GeoLog

Geomorphology

Imaggeo on Mondays: A voyage through scales – The Badlands National Park, South Dakota.

Imaggeo on Mondays: A voyage through scales – The Badlands National Park, South Dakota.

Layer upon layer of sand, clay and silt, cemented together over time to form the sedimentary units of the Badlands National Park in South Dakota, USA. The sediments, delivered by rivers and streams that criss-crossed the landscape, accumulated over a period of millions of years, ranging from the late Cretaceous Period (67 to 75 million years ago) throughout to the Oligocene Epoch (26 to 34 million years ago). Interbedded greyish volcanic ash layers, sandstones deposited in ancient river channels, red fossil soils (palaeosols), and black muds deposited in shallow prehistoric seas are testament to an ever changing landscape.

Fast forward to 500,000 years ago and the landscape was very different. The Cheyenne River diverted the flow of the ancient small streams and rivers down its own river bed, in a geomorphological process called capture. The destructive power of the river dominated over the deposition of sediment. The river cut through the layers of sediments and produced the stunning landscape preserved today.

“The picture was taken in 2009 as I made a road trip with my brother across the United States, from Chicago to San Francisco,” explains Iain Willis, author of today’s Imaggeo on Mondays photograph. “After a long day’s drive, we approached the edge of the Badlands in the late afternoon after turning off route 90. I took the picture of my brother after we’d taken a short walk across a couple of peaks. I didn’t think the picture would be so dramatic as it was actually pretty overcast but as I was setting up the sun was momentarily piercing through. I originally shot in colour but after seeing it in monochrome, it looked far more dramatic.”

Dramatic enough for the judges of this year’s Imaggeo Photo Competition to award Willis the prize for the image which best represented the theme of the 2015 General Assembly: A Voyage through Scales.

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/.

The day the Earth trembled: A first-hand account of the 25 April Nepal earthquake

The day the Earth trembled: A first-hand account of the 25 April Nepal earthquake

On the 25th April 2015, Viktor Bruckman, a researcher at the Austrian Academy of Sciences, and a team of his colleagues were a few hours into a hike between the settlements of Lamabagar, in a remote area of northeastern Nepal, and the Lapchi Monastery when a magnitude 7.8 earthquake struck Nepal. Their journey cut short by the trembling Earth, stranded in the heights of the Himalayas, this is their personal experience of the Gorkha earthquake, summarised by EGU Communications Officer Laura Roberts. 

Researching land use in Nepal

Bruckman is part of an international team of researchers, from Austria, Nepal and China, studying the land use and forest resource management in the densely wooded and remote Gaurishankar Conservation Area, in eastern Nepal. Bruckman and his team want to better understand how the local communities are linked to the resources in the area and how their daily life has been affected since the introduction of the Conservation Area. Their research project also aims to explore how the ongoing building of the largest hydropower plant in Nepal: the Upper Tamakoshi Hydropower Project (UTHP) might disrupt the local populations.

The team conducted a set of semi-structured interviews in order to assess land management practices and the impact of new management policies since the Gaurishankar Conservation Area was set up in 2010 (by Dr. Viktor Bruckman).

The team conducted a set of semi-structured interviews to assess land management practices and the impact of new management policies since the Gaurishankar Conservation Area was set up in 2010 (Credit: Dr. Viktor Bruckman).

To answer these questions, Bruckman and his colleagues travelled to Nepal in April to participate in workshops with government and institutional bodies based in Kathmandu, as well as visiting local communities deep within the Gaurishankar Conservation Area to conduct face-to-face interviews.

Beyond the hydropower construction site there are no roads, meaning the team had to hike across the rugged Himalayas to reach the residents of the most remote settlements and the target location for setting up monitoring plots. Their planned route would take them 25 km from Lamabagar, at 2000 m above sea level, reaching Lapchi Monastery, close to the Tibetan border, two days later having climbed to an altitude of 3800 m.

