Alpine topography in Norway is largely fault-controlled. Linear and asymmetric ranges developed in the footwalls of normal faults that were reactivated after the main phase of Mesozoic rifting, but prior to the Late Cenozoic glaciations. Stark geomorphological contrasts developed across the faults, reflecting differential glacial exploitation of the pre-glacial drainage pattern. Alpine topography developed preferentially in the footwalls. Triangular facets mark the traces of the most recently active faults. At the base of deeply incised, alpine range-front escarpments, the best-exposed faults display metres-thick fault-rock successions and record multiple phases of fault movement. Juxtaposition of Precambrian and Caledonian basement rocks with Jurassic or Cretaceous sedimentary rocks provides evidence for fault activity in or after the Mesozoic for some of the faults. Late Cretaceous or younger reactivation is indicated by jumps in apatite fission-track apparent ages across the faults, and interferometric synthetic aperture radar and earthquake data attest to normal faulting at the present day. Two of the areas described host anomalous clusters of rockslides that may relate to tectonic activity. The most distinct landscape-forming faults in western Scandinavia were probably active in the Cenozoic, and imposed asymmetric landscape patterns from the scale of single mountain ranges to the whole of Scandinavia.

Rock avalanches and related tsunamis represent one of the most serious natural hazards in Norway, and during the last 100 years more than 170 people have lost their lives in western Norway. Large-scale rock-slope failures range from sliding of relatively intact masses of rock, to fully disintegrated rock avalanches. A wide variety of features mirror rock avalanches plunging into valleys or fjords. Bouldery fans, lobes and ridges characterize the proximal parts, while thin debris-flow deposits often occur far beyond this zone. Major deformations of valley-fill and fjord sediments are commonly related to the impact of large volumes of rock. The spatial and temporal pattern of rock-avalanche events in Norway demonstrates that such events are common and occur within certain regions, and are important data for evaluating background hazard levels. The mechanisms for occurrence and triggering of rock-slope failures are still uncertain, but seismic ground shaking and creep processes are probably important although, in some areas, effects of glacial unloading during the deglaciation phase cannot be excluded. The geographic concentrations of events indicate that relatively large earthquakes may have played a role as triggering mechanisms. This hypothesis is strengthened by the identification of postglacial faults in two of the rock-failure zones.

This paper reports new developments on the complex variables boundary element approach for solving three-dimensional problems of cracks in elastic media. These developments include implementation of higher order polynomial approximations for the boundary displacement discontinuities and more efficient analytical techniques for evaluation of integrals. The approach employs planar triangular boundary elements and is based on the integral representations written in a local coordinate system of an element. In-plane components of the fields involved in the representations are separated and arranged in certain complex combinations. The Cauchy–Pompeiu formula is used to reduce the integrals over the element to those over its contour and evaluate the latter integrals analytically. The system of linear algebraic equations to find the unknown boundary displacement discontinuities is set up via collocation. Several illustrative numerical examples involving a single (penny-shaped) crack and multiple (semi-cylindrical) cracks are presented.

Reports of neotectonic deformation in Norway, including Svalbard and offshore areas, have been graded into five classes depending on the quality of documentation and their most likely origin. A large number of the mainland locations have been visited and careful field investigations carried out, while offshore localities have been analysed by 2D and 3D seismic and multibeam data. After a critical evaluation of the 79 neotectonic claims in Norway as a whole, we have classified three of these as 'A - Almost certainly neotectonics' and another seven as 'B - Probably neotectonics.' The majority of the reports are attributed to effects other than tectonic. The present grade A claims include two postglacial faults in northern Norway and one postglacial fault in southern Norway The NE-SW oriented, reverse Stuoragurra Fault in western Finnmark constitutes the Norwegian part of the postglacial Lapland Fault Province. The NW-SE striking Nordmannvikdalen fault in northern Troms is a normal fault trending perpendicular to the extensive system of NE-SW trending reverse faults in northern Fennoscandia. The grade 13 claims include Supposed secondary effects of large-magnitude earthquakes such as abundant liquefaction structures, rock-slope failures and other collapse structures in northern and western Norway. There are indications that three separate, large-magnitude earthquakes affected the Finnmark-Troms region during the period 11,000-9,000 BP. Palaeoseismic events have also been postulated in western Norway. There is, for example, evidence of three regional slide events in western Norway, including one episode shortly after the deglaciation and two events at c. 8,000 and c. 2,000 calendar years BP. The 8,000 y. BP event has been interpreted as the effect of a tsunami generated by the Storegga slide while another 8,000 y. 1311 liquefaction event, in Nord-Trondelag, may also be related to an earthquake. The offshore investigations have not confirmed any firm evidence of neotectonic deformation events, although several distortions in Quaternary reflectors have been mapped in the northern North Sea area, where Subtle features may represent faults associated with gas leakage. A major seismic pulse most likely accompanied each of the deglaciations Following the multiple glaciation cycles in mainland Fennoscandia and Scotland during the last 600,000 years. The interaction of the contraction and dilation of fissures associated with these glaciation cycles may have facilitated fluid and gas leakage through the reservoir seals and gas chimneys, ultimately forming pockmarks on the sea floor. This mechanism could also have contributed to the concentration and pumping of hydrocarbons from their source rocks to reservoir formations. A possible example of this mechanism is shown by a recent earthquake along the postglacial Stuoragurra Fault, which has significantly influenced the groundwater circulation. Our understanding of past and future tectonic activity is especially important for the evaluation of hazard risk related to rock-slope stability.

