The Planpincieux glacier and the Whymper serac above the Grandes Jorasses glacier on the Italian side of the Mont-Blanc massif are under special surveillance by local authorities who are constantly monitoring their movement with radars to avoid a catastrophic collapse on the valley below. While the Grandes Jorasses glacier (a polar glacier) is located at almost 4000 metres, and its movements range between 2 and 20 centimetres per day, the front of the Planpincieux glacier (a temperate glacier) is located at around 2700 metres and can move, in the hot season, up to 150 cm per day. IMAGES AND SOUNDBITES