The hike

On the morning of the 25th April, a team composed of Bruckman, his Nepalese colleague Prof. Devkota, Devkota’s student Puskar and Prof. Katzensteiner from the University of Natural Resources and Life Sciences Vienna (BOKU), set off on the trek to Lapchi. They were accompanied, albeit a little later following breakfast, by three porters who carried the bulk of their scientific equipment, some food and other ‘home comforts’ such as sleeping bags and mattresses. Given the physical effort the trek would involve, many of the food supplies were delivered to Lapchi via helicopter, a few days in advance – local porters would meet the team at settlements downstream of the monastery and deliver the provisions over the course of the next few days.

Despite the constant drizzle and strains of the climb, the entire team was stuck by the beauty of the surroundings: steep cliffs of metamorphosed sedimentary series (Tethys Himalaya within the Central Himalayan Domain), diverse mix deciduous forests and glistening streams.

The moment everything changed

At 12:05, not long after having traversed the most challenging section of the hike thus far, walking along the Lapchi River Valley, the ground under the team’s feet started to quiver. The quiver quickly grew to a strong shake dislodging football sized rocks from the surrounding slopes. The realisation hit the researchers that they were experiencing an earthquake and their primary concern was to seek shelter from the ongoing rock fall triggered by the ground shaking.

“Large rocks, with size equal to small houses, smashed into the river breaking into smaller pieces which where flung in all directions”, describes Bruckman, who by now had found protection, alongside Prof. Devkota, behind a large tree.

A few moments later, the earthquake ended and both emerged from behind the tree unharmed.

Left: Rockfall from the opposite cliffs made our location a highly dangerous place. Right: Seconds after the main tremor was over, everything was changed. The river color turned brown, dust and Sulphur smell was in the air and the path was destroyed by small landslides or rocks (Credit: Prof. Dr. Klaus Katzensteiner).

Left: Rockfall from the opposite cliffs made the researchers’ location a highly dangerous place. Right: Seconds after the main tremor was over, everything was changed. The river color turned brown, dust and Sulphur smell was in the air and the path was destroyed by small landslides or rocks (Credit: Prof. Dr. Klaus Katzensteiner).

They found Prof. Katzensteiner sheltering under a large rock overhang, but there was no sign of Puskar. The three men eyed up a large boulder which had come to rest on the path and feared the worst. Some minutes later, Puskar appeared, unharmed, along the path accompanied by a lama – a Buddhist monk – who’d encouraged the student to run up hill away from the projectiles from the river.

“The lama saved our student’s life; he was almost hit by a large rock which destroyed the water bottle attached to his backpack,” says Bruckman.

A stroke of luck

With their porters some hours trek behind them, almost no food supplies and no other equipment, and worried about potential flash floods as a result of landslides upstream, the group decided to make their way out of the valley and head back towards Lamabagar, only to find that the trail had been wiped out by a massive landslide.

The lama’s knowledge of the local terrain was invaluable as he guided the scientists to a meditation centre, where a group of about 20 lamas kindly took them in, sharing their food, offering tea and a place to sleep.

Having found a place of shelter, Bruckman and his colleagues, knowing how worried their families would be, were desperate to contact them. But amongst the high peaks of the Himalayas, in one of the most remote parts of Nepal, mobile phone signal is hard to come by. Only once, on the morning of the 26th of April, were the group successful in reaching loved ones, but it was enough: they were able to communicate they had survived, but were now trapped in the Lapchi River Valley.

The retreat where lamas provided the scientists with food and shelter (Credit: Prof. Dr. Klaus Katzensteiner).

The retreat where lamas provided the scientists with food and shelter (Credit: Prof. Dr. Klaus Katzensteiner).

Back home, a rescue mission started: The scientists’ families, the officials of their institutions, their countries Foreign Ministries’, Embassies and the local military all rallied to locate and bring home the researchers. Five days after first arriving at the Buddhist meditation centre, the group was rescued by a helicopter, which took them to the safety of military camp Charikot.

Retracing their steps, this time in a helicopter, Bruckman and his colleagues realised the scale of the devastation caused by the earthquake. The first village they’d intended to reach on their hike, Lumnang, was completely destroyed. 80% of the building structures in the valley had disappeared. Landslides has wiped out large sections of the trail, meaning returning to Lamabagar would have been out of the question.

Tragedy

The team’s porters, travelling behind the researchers when the earthquake hit, were far less fortunate. Tragically, one of the team’s porters was killed by a landslide triggered by the earthquake, whilst another was seriously injured. Only one returned safely to Lamabagar. Whilst hiking, the scientists overtook several groups of people also headed towards Lapchi and a team of hydropower experts – they are all reported missing.

