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Bardarbunga: Jokulhaups Alert!

In Iceland, Bethany Ehlmann is touring with students to learn more about the dynamic geological processes that mold and carve our planet in order to learn about other planets, particularly Mars. As the recent earthquakes around Bardarbunga intensify and eruption appears imminent, warnings of Jokulhaups ring from the dells. Bardarbunga! Though we can’t see it, there’s been a lot of buzz about this volcano (and its entertaining name). Unlike Mars (probably), Iceland is very volcanically and tectonically active. Over the last week, hundreds of earthquakes, some reaching magnitudes of over five on the Richter Scale, have been recorded in a swarm beneath the Vatnajokull ice sheet. Their epicenters are below the glacially-buried 2,000-meter tall Bardarbunga volcano and within a series of subsurface faults extending from it.

In places, Krafla's geothermal activity has extensively altered lavas and ashes to create colorful mineral deposits of sulfate, clay, silica, and iron oxides. (Photo by Bethany Ehlmann)
In places, Krafla’s geothermal activity has extensively altered lavas and ashes to create colorful mineral deposits of sulfate, clay, silica, and iron oxides. (Photo by Bethany Ehlmann)

Scientists at the Icelandic geophysical survey think magma has migrated upward into the chamber beneath Bardarbunga and is now radiating outward in north-south oriented, vertically propagating features called dikes. Will there be an actual above-ground eruption? How big will it be? We’re not sure, but stay tuned… This post was actually delayed by my phone getting wet and needing 48 hours to dry. With all the activity and adventuring, sometimes writing from the midst of such a dynamic landscape demands certain concessions. Bardarbunga’s activity has also meant closures in Iceland’s desolate highlands; the fear is not a lava flow or ash cloud (though the latter could disrupt air travel, much like Eyafyllajökull a couple of years ago). The real fear here is a jokulhaup—an enormous flood, activated by melting of glacial ice during an eruption. The waters crash downhill toward the sea, scouring the land. The effect is hard to capture from the ground. I’ve included a picture from Asbyrgi, a horseshoe-shaped canyon formed a couple-thousand years ago by a jokulhaup, but checkout the nearby terrain in satellite images yourself. Deep, wide channels extending hundreds of kilometers are formed.

Asbyrgi, a 1.5 kilometer wide canyon formed by waterfalls during the last jokulhlaup. Pull up your earth view maps and checkout the view from space. Icelandic mythology's alternative perspective: the canyon is the hoofprint of Odin's horse, touching earth.
Asbyrgi, a 1.5-kilometer-wide canyon formed by waterfalls during the last jokulhlaup. Pull up your earth view maps and checkout the view from space. Icelandic mythology’s alternative perspective: the canyon is the hoofprint of Odin’s horse, touching earth. (Photo by Bethany Ehlmann)
Some of Krafla is still steaming hot. We had a thermal IR temperature probe and the steam coming out hit 85C. Not boiling, but you wouldn't want to step in it.
Some of Krafla is still steaming hot. We had a thermal IR temperature probe and the steam coming out hit 85 degrees C. Not boiling, but you wouldn’t want to step in it. (Photo by Bethany Ehlmann)

Amazingly, jokulhaups can have volume flow rates equal to all the world’s rivers combined! Jokulhaups probably occurred on Mars. All the signs are there. The ampitheatre-headed canyons, scoured kilometer-sized mounds in channels… But the big question: what was the water supply? At first glance, it doesn’t look like there were huge glaciers near the channels’ starts on Mars. But, then again, there was about two-billion years since the last jokulhaup to erode and cover the evidence. Other theories say a burst of groundwater release, maybe from melting permafrost, but it’s hard to get enough release quickly enough to get the rate of flow needed to carve the channel. File this as a top case in “Mars: The Unsolved Mysteries.”

The Krafla lavas erupted from fissures (no tall central caldera) in the 1970s and 1980s. Here you can see a chain of cones along the fissure
The Krafla lavas erupted from fissures (no tall central caldera) in the 1970s and 1980s. Here you can see a chain of cones along the fissure. (Photo by Bethany Ehlmann)

So, having spent a night at the isolated highland hut of Nyidalur, we then quickly headed to extend our stay in the Myvatn area as our travel to the volcano of Askja was cut off by mandatory evacuations. But Myvatn was a fabulous base for exploring Krafla, home to Iceland’s largest active geothermal field and eruptions of basalt in the 1970s and 1980s. We see flows like this in several places on Mars, and maybe the silica sinter and salts left by hydrothermal activity too. Myvatn is also home to phreatomagmatic features where volcanic lavas erupted into lakes forming cones of quenched volcanic glass, explosively ejected from vents. I’m not sure if we see this last feature on Mars or not, but there are some cones in Mars’ northern lowlands that look awfully similar. However, they’re covered by debris, so we’d need to get on the ground with rovers to figure it out.

Grassy and peaceful looking now, these 5-10m high volcanic cones formed in hot steam eruptions as lava fissures contacted the surface of Lake Myvatn, thousands of years ago.
Grassy and peaceful looking now, these five- to ten-meter high volcanic cones formed in hot steam eruptions as lava fissures contacted the surface of Lake Myvatn, thousands of years ago. (Photo by Bethany Ehlmann)

Next up: The fourth of Iceland’s big four—glaciers!

Read More By Bethany Ehlmann

Comments

  1. Lanfairya
    PA
    August 27, 11:06 am

    Awesome post! Love the title! It will be my new word of the day Jokulhaups!