GeoLog

Cryospheric Sciences

When mountains collapse…

When mountains collapse…

Jane Qiu, a grantee of the Pulitzer Center on Crisis Reporting, took to quake-stricken Nepal last month — venturing into landslide-riddled terrains and shadowing scientists studying what makes slopes more susceptible to failure after an earthquake. The journey proved to be more perilous than she had expected.

What would it be like to lose all your family overnight? And how would you cope? It’s with these questions in mind that I trekked with a heavy heart along the Langtang Valley, a popular touristic destination in northern Nepal.

Exactly a year ago this week, this remote Himalayan watershed witnessed the single most horrific canastrophy of the Gorkha Earthquake: a massive avalanche engulfed Langtang and nearby villages, leaving nearly 400 people killed or missing.

The quake shook up ice and snow at five locations along a 3-kilometre ridge between 6,800-7,200 metres above sea level. They went into motion and swept huge amounts of loose debris and fractured rocks along their way — before crashing several kilometres down to the valley floor.

The avalanche generated 15 million tonnes of ice and rock, and sent powerful wind blasting down the valley, flattening houses and forests. Wind speeds exceeded 322 kilometres per hour and the impact released half as much energy as the Hiroshima nuclear bomb. Nothing in its path could have survived.

A pile of commemorating stones on the debris that buried Langtang and nearby villages last April, killing and leaving missing nearly 400 people. (Credit: Jane Qiu)

A pile of commemorating stones on the debris that buried Langtang and nearby villages last April, killing and leaving missing nearly 400 people. (Credit: Jane Qiu)

Where the villages used to stand is now a gigantic pile of debris, up to 60 metres deep. It’s effectively a mass grave where people pile up stones and put up prayer flags to mark where their loved ones used to live.

It’s hard to come to terms with the scale of the devastation. Everybody in the valley has lost somebody to the monstrous landslide. About two dozen children from 16 families, who were in schools in Kathmandu during the earthquake, lost all their family in the matter of a few minutes.

It’s a sombre reminder of how dangerous it can be in the Himalayas — where people live so close to ice and where population growth and the search for livelihood often push them to build in hazardous areas.

The only building in the village of Langtang that survived the avalanche. The rocky enclave protected it from the crushing debris and the powerful blast. (Credit: Jane Qiu)

The only building in the village of Langtang that survived the avalanche. The rocky enclave protected it from the crushing debris and the powerful blast. (Credit: Jane Qiu)

Under-appreciated danger

The Langtang tragedy also reminds us how deadly landslides can be during an earthquake — a danger that is often under-appreciated. While earthquakes and landslides are like conjoined twins that go hand in hand, most of the resources go into building houses that can sustain strong shaking, and far too little into mitigating landslide risks.

In both the 2005 magnitude-7.6 Kashmir Earthquake in Pakistan and the 2008 magnitude-7.8 Wenchuan Earthquake in China — which killed approximately 26,000 and 90,000 people, respectively — a third of the fatalities were caused by landslides. While it’s certainly important to build earthquake-proof houses, it’s equally important to build them at safe locations.

In addition to the killer avalanche in Langtang, the Gorkha Earthquake unleashed over 10,000 landslides across Nepal, which blocked rivers and damaged houses, roads, and hydropower stations. Many valleys are totally shattered — with landslide scars running down from the ridge top like gigantic waterfalls, and numerous small failures marring the landscape like fireworks shooting across the sky.

Driving along the Aniko Highway that connects Nepal with Tibet, it’s not difficult to see that many houses had survived the shaking only to be crushed by debris flows and rock falls. The border remains closed because of continuing landslide hazards. The highway, which used to have some of the worst traffic jams in Nepal, is totally deserted.

