Overview of glacial hazards

Introduction | Mass Movements | Rockfall and Avalanches | Ice and snow avalanches | Landslide and debris flow | Case Study

What are glacial hazards?

Glacial hazards in high mountain regions
Figure 1: Schematic illustration of glacial hazards in mountainous regions. Credit: Adapted from Hock et al., 2019 by Caroline Taylor.

Generally, there are two types of hazards found in glacial environments that can impact humans. First, we have direct hazards such as avalanches and rockfalls. Second, we have indirect hazards for instance glacier lake outburst floods (GLOFs) and water resource issues 1 (Figure 1).

Who is affected by glacial hazards?

Glacier recession in high mountains and polar environments can lead to destabilisation, leading to a number of glacial hazards such as glacier collapse, rock and ice avalanche, glacier lake outburst floods (GLOFS) and debris flows.

Some of these hazards can have impacts on people over a short time scale (minutes–days), e.g. ice/snow avalanches and glacial floods. Others can have an impact over much longer time scales (months–years–decades), e.g. water resource problems 1.

Why should we care?

As the climate warms and glacial environments change, hazards are becoming more frequent, thus impacting people more often. Given that, it is important we understand hazards in order to prepare for and mitigate against their impacts 2,3.

Mass movements as glacial hazards

The term ‘mass movement’ covers various geomorphological processes, but generally refers to the downslope movement of snow, ice, rock, and debris, often in combination 2.

Mass movement events are particularly common in mountainous regions due to the steep topography, unstable slopes, and an abundance of materials 5.

Generally, the most frequently observed mass movement events in glaciated regions are:

  • Rock falls and avalanches
  • Snow and ice avalanches
  • Landslides and debris flows

Rockfalls and avalanches

Rock avalanching in the Alps
Figure 2: The 2013 Mount Haast rock avalanche deposit. The X-Y line refers to the position of a radar line taken in this study. Photo credit: Charlie Hobbs, Southern Alps Guiding, New Zealand in Dunning et al., 2015.

Generally, rock avalanches are the result of bedrock slope failures. Here, large amounts of material break off intact rock and travel at high speeds downslope, breaking apart even further as they travel 6. As a result, huge deposits of material on the glacier surface (as can be seen in Figure 2).

Rock avalanches are not to be confused with rockfalls. A rockfall is simple the movement of already loose material thus are generally much smaller than rock avalanches 2.

Snow and ice avalanches

Figure 3: Three mechanisms of snow/ice avalanche; a) Frontal block failure, where small blocks detach from the front, b) ice-slab failure, where large volumes of snow/ice detach, and c) ice-bedrock failure, where the failure of surface snow/ice material also causes bedrock detachment. Credit: Caroline Taylor.

Generally avalanching is the most widely studied mass movement event 1 and has huge impacts in populated valleys across Scandinavia and Central Europe.

Snow and ice avalanches can begin in three ways (Figure 3), causing large volumes of material to be released downslope.

Not only can avalanches have direct impacts in the valleys below, they can also lead to secondary impacts if avalanches dam rivers or enter glacial lakes causing outburst 1.

FUN FACT: Mass movement events are the primary trigger for GLOFs worldwide.

Landslides and debris flows

Landslides and debris flows (made up of a water-debris mix, usually 50-70% sediment) generally originate from steep slopes, talus slopes, and fluvioglacial deposits 5.

As a result, they are most common in periglacial and paraglacial environments due to the abundance of loose materials 9,10.

Often triggered by precipitation 11 these types of mass movement can significantly transform the landscape, altering channel morphology, rerouting rivers, and forming lakes 3.

Case study: 2013 Garhwal Himalaya tragedy

In June 2013 in the Indian Himalaya two large debris flows travelled along the Mandakini River and its tributaries, resulting in widespread devastation reaching as far as 200km downstream (as can be seen in figure 4). Consequently, in the village of Kedarnath, more than 6000 people were killed, countless roads and bridges damaged or destroyed, 30 hydropower plants impacted, and more than 100,000 pilgrims and tourists were left stranded (Figure 4) 9. Half of a major pedestrian route up to Kedarnath was destroyed, which undoubtedly hindered the rescue of pilgrims and evacuation of local people.

Panorama view of Rudraprayag sangam on june 21, 2013.
Figure 4: Panorama view of Rudraprayag sangam downstream on June 21, 2013. Photo credit: Mukerjee, CC BY-SA 3.0, via Wikimedia Commons.

Additional Resources



1. Richardson & Reynolds. An overview of glacial hazards in the Himalayas. Quat. Int. 6566, 31–47 (2000). 

2. GAPHAZ. Assessment of Glacier and Permafrost Hazards in Mountain Regions A Scientific Standing Group of the International Association of Cryospheric Sciences IACS and the International Permafrost Association IPA Swiss Agency for Development and Cooperation SDC Sw. gaphaz.org (2017). 

3. Kumar, A. et al. Anticipating the impact of glaciers, landslides and extreme weather events on vulnerable hydropower projects and the development of an integrated multi-hazard warning system (IMWS). Sustain. Energy Technol. Assessments 65, 103791 (2024). 

4. Hock, R. et al. High Mountain Areas. in IPCC SR Ocean and Cryosphere vol. 4 131–202 (Elizabeth Jimenez Zamora, 2019). 

5. Evans, S. G. & Delaney, K. B. Catastrophic Mass Flows in the Mountain Glacial Environment. in Snow and Ice-Related Hazards, Risks, and Disasters 563–606 (2015). doi:10.1016/B978-0-12-394849-6.00016-0. 

6. Hungr, O. A model for the runout analysis of rapid flow slides, debris flows, and avalanches. Can. Geotech. J. 32, 610–623 (1995). 

7. Dunning, S. A., Rosser, N. J., McColl, S. T. & Reznichenko, N. V. Rapid sequestration of rock avalanche deposits within glaciers. Nat. Commun. 2015 61 6, 1–7 (2015). 

8. Perla, R. I. Avalanche release, motion, and impact. Dyn. snow ice masses 397–462 (1980) doi:10.1016/b978-0-12-179450-7.50012-7. 

9. Allen, S. K., Rastner, P., Arora, M., Huggel, C. & Stoffel, M. Lake outburst and debris flow disaster at Kedarnath, June 2013: hydrometeorological triggering and topographic predisposition. Landslides 13, 1479–1491 (2016). 

10. Clague, J. J. & Evans, S. G. Formation and failure of natural dams in the Canadian Cordillera. Bull. – Geol. Surv. Canada 464, (1994). 

11. Stoffel, M., Tiranti, D. & Huggel, C. Climate change impacts on mass movements – Case studies from the European Alps. Sci. Total Environ. 493, 1255–1266 (2014). 

12. Bhambri, R. et al. Devastation in the Kedarnath (Mandakini) Valley, Garhwal Himalaya, during 16–17 June 2013: a remote sensing and ground-based assessment. Nat. Hazards 80, 1801–1822 (2016). 


I am a glaciologist and natural hazard scientist at Newcastle University. My research focusses on the risk of Glacial Lake Outburst Floods (GLOFs), to help communities better prepare for, respond to, and live alongside hazards.

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