News: 17 July and 21 September 2016 glacier collapses in Tibet
Analysis and documentation by GAPHAZ:
On 17 July 2016 a glacier collapse of roughly 60-70 million cubic metres in volume caused a huge ice avalanche in western Tibet, west of the Aru Co lake, Rutog county, Ngari prefecture, killing 9 herders and hundreds of animals.
An international group of scientists affiliated to GAPHAZ was puzzled about the occurrence of the similarly looking event in Tibet. Strikingly unusual characteristics were this avalanche’s immense size and its distant travel on a very low slope. The group investigated the glacier development before the 17 July 2016 glacier collapse in Tibet and the characteristics of the resulting avalanche, based on a large number of visual and radar satellite images and on computer models. The analyses showed that the 17 July glacier collapse was preceded by precursory movements and crevassing since at least 2013. Such slow glacier destabilisations – called glacier surges – are common in some parts of the world, for instance in the Karakoram or in Alaska, but rare in Tibet. They can lead to an increase of the glacier flow velocities by a factor of 10 or more, and to a rapid advance of the glacier tongue, but no cases have been known so far where they caused big ice avalanches. Computer simulations of the 17 July avalanche suggest that the extreme length of its runout appears to be caused by water lubrication and that considerable amounts of water must have been stored in the glacier at initiation of the collapse.
During their retrospective investigations based on satellite data, scientists found strongly enhanced crevassing on the glacier that collapsed on 17 July for spring/summer 2016. During this work the scientists discovered also that the neighbour glacier, just south of the one that collapsed in July, showed similar signs of destabilisation. Local Chinese authorities made similar observations from the ground and using unmanned aerial vehicles.
Comparing data from the satellite “Sentinel 2” of 19 September 2016 (available on 21 September) with earlier data from a range of satellites, the scientists then discovered strong crevasses on the southern glacier, which alerted them about the possibility of an upcoming second glacier collapse and avalanche. Avalanche computer models were quickly run to estimate the potential area that could be affected by a similar event if it were to occur. In an ad-hoc coordinated way, facilitated through GAPHAZ, the information was used to alert Chinese colleagues, who then informed the local government. By the time these warnings reached the authorities in charge, though, the southern glacier seems already to have collapsed on 21 September 2016 and produced a second huge avalanche of similar size and appearance as the 17 July avalanche. In this case, fortunately, nobody was killed or hurt by the avalanche.
The scientists involved are starting now careful investigations about causes and triggers of the twin glacier collapses and the characteristics of the resulting avalanches. A particular focus is on why two nearby glaciers failed at similar times in similar ways, a fact that points to overarching processes behind the twin events, such as meteorological conditions, longer term climate change, or basic geological or topographic factors.
The 17 July and 21 September 2016 glacier collapses are first of all tragedies for the local people. Scientifically they are striking for the coincidence of two nearby glaciers collapsing within a short time, but demonstrate also the progress in early warning capabilities. The fact that remote observations based on a large number of very different satellite data could be carried out with a delay of only few hours or a day between data acquisition from space and analyses on the ground, involving scientists and satellite teams from several nations, in fact is substantial progress for early warning capabilities related to natural hazards in remote regions.
For more information and contacts please refer to the following document: [link pdf]
Glacier- and permafrost-related hazards represent a continuous and growing threat to human lives and infrastructure in high mountain regions. Related disasters can kill hundreds or even thousands of people at once and cause damage with a global sum on the order of 100 million EURO annually.
Present atmospheric warming especially affects terrestrial systems with surface and subsurface ice involved. Changes in glacier and permafrost equilibrium are shifting hazard zones beyond historical knowledge. Furthermore, human settlements and activities extend towards endangered zones. As a consequence, empirical knowledge will have to be increasingly replaced by improved process understanding.
The recently accelerated retreat of glaciers in nearly all mountain ranges of the world has led to the development of numerous potentially dangerous glacier lakes. In spring 2002, the United Nations Environment Programme (UNEP), therefore, launched a high-level warning in view of the dramatic growth of gigantic glacier lakes in the Himalayas.
Despite of the significant impacts of glacier and permafrost hazards and disasters, and despite of the increasingly urgent need to improve understanding and prevention of glacier and permafrost hazards in high mountains, there is no collaborative scientific initiative under the auspices of an international scientific lead body focussing on such hazards.
The IACS/IPA Standing Group on Glacier and Permafrost Hazards in High Mountains aims at:
- Improving the international scientific communication on glacier and permafrost hazards
- Compiling of a state of knowledge related to glacier and permafrost hazards in high mountains
- Working towards a greater transfer of information and improved communication between the scientific and governmental communities
- Signposting sources of advice to international and national agencies, responsible authorities and private companies
- Acting as a focal point for information for international media during relevant crises
The Standing Group addresses the following themes:
- Processes involved in the formation of glacier and permafrost hazards
- Techniques and strategies for mapping, monitoring, modelling
- Methods of hazard, vulnerability and risk assessment
- Methods of hazard mitigation including styles and effectiveness of remedial works
- Raising awareness of protocols for glacial hazard assessment and remediation
The Standing Group covers among others the following glacier and permafrost hazards:
- Outbursts of glacier lakes, causing floods and debris flows
- Avalanche/landslide-induced displacement wave impacts on glacial lake dams
- Ice break-offs and subsequent ice avalanches from steep glaciers
- Stable and unstable (surge-type) glacier length variations
- Destabilisation of frozen or unfrozen debris slopes
- Destabilisation of rock walls, as related to periglacial and glacial activity
- Adverse effects of rock glaciers and other periglacial slope movements
- Thaw settlement and frost heave
- Earthquake triggering of glacier and permafrost hazards
- Processes and hazards associated to interactions between volcanic activity and glaciers, and
- Combinations or chain reactions of these processes
The Standing Group activities are:
- Compilation and maintenance of a link list related to glacier and permafrost hazards
- Maintenance of a list of scientists and organisations active in the field of glacier and permafrost hazards in high mountains
- Compilation of a bibliography on glacier and permafrost hazards in high mountains
- Workshops on glacier and permafrost hazards
- Special sessions within international scientific conferences (e.g., AGU, EGU)
- Field trips
- Publications (workshop proceedings, special journal issue or a joint review article)
- Lobbying governmental departments, development banks and donor agencies to raise the awareness of key related issues
In addition to IACS and IPA close ties are maintained with:
Chair: Marten Geertsema, University of Northern British Columbia, Canada link
Vice Chair: Duncan Quincey, University of Leeds, UK link
Secretary: Marta Chiarle, IRPI Torino, Italy link
Advisory Board Members
Chris Burn, Charlton University Ottawa, Canada link
John J. Clague, Fraser University, Canada link
Ken Hewitt, University of Waterloo, Canada link
Christian Huggel, University of Zurich, Switzerland link
Andreas Kääb, University of Oslo, Norway link
Jeff Kargel, University of Arizona, USA link
Michael Krautblatter, Technical University Munich, Germany link
John Reynolds, Reynolds Geosciences Ltd, Mold, UK link
Sergey Sokratov, Lomonosov Moscow State University, Russia link