GeoLog

lava

Imaggeo on Mondays: In the belly of the beast

In the belly of the beast . Credit: Alexandra Kushnir (distributed via imaggeo.egu.eu)

Conducting research inside a volcanic crater is a pretty amazing scientific opportunity, but calling that crater home for a week might just be a volcanologist’s dream come true, as Alexandra postdoctoral researcher at the Institut de Physique du Globe de Strasbourg, describes in this week’s Imaggeo on Mondays.

This picture was taken from inside the crater of Mount St Helens, a stratovolcano in Washington State (USA). This particular volcano was made famous by its devastating explosive eruption in 1980, which was triggered by a landslide that removed most of the volcano’s northern flank.

Between 2004 and 2008 Mount St Helens experienced another type of eruption – this time effusive (where lava flowed out of the volcano without any accompanying explosions). Effusive eruptions produce lava flows that can be runny (low-viscosity) like the flows at Kilauea (Hawaii) or much thicker (high viscosity) like at Mount St Helens. Typically, high viscosity lavas can’t travel very far, so they begin to clump up in and around the volcano’s crater forming dome-like structures.  Sometimes, however, the erupting lava can be so rigid that it juts out of the volcano as a column of rock, known as a spine.

The 2004 to 2008 eruption at Mount St Helens saw the extrusion of a series of seven of these spines. At the peak of the eruption, up to 11 meters of rock were extruded per day. As these columns were pushed up and out of the volcanic conduit – the vertical pipe up which magma moves from depth to the surface – they began to roll over, evoking images of whales surfacing for air.

‘Whaleback’ spines are striking examples of exhumed fault surfaces – as these cylinders of rock are pushed out of the volcano their sides grind against the inside of the volcanic conduit in much the same way two sides of a fault zone move and grind past each other. These ground surfaces can provide scientists with a wealth of information about how lava is extruded during eruption. However, spines are generally unstable and tend to collapse after eruption making it difficult to characterize their outer surfaces in detail and, most importantly, safely.

Luckily, Mount St Helens provided an opportunity for a group of researchers to go into a volcanic crater and characterise these fault surfaces. While not all of the spines survived, portions of at least three spines were left intact and could be safely accessed for detailed structural analysis. These spines were encased in fault gouge – an unconsolidated layer of rock that forms when two sides of a fault zone move against one another – that was imprinted with striations running parallel to the direction of extrusion, known as slickensides. These features can give researchers information about how strain is accommodated in the volcanic conduit. The geologist in the photo (Betsy Friedlander, MSc) is measuring the dimensions and orientations of slickensides on the outer carapace of one of the spines; the southern portion of the crater wall can be seen in the background.

Volcanic craters are inherently changeable places and conducting a multi-day field campaign inside one requires a significant amount of planning and the implementation of rigorous safety protocols. But above all else, this type of research campaign requires an acquiescent mountain.

Because a large part of Mount St Helens had been excavated during the 1980 eruption, finding a safe field base inside the crater was possible. Since the 2004-2008 deposits were relatively unstable, the science team set up camp on the more stable 1980-1986 dome away from areas susceptible to rock falls and made the daily trek up the eastern lobe of the Crater Glacier to the 2004-2008 deposits.

Besides being convenient, this route also provides a spectacular tableau of the volcano’s inner structure with its oxidized reds and sulfurous yellows. The punctual peal of rock fall is a reminder of the inherent instability of a volcanic edifice, and the peculiar mix of cold glacier, razor sharp volcanic rock, and hot magmatic steam is otherworldly. That is, until an errant bee shows up to check out your dinner.

By Alexandra Kushnir, postdoctoral researcher at the Institut de Physique du Globe de Strasbourg, France.

This photo was taken in 2010 while A. Kushnir was a Masters student at the University of British Columbia and acting as a field assistant on the Mount St Helens project.

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: Lava highway in Kanaga Island

Imaggeo on Mondays: Lava highway in Kanaga Island

On a rare sunny day, Mattia Pistone (a researcher at the Smithsonian Institution in Washington DC) was able to capture this spectacular shot of Kanaga, a stratovolcano in the remote Western Aleutians, which is usually veiled by thick cloud.

The Western Aleutians form a chain of 14 large and 55 small volcanic islands, belonging to one of the most extended volcanic archipelagos on Earth (1900 km), stretching from Alaska across the northern Pacific towards the shores of Russia.

As part of a team of researchers, Mattia spent three grueling weeks in the isolated region. Being one of the most extended volcanic arc systems on Earth, the Aleutians can shed light on one of the most fundamental questions in the Earth sciences: how do continents form?

