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Thread: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

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    France Administrator Hervé's Avatar
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    Default Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    Largest eruption in recorded history – And we didn’t even know it

    by Robert January 14, 2018

    An echosounder image showing the undersea volcano called Havre Seamount, including a new cone that formed during the July 2012 eruption © NIWA/GNS Science.

    10 Jan 2018 – In July 2012, geologists noted the eruption of a previously little-known underwater volcanic area called Havre Seamount off the coast of New Zealand. Now, after almost 5 years of analysis, they say it was one of the largest eruptions in modern history. No one realized the enormous size of the eruption because it took place underwater.


    High-resolution seafloor topography of the Havre caldera mapped by the autonomous underwater vehicle (AUV) Sentry shows the lava that erupted in 2012 in red. The volcano is nearly a mile deep (1,519 meters). The top of the volcano is at 650 meters below sea level. Credit: Rebecca Carey, University of Tasmania, Adam Soule, WHOI/

    Havre Seamount wasn’t discovered until 2002, and even then researchers weren’t aware that the area was volcanic. But when the area erupted in 2012, “it offered passengers on an airline flight over the Southwest Pacific an unusual display: a raft of porous, floating rock (known as pumice), as big as 150 square miles – that’s 50% bigger than the surface of Paris.” (The raft was far, far larger than that. See note below.)


    Location map of Havre volcano in the Kermadec arc, New Zealand. Open dots are locations of Kermadec arc volcanoes to the south of Havre. NASA Moderate Resolution Imaging Spectroradiometer (MODIS) satellite image taken at 01:26 UTC, 19 July 2012, ~21 hours after the onset of the pumice raft generation. A vapor plume is visible at the source of the raft; whether or not there were particles in the plume is unknown. The red dot is the location of Havre volcano.

    Not just one volcanic cone, the eruption consisted of lava from 14 volcanic vent sites between 900 and 1220 meters (3000 and 4000 feet) below the ocean’s surface.

    If the largest underwater eruption in recorded history could take place completely unbeknownst to scientists, can you imagine how many underwater volcanic eruptions may be heating the seas right now?

    The headline on the article on advances.sciencemag.org called it “The largest deep-ocean silicic volcanic eruption of the past century,” whereas the first sentence of the abstract calls it “the largest deep-ocean eruption in history.” The full article calls it the greatest such eruption “ever recorded,” which I’m guessing is probably the correct description. (all italics mine)

    The full article also mentions that the raft of floating pumice was probably 5 meters (more than 16 ft) thick, and was produced in a period of 21.5 hours or less. It’s hard to imagine that much pumice being created in such a short amount of time.

    https://www.sott.net/article/373881-...say-scientists

    https://www.zmescience.com/science/g...ew-data-shows/

    Abstract of science article here:
    http://advances.sciencemag.org/content/4/1/e1701121

    Full article here:
    http://advances.sciencemag.org/conte.../e1701121.full


    Note:
    In 2012, I posted about a string of 50 newly discovered submarine volcanoes stretching along the Kermadec Ridge off the coast of New Zealand here:
    https://www.iceagenow.info/string-un...vered-zealand/

    Further note:
    In 2012, I also posted about a 10,000-square-mile raft of floating pumice, which I assume came from the same eruption that they’re talking about here. At 10,000 square feet, that “raft” was bigger than the entire state of Vermont (9,616 square miles).
    https://www.iceagenow.info/10000-squ...umice-pacific/

    =============================================

    "Caldera"? Hmmm... looks like an astrobleme to me...
    Last edited by Hervé; 15th January 2018 at 13:05.
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    UK Avalon Founder Bill Ryan's Avatar
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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    That's fascinating. But here's a technical question for Hervé (who is a Ph.D geophysicist):

    Wouldn't an eruption like that create a tsunami? And also be detectable through earthquake monitoring?

    (I assume not, for either, or this wouldn't have been unknown till now.. But why not?)

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    France Administrator Hervé's Avatar
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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    Quote Posted by Bill Ryan (here)
    [...]
    Wouldn't an eruption like that create a tsunami? [...]

    (I assume not, for either, or this wouldn't have been unknown till now.. But why not?)
    For a tsunami to occur, the volume erupted would need to be quasi instantaneous to generate a wave, not protracted over even a few hours (I discussed this somewhere in the El Hierro thread), never mind days. Also, the eruptive material emitted ended up floating at sea surface to form a "raft", hence reducing the effect of a potential volume increase like pouring oil on stormy seas.


    Quote And also be detectable through earthquake monitoring?
    It was detected by seismographs... but not "interpreted" by even curious humans (from here (<---)):

    Quote After the pumice raft was detected, the gears started to turn. Seismologists quickly pinpointed and described a cluster of earthquakes consistent with magma rising into a magma chamber prior to eruption. Retrospective analysis of satellite imagery also revealed the pumice, and so, a mission to map the seafloor topography and monitor any changes was launched in 2015.
    In the end, the under water eruption might have risen the sea level by a few nano-meters, provided the ocean floor didn't concomitantly sink somewhere else.
    PS:
    Quote Hervé (who is a Ph.D geophysicist)
    I am a geologist with a Ph.D... as such I ended up learning quite a bit about quite a number of things in related and unrelated fields
    Last edited by Hervé; 15th January 2018 at 15:20.
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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    So glad you did, Herve!

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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    Herve, nice work! These rafts of pumice, do they cause navigational problems, or do they eventually sink or dissipate? I was at the top of a volcano in Hawaii( we ate lunch at a restaurant up there, lol!) and I was in awe at the size of it, lava tubes, and cooled off lava layers during different eruptions!

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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    I stay informed through the Oppenheimer Ranch Project.

    https://www.youtube.com/watch?v=zeEONlvzsSY

    See what you think....

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    Default Re: Unrecognized For Years: Largest Volcanic Eruption in Recorded History

    Quote Posted by Ol' Roy (here)
    Herve, nice work! These rafts of pumice, do they cause navigational problems, or do they eventually sink or dissipate? I was at the top of a volcano in Hawaii( we ate lunch at a restaurant up there, lol!) and I was in awe at the size of it, lava tubes, and cooled off lava layers during different eruptions!
    Thanks

    Most of the pumice stones end up sinking when the bubble cavities get water-filled like what happened to most of the "Restingolitas" at the El Hierro site.

    As for navigation, sail boats went through them without damages. The most serious would be for a boat to be caught in a bubble jet which reduces the water density and can cause the sinking of boats as with large methane releases from disturbed methane clathrates as suspected for the so-called "Bermuda Triangle" due to continental shelf landslides.
    Last edited by Hervé; 17th January 2018 at 19:00.
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