Snow and avalanche research for the sustainable protection of people and nature

Snow and avalanche research for the sustainable protection of people and nature

The Institute for Snow and Avalanche Research ( SLF/ Schnee- und Lawinen Forschung) in Davos is an interdisciplinary research and service centre. Its 180 employees (including around 25 doctoral candidates in physics and process engineering) conduct research on snow, the atmosphere, natural hazards, permafrost and mountain ecosystems, and develop innovative practical tools for improved forecasting and disaster prevention.

Regular guided tours are offered, allowing visitors to learn about current projects and the state of research. In addition to impressive documentation of avalanche events, rockfalls and debris flows, as well as explanations of measuring instruments and calculation models, visitors may also tour a cold chamber – though not the wind tunnel.

How is the SLF organised, and what are its tasks?

The SLF not only studies snow conditions and climate changes in the Swiss Alps, but also snow and ice conditions in Antarctica. At least one SLF employee is always present on site. In 2025, these were the Spaniard Sergi González-Herreron and the Austrian Dr. Michael Haugeneder, accompanied by two colleagues for an Arctic expedition named “Contrast”. Dozens of snow and firn samples, as well as ice cores from the polar region, are therefore stored in the institute’s cold chambers. These can be analysed step by step under specific parameters when needed, as snow kept at sufficiently low temperatures (up to minus 40 degrees Celsius) and without exposure to air undergoes virtually no change.

“International collaboration is the key to success, as Switzerland is highly renowned and globally leading in this field,” says the American Dr. Michael Lombardo. Smaller institutes exist in Grenoble (France), Innsbruck (Austria), Montana (USA) and Japan, but the comprehensive fundamental research carried out at the SLF is unique. Michael’s specialism concerns are particularly complex wet-snow avalanches.

Anyone may check the current snow situation and potential hazards free of charge on the SLF website.

The SLF forms part of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL/ Wald, Schnee und Landschaft) and therefore of the Swiss Federal Institute of Technology in Zurich (ETH/ Eidgenössische Technische Hochschule). It researches various aspects of snow, such as its structure and how it changes under different conditions. This includes identifying how weak, slide-prone layers form within the snowpack, or how materials (e.g. ski bases) glide most effectively on snow. Another core area is understanding how avalanches form and move across terrain.

The researchers also work on protective measures to optimise risk management. The SLF therefore offers a range of public services, including an avalanche bulletin, advice on avalanche protection for road and urban planning, expert assessments of avalanche accidents and the development of hazard warning systems.

The focus lies on understanding how the “snow of tomorrow” will behave

The connection between science, practice and public outreach has a long tradition at the SLF. Since 1945, when the avalanche warning service of the Swiss Army was incorporated into the SLF, the institute has benefited from having both research and practical application “under one roof”.

Snow and atmosphere

This research unit investigates the physical properties of snow and its exchange processes with the ground and atmosphere. Its aim is to deepen understanding of the formation of alpine hazards such as avalanches, flooding and slope instability, as well as the interactions between the cryosphere and climate change.

The unit also studies the microstructure and metamorphosis of snow. As snow structure changes, so too do its material properties, such as density. While one cubic metre of fresh snow contains so much air that it weighs only 50 to 100 kilograms, older, sintered snow may weigh up to 400 kilograms. This is a crucial insight for understanding large-scale changes within the snowpack, including avalanche formation, water transport and interactions between snow and vehicles or sporting equipment. It helps determine the roles played by snow, slope gradient and ground conditions, whether wet or frozen, in the emergence of natural hazards, their influence on Earth’s climate and how global climate change affects the development of permafrost.

Experiments take place on outdoor test sites such as the Weissfluhjoch above Davos and the avalanche bunker in Arbaz, as well as in laboratories such as cold chambers and wind tunnels using tools such as computer tomography. These experiments allow the mechanical and optical properties of different snow types to be precisely measured. Snow is either taken from nature or produced identically in the laboratory using a “snow machine”, enabling comparative year-round research. Changes in temperature and humidity create different crystal forms; while crystals move freely in clouds and form symmetrical hexagonal shapes, they grow in more branched structures on the nylon threads of the snowmaker.

Experimental Setup Tribometer

Technical snow, such as that used for piste preparation, consists of small ice beads rather than natural delicate crystals. Thanks to computer tomography, snow can be scanned and its changes observed in 3D. Those working long hours in the cold labs wear heavy insulated overalls, while visitors remain only briefly and typically notice little of the dry cold.

The research results feed into numerical modelling systems used for climate analysis and hazard forecasting. During snowmelt, the SLF provides regular snow-hydrological analyses to the Federal Office for the Environment (FOEN) for flood prevention and forecasting.

Further partnerships exist with cryosphere research institutions, high-performance computing manufacturers and modelling experts, as well as warning and safety services and industry.

Avalanches and prevention

This research unit investigates avalanche formation and dynamics on behalf of the Swiss Avalanche Warning Service, with the aim of better forecasting avalanche location, timing and impact. It develops process models based on laboratory experiments and field studies.

