GeoLog

Eyjafjallajökull

Imaggeo on Mondays: The ash cloud of Eyjafjallajökull approaches

Imaggeo on Mondays: The ash cloud of Eyjafjallajökull approaches

This photo depicts the famous ash cloud of the Icelandic volcano Eyjafjallajökull, which disrupted air traffic in Europe and over the North Atlantic Ocean for several days in spring 2010. The picture was taken during the initial phase of the eruption south of the town of Kirjubæjarklaustur, at the end of a long field work day. Visibility inside the ash cloud was within only a few metres.

The eruption was preceded by years of seismic unrest and repeated magma intrusions. A first effusive fissure opened outside the ice shield of the volcano at the end of March 2010, followed by an explosive eruption in the main crater of the volcano in April 2010.

Iceland was well prepared for the eruption – the rest of the world obviously was not. The region around Eyjafjallajökull is sparsely populated, residents were prepared days before the eruption and the evacuation went smoothly. However, the grain size of the ejected volcanic ash was fine enough so that the unfavourable and unusual wind direction during these days transported the ash all the way to Europe and led to air space closures almost all over the continent.

By Martin Hensch, Nordic Volcanological Center, University of Iceland (now at Geological Survey of Baden-Württemberg, Germany)

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: harnessing Earth’s inner heat

Imaggeo on Mondays: harnessing Earth’s inner heat

Iceland, the land of ice and fire, is well known for its volcanicity. Most famously, it is home to Eyjafjallajökull: the volcano which caused wide spread mayhem across European airspace when it erupted in 2010.

But not all the local volcanic activity is unwelcome. High temperature geothermal areas are a byproduct of the volcanic setting and the energy released can be used to power homes and infrastructure. Indeed, geothermal power facilities currently generate 25% of the country’s total electricity production.

“I took the photograph during a three hour walk in the Krafla area, a few kilometres away from Myvatn Lake in Northern Iceland,” explains Chiara Arrighi, a PhD student at the University of Florence in Italy, who took today’s featured image while on a two week holiday on the island.

There are 20 high-temperature areas containing steam fields with underground temperatures reaching 250°C within 1,000 m depth dotted across the country. Krafla, a caldera of about 10 km in diameter, and the wider Myvatn area is one of them. The volcano has a long history of eruptions, which drives the intrusion of magma at (geologically) shallow depths which in turn heats groundwater trapped deep underground, generating the steam field. Only a few hundred meters from the shooting location a power station of 60 MW capacity exploits high- and low-pressure steam from 18 boreholes.

Fumaroles and mud pots, like the one photographed by Chiara, are the surface expression of the geothermal activity. The discoloration of the rocks in the immediate vicinity of the bubbling mire is due to the acidic nature of the water in the pool. The steam is rich in hydrogen sulphide, which oxidises to sulphur and/or sulphuric acid as it mixes with oxygen when it reaches the surface. It deposits around the vents of fumaroles and as sulphuric acid in the stagnant waters, leading to alteration of the surrounding bedrock and soil.

If you pre-register for the 2017 General Assembly (Vienna, 22 – 28 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Imaggeo on Mondays: A Bubbling Cauldron

Imaggeo on Mondays: A Bubbling Cauldron

Despite being a natural hazard which requires careful management, there is no doubt that there is something awe inspiring about volcanic eruptions. To see an erupting volcano up close, even fly through the plume, is the thing of dreams. That’s exactly what Jamie  Farquharson, a researcher at Université de Strasbourg (France) managed to do during the eruption of the Icelandic volcano Bárðarbunga. Read about his incredible experience in today’s Imaggeo on Monday’s post.

The picture shows the Holuhraun eruption and was taken by my wife, Hannah Derbyshire. It was taken from a light aircraft on the 11th of November of 2014, when the eruption was still in full swing, looking down into the roiling fissure. Lava was occasionally hurled tens of metres into the air in spectacular curtains of molten rock, with more exiting the fissure in steady rivers to cover the surrounding landscape.

Iceland is part of the mid-Atlantic ridge: the convergent boundary of the Eurasian and North American continental plates and one of the only places where a mid-ocean ridge rears above the surface of the sea. It’s situation means that it is geologically dynamic, boasting hundreds of volcanoes of which around thirty volcanic systems are currently active. Holuhraun is located in east-central Iceland to the north of the Vatnajökull ice cap, sitting in the saddle between the Bárðarbunga and Askja fissure systems which run NE-SW across the Icelandic highlands.

