feet (150 meters) thick, revealed that around half a million years ago, the Santorini volcano erupted so explosively it was 15 times more violent than the Hunga Tonga-Hunga Ha'apai eruption of 2022. The Tonga eruption shattered several records, triggering the fastest atmospheric waves ever seen and the first known mega-tsunami since antiquity

"We know that this volcano's had many big, explosive eruptions — sort of Krakatoa style," study lead author Tim Druitt, a professor of volcanology at the University of Clermont Auvergne in France, told Live Science. But the newly discovered deposits point to a cataclysmic blast "that we didn't even know had existed."

Extensive land-based research has previously painted a relatively detailed picture of past volcanism  across the Hellenic Island Arc — a string of volcanic islands stretching from Greece to Turkey along a curved line where the African tectonic plate plunges beneath Europe. For instance, geologists knew that Santorini emerged from the sea about 400,000 years ago, as successive eruptions piled volcanic debris onto the seafloor. The present-day Santorini archipelago formed during the Late Bronze Age (1600 to 1200 B.C.), when the explosive Minoan eruption blasted the top off what was then one island. A magma chamber beneath the Kameni islands, in the center of the Santorini caldera, still feeds the volcano today.

Related: Iceland volcano could erupt again 'without warning' as magma still moving beneath Grindavík 

The JOIDES Resolution north of Santorini volcano (in the distance). The ship is a research deep-drilling vessel 460 feet (140 m) long and 200 feet (60 m) high. (Image credit: Thomas Ronge)

But there's only so much scientists can learn on land, Druitt said, because erosion from rain and wind wipes away some geological evidence. "That's why we moved to the marine realm, because in the sea it's calmer," he said.

To find out more about the region's volcanic activity, Druitt and his colleagues drilled into marine sediments around Santorini in late 2022 and early 2023. With help from the International Ocean Discovery Program, the researchers extracted sediment cores from up to 3,000 feet (900 m) below the seafloor at 12 drilling sites.

The team could then read the different layers of sediment "like a book," Druitt said. 

"What you see is volcanic layers from all the eruptions that we knew on land," he said. "But then we go down to deeper levels before the volcano became emergent, when it was still submarine."

It's in these deeper levels that researchers discovered the remnants of a 520,000-year-old eruption that was "bigger than anything else Santorini's produced and probably one of the two biggest eruptions that the whole Hellenic volcanic arc has ever had," Druitt said.

Scientists examine core sections from the expedition. Each recovered core is 31 feet (9.5 m) long and is cut into sections 4.9 feet (1.5 m) long for handling. The sections are then sliced in half along their length for detailed description and collection of samples for further laboratory analysis. (Image credit: Tim Druitt)

The eruption ejected at least 21.6 cubic miles (90 cubic kilometers) of volcanic rock and ash, according to the study, published Jan. 15 in the journal Communications Earth & Environment. The Tonga eruption of 2022, by comparison, produced 1.4 cubic miles (6 cubic km) of debris. 

"It's a lot bigger — 15 times bigger — there, in the heart of Europe," Druitt said.

The discovery is big because it shows that the Hellenic volcanic arc is capable of producing tremendous underwater eruptions. "It gives us an example to study in detail of a very large version of Hunga-Tonga," Druitt said.

Santorini probably won't see an eruption on this scale for another several hundred thousand years, Druitt said. The volcano last erupted in 1950, emitting lava that didn't pose a significant threat. 

However, the magma chamber "will continue to feed eruptions of lava and small explosive eruptions for the coming decades and maybe even centuries," Druitt said.

Sascha Pare
Trainee staff writer

Sascha is a U.K.-based trainee staff writer at Live Science. She holds a bachelor’s degree in biology from the University of Southampton in England and a master’s degree in science communication from Imperial College London. Her work has appeared in The Guardian and the health website Zoe. Besides writing, she enjoys playing tennis, bread-making and browsing second-hand shops for hidden gems.

  • Giovani
    admin said:
    A 500-foot-thick layer of pumice rock on the Mediterranean seabed indicates Santorini volcano ejected 15 times more material than Hunga-Tonga during a previously unknown eruption.

    Underwater Santorini volcano eruption 520,000 years ago was 15 times bigger than record-breaking Tonga eruption : Read more
    The discoveries lately, seamounts of ancient volcanos numbering in the hundreds and more, are a stark reminder that volcanos themselves, without any help from other sources, can determine the earth's destiny.
    Look no further for a sure extinction event. There must be enough magmatic material to easily cover the planet with a mile thick layer.
    Every continent hosts a super-volcano presence. The possibility of cataclysm from a cosmic impact of considerable magnitude could wake up numerous volcanic vents. Our finale is sleeping currently.
  • Giovani
    Cheryl88 said:
    Exactly how would such a super volcanic eruption destroy things? And what would it destroy? The entire planet Earth? Or just all life on Earth while Earth remained intact? Or would the threat be even less than that? Maybe one continent destroyed and the rest in a state of emergency crisis? Or maybe even less than that? Exactly how much destruction are we talking about, Giovani?

