Four of Iceland's Main Volcanoes Are All Preparing For Eruption (icelandmonitor.mbl.is)

Vulcanologists always watch Iceland carefully -- it's the one exposed place on the Mid-Atlantic Ridge, with 130 different volcanoes -- and something big may be brewing. Applehu Akbar writes: Now that four of Iceland's largest volcanoes are showing signs of impending eruption, the world may be in for another summer of ash. Katla, Hecla, Bárðarbunga and Grímsvötn have all had major activity in the past, including vast floods from melting glaciers, enough ash to ground aircraft over all of Europe, volumes of sulfur that have induced global nuclear winter for a decade at a time, and clouds of poisonous fluoride gas. When the mountains of Iceland speak, the whole world listens.
Eruptions are already overdue for both Hekla and Katla -- Hekla's magma chamber has filled up, and Katla last erupted in 1918. "The Katla eruption would lead to the melting of the Mýrdalsjökull glacier, resulting in a glacial flood," reports Tech Times, "likely to hit areas where large crowds are found at any given point of time, especially the black sand beaches of Sólheimasandur and the village of Vik in Southern Iceland."

Comments

Otherwise Known As A Jökulhlaup

[careysub]

Glacier outburst floods are known as "jökulhlaups" in geology, an Icelandic word since it has been the scene of many historic floods of this type.

In 1755 a jökulhlaup from the Katla volcano had a peak flow of up to 400,000 cubic meters/second, about 20 times the flow rate of the Mississippi River, or twice that of the Amazon, making it briefly the largest river in the world.

But that's not the only destructive aspect of Iceland's volcanoes. In 1783 the eruption of the Laki volcano released 14 cubic kilometers of basalt and 1 cubic kilometer of airborne ash. It killed 25% of Iceland's population through poison gas: 500 million tons of hydrogen fluoride and sulfur dioxide were released poisoning the population and the livestock. The fatalities were both from direct poisoning (mostly from the hydrogen fluoride) and later starvation since most of the livestock was killed. The toxic cloud affected much of Europe as well, though not as severely. This eruption also created a three-year long period of unseasonable cold in the northern hemisphere leading to famine killing thousands, and possibly contributing to the French Revolution.

Re:Giaa to the rescue!

[Rei]

Speaking of Mother Earth and Iceland... ;)

That's "Hún Jörð" ("Mother Earth") by the band Sigur Rós - it's an abbreviated version of the Lord's Prayer in Icelandic, except to the Earth instead of God. Also, screaming. Good music for volcanoes preparing to go off.

Or, if you want something more directly volcanic themed, there's always Jón Leif's Hekla. It's often described as the loudest piece of classical music ever composed, although that's only if you perform it with its full design intent of instruments, which I don't think anyone's ever done. Said instruments include "four sets of rocks hit with hammers, steel plates, anvils, sirens, cannons, metal chains, choir, a large orchestra, and organ".

Re:Scale

[Rei]

Also, one thing that's neat when the subglacial eruptions go off is the sigkatlar (I think the english is "ice cauldrons") that form on the top of the glacier. They can get huge - when Bárðarbunga went off, the main (shallow) section of ice that was sinking was the size of New York City (surrounded by deeper but steeper sigkatlar). The big, shallow ones are harder to see, but the smaller ones are often ringed by fissures - which may not look that impressive from far away, but they're really huge.

As a side story: while Bárðarbunga ended up with its last eruption breaking out in the most fortunate place it could have, there would have been something kind of amusing (amid the devastation) had it actually gone off straight over its magma chamber. Many decades ago a plane crashed on the glacier, right over the caldera; the survivors had to survive for days on the ice, in terrible weather, until rescuers could get to them. Because of the huge precipitation rate there, the plane is now deep inside the ice over the caldera. But had it erupted with an explosive eruption from the caldera.... the airplane would have flown again ;)

Re:Scale

[Rei]

Yeah, I love my country. :) We're packed with natural treasures. Geology that changes in realtime** can do that ;)

** Seriously, it really does change over human timescales. Right near Ásbyrgi there's a lake called Skjálftavatn which feeds the excellent fishing river Lítlaá. Neither existed until the 1970s, when tectonic activity from the eruption at Krafla rerouted the underground springs.

Re: Giaa to the rescue!

[knorthern knight]

> Here in the UK people living in flood plains get flooded, who
> would have expected that eh? And then they go complaining
> to the government. That's mostly as bad as it gets.

Many years ago, local governments would dredge river channels every so often, so they wouldn't flood. Good. Then Britain joined the EU. Along came unelected Eurocrats, who imposed ridiculously punitive/expensive standards regarding the disposal of the dredged up mud/silt. Result...
* local authorities couldn't afford to dredge river channels
* river channels silted up
* rivers flooded

Well... like... duhhhh. To add insult to injury, the flooding was wrongly blamed on global warming. It was crap like this that contributed to the Brexit vote result.

Re: Giaa to the rescue!

[popoutman]

Incorrect.
In recent years, more houses have been built in areas that were previously uninhabited. The resulting inability for storm water to drain into the soil and instead being forced to run off, increased the rate that water flowed into the river systems, meaning that rivers peak higher and sooner for the same amount of rainfall. This means more floods for the same weather patterns. Add in climate change and you lot are screwed for flood management.
Absolutely nothing to do with Brexit.
Actually, now that you lot are leaving, you won't get access to the emergency funds to help with problems like this that UK policies have caused over the past few decades...

As an aside, dredging can actually cause floods further downstream as it allows more water to reach the downstream areas in a shorter space of time, causing the river to "pile up" and overspill its banks, where it would not have happened if the dredging had not taken place.