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Iceland
Kinds of Iceland Selected AbstractsMETEOROLOGICAL CONDITIONS DURING SLUSH-FLOW RELEASE AND THEIR GEOMORPHOLOGICAL IMPACT IN NORTHWESTERN ICELAND: A CASE STUDY FROM THE BĶLDUDALUR VALLEYGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2006ARMELLE DECAULNE ABSTRACT. This paper examines triggering factors and geomorphic significance of slush flows in the Bķldudalur valley, northwestern Iceland. The area is prone to release slush flows from two confined gullies, and at least ten flows have been reported since the beginning of the twentieth century. Despite their short path (600 m) and their moderate magnitude (from 6000 to 8000 m3), slush flows in the Bķldudalur valley represent a serious threat for the local community that is situated within the runout and deposition zones. With the help of meteorological data, the release of known slush flows is examined, highlighting the role of heavy rainfall and rapid snow-melt during winter cyclonic activity. The geomorphological impact of slush flows is assessed through the characteristics of the landforms produced during the 1997 and 1998 slush-flow events. It appears that the most obvious characteristics of slush flows in the Bķldudalur valley are the entrainment and deposition of debris, spatially differentiated. Chaotic sedimentation occurs chiefly in the middle part of a clearly concave cone, even if the flows continue beyond the cone. [source] CLIMATE CHANGE AND FISHERIES: ASSESSING THE ECONOMIC IMPACT IN ICELAND AND GREENLANDNATURAL RESOURCE MODELING, Issue 2 2007RAGNAR ARNASON ABSTRACT. . Climate changes in the 21st century are expected to significantly increase ocean temperatures and modify other oceanographic conditions in the North Atlantic. Marine biological research suggests that the impacts on the commercially most important fish stocks in the Icelandic-Greenland ecosystem may well be quite substantial. This will obviously lead to a corresponding impact on the economies of these two countries. However, the timing, extent and biological impact of global warming is quite uncertain. As a result the economic impact is similarly uncertain. This paper attempts to provide estimates of the impact of altered fish stocks due to global warming on the Icelandic and Greenland economies. The approach is one of stochastic simulations. This involves essentially three steps. The first is to obtain predictions of the impact of global warming on fish stocks and the associated probability distribution. For this we rely on recent marine biological predictions. The second step is to estimate the role of the fisheries sector in the two economies. This is done with the help of modern econometric techniques based on economic growth theory and historical data. Obviously these estimates are also subject to stochastic errors and uncertainty. The third step is to carry out Monte Carlo simulations on the basis of the above model and the associated uncertainties. The result of the Monte Carlo simulations consists of a set of dynamic paths for GDP over time with an expected value and a probability distribution for each future year. On this basis it is possible to calculate confidence intervals for the most likely path of GDP over time. The results indicate that the fisheries impact of global warming on the Icelandic GDP is more likely to be positive than negative but unlikely to be of significant magnitude compared to historical economic growth rates and fluctuations. The uncertainty of this prediction, however, is large. For Greenland, the impact on fish stocks and the GDP is highly likely to be positive and quite substantial relative to the current GDP. Due to less knowledge of the relationship between the fisheries sector and the Greenland economy, however, the confidence interval of this prediction is even wider than in the case of Iceland. [source] SETTLEMENT ARCHAEOLOGY IN ICELANDACTA ARCHAEOLOGICA, Issue 2 2001The Race for the Pan-Scandinavian Project in 193 First page of article [source] Fourteenth World Congress on Dental Traumatology Reykjavik, Iceland , May 5,7, 2005DENTAL TRAUMATOLOGY, Issue 4 2005Anthony J. DiAngelis No abstract is available for this article. [source] Unchanged incidence of diabetic nephropathy in Type 1 diabetes: a nation-wide study in IcelandDIABETIC MEDICINE, Issue 2 2005G. Tryggvason Abstract Aims Diabetic nephropathy is an uncommon cause of end-stage renal disease in Iceland in contrast to most industrialized countries. The aim of this study was to examine the incidence of diabetic nephropathy in Iceland. Methods All patients diagnosed with Type 1 diabetes in Iceland before 1992 were studied retrospectively. Patients diagnosed before age 30, who were insulin dependent from the onset, were defined as having Type 1 diabetes. Diabetic nephropathy was defined as persistent proteinuria measured with a dipstick test (Albustix) on three consecutive clinic visits at least 2 months apart. Patients were followed to the end of year 1998, to their last recorded outpatient visit, or until death. The cumulative incidence of diabetic nephropathy was calculated with the Kaplan,Meier method and presented according to the duration of diabetes divided into 5-year intervals. Results A total of 343 patients with Type 1 diabetes were identified. The mean follow-up period was 20.2 ± 11.4 (mean ± sd) years. Only 9.3% of patients were lost to follow-up. Sixty-five patients developed diabetic nephropathy. The cumulative incidence was 22.6% at 20 years and levelled off at 40.3% after approximately 35 years of diabetes duration. No significant changes in cumulative incidence were observed over time. Mean glycated haemoglobin was 8.4% in patients with proteinuria and 7.8% in a group of patients without proteinuria that was matched for age, gender and duration of diabetes (P = 0.04). Conclusions The cumulative incidence of diabetic nephropathy in Iceland is comparable with previously reported cumulative incidence rates and has remained unchanged. Glycaemic control was significantly better in patients without proteinuria. [source] Geographical segregation in Dunlin Calidris alpina populations wintering along the East Atlantic migratory flyway , evidence from mitochondrial DNA analysisDIVERSITY AND DISTRIBUTIONS, Issue 5 2008Ricardo J. Lopes ABSTRACT Dunlin Calidris alpina is one of the most