The avalanche bulletin informs the public daily about avalanche conditions and issues warnings using a five-level system. A comprehensive network of observers and automatic stations provides the necessary data. This unit also develops warning and information systems for authorities and local safety services.

The spread of a fracture within the snowpack – that is, an avalanche – depends not only on volume, slope and temperature, but also on spatial uniformity. Avalanches can thunder down slopes at speeds of up to 300 km/h, causing severe damage. This is demonstrated vividly during guided tours. It is worth noting that most avalanches are triggered by people themselves, usually ski tourers or off-piste skiers. Until recently, it was believed that such avalanches were triggered only by someone positioned above the fracture. It is now known that triggering from below can also occur, meaning the person responsible may also be the victim. How and when fractures form in spontaneous avalanches remains unknown. SLF scientists investigate these processes using loading instruments and a shear apparatus.

At highly exposed sites where snow accumulates repeatedly due to high-altitude winds, blasting is no longer carried out from helicopters. Instead, fixed blasting stations are installed and triggered remotely as a controlled preventive measure.

Another key task is advising the public on avalanche protection and developing risk-based management methods. Davos, for example, has a zoning plan specifying precisely where construction is prohibited or permitted only under strict conditions, such as building earth embankments up to roof height on the upslope side or using high-security glazing. Protecting roads and access routes through snow fences, wire mesh, reforestation, galleries and tunnels is also essential.

All research findings are continuously implemented and feed into teaching and training. The group collaborates closely with other WSL research units, national and international partners, cantonal and federal authorities, industry, associations and public safety and tourism institutions.

Alpine environment and natural hazards

This unit analyses the impacts of climate change and extreme events on physical and ecological processes and process chains in mountain regions, as well as the associated emerging risks. The aim is to better understand changing processes, identify complex interactions and enable early detection and assessment of key impacts on the environment and society. The thematic focus lies on five research groups: Permafrost, RAMMS Rapid Mass (a software for calculating hazard–protection relationships), Mountain Ecosystems, Alpine Remote Sensing and Alpine Mass Movement. Interdisciplinary and transdisciplinary research with other WSL units and national and international partners is fundamental.

A wide range of methods and approaches is used, including advanced thermal and multispectral measurement devices, processing technologies and prototype development, including tailor-made drone and ground-based systems. Long-term monitoring systems for permafrost and biodiversity, as well as field experiments on rockfall and protective forests, form the basis for developing numerical models for science and practice. Climate and extreme weather scenarios are incorporated to produce realistic future scenarios for the alpine environment.

Instrumentation and measurement facilities

Almost none of the required instruments can be purchased ready-made. For this reason, the SLF has a “Test Facilities Team” consisting of designers, mechanics and electronics specialists. The researchers’ specific requirements challenge the team to devise creative solutions. Almost everything is developed in-house, from heavy metal structures to tiny sensors. The team also maintains the numerous systems that operate continuously.

One notable invention is the SnowMicroPen, used to measure the penetration resistance of snow to improve understanding of radar measurements and snow profiles. It allows faster measurement of softer and harder snow layers than the traditional ram penetrometer – and without the laborious task of digging a one- to two-metre snow profile. Some years ago, I personally took part in an avalanche protection course in Valais and know how strenuous it is to cut and prepare a representative horizontal snow profile in the field.

For winter sports enthusiasts, the core instrument of the ski laboratory, the ice and snow tribometer, is of special interest. It tests the gliding properties of ski bases, waxes and grinds.

All of this is costly and funded almost entirely through Swiss tax revenue. Construction of the new building complex alone cost around 11 million Swiss francs in 1996. Previously, the institute was housed in a small hut on the Weissfluhjoch. Today, its annual budget for staff and materials is around 17 million Swiss francs. More than 50% comes from federal funding for the WSL, with the remainder provided by third-party project funding.

Last but not least

Snow is not only something one can feel; it can also be heard in many ways. Dry snow squeaks at very low temperatures, similar to round sand grains with high quartz or silicate content when moisture is low. This sound results from the simultaneous breaking and friction of millions of tiny, brittle ice crystals. The roar of an avalanche resembles a deep rumbling, comparable to the thundering of an aircraft or a powerful waterfall, created by the friction of snow and ice through turbulent airflow.

Snow and ice are both fascinating and fearsome, being simply different states of water. The claim that Inuit languages have more than a hundred words for snow is a myth. Many languages distinguish between specific types of snow resulting from weather conditions, such as old snow, red snow, slab snow, rotten snow, felted snow, firn, drifting snow, crust, wind crust, melt-freeze crust, breakable crust, industrial snow, artificial snow, avalanche snow, loose snow, wet snow, new snow, sticky snow, powder snow, floating snow, slush, wind-drifted snow and wild snow. Ultimately, each term reflects a particular hazard or threat posed by this natural phenomenon. We all know that nature can be tamed only to a very limited extent, and that understanding it is the only meaningful way to coexist with it and its resources.

More information: https://www.slf.ch/en/