Permafrost or permanently frozen ground is defined as soil or rock that remains beneath 0 °C for at least 2 years. Mountain permafrost typically occurs in high mountain environments and can be found in various geomorphological landforms and under variable geological, climatic and topographic conditions. The occurrence of permafrost is strongly dependent on solar radiation, snow distribution, and surface material composition (in more general terms its energy balance). It is a widespread phenomenon in the Alps covering approximately 5 % of the surface area of Switzerland. Warming of permafrost regions due to climate change with associated increase of the active layer thickness and decrease in ice content has been observed at many permafrost sites worldwide. Therefore, monitoring the distribution of permafrost and especially its ground ice characteristics is a topic of ongoing concern.