This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Friday, February 18, 2011

Krafla volcano: an accidental encounter (with magma)!

Lava flowing from Krafla, U.S.G.S. photo
Sometimes serendipity provides more interesting science than a rigorous work plan. This was the case when Wilfred Elders and his research team drilled into Krafla volcano, Iceland, in 2009.  The purpose of the drilling was to explore the environment of a very hot geothermal resource for use in producing power. The results are reported in an article in Geology (Elders et al., Origin of rhyolite that intruded a geothermal well while drilling at the Krafla volcano, Iceland (Geology, 39, 231-234, 2011), and a news release from NSF.

Expecting to find deep magma, at 4.5 kilometers, the scientists instead found magma flowing into their drilled well at 2.1 kilometers! Even more unexpectedly, although the dominant rock at Krafla is basalt (containing 45-50%) silica, the magma that they encountered was rhyolite (containing 65-70% silica). This confirmed the hypothesis that rhyolites can form by partial melting of basalts.

Drilling into hot environments, and extracting hot water from them, is extremely difficult for several reasons: any hot water encountered is likely to be laden with minerals that can precipitate out in pipes, and the rocks become very soft.  When they reached 2 km depth, the drill bit froze up (would not rotate).  When they tried to extract the bit, it became stuck.  They found that an intrusion of magma had filled the bottom 9 meters of the well, so they stopped exploratory drilling and converted the well to a production well.  The well produced dry steam at a temperature of 400 C (dry steam is water vapor that is heated to temperatures much higher than the boiling temperature at the pressure of the source; wet steam is steam that is in equilibrium with liquid water at the same pressure.)  To give you a feel for the potential magnitude of this resource, this steam is hot enough to potentially power 25,000-30,000 homes.  95% of the homes in Iceland are heated with geothermal resources.

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