Ninth International Conference on Permafrost ... - IARC Research

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Rock Glaciers in the Kåfjord Area, Troms, Northern NorwayRegula FrauenfelderDepartment of Geosciences, University of Oslo, Norway,currently at Norwegian Geotechnical Institute, Oslo, NorwayJon TolgensbakkDepartment of Geosciences, University of Oslo, NorwayHerman FarbrotDepartment of Geosciences, University of Oslo, NorwayTom Rune LauknesNORUT AS, Forskningsparken, Tromsø, NorwayIntroductionRock glacier distribution in mainland Norway wasinventoried on a macro scale by Sollid & Sørbel (1992). Theyfound that active rock glaciers exist in the high mountainareas of southern and northern Norway, while relict rockglaciers can be found in low-lying areas near the coast ofnorthern Norway and in higher inland areas.Detailed geomorphological mapping in Troms byTolgensbakk & Sollid (1988) revealed the existence of morethan 100 rock glaciers in the Kåfjord area on the eastern sideof Lyngenfjorden. Most of the area lies inside the glaciallimit of the Younger Dryas (YD) ice sheet (Andersen et al.1995), with the youngest YD moraines situated at the valleyentrances. Compared to surrounding areas with similar reliefand geology, the high frequency of rock glaciers in thisregion is quite striking. The mapped rock glaciers are mostlyof talus-derived origin and are found between the presentcoastline and the highest mountains in the area (c. 1360m a.s.l.). Most of the rock glaciers seem to be associatedwith rockslides caused by neotectonic activity, which wasvery pronounced in the region during the early Holocene(Tolgensbakk & Kverndal 1995, 1996, Dehls et al. 2000).Due to the general orientation of the main fault (NW–SEtrending normal fault, cf. Dehls et al. 2000), the majority ofthe rock glaciers is concentrated in the sectors SW-W-NW(Fig. 1).While most of these rock glaciers seem to be relict today,exceptions can be found. Velocity measurements carried outin the early 1990s on one of the rock glaciers showed surfacemovement in the order of less than 1 cm a -1 (Tolgensbakk &Kverndal 1995, 1996). Measurements on this rock glacier,hereafter called Sannjarriep’pi rock glacier, were continuedduring summer 2006, and the findings are reported in thefollowing.The Sannjarriep’pi rock glacier is situated on the orographicright side of Nordmannvikdalen, a tributary valley to theLyngenfjord. The rock glacier lies on the western slope of a1207 m high peak, is approximately 700 m long and 700 mwide, and is situated between 580 and 780 m a.s.l.MethodsThe deformation of Sannjarriep’pi rock glacier wastracked by two different methods: (a) by polar survey usingan electronic theodolite (Wild DI 3000 Distomat), and (b)by space-borne Differential SAR interferometry (DInSAR)using ERS SAR imagery covering the period 1992–1999(e.g., Bamler & Hartl 1999).For two-dimensional resistivity tomography (ERT) overone of the lobes of the rock glacier, an ABEM Lund multielectrode,high-resolution 2D resistivity system was used,applying the Wenner configuration (Reynolds 1997).Miniature temperature data logger devices have beeninstalled at three locations on the rock glacier in summer2006. These loggers record the ground surface temperature(GST) at shallow depths in a 2 h interval.Measurements of Schmidt-hammer rebound values—aproxy for rock hardness, that is, the rock weathering degree—were performed on three different transects perpendicularto the central flow line of the rock glacier. Samples forcosmogenic nuclide exposure dating have been taken on twoconspicuous ridges and at the front of the rock glacier (seeFig. 2a for location of measurements).ResultsFigure 1. Main aspect of talus-derived rock glaciers in the Kåfjordarea (n = 59).The velocity measurements from summer 2006 show thatthe lower northern lobe of the Sannjarriep’pi rock glacierhas been stagnant during the last 17 years (1989–2006),while the upper southern lobe has been steadily movingwith c. 1 to 6 mm a -1 ; maximum movement is in the orderof 10 cm in 17 years. The DInSAR survey confirms thesemeasurements, with maximum displacement values of-4.9 mm a -1 for the southern lobe (Fig. 2b).77
Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tFigure 2. (a) Location of measurements on the Sannjarriep’pi rockglacier: black dots = bolts for terrestrial survey, white dot = locationof miniature temperature data loggers, stippled lines = Schmidthammerrebound measurement transects, black line = electricalresistivity tomography (ERT) profile. (b) Results of DInSARmeasurements: black = -4.9 mm a -1 , white = stagnant.Figure 4. Ground surface temperatures (GST) and air voidtemperature in the blocky surface layer of the Sannjarriep’pi rockglacier during the period 2006–2007. Air temperature at SørkjosenLufthavn, 20 km northeast of Sannjarriep’pi rock glacier is givenfor comparison.and to Trond Eiken for the post-processing of the distancemeasurements.Figure 3. Result of the Electrical resistivity tomography (ERT)measurements. The active layer is highly heterogeneous,characterized by large air voids in the very coarse blocky surfacelayer. Below the active layer, maximum resistivity values are in theorder of 30 to 100 kOhm.m, being indicative for ice.Mean air temperature at Sørkjosen lufthavn during 2006–2007 was +3.2°C. Applying a lapse rate of -0.005°C/myields