The region, already damaged by the April 25th earthquake, was further rocked by a powerful, magnitude 7.3, aftershock. Since then, Bruckman and his colleagues have been unable to reach their contacts in Lamabagar. Reports indicate that hardly any structures were left standing in the village.

A view of Lamabagar prior to the earthquakes. At 2000m a.s.l., the village lies on the flat riverbed of the Upper Tamakoshi River, which developed as a consequence of a massive landslide (probably earthquake-induced) in the past (by Dr. Viktor Bruckman).

A view of Lamabagar prior to the earthquakes. At 2000m a.s.l., the village lies on the flat riverbed of the Upper Tamakoshi River, which developed as a consequence of a massive landslide (probably earthquake-induced) in the past (Credit: Dr. Viktor Bruckman).

The future

Following the earthquake, the scientists realise that the original research aims are no longer valid and “we would probably not meet the communities’ needs if we stick to the original ideas”, explains Bruckman.

Therefore, the plan is to carefully assess the regions current situation and develop a new research proposal which will focus on supporting the remote villages on a long-term and sustainable basis. In the event of any future field work in the region, the scientist will ensure they carry, at the very least, an Emergency Position Indicating Radio Beacon (EPIRB), if not a satellite phone.

Science aside, their experience in the Nepal means the scientists were deeply touched by the kindness extended to them by the lamas and now seek to support the communities affected by the earthquakes. In particular they want to raise funds for the families of the porters who passed away and were injured while transporting their supplies.

 By Laura Roberts, EGU Communications Officer

A message from Bruckman and his colleagues

Please help us support the affected families.

For the purpose of collecting donations, we opened an account at the University of Natural Resources and Life Sciences Vienna (BOKU). Funds will be collected in a transparent manner and directly used for supporting the porter’s families and the villagers of Lumnang, who have lost everything and they will most likely not receive help from other sources soon. We will facilitate support through the trustworthy Nepalese project partners (including full documentation) and the Lamas of Lapchi monastery and from the retreat where we were able to stay. Please help us to support this remote region; even a small contribution is very much appreciated. Our direct contacts ensure that 100% of the donations reach the target group.

Here are the account details for wire transfer:

Recipient: Universität für Bodenkultur Wien, Spenden IBAN: AT48 3200 0018 0050 0512 BIC: RLNWATWWXXX Payment reference: 7912000003

Payments via Credit Card are also possible (Master Card and Visa). Should you wish to pay per credit card, please send an e-mail containing your name, address, card number, expiry date and security code (3-digits) to c.hofer@boku.ac.at.

We thank you very much for your contribution!

The team after their ordeal. They extend their deepest condolences to the family of the porter that lost his life during our the Prof. Dr. Klaus Katzensteiner).

The team after their ordeal. They extend their deepest condolences to the family of the porter who lost his life during the expedition. (Credit: Prof. Dr. Klaus Katzensteiner).

 

This blog post is a summary of: How a geophysical extreme event dramatically changed fieldwork plans – a personal account of the Gorkha Earthquake, originally posted on the EGU’s Energy, Resources and the Environment Division Blog.

For more information about the 2015 April and May earthquakes, please see the links provided in the original blog post. You can also access more information via this information briefing issued by the EGU.

Imaggeo on Mondays: Seeing the world through a pothole

Imaggeo on Mondays: Seeing the world through a pothole

A beautiful image of a forest reflected in a pool of water within a pothole in southern Finland is this Monday’s Imaggeo image and it brought to you by Mira Tammelin, a Finish researcher.

The photo illustrates a pothole in the Askola pothole area in southern Finland. The pothole area is situated on the steep slopes next to river Porvoonjoki, approximately 70 kilometers to the northeast from the capital city Helsinki and 30 kilometers to the north from the Gulf of Finland. The potholes are carved into an outcrop of Proterozoic rocks that is surrounded by boreal taiga forest, which consists of mainly of coniferous tress such as pine, spruce and larch.