A building in Kodari — which used to be a bustling trade town at the Nepal-Tibet border — was unscathed during the earthquake only to be damaged by large rock falls. (Credit: Jane Qiu)

A building in Kodari — which used to be a bustling trade town at the Nepal-Tibet border — was unscathed during the earthquake only to be damaged by large rock falls. (Credit: Jane Qiu)

Enduring legacy

A major concern is that Nepal will suffer from more severe landslides than usual for a long time. During the last monsoon, the landslide rate was about ten times greater than an average year. And my trek along the Langtang Valley was accompanied by frequent sound tracks of falling rocks and shifting slopes. A number of times, I had to run from boulders crushing down onto the trail — a clear sign that there are lots of instability in the system.

The instability could go on for years or even decades and will be exacerbated by rainfall and aftershocks. This enduring legacy is often not fully taken on board in quake recovery — with devastating consequences. Eight years after the Wenchuan Earthquake, for instance, settlements built after the disaster continue to be inflicted by a heightened level of landslides, which cause floods and destroy infrastructures.

This points to the importance of rigorous risk assessment before reconstruction and close monitoring afterwards. There is also an urgent need to better understand what makes mountainsides more susceptible to landslides after an earthquake and how they recover over time.

To achieve that end, several research groups went into landslide-ridden areas in Gorkha’s immediate aftermath. They wanted to capture what happened to the landscape immediately after the quake, so they could track the changes in the coming years.

Early warning

Last month, I joined one such team — consisting of Christoff Andermann, Kristen Cook and Camilla Brunello, of the German Research Centre for Geosciences (GFZ) in Potsdam, Germany, and their Nepalese coordinator Bhairab Sitaula — on a field trip along the Arniko Highway.

That was their fourth trip in Nepal since last June when they began to map the landslides and installed a dozen broadband seismometers, along with weather stations and river-flow sensors, over 50 square kilometres of badly shaken terrains.

The team often attracted a few curious onlookers when they worked away, but nothing provoked more excitement than the drone, says Cook. The crowd, especially kids, were thrilled to see the little robotic device buzzing around like a gigantic mosquito, she adds. A camera and sensors onboard can help them to locate the landslides and monitor debris movement, especially after rainstorms.

 

Christoff Andermann, Camilla Brunello and Bhairab Sitaula performing maintenance on a broadband seismometer and weather station near the village of Chaku on the Arniko Highway (Credit: Jane Qiu)

Christoff Andermann, Camilla Brunello and Bhairab Sitaula performing maintenance on a broadband seismometer and weather station near the village of Chaku on the Arniko Highway (Credit: Jane Qiu)

Another exciting aspect of their research is the use of seismology to probe geomorphic processes over a large area. Landslides are effectively earthquakes that occur near the surface, and produce signals that can be picked up by seismometers.

The team, led by Niels Hovius of GFZ, can detect precursory seismic signals days before a landslide happens. They also study ground properties by measuring how traffic vibrations travel through the ground.

Because seismic waves travel faster when subsurface materials are wet, the researchers are able to trace how rainfall penetrates into and through the ground. This determines the pressure of water in spaces between soil and rock particles, a key factor controlling slope stability.

Such studies will one day allow researchers to determine the rainfall thresholds that could precipitate a landslide and capture deformation precursors days in advance. This offers a real prospect of an effective early warning system, which is urgently needed in a country that is increasingly plagued by landslides.

By Jane Qiu, freelance science writer in Beijing

Further reading

Qiu, J. Listening for landslides, Nature 532, 428-431 (2016).

Jane Qiu, an awardee of the 2012 EGU Science Journalism Fellowship, is a Chinese freelance science writer in Beijing. She is passionate about the origin and evolution of the Tibetan Plateau and surrounding mountain ranges—a vast elevated land also known as the Third Pole because it boasts the largest stock of ice outside the Arctic and the Antarctic. 

Travelling extensively across the Third Pole, up to 6,700 meters above sea level (http://science.sciencemag.org/content/351/6272/436), Qiu has covered wide-ranging topics—from the meltdown of Himalayan glaciers, grassland degradation, the origin of woolly rhino, to the people of Tibet. Her work regularly appears in publications such as Nature, Science, The Economist, Scientific American, and SciDev.Net.

