On Wednesday night, part of the roof of the Tête Rousse glacier collapsed in on itself, forming a gaping hole where the glacial lake can be seen, in several pockets.
The security perimeter will be immediately enlarged, and will now reach the rocks of the galcier moraine. Climbers must of course take extra care in the area.
Key dates concerning the Tête Rousse Glacier & water pockets
1892: Tête Rousse, a subglacial pocket of 80,000 cubic metres of water gives way, flooding St. Gervais. 175 dead.
1904: Gallery drilled to empty a second water pocket of 22 000 cubic metres.
2008-2010: Following a study on the usefulness of this gallery, the Laboratory of Glaciology and Geophysics of the Environment in Grenoble discovered the presence of a significant amount of water.
2010: 50 000 cubic metres detected. In July, warning system (sirens) set in place to help mass evacuation. Between August 25 and October 8, 48 000 cubic metres of water are pumped.
2011: in spring, the Laboratory of Grenoble predicted water levels would refill before the summer melt. New study to understand where water comes from and to monitor the glacier. In September, the water pocket that had formed was again filled with 25,000 cubic metres. To minimise the risk of another "tsunami" in the valley, the local authorities launch a second, bigger, operation to drain the water.
January 2012: presentation of research at CNRS and the TMR to the Prefect and the Mayor of Saint-Gervais-les-Bains.
July 2012: estimation of water volume in the cavity transmitted by the Bureau of Geological and Mining Research (BRGM) Mayor of Saint-Gervais-les-Bains. Evidence of not one but two water pockets.