[Geysers] Strokkur and Geysir Video and Blue Bubble Questions

[Eric Hatfield]

The video is of Strokkur only.  Geysir itself cannot be seen in that view.  That particular eruption was quite a nice one, and may have topped 100 ft.

As explained on the website, Geysir itself reactivated in June 2000, though I wasn't aware that it had continued its activity until now (?)  It's new eruptions are only about 30 feet per the site.

Strokkur erupts about every 3 to 10 minutes, and it makes a "blue bubble" most of the time.  A central thing in making a blue bubble is having an undisturbed surface of water.  Undisturbed "blue" water has surface tension which wants to keep itself all one piece.  On the other hand, "white" water is a frothy mixture of water and air, where, once initially broken, surface tension makes the water into little droplets.

A sudden eruption under undisturbed water moves all the water above it as a big chunk to the surface, where it is still big enough to look like "blue water" instead of white froth.  Eventually the surface tension is disturbed, and you switch to the usual tiny droplet frothy white water.  The sudden transition gives that fun impression that bubble "explodes."

I watched hundreds of eruptions of Strokkur from WITHIN the crater in 1997.  It was unique in that it reproducibly made these blue bubbles.  Not all the time--sometimes boiling would disturb the surface just before the eruption and the bubble wouldn't happen.  But most of the time you get that domed water, which is blasted away seconds later by the shot of water from below.  In the video the bubble gets about 2 feet high.  Every 20th eruption or so you'll get a really incredible one, that rises to be a full half sphere and seems to last forever (really, say 3 secs.)  From within the crater, those got eye level and sent me running for my life.  The initial burst penetrates those like a gunshot from underneath, giving an amazing split-second "underwater spike" effect.  Looks like a normal spike, but totally encased by clear blue water.  Like a white christmas tree in blue amber.

Strokkur's eruptions are also very variable.  I liken it to Spa.  Most are just sudden little single splashes, but every now and then there will be a huge multiburst one that makes you want to step back.   I would say that most of Strokkur's eruptions are single bursts that reach about 20 ft.  But about one in four is "multiburst," and reaches maybe 60 ft.  The really extraordinary ones give the "superburst" effect like Great Fountain, of rising bursts through bursts.  You might get 5 spikes through spikes, and that may top 100 ft.  The video is an example.

As for how Geysir itself behaves, I've read and written about that before, but never seen it.  I'd love it if they put up a video of the current eruptions on that site!


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