Permafrost in the Gruve-7 mine, Adventdalen, Svalbard

Abstract

Bedrock temperatures were measured over a 12-month period (June 2003–July 2004) at six sites within the Gruve-7 coal mine in the Adventdalen valley, near Longyearbyen (78°N), Svalbard. One site lies 290 m beneath the Foxfonna ice cap, where stable near 0°C conditions were recorded throughout the year. This site is close to the inferred base of permafrost. Other sites at bedrock depths between 35 m and 235 m beneath both glacier-covered and ice-free terrain have mean annual values between −1.2°C and −4.9°C, and annual amplitudes between 0.5°C and 4.5°C. The lowest mean annual ground temperatures (MAGT) of −5.8°C is measured at a depth of c.6 m from the ground surface, and this site is thought to be close to the base of the bedrock active layer. The 3-dimensional nature of the permafrost body is indicated by the fact that the higher permafrost temperatures occur at deeper locations within the massif below the Foxfonna ice cap and glacier, while the lowest temperatures occur where the mine extends beneath ice-free terrain.