abundant shorebirds using coastal habitats in the East Atlantic migratory flyway, that links arctic breeding locations (Greenland to Siberia) with wintering grounds (West Europe to West Africa). Differential migration and winter segregation between populations have been indicated by morphometrics and ringing recoveries. Here, we analyse the potential of genetic markers (mitochondrial DNA , mtDNA) to validate and enhance such findings. We compared mtDNA haplotypes frequencies at different wintering sites (from north-west Europe to West Africa). All birds from West Africa had western (European) haplotypes, while the eastern (Siberian) haplotypes were only present in European winter samples, reaching higher frequencies further north in Europe. Compilation of published results from migrating birds also confirmed these differences, with the sole presence of European haplotypes in Iberia and West Africa and increasingly higher frequencies of Siberian haplotypes from south-west to north-west Europe. Comparison with published haplotype frequencies of breeding populations shows that birds from Greenland, Iceland, and North Europe were predominant in wintering grounds in West Africa, while populations wintering in West Europe originated from more eastern breeding grounds (e.g. North Russia). These results show that genetic markers can be used to enhance the integrative monitoring of wintering and breeding populations, by providing biogeographical evidence that validate the winter segregation of breeding populations. [source] Reconstructing the past in medieval IcelandEARLY MEDIEVAL EUROPE, Issue 3 2006Chris Callow Locating and dating sagas is a difficult but still important task. This paper examines the relationship between the Sagas of Icelanders, which are concerned with tenth- and eleventh-century events, and the contemporary sagas of the mid-thirteenth century. Drawing upon models from anthropology, it looks at how contemporary ideas permeated these historicizing texts and how genealogy and geography act as structures around which the past is remembered. The many political relationships which occur in Laxdęla saga are analysed in relation to those from contemporary sagas from the same area of western Iceland. Since it appears that there is relatively little in common between the political situations depicted in Laxdęla saga and those portrayed in the contemporary sagas, it is likely that Laxdęla saga and the contemporary sagas were actually written down in different periods. It is possible, therefore, that the Sagas of Icelanders give us a view of the past which originates earlier than is usually suggested. [source] Hydrologic and geomorphic effects of temporary ice-dammed lake formation during jökulhlaupsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2003Matthew J. Roberts Abstract Glacial outburst ,oods (jökulhlaups) occur frequently in glaciated environments, and the resultant ,ooding causes geomorphic change and, in some instances, damage to local infrastructure. During some jökulhlaups, ,oodwater is stored temporarily in ice-marginal locations. In July 1999, a linearly rising jökulhlaup burst from Sólheimajökull, Iceland. During this remarkable event, subglacial ,oodwater pooled transiently in two relict ice-dammed lake basins, before draining suddenly back into Sólheimajökull. The signi,cance of such rapid formation and attendant drainage of temporary ice-dammed lakes during jökulhlaups has not been addressed. Consequently, this paper: (i) assesses the hydrologic and geomorphic effects of temporary ice-dammed lake formation caused by lake-basin ,retro-,lling'; and (ii) discusses the impact and signi,cance of transient retro-,lling under jökulhlaup conditions. Pre- and post-,ood ,eldwork at Sólheimajökull enabled the impact and signi,cance of lake-basin retro-,lling to be assessed. Field evidence demonstrates that the July 1999 jökulhlaup had an unusually rapid rise to peak discharge, resulting in subglacial ,oodwater being purged to ice-marginal locations. The propensity for temporary retro-,lling was controlled by rapid expulsion of ,oodwater from Sólheimajökull, coincident with locations suitable for ,oodwater storage. Floodwater inundated both ice-marginal lake basins, permitting signi,cant volumes of sediment deposition. Coarse-grained deltas prograding from the ice margin and boulders perched on scoured bedrock provide geomorphic records of sudden retro-,lling. The depositional characteristics of lake-basin deposits at Sólheimajökull are similar to jökulhlaup sediments documented in proglacial settings elsewhere; however, their depositional setting and association with ice-marginal landforms is distinctive. Findings suggest that temporary ice-dammed lake formation and drainage has the capacity to alter the shape of the ,ood hydrograph, especially if drainage of a temporary lake is superimposed on the original jökulhlaup. Deposits associated with lake-basin retro-,lling have a long-term preservation potential that could help to identify temporary ice-dammed lake formation in modern and ancient glacial environments. Copyright © 2003 John Wiley & Sons, Ltd. [source] Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skei,arįrjökull, IcelandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2001Matthew J. Roberts Abstract This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwater outbursts suggest that englacial sediment emplacement is possible during jökulhlaups. The November 1996 jökulhlaup from Skei,arįrjökull, Iceland presented one of the first opportunities to examine englacial flood deposits in relation to former supraglacial outlets. Using observations from Skei,arįrjökull, this paper identifies and explains controls on the deposition of englacial flood sediments and presents a qualitative model for englacial jökulhlaup deposition. Englacial jökulhlaup deposits were contained within complex networks of upglacier-dipping fractures. Simultaneous englacial deposition of fines and boulder-sized sediment demonstrates that englacial fracture discharge had a high transport capacity. Fracture geometry was an important control on the architecture of englacial jökulhlaup deposits. The occurrence of pervasively frozen flood deposits within Skei,arįrjökull is attributed to freeze-on by glaciohydraulic supercooling. Floodwater, flowing subglacially or through upglacier-dipping