28. August 2007

Fieldwork in Inner Troms, Northern Norway 21-26 August 2007

Contact person for additional information: Hanne H. Christiansen

Permafrost in unstable rock slopes

In late August the geomorphological TSP NORWAY team consisting of Håvard Juliussen and Hanne H. Christiansen, UNIS together with Lars Harald Blikra , ICG, has been on fieldwork in Inner Troms, to study permafrost controlled landforms. We focus on understanding the processes that control the development of cold climate landforms on the mountain slopes that dominate the landscape of Inner Troms.

At the mountain Nordnes, north of Skibotn, we collaborate with the inter-municipality project that has initiated monitoring of two sites on Nordnes (Kåfjord, Lyngen and Storfjord municipality). We study the thermal regime in the open cracks and surrounding bedrock at the top of the mountain slope to increase the understanding of the processes that expands these cracks.

TSP Norway scientist Lars H. Blikra (left) and the Kåfjord community staff working at Nordnes, Steinar, Roald and Henning.

To deliminate the extent of the cracks and to characterise any potential ice content in the cracks we also performed geophysical investigations to study the resistivity of the ground. This type of investigations were also done earlier this summer by Jan-Steinar Rønning and Einar Dalsegg (NGU) along a more than 1 km long profile up the mountain slope, so we focussed on some smaller selected areas around the cracks and in the potential permafrost zone.

During our fieldwork we saw ice bodies in the inner, deeper parts of the cracks and some few first results of the temperature monitoring showed conditions most of the winter around 0˚C. In other cracks we found cold air drainage. This seems to indicate that permafrost may exist in the cracks.

An approximately 1.5 m large ice body in the inner part of a crack at around 630 m asl at Nordnes. This is a good indication of the cold conditions still existing towards the end of summer in the cracks of the unstable rock slopes.

We installed thermistors to register temperatures of the outer 40 cm of the rock surfaces in different parts of the cracks and in the cold air flow of the cracks. These will give us data to understand the size of the thermal expansion in summer and contraction in winter, and a better understanding of the annual air circulation in the cracks. The monitoring project will establish a series of crackmeters and tiltmeters measuring movement, and these data will be available for the TSP project. The monitoring also includes a meteorological station (including two snow-depth sensors) and tree single lasers measuring total movement on selected areas.

The Kåfjord community staff are using 4-wheel driven vehicles for transportation on Nordnes, and they were very helpful in assisting us with our fieldwork, including bringing our heavy equipment down the mountain. We look forward to further collaboration on Nordnes.

Installing thermistors in a north facing rock slope at Nordnes. In the background the foundation for the reflector plate for one of the single lasers is seen.

Preparing for moving equipment with the Kåfjord project 4-wheel driven vehicles on Nordnes.

Text and photos by Hanne H. Christiansen