Qiu’s journey to the Third Pole began with Marine Biological Laboratory’s Logan Science Journalism Fellowship that allowed her to travel to the Arctic and the Antarctic and report climate change first hand. These experiences sowed the seeds for her later fascination with geoscience and environmental studies, and afforded her the insight to draw parallels between these geographically diverse regions.

Announcing the winners of the EGU Photo Contest 2016!

Announcing the winners of the EGU Photo Contest 2016!

The selection committee received over 200 photos for this year’s EGU Photo Contest, covering fields across the geosciences. Participants at the 2016 General Assembly have been voting for their favourites throughout the week  of the conference and there are three clear winners. Congratulations to 2016’s fantastic photographers!

 Glowing_Ice. Credit:  Vytas Huth (distributed via  imaggeo.egu.eu). Ice on Jokulsarlon beach in Iceland. Ice calving off the Breidamerkurjokull, one of the glaciers comprising the Vatnajokull, the largest glacier in Iceland. The is retreating rapidly, and in the process has created a large glacial lagoon known for its spectacular icebergs.

Glowing_Ice. Credit: Katharine Cashman (distributed via imaggeo.egu.eu). Ice on Jokulsarlon beach in Iceland. Ice calving off the Breidamerkurjokull, one of the glaciers comprising the Vatnajokull, the largest glacier in Iceland. The is retreating rapidly, and in the process has created a large glacial lagoon known for its spectacular icebergs.

 'Living flows'. Credit:  Marc Girons Lopez (distributed via  imaggeo.egu.eu). River branches and lagoons in the Rapa river delta, Sarek National Park, northern Sweden. The lush vegetation creates a stark contrast with the glacial sediments transported by the river creating a range of tonalities.

Living flows’. Credit: Marc Girons Lopez (distributed via imaggeo.egu.eu). River branches and lagoons in the Rapa river delta, Sarek National Park, northern Sweden. The lush vegetation creates a stark contrast with the glacial sediments transported by the river creating a range of tonalities.

 'There is never enough time to count all the stars that you want.' . Credit:  Vytas Huth (distributed via  imaggeo.egu.eu). The centre of the Milky Way taken near Krakow am See, Germany. Some of the least light-polluted atmosphere of the northern german lowlands.

‘There is never enough time to count all the stars that you want.’ . Credit: Vytas Huth (distributed via imaggeo.egu.eu). The centre of the Milky Way taken near Krakow am See, Germany. Some of the least light-polluted atmosphere of the northern german lowlands.

In addition, this year, to celebrate the theme of the EGU 2016 General Assembly, Active Planet, the photo that best captured the theme of the conference was selected by the judges. The winner is the stunning ‘Mirror Mirror in the sea’, by Mario Hopmann! Congratulations! Scroll to the top of this post to view Mario’s image.

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/.

Photo Contest finalists 2016 – who will you vote for?

The selection committee received over 400 photos for this year’s EGU Photo Contest, covering fields across the geosciences. The fantastic finalist photos are below and they are being exhibited in Hall X2 (basement, Brown Level) of the Austria Center Vienna – see for yourself!

Do you have a favourite? Vote for it! There is a voting terminal (also in Hall X2), just next to the exhibit. The results will be announced on Friday 22 April during the lunch break (at 12:15).

 'Icebound blades of grass' . Credit: Katja Laute (distributed via imaggeo.egu.eu). A close up of blades of grass totally coated with ice. The photo was taken at sunset along the shoreline of Selbusjøen, a lake in middle Norway. The coating of the ice was built through the interplay of wave action and the simultaneously freezing of the water around the single blades of grass.

‘Icebound blades of grass’. Credit: Katja Laute (distributed via imaggeo.egu.eu). A close up of blades of grass totally coated with ice. The photo was taken at sunset along the shoreline of Selbusjøen, a lake in middle Norway. The coating of the ice was built through the interplay of wave action and the simultaneously freezing of the water around the single blades of grass.

 'There is never enough time to count all the stars that you want.' . Credit: Vytas Huth (distributed via imaggeo.egu.eu). The centre of the Milky Way taken near Krakow am See, Germany. Some of the least light-polluted atmosphere of the northern german lowlands.