Monitored seismic activity in the vicinity of Bárðarbunga volcano had been increasing more-or-less steadily between 2007 and 2014. In mid-August 2014, swarms of earthquakes were detected migrating northwards from Bárðarbunga, interpreted as a dyke intruding to the east and north of the source. Under the ice, eruptions were detected from the 23rd of August, finally culminating in a sustained fissure eruption which continued from late-August 2014 to late-February of the next year.

My wife and I were lucky enough to have booked a trip to Iceland a month or so before the eruption commenced and, unlike its (in)famous Icelandic compatriot Eyjafjallajökull, prevailing wind conditions and the surprising lack of significant amounts of ash from Holuhraun meant that air traffic was largely unaffected.

At the time the photo was taken, the flowfield consisted of around 1000 million cubic metres of lava, covering over 75 square kilometres. After the eruption died down in February 2015, the flowfield was estimated to cover an expanse of 85 square kilometres, with the overall volume of lava exceeding 1400 million cubic metres, making it the largest effusive eruption in Iceland for over two hundred years (the 1783 eruption of Laki spewed out an estimated 14 thousand million cubic metres of lava).

Numerous “breakouts” could be observed on the margins of the flowfield as the emplacing lava flowfield increased in both size and complexity. Breakouts form when relatively hot lava, insulated by the cooled outer carapace of the flow, inflates this chilled carapace until it fractures and allows the relatively less-viscous (runnier) interior lava to spill through and form a lava delta. Gas-rich, low-viscosity magma often results in the emission of high-porosity (bubbly) lava. My current area of research examines how gases and liquids can travel through volcanic rock, a factor that is greatly influenced by the evolution of porosity during and after lava emplacement.

Flying through the turbulent plume one is aware of a strong smell of fireworks or a just-struck match: a testament to the emission of huge volumes of sulphur dioxide from the fissure. Indeed, the Icelandic Met Office have since estimated that 11 million tons of SO2 were emitted over the course of the six-month eruption, along with almost 7 million tons of CO2 and vast quantities of other gases such as HCl. These gases hydrate and oxidise in the atmosphere to form acids, in turn leading to acid rain. The environmental impact of Holuhraun as a gas-rich point source is an area of active research.

By Jamie Farquharson, PhD researcher at Université de Strasbourg (France)

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Snow and ash in Iceland

Imaggeo on Mondays: Snow and ash in Iceland

Featuring today on the blog is the land of ice and fire: Iceland. That title was never better suited to (and exemplified), than it is in this photograph taken by Daniel Garcia Castellanos in June 2013. Snow capped peaks are also sprinkled by a light dusting of volcanic ash. Dive into this post to find out the source of the ash and more detail about the striking peak.

The picture is dominated by a snowed mountain in Southern Iceland, captured in June 2013, three years after the Eyjafjallajökull eruption. When Eyjafjallajokull erupted, it sent ash kilometers high into the atmosphere disrupting the air traffic in most Europe for weeks.

“This striking Icelandic landscape also inspired Tolkien’s fantasy in The Lord of the Rings,” explains Daniel, a researcher at the  Instituto de Ciencias de la Tierra Jaume Almera, in Barcelona.

Eyjafjallajokull is located in the Eastern Volcanic Zone in southern Iceland and the area photographed is among the youngest (less than 0.7 yr in age) and most active areas of Iceland, right on the contact where the Eurasian and the North American tectonic plates meet.The black rock seen in the image is tephra – fragments of rock that are produced when magma or or rock is explosively ejected (USGS) – from the neighboring Torfajökull rhyolitic stratovolcanic system, know for its cone shaped volcanoes built from layer upon layer of lava rich in silica and consequently very viscous. The light-green colour consists of the ubiquitous Icelandic moss.

In the image, the remnants of winter white snow are dotted with fine grey ashes from the Eyjafjallajökull 2010 eruption (about 30 km to the south of this image). Years after the Eyjafjallajökull eruption, the volcano still burns hot and its lighter ashes are still blown over southern Iceland providing this magical colors over the entire region.

Daniel’s adventures in Iceland didn’t stop at simply photographing stunning volcanic landscapes. He also had the privilege to see the inside of one of the volcanoes in the Eastern Volcanic Zone close up. Watch his descent into the Thrihnukagigur volcanic conduit over on his blog, Retos Terrícolas.