Monday, February 27, 2012

Costa Rica's Rincón de la Vieja Volcano Erupts

Rincón de la Vieja, Costa Rica's largest volcanic complex, is experiencing an eruptive phase after 14 years of quiescence. Tremor and explosive activity has been reported by Eruptions blog, and local Costa Rican news sources. The explosions were not damaging to surrounding areas, and are reported to have been contained inside the most active (middle) crater of Rincón de la Vieja. Volcanologists say that this is not the result of new magma being injected into the crater, rather this is a phreatic eruption.

Phreatic eruptions occur when water seeps into cracks or fissures, and comes into contact with cooling magma or superheated rock, which in turn causes the water to flash into steam, creating enough pressure for an explosive event. These types of eruptions are considered to be one of the least dangerous types, however they are still quite dangerous as they can occur with little to no warning. These types of eruptions generally do not generate any seismic signals until they actually occur, and are not able to be predicted. They are typically small eruptions, however larger phreatic eruptions, more specifically, ones that can create a 'maar' have occurred in many other volcanic systems, such as the Soda Lakes maars in Nevada, or the Ubehebe craters.

It is probable that this will be some of the only activity for now from Rincón de la Vieja for a while, unless new magma is injected into the chamber. It is anyone's guess at the moment as to if this has occurred or will occur. However the Costa Rican government would be wise to excersize caution, as a 1966 eruption caused a very large, VEI 3 sized eruption, which produced many deadly pyroclastic flows. An earlier eruption in (around) 1820 BC produced a much larger VEI 4 size eruption, which produced the Río Blanco tephra layer, was the largest eruption of the volcano that we know of.

Rincón de la Vieja is the site of geothermal drilling and exploitation.

Rincón de la Vieja does have the potential for extremely explosive events, and it is looking like the volcano is awaking from its slumber... at least for a little while. It is entirely possible that after these phreatic explosions, that will be all and the volcano will go back to sleep. I for one wouldn't plan any trips to the summit any time soon, and would opt to admire the volcano from a good distance!

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