Saturday, November 16, 2013

Geo-spotlight: Observations of first ever advancing rhyolitic obsidian flow at Puyehue-Cordón Caulle volcano in Chile

A team of geologists from Lancaster University in United Kingdom, University of Mainz in Germany and Victoria University of Wellington in New Zealand have reported for the first time a slow advancing lava flow of rhyolitic (more sticky and viscous lava than the usual red hot flowing basaltic lava) obsidian down the slopes of Puyehue-Cordón Caulle volcano in Chile, in their recent research article in Nature Communications. The most fascinating observation of this flow is that after almost a year from its last eruption in April 2012, when the lava from the vent had ceased to extrude; the flow is still progressing when visited by the team in January 2013.


Moving Rock at Puyehue-Cordón Caulle
Puyehue-Cordón Caulle volcano and its obsidian lava flow, still going nearly a year after the volcano stopped erupting. Credit: NASA Earth Observatory.
The reason for the slow flow is attributed to the thick carapace of solidified rubble strewn slabs, which has kept the lava core insulated from losing heat to the surrounding. Dr. Hugh Tuffen, a researcher from Lancaster University adds, “The effectiveness of the insulation provided by the ~10 m-thick upper crust is staggering - these things may keep moving for years to come. Viscous heating and latent heat of crystallisation in the interior can also help to keep them warm.”

Their results demonstrate how efficient thermal insulation by the shell of solidified lava crust allows prolonged advance of compound rhyolitic flow fields, and reveals unexpected resemblance with processes at basaltic lava flow fields elsewhere. This very unique flow is under the 'Geo-spotlight' and further similar studies of active lava fields will shed lights on the strange motion and emplacement of lava flows in general.

Photo images of the flow in concert with satellite images were used in constructing a 3D animation of the thick flow front. The animation created by a team member Dr. James Mike can be viewed on the BBC news website.

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