Hekla volcano is in the news now because a geophysics professor at the University of Iceland has said that it’s ready to erupt.
Where’s Hekla and why should I worry about it?
The island of Iceland has formed where the the Mid-Atlantic Ridge rises above the surface of the North Atlantic. This ridge is a spreading center – two big tectonic plates are moving apart there, while molten material wells up in between and gets erupted.
Eastern Iceland is on the Eurasian tectonic plate, while the western part of the country is on the North American plate. Hekla sits atop the actual spreading zone:
Hekla is one of the more concerning Icelandic volcanoes.
Unlike its fellow high-threat volcanoes – Laki (technically part of Grímsvötn volcano – it had a flood basalt eruption in the 18th century that wiped out 20% of Iceland’s population and perhaps some people in England), Katla (massive glacial floods) and Öræfajökull (source of a VEI 6 eruption in the 14th century – the word means “wasteland”) – Hekla volcano is located in a relatively unpopulated area where its eruptions might not cause widespread devastation.
However, it’s a very popular hiking destination and gives very little warning, sometimes only minutes, before it erupts.
In addition, the material that comes out of Hekla is high in fluorine. This toxic chemical can destroy grasslands, thereby killing livestock and the people who depend on them (most of Laki’s victims back in 1783-84 died of starvation and disease after the country’s livestock perished).
Then there is the effect an eruption would have on air travel. Remember the VEI 4 eruption of Eyjafjallajökull back in 2010?
Hekla has an even stronger history for VEI 4 – and VEI 5 – eruptions. Everybody gets worried when somebody brings up the possibility of an eruption there.
How real is the threat now?
Just going by the headlines, I discounted the news as “awfulization” talk but had to set down my salt shaker after reading this at Dr. Erik Klemetti’s “Eruptions” blog (see this linked post for hot links):
The media had fun with a statement by Páll Einarsson that Hekla in Iceland is “ready to erupt”. Apparently this prediction is based on GPS measurements of deformation and strain measurements at the volcano that suggest that magma is filling the system in shallow levels, which could lead to an eruption. Interestingly, I just read about borehole strain measurements (along with the seismicity) in 2000 at Hekla that were used to forecast an eruption within 17 minutes of it occurring. Normally, I might think that some of this coverage is fear mongering, but it sounds like a lot of the precursory behavior at Hekla is well-documented, so definitely worth watching. Icelandic officials has even put up warning signs around the volcano and a text messaging system has been implemented to warn people of an impending eruption. Hekla has a webcam pointed at it to check on its status.
Since Dr. Klemetti says it’s definitely worth watching, and since Dr. Einarsson is a credible authority, I figure it is a good time to keep an eye on Hekla.
Perhaps you would like to watch Hekla, too. Fortunately, a lot of good online monitoring links are available in one spot.
I’m not sure what Jón Frímann Jónsson does for a living, but he is a reliable amateur geophysicist, as his comments at “Eruptions” have shown over the years.
As of March 20th, he said on his website “Iceland Geology” that “there are no signs of imminent eruption in Hekla volcano, it’s as quiet as it has been for the past 14 years,” but he also included a list of links to Hekla volcano cams and other online public monitoring sites, saying “If anything happens in Hekla volcano it is going to appear clearly on the above links.”
The only thing I can add to that is a Google-Translate version (sometimes unintentionally funny) of the Icelandic Meteorological Office’s Hekla page. This has historical as well as real-time data that includes official webicorders (what is a webicorder?) – note Jón’s webicorders are his own and he wants you to know that they contain errors.
Webcam links on the Icelandic Met Office page are the same ones Jón links to. There are also graphs showing Hekla’s deformation over the past 48 hours.
A word about deformation
GPS instruments on and around Hekla show that the volcano is expanding. This probably means magma is moving into the volcano (this is part of the data that set off the current hubbub).
However, if you look at those deformation graphs, you might get the impression there’s a wild, pressure-cooker type of reaction going on (some lines are pretty steep and in red):
It’s disconcerting to see something like that when you’re used to thinking of the Earth as solid and unmovable (except for plate tectonics). Is all that pressure going to blow the mountain to smithereens?
Not so much, given how the land moves and how sensitive those instruments are.
Hekla is not expanding the way Geneva rises on an Earth tide.
What those red lines show, I think, is incremental change in the diameter of a borehole over time, measured by incredibly sensitive instruments.
These strainmeters can measure “changes in the diameter of a borehole on the order of four picometers, about one ten millionth of the width of a human hair and smaller than the width of a Hydrogen atom.” (Source)
Geneva’s upward motion during a full moon, so small that few even know it happens, would throw those instruments off the scale – it would be a solid red graph!
So, that dramatic red line actually means that there has been a subtle change in the mountain’s normal movement.
This change isn’t something we would be able to see or feel if we were stood there, but the graph speaks volumes to the volcanologists who set it up and have been studying Hekla for years.
Theirs is a broader and very detailed picture of this volcano, 24/7/365.
We laypeople don’t have that big picture or the training to understand it all, but we can take our cue from the scientists.
They’re not issuing warnings yet, so we don’t have to be anxious. However, I personally wouldn’t choose this time to go on an early spring climb up Hekla.
It’s still pretty cool to be able to watch online as a volcanic event develops in another part of the world.
This is counter-intuitive, but I suspect the really bad news on the graph would be a sudden drop in the red line, which could mean either that the instrument had failed or the volcano had erupted, thereby releasing the strain.
VAACs and other links
The UK Met Office London Volcano Ash Advisory Centre is a link that will only be useful when Hekla (or any other Icelandic volcano) erupts.
NOAA’s Satellite Services Division also has a VAAC page with additional links to some relevant satellite imagery and other volcano URLs.
Sharing the Hekla experience
Here are a couple videos.
German television broadcast on Hekla’s eruption in 2000:
Those are pretty lava fountains, but “Hekla” by Icelandic composer Jón Leifs shows that this volcano can be much more boisterous:
- The Volcanic Explosivity Index. USGS
- Volcanic Hazards in Iceland. (PDF)
- Fluorine poisoning in victims of the 1783-84 eruption of the Laki fissure, Iceland. (PDF)