Debatable Ground

by wjw on June 24, 2019

IMG_3347So here we are atop the Mid-Atlantic Ridge, on the neutral ground between the North American tectonic plate and the Eurasian plate.  Because the land here is very new, there’s not much in the way of bedrock to support it, and in places it’s sort of collapsed— though not here, where this lake can be found in newly-formed highlands.  The sources of this lake are rainwater and springs, and there’s no exit, but trout have found their way into the lake, so at least there’s fishing.

You also see black volcanic sand and precious little plant life.  In Iceland you can drive for miles through lava flows, where the only vegetation is “gray moss,” a spongy plant that over many centuries erodes the lava just enough so that it can be replaced by . . . green moss!  Which continues the erosion process until some scrub can finally take root.

There are some impressive lava fields near Reykjavik, but the lava fields of the south are simply vast, and produce hours of the most boring driving imaginable, with nothing but gray moss and distant mountains to look at.  This was all laid down in the eruption of Laki in 1783, in which a 25-kilometer gash opened up in the earth, and poured out lava for five months, and intermittently for the next 11 years.  Most of Iceland was covered by ash and cinders contaminated by fluorine, which killed most crops and maybe half the livestock.  Though few lives were lost in the actual eruption, nearly a quarter of the population died of starvation— and this a few years after a smallpox epidemic that killed 33%.  The Danish government contemplated evacuating the entire island, and sent a ship to Reykjavik to evacuate whoever wanted to leave— though when the people were told they were intended to colonize the barren sand dunes of Jutland, they responded “We can starve to death here just fine, thank you.”

The eruption was so vast that it had enormous geopolitical consequences.  A sulphur dioxide fog settled over much of Europe, so thick that ships could not leave port.  As people are not equipped to breathe sulphuric acid, thousands died.  The freezing winter of 1784 caused widespread famine, notably in France, where it probably contributed to the French Revolution.

In America, the Chesapeake froze over.  In Asia the monsoon cycle was disrupted, and the Nile failed to flood, resulting in the starvation deaths of a sixth of the population of Egypt.

Active geology can be pretty damned scary.

Another feature of southeastern Iceland is the way the houses are clustered on high points.  Many active volcanoes are covered by glaciers, so when there’s an eruption a lot of ice gets melted in a very short amount of time.  This stuff finds its way to lower levels, and the results can be mass flooding.  The floods not only carry water, but also cinders, big rocks, and whole icebergs.  Past experience has shown which areas flood and to what depths, and so farmhouses are clustered above the high-water line.  Since churches tend to be built on high points, the area is full of stories of churches being saved from catastrophe by divine intervention, while the actual cause seems to have been topology.

These floods can build very rapidly.  We visited one town— it may have been Vik, but I don’t remember— where the inhabitants are expected to evacuate on 40 minutes’ notice.  Good luck with that, say I.  (We lodged well above the flood line.)

Vulcanologists are now very good at predicting eruptions, but this is usually with volcanoes they can see.  A volcano buried under two kilometers of ice is a very different problem.  They listen for micro-quakes and send helicopters over the glaciers to visually look for changes.

But still— 40 minutes’ warning.  My advice is not to silence your phones at night.

Bruce Arthurs June 25, 2019 at 12:57 am

Never heard of the Laki eruption before. Wow. Would that have been classified as a “supervolcano” eruption? Also wondering if Icelandic literature includes novels set in that period? (Is there an Icelandic WJW who wrote an Icelandic version of The Rift?)

wjw June 25, 2019 at 1:10 am

Iceland has generated a surprisingly large amount of literature for such a small country, and I’m sure there are plenty of novels set during the period, all unknown outside the small universe of people who read Icelandic.

Luckily Laki isn’t a supervolcano— if it were, the entire northern hemisphere might have been wiped out.

MathMom June 25, 2019 at 7:16 pm

Realtors always tell you that real estate is a great investment, because they aren’t making any more of it.

Iceland is there to prove Realtors wrong.

All that farmland along the south, on Hwy 1, is geologically new, and really convenient, because you can grow stuff on it! And the Mid-Atlantic Ridge makes Iceland spread and get larger.

Iceland really gets under your skin. It’s hard to stop thinking about it, even when you leave.

Luke June 25, 2019 at 7:44 pm

Flood basalts are not indicative of a supervolcano. Generally. Although they can be co-located, and flood basalts are the first step of a building stratovolcano.

The very short version, is that feldspars with Calcium and Sodium melt at a much lower temperature than feldspar with Potassium, and are much lighter and more liquid in a molten state. They tend to be shallow eruptions, and not violent in any sort of explosive fashion.

It’s when you’ve got a thick paste of K-spar being pushed up from great depth, under high pressure, through weakened tube blocked with “frozen” rock that things get explosive.

In a nutshell, that’s why stratovolcanoes are like they are. The eruptions are from the same magma chamber, with every subsequent eruption having less Plagioclase (Na/Ca-Spar) and more Orthoclase (K-spar)

Bruce June 26, 2019 at 12:48 am

How old is Iceland? Is its emergence still a candidate for one of the mass extinctions?

Lloyd Martin Hendaye June 26, 2019 at 7:01 am

From Kamchatka and Sunda Strait to Central America, the Pacific’s “Rim of Fire” generally dwarfs Iceland’s Mid-Atlantic Ridge. Meantime, by all accounts, North America’s Yellowstone super-volcano complex smoulders well past its periodic re-eruption date.

Let’s face it: Dustmote Earth is far more vulnerable to civilization-ending geophysical catastrophe than populations realize. Now seven centuries past the Holocene Interglacial Epoch (ended AD 1350), as a 70+ year Grand Solar Minimum similar to that of 1645 – 1745 takes form through 2100, the sooner humanity removes en masse off-planet the best for all concerned.

PhilRM June 26, 2019 at 4:06 pm

In 1997 I spent a week driving the Ring Road all the way around the island after attending a conference outside of Reykjavik. In the southeastern part of the island the road is not paved, apparently because it’s destroyed so regularly by subglacial volcanic eruptions that it isn’t cost-effective to do so. In fact, there was a huge flood caused by an eruption the previous autumn, so we ran into a fair bit of road repair. At one point we had to drive for about ten miles on a temporary gravel road while the main road was rebuilt. Since flooding volcanic ash is a great way to produce quicksand, you were stringently warned not to leave the road by the funniest warning signs I have ever seen: some of them had text (in multiple languages) but most of them just had a pictograph of a stick figure sunk to its waist in quicksand with its arms over its head and its mouth open in a scream.

It was also striking how much of the Ring Road was a one-lane road – not one lane in each direction, just one lane.

wjw June 26, 2019 at 10:42 pm

Phil, the Ring Road has been repaired since you last drove it. It’s now two-lane blacktop, except for the bridges, which are mostly single lane. At one point we passed the twisted beams of the previous bridge that had been washed away in an eruption. That bridge was taken down quite =forcefully= —maybe rammed by an iceberg or something.

wjw June 27, 2019 at 11:00 pm

I’ve been in two supervolcanoes in my life, and they’re huge. Toba in New Zealand was over 100km across, and Yellowstone has several overlapping calderas on the order of 40 miles across. Iceland’s volcanoes are impressive, but they’re not super.

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