Thursday, August 22, 201411:05 p.m.
|Bárðarbunga releasing steam from beneath the Vatnajökull Glacier. Photo Credit: Oddur Sigurdsson, Iceland Geological Survey.|
It’s safe to say that Iceland’s remote Bárðarbunga volcano doesn’t look like a typical volcano. Even though it is 6,591 feet tall, it has all but been completely consumed by the massive Vatnajökull glacier, with the only evidence of a volcano being a snow-covered caldera with a tiny hole in the center formed by warm gases melting snow as they travel from the volcano into the atmosphere.
|Isn’t it cute? Photo link: http://www.geo.mtu.edu/volcanoes/iceland/vatnajokull/|
But the above dimple is far from docile. Bárðarbunga has had major eruptions in the past, and it looks as though another one may be in the cards. We have many things to talk about, but before I go any further, let me explain what’s been happening recently with the daintily cute aforementioned volcano.
Bárðarbunga has been the site of a vast swarm of earthquakes recently, with the strongest one (magnitude 4.7) occurring around 18 hours ago at midnight 8/22/2014 Iceland time. Swarms of earthquakes are often a precursor to volcanic activity… Mt. St. Helens was having hundreds of small earthquakes a day before it finally blew its top on 8:32 a.m., May 18, 1980. Between last Saturday morning and Monday evening, the Iceland Meteorological Society measured 2,600 earthquakes, with that 4.7 earthquake being the biggest one measured since 1996.
So far, no magma has made it to the surface, but scientists are concerned that these earthquakes may signal an impending eruption. Even though it has been found that earthquake swarms lead to eruptions less than 10% of the time, a Bárðarbunga eruption could paralyze not only Iceland but all of Europe.
First, let’s talk about the anatomy of this volcano.
It lies under the northwestern edge of the Vatnajökull glacier, and, as I said before, is completely encased in ice. You are not able to see the structure of the mountain. At the rate we are warming up, several generations south of us will surely be able to see parts of the mountain, but we don’t live in a world that has truly felt the effects of anthropogenic greenhouse gas emissions.
Some of you may remember the eruption of the volcano Eyjafjallajökull (aka: “that Iceland volcano”) back in 2010. While Bárðarbunga is easier to pronounce (the anglophone spelling is “Bardarbunga”), they share many similarities, as they have comparable geological properties and are both covered in ice. The difference is that Bárðarbunga is much bigger, and if it does erupt, it will release far more magma.
8,500 years BP, Bárðarbunga released 21-30 cubic kilometers of lava and covered 950 square miles with it. This is speculated to have been the largest lava flow of the Holocene Era, which began at 11,700 years BP (right after the last ice age) and continues today. The Vatnaöldur eruption of 870 was very large, as was the Veiðivötn eruption in 1480. Bárðarbunga hasn’t witnessed an actual eruption since 1862, though it did have some activity in 1996.
So what are the consequences of a possible eruption?
Well, the biggest local consequences will be the threat of massive flooding. A large eruption would melt an incredible amount of water, and this water could sweep villages away. These “volcanic floods” are not unique to Icelandic volcanoes; they occurred as Mt. St. Helens melted snow in 1980 and are actually one of the biggest threats to nearby towns in the event of a Mt. Rainier eruption.
Something with a far broader geographic scope would be the ejection of ash into the atmosphere. Remember the Eyjafjallajökull volcano I was talking about earlier? The 2010 eruptions of it led to the highest travel disruption in Western Europe since World War II. The eruption truly was small… the ash cloud only reached 10 kilometers high, and only 270 million cubic meters of ash was ejected into the atmosphere. Mt. Pinatubo, for instance, ejected 10 billion cubic meters of ash 34 kilometers high. What made Eyjafjallajökull so much more destructive?
|Eyjafjallajökull erupting on April 18, 2010. http://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallajökull|
First off, it’s important to remember that Iceland is right between the U.S. and Europe, so it is important as a hub for air travel. But there are other geological factors at work. When the magma at Eyjafjallajökull’s vent reacted with the nearby glaciers and rapidly cooled, it contracted into much smaller and more jagged/porous ash particles than are usually seen. Moreover, more fine ash was created when small gas bubbles in the molten rock expanded as the magma rose and approached the surface. The median width of all the ash grains was found to be less than 1 millimeter wide, and further away from the vent, 20% of the ash particles were smaller than 16 microns, which is approximately six times thinner than a human hair. In the process of cooling rapidly as it rose, the Because this ash was so light and, due to its rough and porous texture, was aerodynamically favored to stay high in the atmosphere for a long time, massive air travel disruptions resulted. There was also a fairly stagnant weather pattern over Western Europe at the time, so these particles were not carried laterally either. They just sat there and wreaked 1.7 billion dollars worth of havoc on the airline industry.
|Canceled flights at Leeds Bradford Int’l Airport. http://en.wikipedia.org/wiki/Air_travel_disruption_after_the_2010_Eyjafjallajökull_eruption|
If Bárðarbunga were to erupt, it would be in that same jet path, and the ash particles would probably have similar characteristics and be FAR more numerous. The weather would be the wild card.
By the way, Bárðarbunga was recently just updated to a “orange” risk level, which is apparently the highest there is without a volcano already erupting. They updated it after they found out that, in addition to all these earthquakes continuing to happen, the magma is moving closer to the surface.
Bárðarbunga started erupting this morning for the first time. The eruption is small, and it is being extremely carefully monitored.