A recent landslide from the Birch glacier in southern Switzerland has significantly impacted the village of Blatten, burying homes and damming the Lonza River. Authorities reported Saturday that the river is now flowing through the debris, leading to a drop in the level of a newly formed lake and easing immediate flood concerns, though caution remains.
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Glacier Collapse Causes Destruction
The massive landslide of rock, ice, and mud occurred on Wednesday, originating from the Birch glacier in the Lötschental valley.
The collapse sent material into the valley, causing widespread destruction in Blatten village. Many buildings were buried by the debris.
River Dammed, Lake Forms
The immense volume of material blocked the course of the small Lonza River.
This blockage led to the formation of a lake behind the landslide debris, submerging other parts of the village not directly buried. Authorities initially raised concerns about the potential risks posed by the pooling water above the debris mass.
Check dams help regulate water flowing over landslide debris near houses in Blatten, Switzerland.
River Now Flows Through Debris, Lake Level Falls
Authorities in Valais canton confirmed Saturday that the Lonza River successfully began flowing through the landslide mass on Friday.
Geologist and regional official Raphaël Mayoraz stated Saturday that the level of the newly created lake has decreased by approximately one meter since Friday.
Mayoraz explained the lake’s emptying is due to the river eroding a channel through the deposit. He added that this erosion is occurring relatively slowly, which is seen as positive, preventing instability that could trigger further small slides.
Matthias Bellwald, Blatten’s mayor, expressed caution, stating, “The Lonza appears to have found its way, but it is too early to be able to give an all-clear.”
Downstream Measures and Evacuation
Downstream, the outlet of a dam at Ferden, typically used for electricity generation, was partially opened Friday evening. This action aims to manage water levels and regulate the volume behind the dam.
Authorities continue to assess the situation and have not ruled out the possibility of further evacuations downstream if conditions change, although the risk to other villages is currently considered very low.
Days before the main glacier collapse, authorities had ordered the evacuation of about 300 people and livestock from Blatten based on early warnings. Switzerland’s president said on Friday that the government is exploring ways to assist those displaced by the event.
While the Lonza River has found a path through the debris and the lake level has dropped, officials remain cautious about the stability of the landslide material and downstream water management. The focus continues on monitoring the situation and supporting the evacuated residents.