‘There is never enough time to count all the stars that you want’. Credit: Vytas Huth (distributed via imaggeo.egu.eu). The centre of the Milky Way taken near Krakow am See, Germany. Some of the least light-polluted atmosphere of the northern german lowlands.

 'Full moon over Etna's fire'. Credit: Severine Furst (distributed via imaggeo.egu.eu). Etna is one of the most active volcano on Earth but also one the most monitored. As soon as instruments show any signs of volcanic activity, scientists from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) of Catania urge to the summit to gather various eruption data. In this summer evening, the fresh wind sweep the clouds to reveal the rise of the full moon over one of Etna's summit craters where a strombolian eruption is taking place.

‘Full moon over Etna’s fire’. Credit: Severine Furst (distributed via imaggeo.egu.eu). Etna is one of the most active volcano on Earth but also one the most monitored. As soon as instruments show any signs of volcanic activity, scientists from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) of Catania urge to the summit to gather various eruption data. In this summer evening, the fresh wind sweep the clouds to reveal the rise of the full moon over one of Etna’s summit craters where a strombolian eruption is taking place.

 'There is never enough time to count all the stars that you want.' . Credit: Vytas Huth (distributed via imaggeo.egu.eu). Ice on Jokulsarlon beach in Iceland. Ice calving off the Breidamerkurjokull, one of the glaciers comprising the Vatnajokull, the largest glacier in Iceland. The is retreating rapidly, and in the process has created a large glacial lagoon known for its spectacular icebergs.

‘Glowing Ice’. Credit: Vytas Huth (distributed via imaggeo.egu.eu). Ice on Jokulsarlon beach in Iceland. Ice calving off the Breidamerkurjokull, one of the glaciers comprising the Vatnajokull, the largest glacier in Iceland. The is retreating rapidly, and in the process has created a large glacial lagoon known for its spectacular icebergs.

 'Ice lace flower'. Credit: Maria Elena Popa (distributed via imaggeo.egu.eu). Early morning shot of a spider web with frozen water droplets. The photo has been turned upside down, to make it look like a flower.

‘Ice lace flower’. Credit: Maria Elena Popa (distributed via imaggeo.egu.eu). Early morning shot of a spider web with frozen water droplets. The photo has been turned upside down, to make it look like a flower.

 Sphalerite's "Transformer"'. Credit: Dmitry Tonkacheev (distributed via imaggeo.egu.eu). The bulk of Au wire "boards" on the dark-brown phase surface in the form of fascination crystals (usually arborescent). Some of them look like a weapon from the "Transformers" arsenal or parts of his armor. Also bright diamond luster of this creature makes our "Knight" even more ultra-modern.

‘Sphalerite’s “Transformer”‘. Credit: Dmitry Tonkacheev (distributed via imaggeo.egu.eu). The bulk of Au wire “boards” on the dark-brown phase surface in the form of fascination crystals (usually arborescent). Some of them look like a weapon from the “Transformers” arsenal or parts of his armor. Also bright diamond luster of this creature makes our “Knight” even more ultra-modern.

 'Nimbostratus painting the sky'. Credit: y María Burguet (distributed via imaggeo.egu.eu). This photo was taken in Valencia (Spain) during a storm formation. Nimbostratus are described as a grey cloud cover with a veiled appearance due to the precipitation (liquid or solid) holded within them. They are formed when a large layer of relatively warm and humid air ascend above a cold air mass. Together with the Altostratus, it is the core of a warm front.

‘Nimbostratus painting the sky’. Credit: María Burguet (distributed via imaggeo.egu.eu). This photo was taken in Valencia (Spain) during a storm formation. Nimbostratus are described as a grey cloud cover with a veiled appearance due to the precipitation (liquid or solid) held within them. They are formed when a large layer of relatively warm and humid air ascend above a cold air mass. Together with the Altostratus, it is the core of a warm front.

