Is it a plume? Is it a cloud?

While we are waiting for developments, many of our readers are watching the Mila webcams and commenting on atmospheric disturbances over the vast Holuhraun and Vatnajökull landscapes. What comes up over and over again is the question of how to distinguish between cloud formation of all types (small fluffy clouds, elegant lenticular clouds, convection clouds over the glacier) and a potential plume from eruption in Bardarbunga.

Well, we can tell you from experience in watching the Grimsvotn eruption in 2011 on webcams that, if anything happens in Bardarbunga now, you will not have to ask. You will know. When Icelandic central volcanoes erupt, they do not do small and they do not do fluffy nor elegant. They also do not do big. When it’s for real, all they do is enormous.

Here is a timelapse taken as the Grimsvötn 2011 eruption started. During the start of this eruprion, one nuclear bomb equivalent of energy was released every second. So forget puffy fluffy clouds. Think an enormous atomic mushroom going up, expanding to fill in the entire field of view. Like this:

Timelapse by Ingolfur Bruun, Grimsvotn eruption, 21 May 2011.

Two more pictures of how Grimsvotn’s eruption looked like by VC reader Bergsveinn Norddahl:

Grimsvotn’s 20km plume on the first day of eruption. Photo by Bergsveinn Norddahl.

Grimsvotn’s wall of ash engulfing the landscape. Photo by Bergsveinn Norddahl.

Consider also this: Grimsvotn’s plume height was 20km. Using the formula for estimated mass ejection rate (Mastin et al. 2009), this results in 9,701.4 m³/s of ejected mass every second. That is about 288 one hundred ton trucks like this one every second. Think about this, 288 trucks EVERY SECOND.

Haul truck, image from Wikimedia Commons.

So, if something happens in Bardarbunga, you will know. Because what you will see is something of a similar size as Grimsvotn produced and it will be unmissable.

And where to watch? Here is a handy decorated screenshot of the Mila 1 cam, that shows where Bardarbuga is (the large bulge-like extended mountain in the back of the view) and the approximate direction of where Grimsvotn is located, should something happen there.

Screenshot of Mila 1 cam, evening of Sept 13, augmented by Ursula.

And if something does indeed happen, our reader sCyborg produced this visualisation of what can be expected on the webcam (note that this is photoshopped):

Photoshopped imaginary eruption cloud. Screenshot and editing by sCyborg.

Will we actually see something like this? Who knows, volcanoes are unpredictable and what is happening in Bardarbunga has never been observed before, as we all know. However, *if* it does happen, you now know what to expect. No fluffy clouds around, but a serious, enormous plume.

/Ursula & GeoLurking

Reference: Mastin et al. 2009, A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions. Journal of Volcanology and Geothermal Research,186(1-2):10–21,

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Clues appended to the remaining riddles!
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