fractures, would have supercooled as it was raised to the surface faster than its pressure-melting point could increase as glaciostatic pressure decreased. Evidence for floodwater contact with the glacier bed is supported by the ubiquitous occurrence of sheared diamict rip-ups and intra-clasts of basal ice within jökulhlaup fractures, deposited englacially some 200,350 m above the bed of Skei,arįrjökull. Evidence for fluidal supercooled sediment accretion is apparent within stratified sands, deposited englacially at exceptionally high angles of rest in the absence of post-depositional disturbance. Such primary sediment structures cannot be explained unless sediment is progressively accreted to opposing fracture walls. Ice retreat from areas of former supraglacial outbursts revealed distinct ridges characterized by localized upwellings of sediment-rich floodwater. These deposits are an important addition to current models of englacial sedimentation and demonstrate the potential for post-jökulhlaup landform development. Copyright © 2001 John Wiley & Sons, Ltd. [source] Stochastic models for simulation of strong ground motion in IcelandEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2001Sķmon Ólafsson Abstract Two types of modelling approaches for simulating ground motion in Iceland are studied and compared. The first type of models, named discrete-time series models (ARMA), are based solely on measured acceleration in earthquakes occurring in Iceland. The second type of models are based on a theoretical seismic source model called the extended Brune model. Based on measured acceleration in Iceland during the period 1986,1996, the parameters for the extended Brune models have been estimated. The seismic source models are presented here as ARMA models, which simplifies the simulation process. A single-layer soil amplification model is used in conjunction with the extended Brune model to estimate local site amplification. Emphasis is put on the ground motion models representing the variability in the measured earthquakes, with respect to energy, duration and frequency content. Demonstration is made using these models for constructing linear and non-linear probabilistic response spectra using a discretised version of the Bouc,Wen model for the hysteresis of the second-order system. Copyright © 2001 John Wiley & Sons, Ltd. [source] An Evaluation of the Cod Fishing Policies of Denmark Iceland and NorwayEUROCHOICES, Issue 3 2004R. Arnason Summary An Evaluation of the Cod Fishing Policies of Denmark, Iceland and Norway Many ocean fisheries are subject to a fundamental economic problem generally referred to as the common property problem. This problem manifests itself as excessive fishing fleets and fishing effort, depressed fish stocks and little or no profitability of the fishing activity, irrespective of the richness of the underlying marine resources. European fisheries represent some of the most dramatic examples of the common property problem. This article employs simple empirical models and recently developed mathematical techniques to examine the economic efficiency of three European fisheries, namely the Danish, Icelandic and Norwegian cod fisheries, The optimal harvesting policies for each of these fisheries are calculated. Comparing these optimal policies with actual harvests provides a measure of the relative efficiency in these three cod fisheries. The comparison confirms the widely held impression that the cod harvesting policies of ail three countries have been hugely inefficient in the past. Moreover, it appears that the inefficiency has been increasing over time. Only during the last few years of our data are there indications that this negative trend may have been halted. Somewhat more surprisingly, in spite of radically different fisheries management systems, we find relatively little difference in the level of stock over-exploitation between these three countries. Politiques compareées de pźhe ą la morue au Danemark, en Islande et en Norvčge Beaucoup de pźcheries océaniques sont confrontées au problčme nique fondamental de la "propriété collective". Celui-ci se manifeste par des flottes de taille excessive, au service d' efforts de péche exagérés, qui aboutissent ą détruire les stocks de poisson et la rentabilité des pécheries, en dépit de la richesse des ressources marines sousjacentes. Les pźcheries européennes constituent actuellement l'un des exemples les plus dramatiques des problčmes associés a la propriété collective. On présente ici un modčle empirique assez simple mais associéą de nouvelles techniques mathématiques récemment développé es pour mesurer l' efficacitééconomique de trois types de politiques de pźche ą la morue, au Danemark, en Norvčge et en Islande. On commence par calculer le volume optimal des prises pour chacun de ces pays. La comparaison entre le niveau optimal et le niveau réel des prises permet de mesurer le degré d' efficacité des politiques suivies. Elle permet de confirmer l'opinion largement répandue selon laquelle les politiques passées ont été extrźmement peu efficaces. En outre, il apparaīt que l'inefficacité est croissante avec le temps. C'est seulement dans les toutes derničres années des séries de données que l' on observe un infléchissement de cette tendance négative. Enfin, et c'est le plus surprenant, on trouve peu de differences entre les trois pays en ce qui conceme le degré de surexploitation du stock, et cela, bien que les principes de gestion des pźcheries y soient entiArement différents. Eine Bewertung der Kabeljaufischereipolitik in Dänemark, Island und Norwegen ahlreiche Hochseefischereien tehen einem grundlegenden ftliehen Problem gegenüber, das allgemein als Problem des kollektiven Eigentums bezeichnet wird. Dieses Problem zeigt sich in übermäßig großen Fangflotten und beträchtlichem Fischereiaufwand, geschrumpften Fischbeständen und geringer oder fehlender Rentabilität der Fischerei; dabei ist die Höhe der Fischressourcen unbedeutend für das Problem. Die europäischen Fischereien stellen einige der drastischsten Beispiele für das Problem des kollektiven Eigentums dar. In diesem Beitrag werden einfache empirische Modelle und kürzlich entwickelte mathematische Verfahren angewendet, um die wirtschaftliche Effizienz von drei europäischen Fischereien zu untersuchem der dänischen, der isländischen und der norwegischen