    If you wish to think the worst and to exaggerate the danger, well, I want something much more accurate than a nay-sayer’s word. The only thing I can agree upon is the conclusion that a super volcanic eruption is possible and that an even bigger one is possible. But given the age of the Earth, it is highly improbable that it will occur in my lifetime. As for the human race, I strongly suggest space colonization as an insurance against any such planetoid catastrophe.

    Life is fragile and so there will always be threats to life. Even if we colonize our entire Milky Way galaxy, there might still be galaxy threatening dangers. The only thing that life can do to survive is to keep trying. And negativism from doomsayers kills our hopes and may stop some of us from even trying. Why live in such a negative world?
    My gosh, do you engage in any critical thinking? Space colonization as insurance? Of course, anyone espousing "exaggerations" concerning new findings and actual conditions necessary for exactly what I've described is a fearmonger.
    "Negative world"? You said it. I don't know where you are coming from, but the negativism is originating with yourself.
    Any original thoughts and topics originating from your life narrative? I mean without your small comfort zone, which hampers any worthwhile theories?
  • Giovani
    Cheryl88 said:
    Space colonization as insurance for the human race, not for the people living on that world. It would be sad for people to die, but world ending catastrophes are world ending. Hopefully the human race can still live on.

    Change that misunderstanding of yours and would you still say that I am negative, devoid of critical thinking, have a small comfort zone, or anything else? If so, then we’ll get into it.

    By the way, I do like your use of the word “fearmonger”. Finding the right word is such a difficult thing for me. Needs creativity and other kinds of thinking. So much easier is solving a math equation. Simple straightforward thinking.
    The superficial reasoning you use is a common obstacle to moving out of your comfort zone.
    I see it all the time. The pie in the sky topics is a Musk original, such as inhabiting another planet for "insurance". Daydreams.
    Keep studying and adding to your awareness.
    I talk of realities quite possible. I'm not concerned at all, nor do I expect people to be alarmed at my comments.
    Happy Thursday!
  • Giovani
    Cheryl88 said:
    Are you saying that you do not believe that space colonization is someday possible for the human race? Not today, yes, and not in the near future, but if we can get past current crisis, survive into the future generations from now, and continue our work on exploring outer space, then I see the attempt at space colonization as inevitable. True, if we find it to be impossible to terraform a planet or that there are no planets anywhere that can sustain an atmosphere or human life, then you might be right. But we won’t know that until after we try. And in the meantime, to say no it can’t be done, we are just dreaming, no sense trying, well, isn’t that a bit pessimistic?

    I am in favor of caution, which is a good thing, but too much of a good thing can become a bad thing. Giving up before you even start to try, that is too much caution. I understand too much optimism can lead to trouble, but too much pessimism means suicide. And I think you had better look at how pessimistic you are.

    As for the Elon Musk comment, I see that as a sort of namecalling tactic. You are trying to associate me with Musk. How about I associate you with someone negative? No, I’d rather just come out straightforward on this. Not do transparent ploys like you.

    As for today’s reality, what we need today is a way of getting to the point faster. Like how mathematical equations do. Mathematics were able to resolve arguments quickly and conclusively between the scholars of the past. But only for such scientific fields like physics. Unfortunately all we still have today are primitive languages. And with these languages, ploys such as yours, namecalling, double talk, etc. cloud the issue so that no one can see the answers anymore. We need a language much more logical, clear, and to the point. That way we can communicate with each other far more effectively than we do today.

    And if you think I am wrong in this, just look closely at any debate in these threads. So much trash on the loose.

    For example, you accused me of having superficial reasoning. Prove it. If you are unable to justify your words with logical proof, then you are just namecalling.
    I don't have to name call. The popular culture of accepted narratives, such as ever inhabiting outer planets, is the most familiar human trait of what to hope for, and absent of any posits or further deeper examinations, I can generally understand the person's view.
    How could I judge you? I'm not mean, but confrontative due to what I've learned. Musk is for example, a very smart man who apparently believes in his endeavors. His exploratory information is voluminous and impressive. The amazing technological feats seemingly many years before their time, with the emphasis on constructing a spaceship to Mars, unparalleled.
    Tesla is a means to fund this massive undertaking. Musk must know something most of us don't.
    Musk is more than has been revealed. His predictions and brain implants are a clue to the big picture.
    So good to have you as a sounding board. No time for name calling. Have a good day.