 'Living flows'. Credit: Marc Girons Lopez (distributed via imaggeo.egu.eu). River branches and lagoons in the Rapa river delta, Sarek National Park, northern Sweden. The lush vegetation creates a stark contrast with the glacial sediments transported by the river creating a range of tonalities.

‘Living flows’. Credit: Marc Girons Lopez (distributed via imaggeo.egu.eu). River branches and lagoons in the Rapa river delta, Sarek National Park, northern Sweden. The lush vegetation creates a stark contrast with the glacial sediments transported by the river creating a range of tonalities.

 'View of the Mausoleum'. Credit: Mike Smith (distributed via imaggeo.egu.eu). The north Antrim coast in Northern Ireland, featuring one of the most spectacular coastal roads. In the distance the Mussenden Temple, built in 1785 as a reclusive library 40 m above the Atlantic Ocean.

‘View of the Mausoleum’. Credit: Mike Smith (distributed via imaggeo.egu.eu). The north Antrim coast in Northern Ireland, featuring one of the most spectacular coastal roads. In the distance the Mussenden Temple, built in 1785 as a reclusive library 40 m above the Atlantic Ocean.

 'Frozen angel'. Credit: Mikhail Varentsov (distributed via imaggeo.egu.eu). Go-Pro camera, covered by hoarfrost, at sunrise, looks like fantasy-style angel with sword and banner. Photo made during NABOS-2015 expedition.

‘Frozen angel’. Credit: Mikhail Varentsov (distributed via imaggeo.egu.eu). Go-Pro camera, covered by hoarfrost, at sunrise, looks like fantasy-style angel with sword and banner. Photo made during NABOS-2015 expedition.

In addition, this year, to celebrate the theme of the EGU 2016 General Assembly, Active Planet, the photo that best captured the theme of the conference was selected by the judges. The winner is this stunning photo entitled ‘Mirror mirror in the sea…’, by Mario Hoppmann! Congratulations! This too is being exhibited in Hall X2 (basement, Brown Level) of the Austria Center Vienna.

 'Mirror Mirror in the sea...' . Credit: Mario Hoppmann (distributed via imaggeo.egu.eu). A polar bear is testing the strength of thin sea ice. Polar bears and their interaction with the cryosphere are a prime example of how the biosphere is able to adapt to an "Active Planet". They are also a prime example of how the anthropogenic influence on Earth's climate system endangers other lifeforms.

‘Mirror Mirror in the sea…’ . Credit: Mario Hoppmann (distributed via imaggeo.egu.eu). A polar bear is testing the strength of thin sea ice. Polar bears and their interaction with the cryosphere are a prime example of how the biosphere is able to adapt to an “Active Planet”. They are also a prime example of how the anthropogenic influence on Earth’s climate system endangers other lifeforms.

Imaggeo on Mondays: Mother Tree

 Mother Tree, Mongolia . Credit: Gantuya Ganbat (distributed via  imaggeo.egu.eu)

Mother Tree, Mongolia . Credit: Gantuya Ganbat (distributed via imaggeo.egu.eu)

Landlocked, home to mountains, deserts and the southernmost permafrost territories, Mongolia’s climate is harsh.  Warm, often humid summers, give way to freezing winters where temperatures dip as low as -25°C. Rainfall is restricted to a short period in the summer months of June and August.

These climatic factors, combined with the lack of a strong forest management strategy and anthropogenic influences, mean that only 11% of the vast 1567 million km²  of the Mongolian territory (that is larger than the area covered by Germany, Italy, France and the UK combined), is covered by forests.

The majority of forests are located in the northern part of the country, along the border with Russia. They form a transition zone between the cold, subarctic forests of Siberia and the vast steppes of southern Asia.

This week’s Imaggeo on Mondays image is the imposing, and holy, Mother Tree. Located in one of the many Tujiin Nars (pine forests) of the northern Selenge Aimag province, this giant pine is worshiped by locals who believe if you ask a wish of the Mother Tree, it will come true. Its lowermost branches are lavishly decorated with Khadags, traditional Tibetan Buddhist ceremonial scarves, brought as offerings by locals and foreign visitors alike.

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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