The Earth’s landmasses are made of continental crust, which is thought to be largely andesitic in composition. That could mean it is dominated by a silicon-rich rock, of magmatic origin, which is fine grained and usually light to dark grey in colour. However, basaltic magmas derived from the Earth’s upper mantle and erupted at active volcanoes contribute to chemistry of the continental crust. The fact that continental crust bears the chemical hallmarks of both suggests that the formation of new continents must somehow be linked to motion of magma and its chemistry.

Establishing the link between magma generation, transport, emplacement, and eruption can therefore significantly improve our understanding of crust-forming processes associated with plate tectonics, and, particularly, help determining the architecture and composition of the continental crust. The Alaska-Aleutian archipelago is a natural laboratory which offers a variable range of volcanic rocks. The islands present a perfect opportunity for scientists to try and understand the origin of continents.

By collecting samples of volcanic ash erupted at Kanaga and other volcanoes of the Aleutian arc, Mattia and his colleagues are currently investigating the origin of this volcanic ash. Understanding its chemistry allow the team to get a clearer idea of the conditions that were present while the magma was forming and ascending, for example, how much water and iron were present.

The team were based on the Maritime Maid research vessel, and hoped from island to island collecting samples and taking measurements of volcanic activity as part of a large research consortium called GeoPRISMS, funded by the National Science Foundation. The field work was supported by a Bell 407 helicopter and its crew.

Today’s featured image shows an andesitic lava flow erupted in 1906. The volcanic deposits were explored during the field geological mission by Mattia and the team. Kanaga last erupted in 1994. Ash from that eruption was found in the nearby island of Adak. Even at present, there is a highly active system of fumaroles at the summit of the volcano.

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: Life on bare lava

Life on bare lava

There are plenty of hostile habitats across the globe but some flora and fauna species are resourceful enough to adapt and make extreme environments their home. From heat-loving ants of the Sahara to microbes living in the light-deprived ocean depths, through to beatles who brave the bitterly cold Alaskan winter, there are numerous examples of plants, animals and bugs who strive in environments often considered too challenging to harbour life. In today’s post, brought to you by geomorphologist Katja Laute, we feature Vinagrerilla roja, a plant species adept at making difficult terrains its home.

Vinagrerilla roja (Rumex vesicarius) / the Canary Island bladderdock is one of the most successful endemic plants for colonizing new territory in arid and volcanic areas. The photo was taken on the crater rim of the volcano Montana Bermeja (157 m asl.), located at the northernmost edge of the volcanic island La Graciosa. The island was formed by the Canary hotspot and is today part of the protected Chinijo Archipelago Natural Park which shelters endemic and highly endangered species of the Canary Islands.

The volcano Montana Bermeja is composed of red lapilli (pea to walnut-sized fragments ejected during an eruption) which seems to impede any kind of life. But as the photo shows, the bladderdock is actively growing in this apparently hostile environment. That plant life emerges from such a barren and rough volcanic environment seems almost impossible.

Only very few pioneer species succeed and manage to survive in such harsh environments with little to no soil and under an almost desertic climate. Being located on the northern side of the crater rim enables the bladderdock to capture moisture out of the reoccurring Atlantic winds. As these pioneer species grow, their dead leaves and roots will enrich the soil with organic content providing the base for a chain of ecological succession.

By Katja Laute, researcher at IUEM, Brest, France

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/.

A journey into the Cordon Caulle volcano

A journey into the Cordon Caulle volcano

There is no escaping the fact that one of the perks of being an Earth scientist is the opportunity to visit incredible places while on field work. There is also no doubt that, geologist or not, walking on an active volcano is awe inspiring. Maybe you’ve had the experience of doing so yourself (if so, share your story with us in the comments section, we’d love to hear from you!), but if you haven’t then perhaps this post by Fabian Wadsworth, a volcanology PhD student at the Ludwig-Maximillian Universitat of Munich, Germany and part of the VUELCO project, might give you a feel for what it is like. In the post, Fabian describes his experience of journeying into the Cordon Caulle volcano, in Chile. A regular hiker of the German Alps, Fabian described the difference between climbing the impressive, but well-established trails of the Bavarian mountains to his trip to Chile: “a volcano, is dynamic on a large scale and provides little comfort at all. Hiking in active volcanic landscapes is, for me, more vivid and awakening for this reason.”

Ian Schipper with Jon Castro watching the mouth of the volcano churning out volcanic ash. Image Credit: Dr. Hugh Tuffen

Ian Schipper with Jon Castro watching the mouth of the volcano churning out volcanic ash. Image Credit: Dr. Hugh Tuffen

Dr. Hugh Tuffen, Dr. Ian Schipper and Prof. Jon Castro are volcanologists who study how magmas move, flow and explode on their way up to and over the Earth’s surface. They invited me to join them to Cordon Caulle in January 2014, just two years after it stopped erupting explosively in 2012. This team of researchers had been there in 2011 and in 2012 when it was most vigorously exploding and this post combines photographic reflections on their experience and some from my trip to give you a view of this place and the hike that led us into the volcano’s mouth.

