10. Engineering and enviromental geology
10.1. Geohazards in the Nordic and Arctic regions
Artificially supply of water for release of the Veslemannen instability at Mannen in Romsdalen, western Norway
Lars Harald Blikra1, Lene Kristensen1 and Gustav Pless1
1The Norwegian Water Resources and Energy Directorate
Permanent monitoring and early warning systems were established at the unstable rock slope Mannen in 2009. The instrumentation includes a comprehensive surface network in addition to 120 m deep instrumentation in two boreholes. A periodic ground-based InSAR campaign in 2014 identified large displacements in a small portion of Mannen (Veslemannen instability). The volume is between 120.000 and 180.000 m3. The possible runout area includes some few houses, a farm and the railway. Stages of increased velocities in 2014, 2015 and 2016 led to evacuation of people, animals and closing of the railway. These events have attracted a massive media interest. This has shown to be a challenging situation for the evacuated people, the municipality and for NVE having the responsibility for the monitoring.
NVE decided to artificially add water in order to reduce the stability and possibly release a part or the entire Veslemannen instability, and was performed two times in October 2017 during periods were people were evacuated (red hazard level). The displacements before the experiment was already significant and the additional water supply had an effect in terms of increased displacements. However, the area stabilized again when temperatures lowered below zero and the precipitation came as snow.
There are a series of challenges related to “helping nature” in terms of artificial triggering of landslides. This includes the media attention and communication issues related to evacuated people, municipality and other
An automatic watch of a slope, Lac à l’Eau-Claire, Nunavik
Armelle Decaulne1 and Najat Bhiry2
1CNRS, LETG UMR6554, Nantes, France, 2Université Laval, Centre d’études nordiques, Quebec city, Canada
The slope topography and talus morphometry in Lac à l’Eau-Claire (56°20’N; 76°17’W) indicate inherited and active gravity processes. Evidence of recent activity has been observed during field investigations. However, the identification of gravity processes on slopes remains difficult, as no event has ever been reported and no witness is able to relate any event in this remote area. Nevertheless, Lac à l’Eau-Claire is traversed by Cree and Inuit hunters and fishermen all year-round, and a well-known place for trap. Lac à l’Eau-Claire is also part of the Tursujuq National Park, and welcomes tens of tourists each year. Gravity processes thus become not only physical processes, but raise hazard and risk issues.
In an attempt to better know the year-round gravity processes acting on Caribou slope, we installed in August 2016 an automatic camera. This slope has been selected because it presents fresh scattered boulders indicative of recent slope activity; furthermore, the apical rockwall is heavily affected by frost weathering and deep cracks are opening on the uppermost of the rockwall. From the collection of 2855 pictures, we are able to survey gravity movements and snow cover evolution on the slope.
The camera at Caribou slope, and three other on different slopes, is now operating. Additional cameras surveying slopes and slope processes have also been installed in other places encountering gravity processes in Nunavik: in Tasiapik valley, south-east of Umiujaq; and over the road leading to the airport in Kangiqsualujjuaq.
Artificially triggering of Rock Fall in Norway. Methods, consequences and lessons learned.
Ulrik Domaas1 and Trond Vernang1
1Norwegian Geotechnical Institute
Securing roads, housing areas, construction sites and protective work from rock fall may involve artificially blasting, scaling and other means in addition to ordinary protective work with rock bolts, wire rope nets, wire rope fences and dams. Foreseeing the consequences of artificially release of rock fall for human activities below are difficult to evaluate due to the complexity of such activity. Making evacuation plans without knowing the exact outcome of rock fall release is necessary to do before executing the rock fall release. Improved planning, hazard zoning, involvement of local authorities, police and rescue team can give a successful outcome. Close cooperation with entrepreneurs and decision makers during the work is vital. Information in peoples meeting and in local newspapers is necessary. Triggering of loose rock with moderate volumes may cause larger rock fall volume than expected, producing dust cloud and rock fragment splashing far beyond known runout. Rock fall material may also trigger debris flow days after the event itself. Removing loose rocks with water or free hanging iron ball under helicopter is efficient to clear an unstable area. Use of air pillow or rubber mats may be efficient to release single blocs but can be difficult in steep mountainsides. Systematic assembled knowledge of methods, cases, and unforeseen consequences from artificially triggered rock falls is needed and will be beneficial to all sides of the industry.
Continuously monitoring of Gámanjunni 3, 26 Mm3 unstable rockslide, Kåfjord, northern Norway.
Gudrun Dreiås Majala1, Lars Harald Blikra1, Lene Kristensen1 and Ingrid Skrede1
Gàmanjunni 3 is classified as a high-risk object based on the movement, structures and the consequences of the rockslide. As a high-risk object, the unstable rockslide need continuously monitoring.
