Catastrophe imminent: Glacier rupture leads to flood danger
A catastrophic glacier collapse in the Lötschental valley of the Swiss canton Wallis has left a meter-high debris dam blocking the Lonza river, with vast amounts of water accumulating behind it. The threat of a flood wave, debris flow, or landslide, should the dam break, has led to the evacuation of several houses in two hamlets. Drone images reveal that most of Blatten, where the collapse occurred, is covered by a meter-high layer of debris, with only a few houses spared—now submerged by the Lonza.
Beat Rieder, a member of Parliament from neighboring Wiler, called it a century's catastrophe on Swiss television, stating, "This is an event the valley has never experienced since the dawn of history." People in Blatten have lost everything they've built throughout their lives. Ried, just one kilometer upstream, is also affected.
Geologist Flavio Anselmetti from the University of Bern expressed concern, stating that if water accumulates up to the crown of the landslide dam, the river could erode the rock-ice mixture, making it unstable and causing the dam to break. Flood waves or debris flows from this potential lake outburst could then threaten communities in the lower valley. The Swiss army has been mobilized, and the situation is being assessed hourly with drones and helicopter overflights.
Rescue teams and the army cannot intervene, as the canton of Wallis announced, due to the danger posed by the remaining 300,000 cubic meters of rock that could still collapse from the Kleine Nesthorn mountain. Debris flows could occur at any moment, and the debris cone is also too unstable to be entered.
While it is difficult to attribute a single event directly to climate change, Jan Beutel, a professor at the University of Innsbruck, stated that the strong changes in the high mountains today are largely due to climate change over the past decades. Climate change contributes to glacier melt, rapid snowmelt, and the thawing of permafrost, making mountains more prone to collapse and instability.
Nearly 300 residents of Blatten have lost their homes. Approximately 90% of the village, including around 130 houses and the church, is buried under a layer of debris estimated to be between 50 and 200 meters thick. The avalanche, two kilometers long and around 200 meters wide, was caused by the collapse of three million cubic meters of rock, debris, and ice from the Birch glacier. Blatten, the last village in the 27-kilometer-long Lötschental valley, is located at approximately 1500 meters.
The monitorings of Swiss mountains had already issued warnings in mid-May about a landslide threat above the village. However, the call to evacuate within an hour came rather suddenly on May 19, as cracks in the rock grew rapidly. Many residents were able to pack their essentials and leave before the disaster struck.
Despite the evacuation, a 64-year-old local resident remains missing. Bishop Jean-Marie Lovey of Sion offered words of consolation from the prophet Isaiah: "Though the mountains be shaken and the hills be removed, yet my unfailing love for you will not be shaken nor my covenant of peace be removed (Isaiah 54:10)."
The Lötschental is a popular tourist destination, offering hiking, climbing, mountain lakes, and vast untouched nature in the summer, and kilometers of ski slopes in the winter. Once difficult to reach, its accessibility improved significantly with the opening of the Lötschberg tunnel in 1913 and the construction of a road in the 1950s.
The science of climate-change and environmental-science play a significant role in the catastrophic glacier collapse in the Lötschental valley, as changes in the high mountains, such as glacier melt, rapid snowmelt, and the thawing of permafrost, are largely due to climate change over the past decades, making mountains more prone to collapse and instability.
The weather conditions in the aftermath of the collapse are a concern, as the accumulated water behind the debris dam could cause a flood wave, debris flow, or landslide if the dam breaks, potentially threatening communities in the lower valley.