This volcano is unique. It is a type of volcano that produces vast quantities of volcanic glass: obsidian. As well as erupting a huge volcanic cloud, typical of many eruptions, it slowly pushed out a dark tongue of obsidian that was hot enough to squeeze at glacial rates down and away from the source. This kind of eruption is rare and Cordon Caulle is the only time in history that such a phenomenon has been witnessed and studied. Scientists are working to understand how the region can be blanketed by volcanic ash – the result of massive explosions – while this seemingly gentle tongue is pushed out at the same time. In this way, obsidian is one of the most interesting materials to volcanologists and it draws us from all over the world to hike in these wonder-places.

From Puerto Monnt we travelled the 125 km northeast deep into the Andes. The hike to the volcano begins with a long journey through forest up to the highland plateaus. In 2012 this forested land was densely covered in ash from the volcano, Hugh told me, but by 2014 had fully recovered its lush green. From the plateau, the Andes unfold before you and make the many hours hiking feel insignificant. We carried our equipment as well as water, food and sleeping gear ready for a week or more spent in the shadow of the lava. In 2012, the noise of the eruption was intense and could be heard for kilometres around. By 2014-2015, all was quiet except for the buzzing of horseflies and the occasional creek from the heavy glass lava that still crumbled its way over the sand.

The forest land on the hike up in 2012. Hugh remembers the ash filling his hair and covering everything. Image Credit: Dr. Hugh Tuffen

The forest land on the hike up in 2012. Hugh remembers the ash filling his hair and covering everything. Image Credit: Dr. Hugh Tuffen

All around are the dunes of the highland plateaus, ribbed with rainwater gullies and patches of ice, which quench the thirst of hardworking volcanologists.

The dunes of the highland plateaus light up in the low sun. Image Credit: Dr. Hugh Tuffen

The dunes of the highland plateaus light up in the low sun. Image Credit: Dr. Hugh Tuffen

Walking from site to site is hard because the ash-laden sand is soft and sometimes you sink deep. Boots fill with pebble-sized volcanic shards that litter the ground from the last eruption. The distances are also deceptive. The lava, this slow-moving lava flow of glass, is almost forty meters high and many kilometres wide. We made basecamp at one end of the lava and each day hiked to places of interest, sometimes for hours, around the plateaus.

Hugh returned in 2015 yet again with Mike James and student Nathan Magnall and walked between slivers of cloud and tongues of glassy lava. Image Credit: Dr. Hugh Tuffen

Hugh returned in 2015 yet again with Mike James and student Nathan Magnall and walked between slivers of cloud and tongues of glassy lava. Image Credit: Dr. Hugh Tuffen

Starting before dawn, we took one day to set off for a place no one has seen before. We wanted to climb into the mouth of the volcano; into the vent from where the lava was being pushed out back in 2011 and 2012. No one has been into such a place before – the source of obsidian – and we thought that some of the observations we could make would hold a key to the puzzle of these eruptions. We hiked for hours around the great lava flow and to the back side of the vent area. We put on our gas masks to filter some of the still-circulating toxic volcanic gases and particles and we pulled our hats down against the fierce sun. We climbed the cone to the top and peered down into the vent area itself. From that vantage point we circled down the cone’s rim and into the vent proper. From there, gazing back up at the inner walls of the volcano, Hugh, Jon and Ian remembered watched this area explode and writhe just a few years before at the height of eruption. With an uneasy feeling, we set about learning what we could from the rocks and glass at the source of obsidian on our Earth’s surface.

Snatching our hard-won science, we returned to camp only after dark, hungry and thirsty and shared the small celebratory whisky ration we had brought with us. This day, inside the volcano, will remain among the most vivid in my life. And now, back in Munich, I can readily recall the sulfur smell and shine of the glass in that place.

Hugh, Ian and Jon will no doubt continue to return to this enigmatic place to learn more each year and will listen out for the next time obsidian erupts. Nathan Magnall has recently embarked on a PhD project focused on unveiling more of the mysteries of this place and Tuppence Stone, Toby Strong and Christiaan Munoz Salas, who joined Hugh in January 2015, filmed for the forthcoming BBC2 Patagonia series. You can also watch Hugh talk about Cordon Caulle in the video below too – skip to minute 13:00.

The poetry of the place should surely draw people from all disciplines to walk on those new stones – something I emphatically encourage you to do.

By Fabian Wadsworth, PhD Student Ludwig-Maximillian Universitat.

This post was originally posted on the Yetirama Blog. For the original post, please follow this link. We are very thankful to Dr. Hugh Tuffen for the use of his images in this post.

 

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