12. September 2008
field work in Finnmark and Troms, Northern Norway 2008
Contact person for additional information: Hanne H. Christiansen
Text and photos by Etzelmüller, Bernd,University of Oslo
27.7. and 7.8. field work was carried out for the Norwegian TSP project. All
boreholes drilled and instrumented in 2007 were read out, and an extensive
number of geophysical soundings were done. The work was carried out in
co-operation with the Norwegian Geological Survey (NGU), the Universities of
Karlsruhe (Prof. Christian Hauck)
and Jena (Christin Hilbich), Germany, and the University of Ottawa,
Canada (Prof. A. Lewkowicz).
The sites in Lavkavagge/Troms and Iskoras/Finnmark show that the lower boundary of mountain permafrost is close to these borehole location elevation. The bore hole temperature monitoring allows us now to follow the ground temperature development as response to climate change. In addition to ground temperatures, air and surface temperatures are monitored along a north-south transect over the Iskoras mountain. This will give valuable information about air temperature inversions and snow conditions.
temperatures at Lavkavagge, northern Troms, 750 m a.s.l. The borehole is
probably still not in equilibrium after drilling operation. However, there are
clear evidence of shallow permafrost in the bore hole as expected. The right
illustration shows a 2D-plot of temperature-depth development in the borehole
between June and August 2008.
temperatures at Iskoras, Finnmark, 600 m a.s.l. The borehole indicate permafrost
condition, shallow and very close to 0oC. Snow cover is very low at this site,
and thus marginal to permafrost. We expect heavy winter inversion at this site,
as the Iskoras meteo data clearly show warmer winter temperatures than in the
nearby valley of Karasjok. This is further investigated by a monitoring program
for air and ground surface temperatures along a north-south transect in the area
(Picture lower right, with PhD-stud Karianne Lilleøren, UiO, and Prof.
Antoni Lewkowicz, University of Ottawa, Canada).
Geophysical soundings help to determine ground properties and possible variations of ice content in the ground along profile lines. We used DC resistivity tomography and seismic tomography. The NGU also measured a 2 km long profile over the Iskoras mountain along a north-south transect. These data are now under processing.
Hauck, University of Karslruhe/University of Fribourg,
diagrams above show first processing results of the DC resistivity tomography.
The upper diagram is a 2 km long profile with 10 m electrode spacing, while the
inlet profile shows a 250 m long profile with 2 m electrode spacing. Blue
areas are high resistivities and either bedrock or permafrost. These
resistivities will be combined with seismic velocities, to determine the
possible amount of solid material, ice, water and air along the profile.