Magma ‘highway from hell’ study may improve volcano forecasting

In 1963, Costa Rica's largest stratovolcano, Irazú, blew its top, starting an eruption that lasted for the next two years. Scientists studying this eruption believe it may have been caused by a fast moving flow of magma they're calling a 'highway from hell', and their findings could help improve efforts to predict when volcanoes will erupt.

Currently, there are several volcano alert systems in place, from the U.S. Geological Survey, Mexico's CENAPRED and GeoNet in New Zealand, for example. However, although these agencies, and others like them, monitor volcanoes closely and have plenty of information about the warning signs of impending eruptions, actual prediction of these events is difficult, at best.

[ Related: Alaska volcano discoveries signal Canada’s need for closer monitoring ]

The main reason for this is simply the complexity of what's going on inside and under the volcano. There are numerous processes going on under the surface, deep down, where the magma is feeding from, and with all the layers of rock and earth above that, not to mention inside the magma chamber of the mountain and the mountain itself. It could be said that every volcano is unique. So, without a way to see all of what's going on, scientists watch for tremors, gas emissions, and activity inside the volcano crater, and compare that with what they've seen from this volcano in the past. Even then, the signs that they see may not even lead to an eruption.

Since magma tends to rise very slowly, it adds a level of difficulty to the idea of prediction, because signs could be missed. However, with Irazú, volcanologists from the Lamont-Doherty Earth Observatory of Columbia University studied the ash from the 1963-65 eruption, and found that the magma traveled from the Earth's upper mantle, roughly 20 kilometres down, to the surface, in just a few months.

"There has to be a conduit from the mantle to the magma chamber," geochemist Terry Plank, one of the two authors of the study, said in a statement. "We like to call it the highway from hell."

"If we had had seismic instruments in the area at the time we could have seen these deep magmas coming," said volcanologist Philipp Ruprecht, according to the statement. "We could have had an early warning of months, instead of days or weeks."

No seismographs were on Irazú at the time of its eruption, but since then, there have been other eruptions that fit this same pattern. The 1991 eruption of Mt. Pinatubo, in the Philippines, was preceded for weeks by deep earthquakes that are now thought to have been due to one of these 'highways from hell'. The same thing likely happened with the Eyjafjallajökull volcano in Iceland, during the 2010 eruptions, since researchers with the University of Cambridge and the University of Iceland reported measuring seismic shockwaves during the eruptions that went down deep below the surface. This suggests that there was a direct connection between the surface and the mantle.

Not all volcanoes will have this fast rising magma, of course. However, with the potential for a powerful eruption to happen very quickly, learning to recognize these is very important. Ruprecht and Plank believe the key to better forecasting potential is to look deeper.

"Signs of volcanic unrest are typically monitored at the surface or upper crust," they wrote. "New efforts should look deeper, tracking magma movement from the base of the crust to the surface in the months to years before eruptions."

[ More Geekquinox: Newly-discovered ant species are ‘the stuff of nightmares’ ]

Besides the monitoring done by agencies around the world, there are some efforts to forecast volcanic eruptions and earthquakes. The International Earthquake and Volcano Prediction Center, in Orlando, Florida, has been testing prediction techniques and issues warning notices, some giving months of notice of an impending event.

Here in Canada, we apparently depend on the assistance of the U.S. Geological Survey in monitoring our volcanoes. There hasn't been an eruption in Canada, apparently, in the last 200 years or so. However, western and northwestern Canada is quiet geologically active, and as we've been seeing eruptions in volcanoes in Alaska recently, an eruption somewhere mountains of British Columbia can't entirely be ruled out.

(Photos courtesy: Wikipedia)

Geek out with the latest in science and weather.
Follow @ygeekquinox on Twitter!