The section for rockslide management in NVE are in charge of all unstable rock slopes (7 in present) that are classified as high-risk objects and some objects that needs periodic monitoring. NGU is responsible for the mapping and classification of large rock-slope failures.
Gámanjunni 3 is a 26 Mm3 large unstable rockslide located in Kåfjord, northern Norway, and is the third monitored site in the municipality. Gàmanjunni 3 has a movement of 2-6 cm/year towards W-SW and has a fully developed wedge with a 150 m vertical displacement. A large rockslide from Gámanjunni 3 will cross the valley and dam the river.
Since October 2016 NVE have established 10 GPS-antennas, 3 different web cameras, 4 platforms for helicopter and a weather station that forms the monitoring network. A ground-based radar in the valley further monitor the rockslide. In order to improve the signal from the satellite radar (InSAR), corner reflectors are placed in the unstable area. Investigations in terms of resistivity and seismic surveys have been performed in order to build a better geological model. Run-out modelling, dam-breach analysis and flood modelling are completed.
Permafrost rock walls in norway – Thermal regime and geomorphological processes in time and space
Bernd Etzelmüller1, Florence Magnin1, Kristin S. Myhra2, Benjamin Jacobs3, Michael Krautblatter3 and Sebastian Westermann1
1University of Oslo, 2Western Norway University of Applied Sciences, 3Technical University Munich, Germany
The role of the ground thermal regime on geomorphological processes in settings associated to steep slopes has received considerable attention in the past. It is evident from recent studies that e.g. rock walls have a profound effect on the thermal regime in mountain sides, a.o. influencing rock wall stability, weathering regimes and glacier-permafrost interaction in space and time. This presentation discusses the importance of the thermal regime in space and time on geomorphological processes in steep slopes. We combine direct observations of air, ground and rock wall temperatures with numerical simulations. We present results from both thermal (2D transient thermal model – CryoGRID 2D) and thermo-mechanical modelling along with Electrical Resistivity Tomography (ERT) validation of different sites dominated by unstable rock slopes in Norway. We analyse how thermal gradients in rock walls may influence important geomorphological processes related to weathering, talus developments, material accumulation and ice aggregation in coarse material. On longer time scales we hypothesise that permafrost dynamics associated with glaciation and deglaciation phases may have influenced the development and stability of large-scale valley systems.
Artificial trigger of the large-scale Chapf rock instability by two blastings in 2001/2002, Bernese Oberland, Switzerland.
1Kellerhals + Haefeli AG, Bern, Switzerland
A large unstable rock mass of about 250’000 m3 called Chapf near Innertkirchen (Bernese Oberland, Siwtzerland) was continuously monitored during 50 years. The Grimsel Pass road is situated about 1‘000 m below and was thus endangered. The movement was accelerating from about 1 cm/year up to 0.6 cm/day during the years 1999 to 2001. Therefore the Canton of Bern decided to take emergency measures. First, the collapse was intended to be triggered by infiltrating water into the open joints, as the movements reacted strongly to precipitation. The watering had to be stopped due to the seasonal decrease of the available water. Finally, the unstable rock mass was removed by two big blastings.
The removal was carried out in two steps from the top to the bottom. In a first step, 156 boreholes up to 95 m deep were drilled in the upper half of the about 150 m high rock wall. With a digital elevation model based on aerial photographs and laser scanning a 3D-model of the joints was elaborated in order to determine the explosive charge. The blasting in October 2001 with a total of 19’000 kg of explosiv denudated about 150’000 m3 of rock.
The second blasting in August 2002 was planned with a similar approach as 2001 (21’000 kg of blasting charge). About 110’000 m3 of rock were blasted. Both blastings were very successful: The stable rock wall of the Chapf was not affected and consequently this area does not endanger the Grimsel Pass road anymore.