Potholes are cylinder-shaped cavities that form when stones carried by water start to circle in an eddy and churn the surrounding rock for an extended period of time. The majority of Finnish potholes, including those in Askola, were formed under a melting continental ice sheet during the late stages of the last glaciation 13 000 – 10 000 years ago. The area is also archaeologically important as it is one of the first places in Finland where humans settled after the deglaciation.

The more or less 20 potholes in Askola vary in shapes and sizes and some of them belong to the largest in the world. The largest pothole in Askola, called The Giant’s Tub, is 4.2 meters wide and 10.3 meters deep. The pothole in the picture is one of the smaller potholes in the area with a diameter less than a meter. It has filled with rainwater thus reflecting a beautiful, sunny midsummer day.

By Mira Tammelin, Research Fellow at the University of Turku, Finland.

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: Foehn clouds

This week’s post is brought to you by Stefan Winkler, a Senior Lecturer in Quaternary Geology & Palaeoclimatology, who explains how the mountain tops of the Southern Alps become decorated by beautiful blanket-like cloud formations.

The Sothern Alps of New Zealand are a geoscientifically dynamic environment in all aspects. They are arguably one of the youngest high mountain ranges in the world formed at the plate tectonic boundary between the Australian and the Pacific Plate. Their dominating tectonic structure, the Alpine Fault running some 600 km mainly parallel to the mountain ranges of New Zealand’s South Island, caused not only an impressive horizontal displacement of rock formations, but also an overall vertical uplift of estimated c. 20 km during the past 10 – 15 Million years. Aoraki/Mt.Cook visible in the left background on the image with its height of ‘only’ 3724 m a.s.l. is the highest peak of the mountain range that is currently uplifted by 4 – 5 mm per year. Together with reconstructed uplift rates of up to 10 mm per year for the centre of the Southern Alps this indication how efficient and important weathering and erosion processes are in this region.

Foehn clouds over Aoraki/Mt.Cook. Credit: Stefan Winkler (distributed via imaggeo.egu.eu)

Foehn clouds over Aoraki/Mt.Cook. Credit: Stefan Winkler (distributed via imaggeo.egu.eu)

The ranges of the Southern Alps rise just 10 – 15 km inland the West Coast of the South Island as a wall parallel to the coast line up to 3,000 metres and more. They are a major topographic obstacle for the predominantly westerly airflow and provide a classic example of how ‘föhn’ winds are generated along mountain ranges perpendicular to an air flow. Föhn winds are dry and warm, forming on the downside of a mountain range. On the western slopes of the Southern Alps, orographic precipitation amounts to impressive 5,000 mm at the base and 10,000 mm + on in the high-lying accumulation areas of the mountain glaciers concentrating around the Main Divide. At and east of the Main Divide this locally named ‘Nor’wester’ creates impressive foehn clouds (altocumulus lenticularis, hogback clouds, seen in this week’s Imaggeo on Mondays image) that form in waves parallel to the Main Divide and are often streamlined by the high wind speed. The frequent occurrence of strong and warm Nor’westers contributes to the sharp decline of precipitation immediately east of the Main Divide.

The foreground of the image displays another aspect of this dynamic environment: the current wastage and retreat of glaciers in New Zealand. The section of the proglacial lake with its sediment-laden greyish water colour on the image would still have been covered by the debris-covered lower glacier tongue of Mueller Glacier only 15 years ago. Now, the terminus has retread to a position to the left outside the image. The lake is bounded by the glacier’s lateral moraine – unconsolidated accumulations of rock and soil debris resulting from weathering of the rock walks surrounding a glacire – that are more than 120 m high from base to top (or crest, to give it its technical name) and were last overtopped during the so-called ‘Little Ice Age’ when the glacier surface reached higher than its crest. At this glacier, the maximum of this Little Ice Age has been dated to 1720/30, but as late as during the late 20th century it remained close to its frontal maximum position and had only shrunk vertically. Today the lateral moraines are heavily reworked and eroded by paraglacial processes following the latest vertical and horizontal ice retreat. In some places on Mueller Glacier’s foreland the crest of lateral moraines retreat up to 1 m per year back and give again evidence of a very dynamic geo-ecosystem.

By Stefan Winkler, Senior Lecturer in Quaternary Geology and Palaeoclimatology at the Univeristy of Canterbury.

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/.

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