Tuesday, May 20, 2014

Antarctic Ice Melt Could Unleash Volcanoes

The news on the environment lately hasn't been very good. Climate change has reached a tipping point with over 400ppm carbon in the atmosphere (a tipping point scientists have said is the point at which man-made changes to the climate become irreversible). Ocean acidifcation is reaching epic proportions and wreaking havoc on the oceans ability to sustain life. And to top that all off, scientists now say that the ice sheets in Antarctica have 'reached the point of no return' and their gradual slide into the ocean will raise sea levels by up to 30 feet (10m) in the coming two centuries.

Oh, but they forgot about volcanoes!

As has been speculated in a much smaller environment, 'post-glacial rebound', the process where land raises (in some cases rapidly) due to the absence of ice, could result in more frequent volcanic eruptions. This has been theorized in places like Iceland, where 'seasonal' volcanism sometimes occurs (although, of course, not always). The theory goes something like this: If you have a large volcanic system that is covered by thick layers of ice, the weight of that ice presses down the volcano and surrounding crust, thus containing any surface volcanic activity.

We do  know that volcanoes can erupt under ice. Such eruptions can create devastating ash clouds such as the one emitted during the 2010 eruption of Eyjafjallajökull in Iceland, and others leave flat topped mountains called 'tuyas', which formed when volcanoes erupted under the ice, but never broke through to the surface. Tuyas are common volcanic mountains in Western Canada in volcanic complexes such as the Tuya Volcanic Field, and other systems.

But we're not talking about Tuyas, we're talking about large stratovolcanoes. Really big ones.

You wouldn't think of Antarctica as the first place to find active volcanoes, but you'd be wrong. In fact, we don't even know how many active volcanic systems exist in Antarctica, and which ones might be active far beneath the ice. Only recently has some technology been able to scan beneath the ice sheet, but these scans only reveal topography. Not heat, or chemical composition of the rock to tell us where certain spots might be. So the question of crustal rebound reaches a new level of uncertainty with Antarctica.

Antarctica does have at least one historically active volcano, and possibly several more. Mt Erebus is the most active in Antarctica with many historical eruptions documented since the 1970's, however other volcanoes have been spotted with fumerolic activity, and some are suspected to have had minor eruptions in historical time. What's occurring beneath the ice sheets however is anyone's guess. And in the next couple hundred of years, if crustal rebound truly does allow for easier magma flow to the surface, we'll probably find out if there are any more.

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