Geological observations of the landslide of June 17, 2017 in Karrat Fjord (central West Greenland)
Pierpaolo Guarnieri1 and Erik Vest Sørensen1
1GEUS-Geological Survey of Denmark and Greenland
On June 17, 2017 a landslide occurred along the southern slope of the 2180 m-high Umiamakku Auffaa in the Karrat Fjord, central West Greenland (Lat. 71º 38’). The rock mass slid into the Kangilleq Fjord generating a tsunami that severely damaged the village of Nuugaatsiaq located 35 km to the south-west. The Karrat Fjord region is part of a geological mapping project in the Uummaanak region between the Geological Survey of Denmark and Greenland (GEUS) and the Government of Greenland. During field operations conducted in 2015-2017 a large number of oblique, high-resolution stereo-images were acquired for photogrammetric studies coupled with geological observation covering the entire region. This allows us to study the geology and structure of the region in three dimensions and in great detail. Detailed oblique photos along the southern flank of Umiamakku Auffaa were collected in 2015, two years before the rockslide event, and again in July 2017, one month after the disastrous event. This gives us unique control of the geological and structural setting before and after the landslide event and furthermore allows us to estimate the size of the landslide precisely. The geology of that particular area is represented by quartzites, amphibolites and meta-pelites belonging to the Palaeoproterozoic Qeqertarssuaq Formation. 3D-photogeology in the GEUS Photogrammetry-Lab and field data shows strongly foliated meta-volcanic and meta-sandstone rocks dipping 20° to the SW. The downslope setting toward the fjord and the tectonic layering suggest a lithological and structural control for the landslide mechanism.
Cosmogenic nuclide dating of rock-slope failure deposits and rock slope deformation in Troms county, northern Norway
Reginald L. Hermanns1, Martina Bøhme1, John Gossse2 and Samuel Niedermann3
1Norges geologiske undersøkelse, 2Dalhousie university, 3GeoForschungsZentrum Potsdam
Systematic mapping for unstable rock slopes has been carried out in Troms county since 2007 and 129 unstable rock slopes were recognized (more than one third of all known in Norway). Despite this large number, the 1810 Pollfjellet rock avalanche is the only historic event in the county. We dated deposits of rock-slope failures and rock slope deformation by cosmogenic nuclide (CN) dating. Most of the deposits of rock-slope failures date to shortly after deglaciation in this region. However, ages also span the entire Holocene.
Four sliding surfaces that dissect high altitude flat surfaces have been sampled for CN dating. Two of these top surfaces have been dated to be older than LGM, while for the remaining two results are expected soon. Two of those surfaces are dissected by deep-seated gravitational slope deformations (DSGSDs). Both topmost sliding surfaces have ages in the upper part that predate LGM. Both DSGSDs have collapse deposits along their foot that date shortly after deglaciation. The other two top surfaces are dissected by rockslides. Both became active within or at the end of the thermal maximum within the Holocene. None of those are related to any rock-slope failure deposit. Our data thus suggest that rock-slope deformation in Troms county is a process that has been active from before the LGM and DSGSDs can survive glacial cycles in cold-based ice environments, while rock slides rather seem to be phenomena that started and peaked after deglaciation and maintain on a low constant rate within the Holocene.
Destabilisation and temporal deformation patterns of rock-slope instabilities in Northern and Western Norway
Paula Hilger1, Reginald L. Hermanns2, Kristin S. Myhra3, Bernd Etzelmüller4 and John C. Gosse5
1Geological Survey of Norway; University of Oslo, 2Geological Survey of Norway; Technical Univeristy Trondheim, 3Høyskole på Vestlandet, Sogndal; University of Oslo, 4University of Olso, 5Dalhousie University, Halifax, Canada
More than 300 active rock slopes demonstrating post glacial deformation are mapped in Norway, whereof seven are classified as high-risk objects because of their sliding rates and potential impact on infrastructure. In addition to post-glacial stress increase, we expect water pressure and altitudinal permafrost dynamics to significantly impact these gravity driven slope processes along complex pre-existing bedrock structures.
To improve understanding of the potential influence of post-glacial permafrost dynamics on rock-slope failures, we use terrestrial cosmogenic nuclide (TCN) dating along three sliding surfaces to derive the timing of initial failure and potential sliding patterns since the onset of deformation. Preliminary TCN ages of the Mannen and Revdalsfjellet 2 instabilities in western and northern Norway respectively, suggest that sliding started close to the Holocene Thermal Maximum, when mountain permafrost presence was at a minimum. This indicates that permafrost thawing may have contributed to the timing of these rock-slope instabilities. The preliminary results of Revdalsfjellet 1, which is an adjacent but independently moving rock body to Revdalsfjellet 2, suggest a movement onset during strong temperature fluctuations in the mid Holocene.
Recent acceleration of deformation at the Mannen site could be connected to late stage permafrost thawing at the lower boundary of altitudinal permafrost, whereas relatively slow displacement rates at the Revdalsfjellet instabilities connected to their low elevation of 600 m a.s.l. seem to be dissociated from continuous permafrost. The different timing of the initial failure at the two adjacent instabilities demonstrates the structural complexity of the sites and importance of local settings.
Monitoring active rock fall and avalanche events
Lene Kristensen1, Ingrid Skrede1 and Lars Harald Blikra1
Movements in release areas have been measured prior to both rock fall events and snow avalanches in Western and Northern Norway. Our results indicates that both prior movement and acceleration phases can be identified rock falls and avalanches and may potentially be used as early warning. However – in several instances we have measured large movements and accelerations that stopped due to changed conditions (meteorology etc.).
