Katla volcano (posted 20 April 2012)

(News & Editorial/Katla volcano (posted 20 April 2012))

Fears of a huge new volcanic eruption in Iceland: Previous eruptions of Eyjafjallajokull have been followed by much larger blasts by nearby volcano
April 11, 2012,  The Telegraph, By Andy Hooper ( Dr Andy Hooper is an assistant professor at Delft University of Technology)

This month marks the second anniversary of the eruption of Eyjafjallajokull that left millions stranded across Europe, and cost airlines an estimated $400 million a day for six days. But alarmingly, there are signs of high activity beneath the much larger, neighbouring Katla caldera in Iceland — a possible sign of an impending eruption.
This should prompt extensive high-level contingency planning across Europe, as Katla has the potential to be much more damaging than Eyjafjallajokull.
Since Iceland was settled in the ninth century, Katla has erupted on average every 60 years, but has not had a significant eruption since 1918. Ominously, eruptions of Eyjafjallajokull in 1821-23 and 1612 were followed within months by eruptions of Katla. Judged by the historical calendar, an eruption is overdue.

Last July, a flood of water burst from beneath the ice cap on top of Katla, washing away a bridge. This indicates that an extra pulse of heat reached the base of the ice. Since then, there have been erratic movements of the surface of the volcano, measured by precise GPS instruments, and bursts of high earthquake activity beneath Katla’s caldera. These observations imply that magma has risen to shallower depths.

Katla’s eruption in 1918 produced five times as much ash as the 2010 Eyjafjallajokull one. A major eruption could result in large parts of Iceland being flooded as snow and ice melted; significant poisoning of Icelandic agriculture; destruction of property; and, of course, the grounding of aircraft across Europe.

If enough material is ejected it could even have a cooling effect on the global climate for a few years. A precedent for that would be the 1783-84 eruption from the fissure of Laki, which is part of the same volcanic system, Grimsvotn, that erupted last year. This was a very large eruption of 15 cubic kilometres (3.6 cubic miles), compared to the fraction of a cubic kilometre ejected in 2010, and had a huge impact on the northern hemisphere, reducing temperatures by up to 3C. This had catastrophic effects far beyond the shores of Iceland (where at least a fifth of the population died), with thousands of recorded deaths in Britain due to poisoning and extreme cold, and record low rainfall in North Africa.

Large eruptions such as this occur only every few hundred years on Iceland, but the potential for danger is significant. Even if deaths from famine are less likely today, a recent study of the potential effects of the air pollution caused by such an eruption estimates that it could lead to between 52,000 and 228,000 fatalities throughout Europe.

Meanwhile, nearby Hekla has erupted about once every 10 years in recent times, with the last being in 2000. Similarly, volcanoes beneath the largest ice cap, Vatnajokull, are entering a period of increased volcanic activity – the peak of a 140?year cycle.

This trend is being exacerbated by climate change. Vatnajokull has lost an estimated 400? billion tonnes of ice since the end of the 19th century. This has reduced the pressure on the hot mantle material beneath the crust, leading to increased magma generation. At the end of the last ice age, this same effect led to eruption rates some 30 times higher than at present. The current rate of ice loss is much lower than then, but we can still expect the formation of extra magma equivalent to that which erupted from Eyjafjallajokull in 2010 every 10 years or so.

There is a question mark over whether and when all this extra magma will erupt, however. Studies indicate that the timelag between generation and eruption could be as much as a few hundred years. In the meantime, the shrinking of the ice cap also causes stress changes in the crust that can encourage, or discourage, capture of the magma on its way up, depending on the path it takes.
The scale of the chaos that an eruption could cause is difficult to estimate. Partly it would depend on which way the winds are blowing but also on the style, size and duration of the eruption. Perhaps surprisingly, the magnitude is less important than the type of eruption.

While the Eyjafjallajokull eruption was relatively small, it caused such havoc because the materials ejected had the perfect make-up to ground flights: fine ash was deposited high enough to remain airborne for days, affecting the airspace of continental Europe. An eruption of Katla is likely to have a similar explosive style, due to the interaction of the magma and the overlying ice cap – the heat of the magma causes the transformation of ice to steam, which expands and fragments the magma.

A key goal for scientists and aviation authorities must be to develop predictive capability as to the nature of forthcoming eruptions. We would then be able to construct better plans for dealing with the impact, including the threat to agriculture and air travel.
To this end, my group at Delft University of Technology is working with the University of Iceland and others to develop more accurate models of volcanic plumbing systems. Using GPS receivers, satellite-borne radar, and advanced algorithms, we have been able to track the movement of magma and create maps of magma storage.
Just as importantly, the risks associated with the largest Icelandic eruptions, such as that which occurred in 1783-84, need to be thoroughly assessed. Even though these events occur only every few hundred years, the potential for widespread loss of life means we need to be properly prepared.
As we face continuing volcanic activity in Iceland and across the world, it is vital we improve the science of eruption prediction and so guard against the worst consequences.

B.  Weather affects timing of some natural hazards: Seasonal patterns in earthquakes and volcanic eruptions can be linked to rain and snow
December 9th, 2011, Science News, By Devin Powell and Alexandra Witze
Pasted from <http://www.sciencenews.org/view/generic/id/336856/title/Weather_affects_timing_of_some_natural_hazards
SAN FRANCISCO — If you want to know the chance of an earthquake in the Himalayas or a volcanic eruption in Iceland, check the calendar. Seasonal patterns of rainfall and snowfall can affect how often quakes and volcanoes go off, scientists reported December 8 at a meeting of the American Geophysical Union.
[Photo above: Looking up at Katla volcano during the winter, the mountain is covered by the beautiful Myrdalsjökull Glacier.]

