Some times a weak layer in the snow can collapse suddenly over large areas and with a great deal of noise. Actually, it can appear quite scary. This happened to one of the overwintering teams at the Plateau Station in the 1960-ies.
21 Dec 2007
78.64622 deg S
35.64052 deg E
3619 meters above sea level
Maximum & Minimum temperatures: -27 to -36 °C
One morning everybody woke up at Plateau Station due to a dramatic sound that appeared tobe traveling through the camp. This was a very scary episode for the personnel that did not know what had happened. After the noise had died down, they realized that it had been a firn quake. In very cold conditions large snow crystals grow and they are very loosely bonded. Thus, this weak layer in the snow can suddenly collapse. The personnel at Plateau Station figured that the surface lowered about 1 cm during this event.