11 comments on “Bogoslof Update – August 2018

    • Exchanged e-mails with AVO on the visit. Whatever they wrote up about the visit wasn’t ready for release. Really liked the photos.

      Thanks for the plot. Looks like they have a sensor / calibration problem on the vertical axis. Can’t prove it, but it sure looks that way. Hope all is well with you and yours. Cheers –


  1. Yes the pictures are super cool, you see the steam (and the birds!).
    On Mayotte for the vertical axis, it is because they have not enough instrum nearby (this should get better soon as there is a team from IPGP going on site to install new devices). So you get the standard depths 10 and 20 km. I do not know for the one at 16 km. I’m doing the plot with USGS data, but they have fewer events and less precision.


    • The new ocean-bottom array is to collect data for 6-7 month before they are supposed to come up to the surface automatically. Then they are read out and calculated, and – with all the secrecy involved – we will be very lucky to hear of any results before one year is over… 😦


  2. Thanks for the update, agimarc!
    You write “The [2017] eruption did build a dome that was not destroyed during the eruption sequence” … is that dome still there, and visible above surface? Then, IT would cover the previously active vent?

    Or, if the last active vent is indeed deep under water, I wonder if a new dome might still be growing there, undetected, because of no instruments near the volcano?

    Lack of funding should soon be a thing of the past, since the new bill for a “National Volcano Early Warning and Monitoring System (NVEWS)” has just passed both the House and Senate.

    Btw, a new paper on volcanic lightning has just come out:


    • Howdy Granyia –

      Weirdness about the dome claim. The papers on this eruption sequence were adamant about no remaining dome. It was destroyed in the final series of eruptions August 2017. Problem is the peak looks a lot like a dome to me, but what do I know?

      Only other place I’ve seen this sort of difference between what my eyeballs think they see and the experts write up was Kunlun, which to my eyes look like a relatively run of the mill intraplate basalt monogenetic field. Yet several papers were adamant about no basalt. Trachyites instead. I am likely missing something and will keep scratching my head about it until I don’t. Cheers –


  3. Re: the 2016-17 lava dome:

    Looking for clarification at the AVO’s Bogoslof photos, I find that sadly the descriptions are more than enigmatic – a bit more care with them would’ve been awfully nice… So, we have here the 2016-17 lava dome (image 08/2018):

    I suppose it is the sulfury part, growing out of – what? – an older cliff that has been there before the eruption? Or, is the new dome the whole black structure, with only a side patch presently active?

    This image (Dec. 2018) shows the location of the new dome among what appears all to be 2017 lavas:

    Looking at this image and its caption, I would understand that the entire mountain is the new lava dome: “[…] August 2018. South side of 2016-17 dome.”

    In conclusion, (from the skimpy information given with the images) I would understand that the new lava dome is being emplaced above the southernmost of the three possibly active vents on the island. It is a formidable hill already and looks as if it may possibly grow and could survive up to the next explosion. (The former main vent would be in the middle of the island, below what appears to be a watery surface in the aerial images; 2019 sentinel images show no big lake at all. The third, another new vent, is somewhere near the 1992 dome, still steaming.)

    Sentinel-2 image of 4 February 2019:



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