Kabeljaufischerei. Für jede dieser Fischereien wird die optimale Nutzungsstrategie berechnet. Aus dem Vergleich dieser optimalen Nutzungsstrategie mit den tatsächlichen Erträgen ergibt sich ein Maß fur die relative Effizienz, die bei diesen drei Kabeljaufischereien vorliegt. Der Vergleich bestätigt den weit verbreiteten Eindruck, dass die Strategien zum Kabeljaufang in alien drei Ländern in der Vergangenheit enorm ineffizient waren. Darüber hinaus wird deutlich, dass die Ineffizienz im Laufe der Zeit zugenommen hat. Lediglich die Daten der letzten jahre enthalten Hinweise darauf, dass dieser negative Trend zum Stillstand gekommen sein könnte. Obwohl sich die Fischwirtschaft in jedem dieser drei Länder sehr stark unterscheidet, lassen sich erstaunlich wenige Unterschiede im Maß der Übernutzung des Fischbestandes finden. [source] Distress and coping in cancer patients: feasibility of the Icelandic version of BSI 18 and the WOC-CA questionnairesEUROPEAN JOURNAL OF CANCER CARE, Issue 1 2006E. HJÖRLEIFSDÓTTIR rnt, doctoral student The aim of this study was to test the feasibility of two instruments within an Icelandic context, the Brief Symptom Inventory 18 (BSI 18) and the Ways of Coping Inventory , Cancer Version (WOC-CA) with specific focus on gender and type of treatment and coping techniques among cancer patients during time of treatment. The sample consisted of 40 cancer patients in three oncology outpatient clinics in Iceland, 53% were women and 47% men. The majority of the participants belonged to the age group 51,70. Cronbach alpha, means, confidence intervals and standard deviations were used for analysis as well as Mann,Whitney U -test for testing differences between genders in relation to psychological distress and coping. Anxiety was the factor causing the greatest distress, mainly reported by patients receiving chemotherapy. More women experienced depression than men, women (18.4%), men (8.3%). Distancing was the most frequently reported coping strategy, and men seemed to focus on the positive side more often than women did (P < 0.01). Although the results should be approached with caution, as the sample size was small, they do provide support for the strength of the measurements. Also the findings indicate that gender differences should be taken into account. [source] Disease burden of chronic lymphocytic leukaemia within the European UnionEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2008Louise Watson Abstract Objective:, Whilst Chronic lymphocytic leukaemia (CLL) is considered a rare disease, to our knowledge, the current prevalence of CLL within the European Union (EU) member states is not published. Understanding the number of individuals with CLL is vital to assess disease burden within the wider population. Methods:, Using 2002 data from the International Agency for Research on Cancer, we estimated the number of individuals with CLL (ICD-10 C91.1) from those reported for all leukaemias (C91,95) and extrapolated the figures by the population increase within the EU between 2002 and 2006, the last year with fully updated community population estimates. One- and 5-yr partial prevalence estimates are reported (i.e. the number of individuals still living 1,5 yr post-diagnosis). We then applied proportional estimates from the literature to assess those requiring immediate treatment, those under observation and their likely progression rates. Results:, We found that within the 27 EU states plus Iceland, Norway and Lichtenstein, 1- and 5-yr CLL partial prevalence estimates totalled approximately 13 952 and 46 633 individuals respectively in 2006. By applying Binet staging to the 1-yr estimate, 40% of patients will be stage B/C and require immediate treatment. Thus, 5581 individuals may be treated within the first year of diagnosis. Of the 60% (8371) under observation, by 5 yr up to 33% (2763) may have more advanced disease with increased risk of mortality. Conclusion:, Whilst CLL is a rare disease, the number of individuals burdened by the disease within the EU is considerable and thousands of patients require treatment and physician care, which has cost implications for member states. [source] Nitrification in terrestrial hot springs of Iceland and KamchatkaFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Laila J. Reigstad Abstract Archaea have been detected recently as a major and often dominant component of the microbial communities performing ammonia oxidation in terrestrial and marine environments. In a molecular survey of archaeal ammonia monooxygenase (AMO) genes in terrestrial hot springs of Iceland and Kamchatka, the amoA gene encoding the ,-subunit of AMO was detected in a total of 14 hot springs out of the 22 investigated. Most of these amoA -positive hot springs had temperatures between 82 and 97 °C and pH range between 2.5 and 7. In phylogenetic analyses, these amoA genes formed three independent lineages within the known sequence clusters of marine or soil origin. Furthermore, in situ gross nitrification rates in Icelandic hot springs were estimated by the pool dilution technique directly on site. At temperatures above 80 °C, between 56 and 159 ,mol NO3, L,1 mud per day was produced. Furthermore, addition of ammonium to the hot spring samples before incubation yielded a more than twofold higher potential nitrification rate, indicating that the process was limited by ammonia supply. Our data provide evidence for an active role of archaea in nitrification of hot springs in a wide range of pH values and at a high temperature. [source] Trophic role of Atlantic cod in the ecosystemFISH AND FISHERIES, Issue 1 2009Jason S. Link Abstract As the world's oceans continue to undergo drastic changes, understanding the role of key species therein will become increasingly important. To explore the role of Atlantic cod (Gadus morhua Gadidae) in the ecosystem, we reviewed biological interactions between cod and its prey, predators and competitors within six ecosystems taken from a broad geographic range: three are cod-capelin (Mallotus villosus Osmeridae) systems towards cod's northern Atlantic limit (Barents Sea, Iceland and Newfoundland,Labrador), two are more diverse systems towards the southern end of the range (North Sea and Georges Bank,Gulf of Maine), and one is a species-poor system with an unusual physical and biotic environment (Baltic Sea). We