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The underground mechanism of geysers

In Earth Magazine for August 2013, I was fascinated to read about two recent studies that have shown convincingly that the very oldest theory explaining geyser activity may be close to the truth, although knowledge is still incomplete and may not apply to all geysers.

Sir George Steuart Mackenzie postulated after visiting Iceland’s geysers in 1810 that a geyser’s plumbing needs to include a horizontal cavity serving as a bubble chamber. There, after an eruption, more and more steam can accumulate between the surface of the water and the roof of the cavity, gradually building up pressure. When the pressure grows too high, the steam and water escape through the geyser’s vertical shaft.

Iceland’s geysers were not part of the studies reported by modern Russian and French researchers. They studied (respectively) the Kamchatka Geyser Valley and Yellowstone’s Old Faithful. Volcanologist Alexander Belousov concluded, by lowering video cameras into their shafts, that four geysers in the Kamchatka field have similar configurations that fit Mackenzie’s bubble trap model.

Geophysicist Jean Vandemeulebrouck meanwhile has been revisiting 1992 data from geophones located around Old Faithful Geyser by seismologist Sharon Kedar. By digitizing and analyzing her data, the French team were able to obtain an acoustic picture of OFG’s inner workings. They found that pressure builds up in a bubble trap there between geyser eruptions, just as in the Russian study.

Belousov suggests that the similarity of internal structures could be attributed to landslides in the case of the Kamchatka geysers and to glacial moraine deposits in Yellowstone and El Tatio, Chile (the third of the world’s primary geyser fields). Both types of terrain form conduits and cavities underground, as well as being located over sources of water and geothermal heat.

Besides reading Earth Magazine this month, I gleaned some information for this post from my newly published travelogue by Jules Leclercq, Yellowstone, Land of Wonders, page 117.

Cliff Geyser on Iron Spring Creek

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