Floating rocks in the ocean lead to an undersea eruption… seen from space!

By Phil Plait | August 21, 2012 6:44 am

[Note: At the bottom of this post is a gallery of more amazing pictures of volcanoes taken from space.]

Sometimes, the best way to observe the Earth is to get off it. It really helps if you want to solve some mysteries.

And scientists had a good one on their hands in recently. You should really read the journal of science journalist Rebecca Priestly, who reported on all this first hand, but here’s a summary. On August 9, the crew of the HMNZS Canterbury were on a scientific voyage in the Pacific when they got word to change course. A huge anomaly was reported near their position, and it looked like it might be a gigantic floating "raft" of pumice, possibly from an undersea eruption. They got samples, and sure enough it was pumice. Such rafts have been seen before from other volcanic eruptions.

But what volcano was at the root of this one? Early guesses were that it was from Monowai, which had recently erupted in early August. But satellite imagery taken on July 19 – weeks earlier – pinpointed the location of the raft’s origin:

[Click to hephaestenate.]

This image, taken by NASA’s Terra Earth-observing satellite, shows the eruption of the Havre Seamount, located a few hundred kilometers northeast of Auckland, New Zealand. The plume is clearly visible. The gray patch right in the middle of the picture is the floating island of pumice. To the left of the plume is teal water, stained by ash. The volcano itself is more than a thousand meters under the sea’s surface, but the eruption was strong enough to break through. At the time this image was taken, the raft was already about 15 kilometers (9 miles) long. It eventually grew to more than 20,000 square kilometers (about 10,000 square miles).

This area of the ocean is very, very large, and without satellite images the exact location of this volcano would have been very difficult to spot. Scientists from Tahiti and New Zealand were able to connect earthquake reports on July 17 and 18 to the event (even though they occurred long before the raft was first sighted), and then other scientists were able to find the above image in the Terra archives. It took collaboration, people from around the world, and the open nature of science to be able to find the culprit volcano behind this mysterious event.

Science! Solving mysteries we otherwise couldn’t! I love this stuff.

Image credit: Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC

CATEGORIZED UNDER: Cool stuff, NASA, Pretty pictures, Science

Comments (17)

  1. Brian

    10,000 square mile floating “raft” of pumice!?

    Wow. I had no idea…

  2. Chris

    I don’t think raft is the best term. At least for me it conveys an image of a 20,000 km^2 solid floating rock, but in reality (at least from reading the attachments) it seems more like a bunch of smaller floating rocks floating in the same place, kind of like someone dumped a billion rubber duckies overboard. All in the same place, but not a solid structure you could go and walk on.

  3. kevbo

    Just being pedantic, but in this case, wasn’t it ‘technology’ that solved the mystery?

  4. Wzrd1

    @kevbo #3, was it technology that located the pumice raft? Was it technology that found older reference images?
    It took humans to NOTICE the new item in the images. Our technology captured the images, it took scientists to notice them, then look for the source. It took human curiosity to even bother to look in the first place. :)

  5. That is pretty damn awesome.

  6. Just to put this in perspective, that’s more landmass than Israel (7,850 sq mi) or Vermont (9,615 sq mi).

  7. LAVA soap for 100 generations could be secured for the taking. A once in a milennium natural resource has been squandered, and we are doomed. When does it begin enabling Enviro-whiner fundraising? Save the penguins, basking sharks, humpback whales, Maori subsistence fishermen, the lesser aquatic half-blind walking fly. The absolute greatest tragedy would be that the pumice has a few ppm of leachable iron to fertilize Southern Sea photosynthesis, crashing atmospheric CO2 levels to “normal” values. Cram a bar of LAVA into Al Gore’s, ah, mouth.

  8. Let me tell you, it was a blast to track this eruption down using those Terra and Aqua images!

  9. oldebabe

    Too cool. More, more, more…

  10. Mike

    It’ll be interesting to see how long this raft lasts as it is gradually dispersed by ocean currents and the pumice becomes waterlogged. Some of the pumice ejected by Krakatau in 1883 was eventually washed ashore in East Africa the following year (and in some gruesome cases brought with it the skeletons of people killed in the eruption. There are even credible accounts that some of the pumice was still washing ashore in the Indian Ocean some twenty years after the eruption.

    And just to remark on Chris’ comment above – raft is the correct geological term. Again in the case of Krakatau the pumice was more than 3m thick around Indonesia and could easily support the weight of a man.

  11. Jess Tauber

    Some have implicated this stuff (well, not this PARTICULAR batch) in origin-of-life chemistry- the fact that it floats, is very porous, with huge reactive surface area (depending on the type) gives it interesting properties. Degradation after formation would have been rather different in an anoxic environment, and who knows how much would have been created in the early earth, with shallow seas and thin continental crust. With giant moon-made tides, radioactives sizzling the beaches, etc. perhaps these rocks were the ancient embassadors for early life or prebiotics, carrying materials and messages all over the world.

  12. Georg

    This is really weird!
    The fact that some pumice is formed 1000 meters below sea,
    means that the gases expanding the lava into pumice (before contact with
    water!) had a pressure greater than at least 100 bars.

  13. Captn Tommy

    “On August 9, the crew of the HMNZS Canterbury were on a scientific voyage in the Pacific when they got word to change course. A huge anomaly was reported near their position,…”

    How Kirkian, this could be the teaser for a steampunk “SEA TREK, 1866”. Will the
    HMS Enterprise (there was one) arrive in time to save the day???
    Mr. Scott,… I… Need … 9 knots, Now!
    Ach! Cahpt’n Ah’ll dooo wit Ah Kin…

    Oh the nerdiness in some of us.

  14. Science is still on the case of this mystery – we brought pumice samples back to New Zealand and a PhD student at Victoria University of Wellington, who’s been working on the volcanoes of the Kermadec Arc, will now analysing the pumice on behalf of the science organizations that brought it home – NIWA and GNS Science. Matching the chemical signature of the samples we brought home to the Havre volcano will confirm its origin. Results in about a month!

  15. dougss
  16. CatMom

    So I guess Pandora isn’t the only planet with floating rocks. :)


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