attempt a synthesis of the role of cod in these six ecosystems and speculate on how it might change in response to a variety of influences, particularly climate change, in a fashion that may apply to a wide range of species. We find cod prey, predators and competitors functionally similar in all six ecosystems. Conversely, we estimate different magnitudes for the role of cod in an ecosystem, with consequently different effects on cod, their prey and predator populations. Fishing has generally diminished the ecological role of cod. What remains unclear is how additional climate variability will alter cod stocks, and thus its role in the ecosystem. [source] The effects of the net fishery closure on angling catch in the River Hvķtį, IcelandFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2003S. M. Einarsson Abstract Between 1991 and 2000, angling associations on the tributaries of the River Hvķtį leased net fishery rights in the Hvķtį mainstem, with the aim of eliminating net fishery harvest and improving the rod catch. The rod catch and net catch in the Hvķtį system were significantly correlated (r = 0.94; P <,0.001) over the 10-year period prior to (1981,1990) closure of the net fishery. The rod fishery in the tributaries of the River Hvķtį was also significantly correlated to the rod fishery in selected groups of rivers in west (r = 0.80; P < 0.01) and north (r = 0.73; P < 0.05) before the closure. Significant increases (P < 0.01) were observed in rod catches in the Hvķtį tributaries between 1991 and 2000 after the closure, while rod catches in control regions decreased. Based on evaluation of rod catch trends before and after the closure, it was estimated that the net fishery lease increased rod catches in the tributaries between 1773 and 2175 fish (28,35%). The increase in rod catches also suggested that the rod fishery may be taking 39,52% of the estimated previous net catch. The high price paid annually for the net fishery lease just to eliminate net fishing (,135 000) reflects the high value of rod caught salmon compared with salmon caught by the net fishery. [source] METEOROLOGICAL CONDITIONS DURING SLUSH-FLOW RELEASE AND THEIR GEOMORPHOLOGICAL IMPACT IN NORTHWESTERN ICELAND: A CASE STUDY FROM THE BĶLDUDALUR VALLEYGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2006ARMELLE DECAULNE ABSTRACT. This paper examines triggering factors and geomorphic significance of slush flows in the Bķldudalur valley, northwestern Iceland. The area is prone to release slush flows from two confined gullies, and at least ten flows have been reported since the beginning of the twentieth century. Despite their short path (600 m) and their moderate magnitude (from 6000 to 8000 m3), slush flows in the Bķldudalur valley represent a serious threat for the local community that is situated within the runout and deposition zones. With the help of meteorological data, the release of known slush flows is examined, highlighting the role of heavy rainfall and rapid snow-melt during winter cyclonic activity. The geomorphological impact of slush flows is assessed through the characteristics of the landforms produced during the 1997 and 1998 slush-flow events. It appears that the most obvious characteristics of slush flows in the Bķldudalur valley are the entrainment and deposition of debris, spatially differentiated. Chaotic sedimentation occurs chiefly in the middle part of a clearly concave cone, even if the flows continue beyond the cone. [source] Re-Dating the Moraines at Skįlafellsjökull and Heinabergsjökull using different Lichenometric Methods: Implications for the Timing of the Icelandic Little Ice Age MaximumGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2004Krista M. Mckinzey Abstract Little Ice Age (LIA) moraines along the margins of Skįlafellsjökull and Heinabergsjökull, two neighbouring outlet glaciers flowing from the Vatnajökull ice-cap, have been re-dated to test the reliability of different lichenometric approaches. During 2003, 12 000 lichens were measured on 40 moraine fragments at Skįlafellsjökull and Heinabergsjökull to provide surface age proxies. The results are revealing. Depending on the chosen method of analysis, Skįlafellsjökull either reached its LIA maximum in the early 19th century (population gradient) or the late 19th century (average of five largest lichens), whereas the LIA maximum of Heinabergsjökull occurred by the mid-19th century (population gradient) or late-19th century (average of 5 largest lichens). Discrepancies (c. 80 years for Skįlafellsjökull and c. 40 years for Heinabergsjökull) suggest that the previously cited AD 1887 LIA maxima for both glaciers should be reassessed. Dates predicted by the lichen population gradient method appear to be the most appropriate, as mounting evidence from other geochronological reconstructions and sea-ice records throughout Iceland tends to support an earlier LIA glacier maximum (late 18th to mid-19th century) and probably reflects changes in the North Atlantic Oscillation. These revised chronologies shed further light on the precise timing of the Icelandic LIA glacier maximum, whilst improving our understanding of glacier-climate interactions in the North Atlantic. [source] A Polygenetic Landform At Stķgį, Öręfajökull, Southern IcelandGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2004Tim Harris Abstract Recent research has identified problems inherent in the identification and description of landforms. Morphologically similar small-scale glacial and periglacial landforms can be misinterpreted, thus hindering environmental reconstruction. This study reveals that a landform resembling a moraine at Stķgįrjökull, southern Iceland, is the product of both glacial deposition and mass movement. The landform has two distinct morphological and sedimentological components: a basal, lithologically diverse component, and an upper, lithologically homogenous component. Clast lithological analysis, particle shape and particle size measurements demonstrate that the basal component of the landform consists of sediment whose characteristics match nearby moraines. In contrast, the source of the upper component is a narrow outcrop of rock above the valley floor. Evidence suggests that frost-shattered material was transported across a perennial snow patch to a small moraine, leading to growth of the ,moraine'. This combination of