Montroc Avalanche
Facts and figures
Part of the European avalanches of 1999
a hamlet in eastern France
located in the territory of the commune of Chamonix.
Date of the event: 9th February 1999
At around 2:40pm on the 9th of February, while the committee discussed the situation, a slab of snow some 1.5 meters deep and over an area of 30 hectares broke away
Causes
cold and dry conditions with very little snow creating a weak base for future snow; Ideal conditions for the formation of hoar crystals and a fragile base for future snowfall
In February, 3 days of heavy snow and strong winds dumped over 2 metres of snow on the slopes above Montroc
Slopes above Montroc were over 35°
Slab avalanche travelling at 60mph brought 300,000m³ of snow towards Montroc
Had 0 defences despite the fact that the experts of the Avalanche Consultative Committee met to discuss the growing crisis
Clueless to how to carry out the evacuation plan since there are over 100 known avalanche paths in the valley
Travelling at 60 mph with a pressure of 5 tonnes per m2, chalets were pulverised and the debris carried over 100 meters
Impact
14 buildings were destroyed and 6 damaged
12 people were killed
Montroc was cut off and only accessible by air
The mayor of Chamonix was found guilty of second degree murder for failing to evacuate Montoc in advance
Responses
Sniffer dogs, heat seeking cameras and poles used to rescue 20 people
Helicopters used their propellers to dislodge snow to reduce to reduce the risk of further avalanches