a mean air temperature at the front of the rock glacier(580 m a.s.l.) of c. +0.3°C for the same period. During thisperiod, mean ground surface temperature (GST) on the rockglacier was between +1.0°C (at 10 cm depths, within finedebris) and +1.6°C (below 7 cm thick moss cover on top oflarge boulder). Mean air temperature measured in an air voidof the coarse blocky layer was 1°C (Fig. 4).The results of the Schmidt-hammer rebound measurementsshow that the rock glacier is, indeed, a continuous landformwith increasing surface age from its source zone (close to thefoot of the rock-free face behind it) to its tongue. This resultis a prerequisite for the correct interpretation of cosmogenicnuclide exposure dating.AcknowledgmentsFieldwork has been financially supported by theDepartment of Geosciences, University of Oslo and theSwiss Academy of Sciences (Reisestipendien in Botanik,Zoologie und Erdwissenschaften). The ERS-1/2 data set isprovided by the European Space Agency (ESA) under theproject AOALO.3668. Further thanks go to Christian Hauckfor his help with the interpretation of the geophysical resultsReferencesAndersen, B.G., Mangerud, J., Sørensen, R., Reite, A.,Sveian, H., Thoresen, M. & Bergstrøm, B. 1995.Younger Dryas ice-marginal deposits in Norway.Quaternary <strong>International</strong> 28: 147-169Bamler, R. & Hartl, P. 1998. Synthetic aperture radarinterferometry. Inverse Problems 14: R1.Dehls, J., Olesen, O., Olsen, L. & Blikra, L.H. 2000.Neotectonic faulting in northern Norway; theStuoragurra and Nordmannvikdalen postglacialfaults. Quaternary Science Reviews 19: 1447-1460Reynolds, J.M. 1997. An Introduction to Applied andEnvironmental Geophysics. Chichester: John Wiley& Sons, 796 pp.Sollid, J.L. & Sørbel, L. 1992. Rock glaciers in Svalbardand Norway. Permafrost and Periglacial Processes3: 215–220.Tolgensbakk, J. & Sollid, J.L. 1988. Kåfjord, kvartærgeologiog geomorfologi, 1:50,000, 1634 II. GeographicalInstitute, University of Oslo (map).Tolgensbakk. J. & Kverndal A.-I. 1995. Fjellskred ogsteinbreer I Kåfjordområdet, Troms. Geonytt 22: 70.Tolgensbakk. J. & Kverndal A.-I. 1996. Rock glaciers andNeotectonics in the Kåfjord area, North Norway.Abstracts of the 28th <strong>International</strong> GeographicalCongress: 471–472.78
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ContentsPreface ...................
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Mapping and Modeling the Distributi
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Satellite Observations of Frozen Gr
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xiiIce Wedge Thermal Regime in Nort
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xivPermafrost Response to Dynamics
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NICOP SponsorsUniversitiesUniversit
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Deep Permafrost Studies at the Lupi
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Effect of Fire on Pond Dynamics in
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Cryological Status of Russian Soils
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Acoustical Surveys of Methane Plume
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Permafrost Delineation Near Fairban
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Preparatory Work for a Permanent Ge
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A Provisional Soil Map of the Trans
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Martian Permafrost Depths from Orbi
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Time Series Analyses of Active Micr
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Impact of Permafrost Degradation on
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DC Resistivity Soundings Across a P
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Modeling Thermal and Moisture Regim
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A Provisional Permafrost Map of the
Page 48 and 49: Alpine Permafrost Distribution at M
Page 50 and 51: Cryogenic Formations of the Caucasu
Page 52 and 53: Modeling Potential Climatic Change
Page 54 and 55: A Hypothesis: A Condition of Growth
Page 56 and 57: Modeled Continual Surface Water Sto
Page 58 and 59: Freeze/Thaw Properties of Tundra So
Page 60 and 61: Discontinuous Permafrost Distributi
Page 62 and 63: Thermal Regime Within an Arctic Was
Page 64 and 65: Seasonal and Interannual Variabilit
Page 66 and 67: Twelve-Year Thaw Progression Data f
Page 68 and 69: Continued Permafrost Warming in Nor
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Page 72 and 73: A Permafrost Model Incorporating Dy
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Page 78 and 79: The Importance of Snow Cover Evolut
Page 80 and 81: The Account of Long-Term Air Temper
Page 82 and 83: The Combined Isotopic Analysis of L
Page 84 and 85: Adaptating and Managing Nunavik’s
Page 86 and 87: Human Experience of Cryospheric Cha
Page 88 and 89: HiRISE Observations of Fractured Mo
Page 90 and 91: A Soil Freeze-Thaw Model Through th
Page 92 and 93: Mapping and Modeling the Distributi
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Page 96 and 97: Historical Changes in the Seasonall
Page 100 and 101: Snowpack Evolution on Permafrost, N
Page 102 and 103: Climate Change in Permafrost Region
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