processes is unlikely to be unique, but the geological peculiarities of the field site permitted their identification. It is possible that many similar ,moraines' could be enlarged by subaerial feeding, leading to false reconstruction of glacier form and/or associated rates of erosion and sedimentation. Such polygenetic landform genesis therefore has implications for environmental reconstruction. [source] Lichenometric dating in southeast Iceland: the size,frequency approachGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2004Tom Bradwell This paper presents a calibrated dating curve based on the gradient of the size-frequency distribution of yellow-green Rhizocarpon lichens. The dating potential of this new curve is tested on surfaces of known age in southeast Iceland. This particular size,frequency technique is also compared with the more traditional largest-lichen approach. The results are very encouraging and suggest that the gradient can be used as an age indicator, at least on deposits formed within the last c. 150 years , and probably within the last c. 400 years , in the maritime subpolar climate of southeast Iceland. Using both lichenometric techniques, revised dates for moraines on two glacier forelands are presented which shed new light on the exact timing of the Little Ice Age glacier maximum in Iceland. [source] Land Cover Characteristics in Ne Iceland with Special Reference to Jökulhlaup GeomorphologyGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3-4 2003Petteri Alho ABSTRACT Subglacial eruptions in Vatnajbkull have accounted for several jökulhlaups (glacial outburst floods) in the Northern Volcanic Zone (NVZ). These events and aeolian processes have had a considerable impact on the landscape evolution of the area. Most of this area is occupied by barren land cover; the northern margin of the barren land cover is advancing northwards, burying vegetation under wind-blown sediment. This paper presents a land-cover classification based on a supervised Landsat TM image classification with pre-processing and extensive field observations. Four land cover categories were identified: (a) lava cover (34.8%); (b) barren sediment cover (39.0%); (c) vegetation (25.1%); and (d) water and snow (1.1%). The mapping of sand transport routes demonstrates that a major aeolian sand transportation pathway is situated in the western part of the study area. The sedimentary formation elongated towards the northeast is evidence of active and continuous aeolian sand transportation towards the north. Interpretation of the satellite image suggests that four main areas are affected by jökulhlaups along the Jökulsįį Fjöllum: Įsbyrgi, Grķmsstašir, Heršubreiš,Möšrudalur, and the Dyngjujökull sandur. In addition, jökulhlaup-related sediment cover (8%) in the study area, together with erosional features, are evidence of a severe and extensive jökulhlaup-induced process of land degradation. [source] Jökulhlaup-related Ice Fracture and Supraglacial Water Release During the November 1996 Jökulhlaup, Skeišarįrjökull, IcelandGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1-2 2001R.I. Waller During the initial stages of the November 1996 jökulhlaup at Skeišarįrjökull, Iceland, floodwaters burst onto the glacier surface via a series of fractures. This supraglacial drainage led to the formation of a number of distinct ice surface depressions, one of which is investigated in detail. The morphology and structural characteristics of this feature are described, as well as the sedimentology of an associated assemblage of debris-filled fractures. This work suggests that debris-charged subglacial floodwaters travelled up to the glacier surface, where supraglacial flow occurred initially via an extensive network of fractures, orientated parallel to the glacier margin. Supraglacial discharge became progressively more focused into a series of discrete outlets, leading to the mechanical erosion of a number of depressions on the glacier surface. The associated transfer of subglacially derived floodwaters to high levels within the glacier resulted in the rapid entrainment of large volumes of sediment which may influence the patterns, processes and products of ice-marginal sedimentation in the future. [source] "SCENOPHOBIA", GEOGRAPHY AND THE AESTHETIC POLITICS OF LANDSCAPEGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 3 2007Karl Benediktsson ABSTRACT. Recent critiques of the nature,culture dualism, influenced by diverse theoretical stances, have effectively destabilized the "naturalness" of nature and highlighted its pervasive and intricate sociality. Yet the practical, ethical and political effects of this theoretical turn are open to question. In particular, the emphasis on the sociality of nature has not led to reinvigorated environmental or landscape politics. Meanwhile, the need for such politics has if anything increased, as evident when ongoing and, arguably, accelerating landscape transformations are taken into account. These concerns are illustrated in the paper with an example from Iceland. In its uninhabited central highland, serious battles are now being fought over landscape values. Capital and state have joined forces in an investment-driven scramble for hydropower and geothermal resources to facilitate heavy industry, irrevocably transforming landscapes in the process. Dissonant voices arguing for caution and conservation have been sidelined or silenced by the power(ful) alliance. The author argues for renewed attention to the aesthetic, including the visual, if responsible politics of landscape are to be achieved. Aesthetic appreciation is an important part of the everyday experiences of most people. Yet, enthusiastic as they have been in deconstructing conventional narratives of nature, geographers have been rather timid when it comes to analysing aesthetic values of landscape and their significance, let alone in suggesting progressive landscape politics. A political geography of landscape is needed which takes aesthetics seriously, and which acknowledges the merit of engagement and enchantment. [source] The Nordic Volcanological Institute: understanding volcanoes at spreading centresGEOLOGY TODAY, Issue 2 2009Kent Brooks The Nordic countries (known as ,Norden') are not immediately associated with volcanoes: Norway with folded mountains cut by fjords and its offshore oil and gas