Ice boost! Why rock avalanches containing ice travel so far
Rock avalanches are a major hazard in mountainous regions. In cold areas, the presence of ice can make these avalanches even more hazardous, as rock-ice avalanches typically travel much farther than rock avalanches. However, the mechanism through which the mobility of avalanches is affected by the presence of ice is poorly understood.
Fan et al. [2024] use a new experimental flume equipped with high-speed cameras that can be kept at a temperature of −10°C to document the impact of the addition of ice fragments on the mobility of rock avalanches. Using this setup, the authors collect unique information on the complex interactions between fragments within the avalanche. For the first time, they document how particle segregation occurs in these rock-ice avalanches, and how this segregation can in turn affect how far the avalanche travels.
Based on these results, the authors propose a new equation to calculate the friction coefficient of rock-ice avalanches based on the relative ice content in the mixture. This friction coefficient can be used to predict how far a given rock-ice avalanche would travel. This represents an important development for the prediction and mitigation of avalanche hazard in high mountain areas, in particular as the retreat of glaciers induced by climate change is leading to an increasing exposure of slopes containing a mixture of rock fragments and ice.
