Rock avalanches are a significant hazard in mountainous regions, but when ice is present, the risk escalates dramatically. In colder regions, rock-ice avalanches avalanches consisting of both rock and ice tend to travel much farther than those made up of rock alone. Despite this well-known behavior, scientists have long struggled to understand the exact mechanism behind this increased mobility.
A recent study led by Fan et al. [2024] sheds new light on this mystery using advanced experimental methods. The researchers developed a state-of-the-art flume setup equipped with high-speed cameras that can operate at temperatures as low as −10°C. This allowed them to closely observe how ice fragments interact with rock fragments during avalanche simulations, offering unprecedented insight into the complex dynamics of rock-ice avalanches.
One of the study’s major breakthroughs was documenting, for the first time, how particle segregation occurs in rock-ice avalanches. Segregation refers to how particles separate or move within the avalanche as it travels. The researchers found that this segregation plays a critical role in determining the distance traveled by the avalanche.
Building on these observations, the team proposed a new equation to calculate the friction coefficient of rock-ice avalanches, which is directly influenced by the relative content of ice in the mixture. The friction coefficient is a critical factor in predicting how far an avalanche will travel. With this new equation, scientists and hazard managers can better predict avalanche mobility and develop more accurate risk assessments in mountainous areas.
This study has major implications for avalanche hazard prediction and mitigation, especially as climate change accelerates glacier retreat. As glaciers continue to melt, more slopes containing mixed rock and ice are becoming exposed, leading to an increased risk of rock-ice avalanches.
Fan et al.’s findings provide a vital tool for better understanding and managing this growing hazard, offering new hope for improving safety in high-altitude regions vulnerable to avalanches.