deposits, Sweden and Finland by the western part of the Baltic shield, a huge area of Precambrian rocks, of which gneisses form a large part, and Denmark, a country of Mesozoic and Cenozoic rocks, where glacial, superficial deposits are of major importance. But Norden also includes Iceland, where everyone immediately thinks of volcanoes and glaciers. Clearly volcanological research would be expected to be a major priority for the Icelandic nation. However, in the other Nordic countries old volcanic and other igneous rocks play a significant role, comprising a large part of the Precambrian and Caledonian terrains and being a key to many of the commercial mineral deposits which play a major role in the economies of Norway, Sweden and Finland. Even Denmark, a country of sedimentary rocks has an impressive sequence of Paleogene volcanic ashes and the Faeroe Islands, made up almost entirely of basalts, are part of Denmark. [source] Crustal structure of central and northern Iceland from analysis of teleseismic receiver functionsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2000Fiona A. Darbyshire We present results from a teleseismic receiver function study of central and northern Iceland, carried out during the period 1995,1998. Data from eight broad-band seismometers installed in the SIL network operated by the Icelandic Meteorological Office were used for analysis. Receiver functions for each station were generated from events for a wide range of backazimuths and a combination of inversion and forward modelling was used to infer the crustal structure below each station. The models generated show a considerable variation in the nature and thickness of the crust across Iceland. The thinnest crust (20,21 km) is found in the northern half of the Northern Volcanic Zone approximately 120 km north of the centre of the Iceland mantle plume. Thicker crust (24,30 km) is found elsewhere in northern and central Iceland and the thickest crust (37 km) is found close to the plume centre. Velocity,depth profiles show a distinct division of the crust into two main sections, an upper high-velocity-gradient section of thickness 2,8 km and a lower crustal section with small or zero overall velocity gradient. The thickness of the upper crust correlates with the tectonic structure of Iceland; the upper crust is thickest on the flanks of the northern and central volcanic rift zones and thinnest close to active or extinct central volcanoes. Below the Krafla central volcano in northeastern Iceland the receiver function models show a prominent low-velocity zone at 10,15 km depth with minimum shear wave velocities of 2.0,2.5 km s,1. We suggest that this feature results from the presence of partially molten sills in the lower crust. Less prominent low-velocity zones found in other regions of Iceland may arise from locally high temperatures in the crust or from acidic intrusive bodies at depth. A combination of the receiver function results and seismic refraction results constrains the crustal thickness across a large part of Iceland. Melting by passive decompression of the hot mantle below the rift zone in northern Iceland forms a crust of thickness ,20 km. In contrast, the larger crustal thickness below central Iceland probably arises from enhanced melt production due to active upwelling in the plume core. [source] The seismic anomaly beneath Iceland extends down to the mantle transition zone and no deeperGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2000G. R. Foulger A 3-D teleseismic tomography image of the upper mantle beneath Iceland of unprecedented resolution reveals a subvertical low wave speed anomaly that is cylindrical in the upper 250 km but tabular below this. Such a morphological transition is expected towards the bottom of a buoyant upwelling. Our observations thus suggest that magmatism at the Iceland hotspot is fed by flow rising from the mantle transition zone. This result contributes to the ongoing debate about whether the upper and lower mantles convect separately or as one. The image also suggests that material flows outwards from Iceland along the Reykjanes Ridge in the upper 200 km, but is blocked in the upper 150 km beneath the Tjornes Fracture Zone. This provides direct observational support for the theory that fracture zones dam lateral flow along ridges. [source] Variable sensitivity of plant communities in Iceland to experimental warmingGLOBAL CHANGE BIOLOGY, Issue 4 2005Ingibjörg S. Jónsdóttir Abstract Facing an increased threat of rapid climate change in cold-climate regions, it is important to understand the sensitivity of plant communities both in terms of degree and direction of community change. We studied responses to 3,5 years of moderate experimental warming by open-top chambers in two widespread but contrasting tundra communities in Iceland. In a species-poor and nutrient-deficient moss heath, dominated by Racomitrium lanuginosum, mean daily air temperatures at surface were 1,2°C higher in the warmed plots than the controls whereas soil temperatures tended to be lower in the warmed plots throughout the season. In a species-rich dwarf shrub heath on relatively rich soils at a cooler site, dominated by Betula nana and R. lanuginosum, temperature changes were in the same direction although more moderate. In the moss heath, there were no detectable community changes while significant changes were detected in the dwarf shrub heath: the abundance of deciduous and evergreen dwarf shrubs significantly increased (>50%), bryophytes decreased (18%) and canopy height increased (100%). Contrary to some other studies of tundra communities, we detected no changes in species richness or other diversity measures in either community and the abundance of lichens did not change. It is concluded that the sensitivity of Icelandic tundra communities to climate warming varies greatly depending on initial conditions in terms of species diversity, dominant species, soil and climatic conditions as well as land-use history. [source] Hereditary breast and ovarian cancer in Asia: genetic epidemiology of BRCA1 and BRCA2,HUMAN MUTATION, Issue 6 2002Alexander Liede Abstract Ethnic differences in cancer incidence and mortality result from differences in genetic and epidemiologic risk factors. Mutations in BRCA1 and BRCA2 account for a small proportion of all breast cancer cases, but for a