Monday, October 31, 2011

Uturuncu - The Bolivian waking giant

Uturuncu volcano in Bolivia is inflating at a (geologically) breakneck pace of 2cm a year, since measurements began at the volcano in 2000. This has been found to be one of the largest inflating volcanic regions on earth, with some concerned that this could lead to a supervolcano eruption in the future. Scientists however point out that it would take a combination of crustal structural weakness, large magma reservoir, and other factors that make this scenario extremely unlikely.

When large magma chambers inflate, it's really anyone's guess as to what can happen. Some times, small fractures in the crust can lead to a monogenetic volcanic field such as Michoacan-Guanajuato in central Mexico, large fissure type eruptions such as the famed Laki eruption in Iceland during the 1700's, large caldera forming events such as the catastrophic destruction of Mount Mazama in the Cascades which forms Crater Lake/Wizard Island, or of course the worst case scenario of a Toba or Yellowstone type eruption.

As humans living today have not even come remotely close to witnessing a super volcanic eruption (or any eruption with a higher than VEI 7), it remains highly unlikely that the inflation at Uturuncu would lead to a super volcano.

Uturuncu is thought to have last erupted during the Pleistocene, however fumeroles, and post glacial lava flows are present, suggesting later stage activity. These Andes range volcanoes are sneaky, and erupt without a moment's notice sometimes. Chaiten volcano in Chile was thought to be a long dormant dome, when it erupted quite suddenly in 2008, and the eruption is ongoing.

The Andes range along the Pacific Plate has seen major subduction earthquakes in quite recent history, ranging from mag 5.0-8.6, with a 5.7 quake having just occurred yesterday along the same latitude near Uturuncu. The constant seismicity in the area is a reminder of how easily our earth's crust can generate new magma by tectonic friction and subduction. Indeed the Pacific Ring of Fire is the most active region volcanically on the planet.

Chile and Peru have seen some of the most active seismicity in their history lately, and it would not surprise me in the very least if this leads to long dormant volcanoes such as Uturuncu erupting. As I had pointed out in an earlier post, Chile's Hudson volcano (which nobody even knew WAS a volcano until it erupted in the 1970's) has also sprung back to life, creating quite a buzz.

Uturuncu is NOT in imminent danger of eruption. This is a log-term trend that has been the center of ongoing debate amongst volcanologists and geologists for around a decade now. Indeed, there is no way to properly tell how long this has been going on as the region is very remote, and technology has only been sensitive enough to detect this within recent years.

New technology has enabled volcanologists to map magma chambers by recording seismic waves that pass through high and low velocity zones. Low velocity zones can be interpreted as magma chambers. Only recently were scientists able to actually map out the shape, depth, and size of the Yellowstone magma chamber (and much to their surprise, it is far larger, far deeper than they thought).

This technology should be used by scientists to map the underground chamber at Uturuncu. The more we understand how this magma is intruding, the better guesses can be made as to whether this volcano is a threat, and proper measures could be taken.

Here are some links to the sources I referenced for this article! Enjoy reading about them as much as I did!

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