The Slopes are Shifting: Tackling Landslides From Across Disciplines

It often begins with an earthen growl through the rainfall: a low, deep rumble from the hillside. Then the ground starts to move. Within moments, rocks and debris are racing downhill, becoming a flood of enormous force. ‘You have only seconds to react. I would probably shock-freeze’, admits ECH-member Ugur Öztürk, ‘but a survivor shared how he quickly opened all windows and doors. This way, the sludge could flow through his house instead of burying him alive.’

Such wit can save one life. What saves many is knowledge and preparation. As a researcher at the University of Vienna, Öztürk investigates the factors of landslide risk and severity. Surprisingly, it is not primarily climate change or natural causes that drive the risk of deadly hazards – it is ourselves.

Nature is the intuitive culprit of a landslide. Combine steep slopes and unstable soil with a triggering event like heavy rainfall and there is pandemonium. ‘But most fatal landslides appear in human-transformed environments’, explains Öztürk. ‘In urban areas, the effect of human activity is five times larger than natural causes.’ For instance, a healthy forest stabilizes a hill up to 26° inclination. Without the stabilizing root networks and plastered with informal settlements – houses, suboptimal drainage, etc., this decreases to 18°. If the same hill also experiences more frequent extreme rainfall events due to climate change – it decreases to 15°. Once again, vulnerability is distributed unequally: In lower-income countries, 50% of mountain land cover is altered by human activity, in high-income countries it is only 7%.

Öztürk stresses that human-driven climate change is intensifying the risk and impedes accurate forecasting. It may seem like a lost uphill battle – but only at first.

The belief that more information directly changes behaviour is just that – a belief. Research shows that simply telling people about environmental risks does not lead to action. ‘It is the feeling of self-efficacy, the norms of your community and role models, how included you feel in the decisions, and your general risk perception that play a role’, says psychologist Nina Vaupotič. As postdoctoral researcher at the University of Vienna, she specializes in risk communication. She wants to find out what increases trust in topics like environmental pollutants and 5G technology. As member of the Environment and Climate Research Hub (ECH) her research will soon focus on geohazards, too.

‘We showed that communicating complexity, particularly when accompanied by concrete solutions, increases trust in scientists without discouraging action’, says Vaupotič. With landslides, uncertainty is an inherent part of the hazard. Acknowledging uncertainties while offering clear recommendations may help build trust in scientific information and strengthen people’s belief in their ability to respond effectively.

She also showed that admitting knowledge gaps leads to trust. ‘Intellectual humility is natural to science. For many scientists recognising limitations of their research is a fundamental part of their profession’, says Vaupotič. Therefore, she adds: ‘The overall impact of communicating uncertainty is still inconclusive. It depends on the context.’ In cases without consensus in the expert community, uncertainty can confuse the audience. With landslides, for instance, engineers may propose technological solutions that fix acute problems for a few years; urban developers may recommend deeper socioeconomic measures whose impact only unfolds in the long term. So who should decision makers resort to? Communicating such controversy ultimately decreases risk perception and policy support, even in people who know that science is a debate. ‘Ideally, one strikes a balance, acknowledging uncertainties truthfully without overemphasizing them – especially when the goal is to encourage people to act.’

The newly launched project STRENGTH at the University of Vienna has set a goal to approach landslide research holistically. Project leads geomorphologist Thomas Glade and Sabine Pahl, psychologist and Co-Director of the ECH, together with the hub’s members Öztürk and Vaupotič and their colleagues from data science and environmental economics are making up the geoforensics task force. After a landslide, they will travel to the site and gather as much information as they can: The geomorphologists decipher the sequence of events and the factors that led to them. The psychologists will interview people, what information and training people received, how they perceived risk, and how it all affected their reactions and choices. The multidisciplinary approach covers the whole spectrum of a landslide event. Ultimately, the project seeks to transform lessons from past disasters into greater resilience, helping communities around the world prepare for and respond to the growing risks of a changing environment.