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: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!

[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.