In the Himalayas, the weight of water from monsoon rains helps dampen seismicity for a few months each year, says geophysicist Thomas Ader of Caltech. Seismic records collected from 1998 to 2004 show that the number of quakes drops in the rainy summer months and rebounds when things dry out.

Water from monsoon storms runs off the mountains and into India, where its weight bends the Earth’s crust slightly. From season to season, this bending causes the surface to move back and forth, as recorded by Global Positioning System stations, in time with the rise and fall in earthquake frequency.
Calculations by Ader and his colleagues suggest that the flexing eases the stress on the fault where two tectonic plates collide beneath the Himalayas. This change in stress is quite small — less than a hundred-thousandth of the stress caused by the motion of the plates. But it lasts for months, perhaps giving the earthquakes time to slowly incubate.
“It’s a very rare way of changing the stress on a fault,” Ader said at a news conference at the geophysics meeting.

In this case, though, what goes down must come up. When the drier months come, the land rebounds, freed of its watery burden. An uptick in the number of earthquakes ushers in the winter.
In Iceland, the opposite is true: Summer is the time of greater hazard, when the country’s massive ice caps slim down during the annual melt. Where that ice happens to sit atop active volcanoes, the changes can trigger eruptions below, says Fabien Albino, a geophysicist at the University of Iceland in Reykjavik.
Albino and his coworkers have created computer simulations of how stress changes within rock when overlying weight is removed. Above the Icelandic volcano Katla, for instance, the ice cap is 6 meters thinner in the summer than in winter. This change translates to a tiny but noticeable shift in rock stress, Albino says.

Katla erupted most recently in 1918, 1955, 1999 and possibly in 2011. Each time the eruption happened between May and November. More small earthquakes also occur around Katla in summer than winter, Albino says.

[Photo above: Looking down into Katla’s 6 mile in diameter volcanic caldera.]

In the short term, the work suggests that magma will rise within Katla — and possibly erupt — during warmer months when the stress is unloaded from top, Albino says. In the longer term, a different phenomenon helps dictate how Katla responds: Iceland’s ice has been retreating for more than a century, and that long-term decline means that Katla has a little bit less ice covering it every year to suppress eruptions.
In related work, Albino has studied possible links between Katla and the neighboring volcano Eyjafjallajökull, whose 2010 eruption temporarily closed European airspace. Albino’s calculations suggest that the stress changes caused by Eyjafjallajökull’s eruption were not enough to affect future eruptions at Katla, as some scientists had suggested.
Other factors, such as how fluid flows through the rock, still connect the two volcanoes, says geophysicist Andrew Hooper of the Delft University of Technology in the Netherlands.

C.  How ice ages begin
December 5, 2011, CDAPress, Below is an article from, Robert Felix, author of “Not By Fire, But By Ice.” He details how ice ages begin.
Mr Felix’a article was found at: <http://www.cdapress.com/columns/cliff_harris/article_a5c88e38-98f0-5c34-8a29-c84f2fba2a39.html>

Robert Felix’s report:
“Remember this fall’s pre-Halloween blizzard? Headlines across the U.S.A. called it “historic.” Historic because it dumped record snowfall on at least 20 cities from Maryland to Maine. Historic because it was the most snow – and the earliest – in many areas since the end of the Civil War.
And we’re not talking mere tenths of an inch here. This snowfall not only shattered the old records, it obliterated them! With 32 inches of snow, Peru, Mass., won the prize. Two-and-a-half feet! Waist deep! Before Halloween!
This is how ice ages begin. Not by huge glaciers slowly grinding out of the north, not by temperatures plunging to Siberian levels, but by more and more snow piling up from one season to the next without completely melting. Unfortunately, we’re getting that snow.

According to Rutgers University Global Snow Lab, three of the four snowiest winters in the Northern Hemisphere have occurred in the last four years.
Last year’s blizzard-filled winter and unusually cold, wet spring left record snowpack at more than 90 measuring sites across the western United States. Hard freezes killed fruit and vegetable crops last winter in the Deep South from Florida to Texas.
By Memorial Day, epic snowpack totals had been reported in Colorado, Utah, Wyoming, Montana, Idaho, Oregon, Washington and California.

On California’s Mammoth Mountain, the snowpack measured an incredible 728 percent of normal. At Oregon’s Mt. Bachelor Ski Resort, snow totals reached 650 inches, far eclipsing the previous record of 606 inches. In Washington, Crystal Mountain broke its all-time snowfall record for the second time in only 11 years. And the snow kept coming. In early June, Utah’s Snowbird ski resort reported a record snowpack at 525 percent of normal. People skied near Lake Tahoe on July 4th of this year!

And lest we forget, just a few months ago the Missouri River suffered its second 500-year flood in 15 years. Why? Because of heavy rains and melting record snowpack.

Glaciers are also growing in the United States. Even though last winter’s historic snowpacks have not yet melted, new snow is already piling up in the Rocky Mountains, the Cascades and the Sierra Nevada Mountains.
In Montana’s Glacier National Park, in Colorado’s Front Range, in Wyoming’s Grand Tetons, the glaciers and snowfields are actually gaining volume. Meanwhile, scientists have measured a “very modest” increase on Sperry Glacier in Montana’s Glacier National Park.
Mind you, these are not the only glaciers growing in the United States. Glaciers are also growing in California, Alaska and Washington state.
This is how ice ages begin. And our leaders keep screaming about global warming”.

(End of post)


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