much higher proportion of cases with a strong family history of breast or ovarian cancer. Germline mutations in BRCA1 and BRCA2 have been identified in individuals of many races and ethnic groups and the frequency of mutations varies between these groups. Some of the differences in cancer risk between populations may be the result of founder mutations in these genes. The cost and time required for mutation analysis are reduced considerably when founder mutations are identified for a specific ethnic group. The BRCA2 999del5 mutation in Iceland and three BRCA mutations in Ashkenazi Jews are well characterized. However, considerably less is known about the contribution of mutations in the BRCA1 and BRCA2 genes outside of European groups. Studies conducted on the Asian populations described here have expanded our current knowledge of genetic susceptibility and its contribution to breast and ovarian cancer rates in Asian populations. Hum Mutat 20:413,424, 2002. © 2002 Wiley-Liss, Inc. [source] Hydrodynamics and geomorphic work of jökulhlaups (glacial outburst floods) from Kverkfjöll volcano, IcelandHYDROLOGICAL PROCESSES, Issue 6 2007Jonathan L. Carrivick Abstract Jökulhlaups (glacial outburst floods) occur frequently within most glaciated regions of the world and cause rapid landscape change, infrastructure damage, and human disturbance. The largest jökulhlaups known to have occurred during the Holocene within Iceland drained from the northern margin of Vatnajökull and along the Jökulsį į Fjöllum. Some of these jökulhlaups originated from Kverkfjöll volcano and were routed through anastomosing, high gradient and hydraulically rough channels. Landforms and sediments preserved within these channels permit palaeoflow reconstructions. Kverkfjöll jökulhlaups were reconstructed using palaeocompetence (point measurements), slope,area (one-dimensional), and depth-averaged two-dimensional (2D) hydrodynamic modelling techniques. The increasing complexity of 2D modelling required a range of assumptions, but produced information on both spatial and temporal variations in jökulhlaup characteristics. The jökulhlaups were volcanically triggered, had a linear-rise hydrograph and a peak discharge of 50 000,100 000 m3 s,1, which attenuated by 50,75% within 25 km. Frontal flow velocities were ,2 m s,1; but, as stage increased, velocities reached 5,15m s,1. Peak instantaneous shear stress and stream power reached 1 × 104 N m,2 and 1 × 105 W m,2 respectively. Hydraulic parameters can be related to landform groups. A hierarchy of landforms is proposed, ranging from the highest energy zones (erosional gorges, scoured bedrock, cataracts, and spillways) to the lowest energy zones (of valley fills, bars, and slackwater deposits). Fluvial erosion of bedrock occurred in Kverkfjallarani above ,3 m flow depth, ,7m s,1 flow velocity, ,1 × 102 N m,2 shear stress, and 3 × 102 W m,2 stream power. Fluvial deposition occurred in Kverkfjallarani below ,8 m flow depth, 11 m s,1 flow velocity, 5 × 102 N m,2 shear stress, and 3 × 103 W m,2 stream power. Hence, erosional and depositional ,envelopes' have considerable overlap, probably due to transitional flow phenomena and the influence of upstream effects, such as hydraulic ponding and topographic constrictions, for example. Holocene Kverkfjöll jökulhlaups achieved geomorphic work comparable to that of other late Pleistocene ,megafloods'. This work was a result of steep channel gradients, topographic channel constrictions, and high hydraulic roughness, rather than to extreme peak discharges. The Kverkfjöll jökulhlaups have implications for landscape evolution in north-central Iceland, for water-sediment inputs into the North Atlantic, and for recognizing jökulhlaups in the rock record. 2D hydrodynamic modelling is likely to be important for hazard mitigation in similar landscapes and upon other glaciated volcanoes, because it only requires an input hydrograph and a digital elevation model to run a model, rather than suites of geomorphological evidence and field-surveyed valley cross-sections, for example. Copyright © 2006 John Wiley & Sons, Ltd. [source] Long-term variability in precipitation and streamflow in Iceland and relations to atmospheric circulationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2009Jóna Finndķs Jónsdóttir Abstract How the variability of the atmospheric circulation affects precipitation in Iceland is not completely understood. Also, the sea surface temperature (SST) has a strong influence on the temperature over the country, and thereby, snow and glacial melt. This study, therefore, aims at explaining how atmospheric circulation and sea surface temperature influence seasonal and annual precipitation, and, consequently, runoff in Iceland. Empirical orthogonal function (EOF) analysis is performed on annual and seasonal time series of precipitation and discharge to identify their key modes of variability during the period 1966,2004. The correlation between the time series of each EOF mode with individual time series of sea level pressure (SLP), air temperature and SST was then evaluated. The analyses evidenced how large-scale climate variables are connected to the regional precipitation and runoff in Iceland. They showed that the strength of the polar vortex may be, at least, as important for the precipitation in some areas of Iceland as the strength of the Icelandic Low (IL). Moreover, the location of the semi-permanent IL often defines the predominant wind direction over the country and, as such, the regions of preferred precipitation. Since the watersheds act as large precipitation gauges with response patterns depending on the geology and glaciers, the variability of the annual discharge closely resembles the variability of precipitation, except for the glacial rivers. Glacial melt is highly correlated to air temperature and SST, and the spring discharge is affected by winter and spring temperatures. The results also revealed that Icelandic hydrological conditions in the spring can be forecasted by precipitation and temperature of the autumn and winter seasons, as well as by the general prevalent circulation patterns. Additionally, a potential for seasonal forecast of precipitation, and river discharge in other seasons was identified, particularly if seasonal forecast of SLP is available. 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