The Berill Fault of northern West Norway, documented here for the first time, is a N-S striking and moderately west dipping reverse fault with a throw of 2 to 4 metres. It is responsible for an escarpment, up to 6 metres in height, which can be followed across a prominent mountain ridge. The mapped escarpment, well displayed both in Quarternary sediments and bedrock, is approximately 2.5 km long. The bedrock of the hanging wall displays a number of clefts and fractures, as do overlying till and colluvium. In one part of the hanging wall, a 400 to 700 m large collapse field (slide block), has loosened and slid several tens of metres down slope. Since the fault affects Quaternary deposits of Younger Dryas age, movement must post-date the latter. Little modification of the faulted colluvial fans suggests that movement took place in the second half of the Holocene. In a regional perspective, the fault may be associated with a series of strike parallel lineaments in the bedrock. If these lineaments constitute segments of a neotectonic fault zone, the throw versus surface-rupture-length ratio becomes approximately 2 x 10(-4), a realistic number compared to the high value of c. 1,2 x 10(-3) for the Berill Fault escarpment; the former number is more feasible when weighted against observations in other neotectonic regions. There is a higher frequency of rock avalanches near the Berill Fault and in the surrounding region, suggesting a link between rockslope failures and a major palaeoseismic event.

In order to obtain age estimates for the formation of two rockfall-avalanche deposits in Norangsdalen, degree of rock-surface weathering was measured using a type 'N' Schmidt hammer at six sites in Norangsdalen/Nibbedalen, Sunnmore, Norway. By assuming a linear weathering rate, the mean Schmidt hammer rebound (R-) values obtained on the rockfall-avalanche deposits compared to mean R-values obtained on sites of 'known' age indicate that the rockfall at skylstad may have occurred 6000 +/- 700 BP, while the rockfall avalanche at Uraseter may have been deposited 4200 +/- 800 BP. The indication that these rockfall events occurred in the mid-Holocene may suggest that they were initiated in connection with the deteriorating and changing climate conditions characterizing the period after the Holocene climatic optimum. This study demonstrates the potential for using the Schmidt hammer to obtain age estimates for rockfall-avalanche deposits in Norway.

The geographical and altitudinal distribution of block fields and trimlines in southern Norway are discussed in relation to the vertical extent of the continental ice sheet during the Late Weichselian glacial maximum. Inferred from these considenitions and formerly presented ice-sheet phases for the last glaciation in southern Norway, a new model on the Late Weichselian ice sheet is presented. This mod el indicates a low-gradient, poly-centred ice sheet during maximum glaciation with the ice divide zone located ei ose to the present main watershed. During the deglaciation, the margin of the ice sheet retreated to the coast and fjord areas of western Norway. This induced a backward lowering of the iee-sheet surface, and the culmination zones in areas with low pass-points between eastern and western parts of southem Norway thus migrated E/SE of the present main watershed. During maximum glaciation the are as of greatest relative ice thickness were located to the central lowland areas of eastern Norway, to the Trondelag region, and along the deeper fjords of western Norway.

Block fields and weathering limits in the mountains around inner Nordfjord, and glacial striae, erratics, block fields and alpine mountain morphology in the outer Nordfjord-Møre area, give information about the altitude of the surface of the continental ice sheet during the Late Weichselian glaciation. The ice sheet in the accumulation zone on the northern Jostedal Plateau was relatively thin during the peak of the Late Weichselian glaciation, due mainly to effective ice-drainage through the deep fjords and valleys. A longitudinal profile for the surface of the ice sheet from the northern Jostedal Plateau through Møre to the edge of the continental shelf has been reconstructed for the Late Weichselian glacial maximum.