GeoLog

mountain glaciers

Imaggeo on Mondays: A dramatic avalanche from Annapurna South

Imaggeo on Mondays: A dramatic avalanche from Annapurna South

The Annapurna massif is located in an imposing 55 km long collection of peaks in the Himalayas, which behave as a single structural block. Composed of one peak (Annapurna I Main) in excess of 8000 m, a further thirteen peaks over 7000 m and sixteen more of over 6000 m, the massif forms a striking structure within the Himalayas. Annapurna South (pictured in today’s featured image), the 101st tallest peak in the world, towers 7219 m above sea level.

Glaciers in High Mountain Asia, a region that includes the Himalayas, contain the largest volume of ice outside the polar regions. The water trapped, as ice, in the glaciers of the Himalayas is an important source of drinking water, water for irrigation and water for hydropower generation throughout the region. As the Earth’s climate changes and negatively affects glaciers world-wide, scientists are working hard to understand what increased glacier melting means for the communities which depend on them.

Emily Hill is one such scientist. Her and a team of colleagues spent 2 weeks at Annapurna Base Camp in Nepal conducting measurements on the debris covered South Annapurna Glacier.

“We frequently heard avalanches but often they were over too quick to capture on camera. Fortunately, this was one of the largest and the camera was at the ready. These avalanches are an important source of mass for the glacier below,” reminisces Emily.

Glaciers accumulate ice throughout the winter months, as snow adds to the glacial column during the cold months. In addition, avalanches deliver additional snow throughout the year.

“I’m not too sure of the scale of the avalanche, it could probably have been a couple of 100 m across. The avalanche occurred early afternoon when the solar radiation was highest and increased melt is likely to have caused the failure,” describes Emily.

Avalanches in the region are not only an important source of mass accumulation for many of the glaciers, they also pose a hazard not only to climbers of these mountains but also further down along the tourist trail up to Annapurna Base Camp, where there is an avalanche risk section of the route.

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: Tongue of a small giant

Imaggeo on Mondays: Tongue of a small giant

In a world where climate change causes many mountain glaciers to shrink away, bucking the ‘melting’ trend is not easy. In today’s post, Antonello Provenzale, a researcher in Italy, tells us of one glacier in the Alps which is doing just that.

Mountain glaciers are retreating worldwide, with the possible exception of the Karakoram area. For most glaciers, ablation (ice melt) during the warm season is stronger than the accumulation of new ice by snowfall. As a result, while glacier ice flows downhill, the accelerated melting at lower elevation forces the terminus of the glacier to retreat uphill, with a net loss of ice volume.

Such behavior is especially evident on the southern flank of the Alps, where many mountain glaciers have dramatically reduced their dimensions, often fragmenting into smaller, detached pieces.

An important exception is represented by the Miage glacier in Val Veny, Val d’Aosta, northwestern Italy, at the base of the Mount Blanc massif. This glacier is covered with a thick layer of debris, which protects the underlying ice from the direct heating by sunlight. The rocks which make up the debris are poor heat conductors and thus preserve the ice beneath them, making this glacier particularly stable.

This glacier is so stationary that vegetation and trees have grown on its margins and on the debris. Several ponds punctuate the surface of the glacier, as well as some areas on its sides. The Miage lake, for example, is directly in contact with the slowly flowing ice and it is sometimes run by large outburst waves generated by huge blocks of ice and rock falling into the lake water.

This picture was taken in September 2014, during a field excursion of the Italian Glaciological Committee. The image is a composition (stitch) of several images taken with a moderate wide angle lens on a rangefinder digital camera.

By Antonello Provenzale studies Geophysical Fluid Dynamics, Earth System processes and Geosphere-Biosphere interactions at the Institute of Geosciences and Earth Resources of the National Research Council of Italy.

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: The retreating glaciers of the Svaneti Range, Georgia

Imaggeo on Mondays: The retreating glaciers of the Svaneti Range, Georgia

Today’s Imaggeo on Mondays picture shows the central section of the Svaneti Range, located in the Svaneti Region – a historic province of northwestern Georgia. The range is the second biggest range formed by the modern glaciation on the southern slopes of the Georgian Caucasus Mountains. In today’s post, Levan Tielidze, a researcher at Ivane Javakhishvili Tbilisi State University, writes about the ice capped peaks of these high mountains and highlights the precarious balance of this cryospheric system.

Svaneti range is approximately 100 km long and is distinguished by the height of its relief, as well as by the fact that the area covered by glaciers in the region exceeds that covered elsewhere in the southern slopes of the Georgian Caucasus.These features define the range and lead it to be divided into three sections: eastern, central (shown in this picture) and western. The eastern and western sections are lower in altitude than the central region and modern ice cover cannot be found there, with the exception of Mount Dadiashi which stands at 3535 m asl.

However, glaciers do cap the peaks in the central areas of the range, and can be found between the sections of Lasili and Leshnuri. Here is where you’ll find the highest peak of the mountain range: Laila (Laila-Lehli) -4009 m asl.

The glaciers in this region are retreating and losing volume. Data from the 1960s indicated that glaciers in the range numbered up to 48 and covered an area of approximately 27.76 km2 , equivalent to the size of just over 2500 football pitches. By 2014 the area covered by the glaciers in the region had shrunk by 27.5% and now only covers approximately 20.13 km2.

Some of the largest glaciers of the northern slopes of the range are formed on Laila peak, which itself is covered by a glacier cap. Among these glaciers the largest is Eastern Laila, located in the Khumpreri River basin. The glacier is formed of two ice streams which flow from separate valleys. In 1960 the glacier area was  close to 5.96 km2; its terminus ended at a height of 2300 meters asl. By 2014 the eastern Laila’s area decreased to 3.55 km2 and has retreated to an altitude of 2640 m asl. The total glacier length is now approximately 4.52 kilometers.

The glaciers are an important source of water for agricultural production in Georgia, and runoff in large glacially-fed rivers (Kodori, Enguri, Rioni, Tskhenistskali, Nenskra) supplies several hydroelectric power stations. In addition, glacier outburst floods and related debris flows are a significant hazard in Georgia and in the Caucasus. Future trends in glacier change are thus a topic of considerable interest to the region.

By Levan Tielidze, Institute of Geography, Tbilisi State University, Georgia

If you pre-register for the 2016 General Assembly (Vienna, 17 – 22 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/.

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