This paper provides a snapshot of the permafrost thermal state in the Nordic area obtained during the International Polar Year (IPY) [2007][2008][2009]. Several intensive research campaigns were undertaken within a variety of projects in the Nordic countries to obtain this snapshot. We demonstrate for Scandinavia that both lowland permafrost in palsas and peat plateaus, and large areas of permafrost in the mountains are at temperatures close to 08C, which makes them sensitive to climatic changes. In Svalbard and northeast Greenland, and also in the highest parts of the mountains in the rest of the Nordic area, the permafrost is somewhat colder, but still only a few degrees below the freezing point. The observations presented from the network of boreholes, more than half of which were established during the IPY, provide an important baseline to assess how future predicted climatic changes may affect the permafrost thermal state in the Nordic area. Time series of active-layer thickness and permafrost temperature conditions in the Nordic area, which are generally only 10 years in length, show generally increasing active-layer depths and rising permafrost temperatures.
Abstract. Terrestrial laser scanning (TLS) provides highresolution point clouds of the topography and new TLS instruments with ranges exceeding 300 m or even 1000 m are powerful tools for characterizing and monitoring slope movements. This study focuses on the 35 million m 3Å knes rockslide in Western Norway, which is one of the most investigated and monitored rockslides in the world. The TLS point clouds are used for the structural analysis of the steep, inaccessible main scarp of the rockslide, including an assessment of the discontinuity sets and fold axes. TLS acquisitions in 2006, 2007 and 2008 provide information on 3-D displacements for the entire scanned area and are not restricted like conventional survey instruments to single measurement points. The affine transformation matrix between two TLS acquisitions precisely describes the rockslide displacements and enables their separation into translational components, such as the displacement velocity and direction, and rotational components, like toppling. This study shows the ability of TLS to obtain reliable 3-D displacement information over a large, unstable area. Finally, a possible instability model for the upper part ofÅknes rockslide explains the measured translational and rotational displacements by a combination of southward planar sliding along the gneiss foliation, gravitational vertical settlement along the complex, stepped basal sliding surface and northward toppling toward the opened graben structure.
The Kregnes “moraine” ridge in Gauldalen, a north‐trending valley south of Trondheim, is a Gilbert‐type delta formed at a Younger Dryas glacier terminus. The gravelly delta consists of a north‐dipping foreset, 150 m thick, comprised of turbidites, debrisflow beds and debrisfall deposits. The bottomset consists of turbiditic sand and mud layers. The topset, 2–3 m thick, is a braided‐river alluvium with local beach deposits, matching the marine limit of 175 m a.s.l. The fjord‐wide delta front had an extent of 3 km and prograded over a distance of 1.5 km, in probably less than 100 years, with the delta toe climbing by 50 m against the basin's rapidly aggrading muddy floor. The delta advanced through the alternating episodes of its toe aggradation and progradation, related to the increases and decreases of the delta‐slope gradient. Slope steepening led to intense sediment sloughing by chutes and occasional large‐scale failures. The fjord's wave fetch was low and the wave base no deeper than 1.5‐2 m, but strong storm waves occasionally reworked the delta front to a depth of 6 m. Glacitectonic deformation was limited to the system's upfjord end. Allostratigraphic analysis suggests that the proglacial system commenced its development as an ice‐contact submarine fan that was deformed, quickly aggraded to the sea surface and turned into an ice‐contact delta, which further evolved into the large glaciofluvial delta. The Kregnes ridge represents an episode of the ice‐front re‐advance due to climatic deterioration and is tentatively correlated with the Hoklingen substage.
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