Debris flows are a mixture of boulders, sediments and water. They often occur during heavy precipitation events in steep alpine terrain and plow through gorges and mountain streams towards the valley in an uncontrolled fashion. In Switzerland alone, there are several hundred occurrences every year. Climate change facilitates this natural phenomenon as permafrost is becoming increasingly unstable and extreme weather events are on the rise. If debris flows are particularly large or if they occur in unexpected areas, they develop a considerable destructive potential that threatens human lives, infrastructure and the environment.
Warning systems play an important role in reducing the risk in exposed areas. It is crucial to be able to detect the approaching mud and debris as early and reliably as possible. Alarm systems are currently based on equipment that typically has to be installed in accessible, low-elevation valley sections. They register debris flows relatively late – a widespread problem in debris flow detection.
Researchers at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL have now developed a new type of detector that can recognize debris flows earlier. From a safe distance, it identifies even the smallest vibrations induced by debris flows shortly after they are mobilized. The scientists led by Fabian Walter, ETH Professor of Glacier Seismology, presented their novel approach in the scientific journal Geophysical Research Letters.