The movements have been measured primarily using ground based InSAR systems (LiSALab), while change detection and analysis has been aided using point clouds from terrestrial laser scans. In combination the datasets allows for detailed detection of how movement relates to rock structures.
The examples presented are a part of a research project, aiming to obtaining acceleration curves of different types of slide events. NVE is responsible for all types of geohazard relating to slides (rock, clay, avalanches etc.) as well as flooding in Norway. The Section for Rockslide Managements primary responsibility is monitoring of seven high risk rock slides in Norway, and periodic monitoring of less risky objects. We base the monitoring on the assumption that large rock slopes develop over time and accelerates prior to failure. In the project we extend the methodology and equipment to study other types of slides.
Measurements of movement in source areas can greatly aid a visual inspection of stability and provide a basis for handling crisis situations after slides to buildings or infrastructure. Furthermore is increases NVEs preparedness to handle various types of geohazards.
Sensitivity to coastal erosion in southern Sweden shown in a map viewer
Kärstin Malmberg Persson1
1Geological Survey of Sweden
A rising sea level is expected to cause increased coastal erosion in southernmost Sweden where the postglacial isostatic uplift is negligible. To predict where coastal erosion will be most intense and which areas are most sensible to erosion, detailed geological data are necessary. The coast of Skåne displays great variation in geology and topography and while some parts are highly sensible to erosion, other parts are very resistant.
The Geological Survey of Sweden has carried out combined land- and sea-based geological mapping along the coastline of Skåne. The collected data on land include beach sediment composition, beach morphology, sediment stratigraphy, signs of active erosion and constructions for coastal protection. Information collected on the sea floor includes surface sediment composition, detailed bathymetry and patterns of erosion and deposition caused by waves and currents.
The information has been used to classify the shoreline into different coastal types with different sensitivity to erosion (Malmberg Persson et al. 2016). An attempt to estimate the erosion conditions after a one-metre rise of the sea level has also been made. The most common coastal type today is sandy beaches with alternating erosion/accumulation but in balance over an extended time (31 % of the coast). 12 % of the coast is subject to net erosion.
These features, and more information, are shown in a map viewer: https://apps.sgu.se/kartvisare/kartvisare-skanestrand.html
The information can be used for e.g. coastal physical and marine spatial planning and for study of sediments and sedimentary processes in coastal environments.
Malmberg Persson, K., Nyberg, J., Ising, J. & Rodhe, L. 2016: Skånes känsliga stränder – erosionsförhållanden och geologi för samhällsplanering. SGU-rapport 2016:17, 61 pp.
Integrated analysis of past, and potential future rock slope failures of various size from Rombakstøtta, Norway
Odd André Morken1, Reginald Hermanns2 and Paula Hilger1
1NGU, 2NGU, NTNU
Catastrophic failure of large rock slopes has led to fatalities in Norway several times per century. The Geological Survey of Norway (NGU) carry out systematic mapping of potentially unstable rock slopes in Norway. In this context, a hazard analysis and preliminary consequence assessment of the unstable rock slope at Rombakstøtta, has been carried out. Additionally, a fragmentation cycle analysis, used to assess the fragmentation of the rock mass during a failure, and to separate rock fall deposits from rock avalanche deposits, has been developed and tested.
The study area is in a north facing slope along a fjord, within the arctic circle and close to the city of Narvik. Based on delimiting lineaments observed in the field, aerial photos, photo
panoramas and digital elevation models, eight failure scenarios are defined. Application of NGU´s hazard analysis as well as volume estimation and run-out analysis were done for all scenarios. Four of the scenarios have modelled run-out reaching vital infrastructure and the fjord.
The fragmentation cycle analysis has been developed and applied inspired by Charrière et al. (2016). Results suggest that the rock avalanche deposits at Rombakstøtta underwent 0-3 fragmentation cycles during failure and transport. And that rock fall deposits generally experienced more than 4 fragmentation cycles during failure and transport.
Charrière, M., Humair, F., Froese, C., Jaboyedoff, M., Pedrazzini, A., Longchamp, C. 2016: From the source area to the deposit: Collapse, fragmentation, and propagation of the Frank Slide. GSA Bulletin ; 128 (1-2): 332–351.
The triggering factors of the Móafellshyrna debris slide in northern Iceland: intense precipitation, earthquake activity and thawing of mountain permafrost
Þorsteinn Sæmundsson1, Costanza Morino2, Jón Kristinn Helgason3, Conway Susan4 and Halldór G. Pétursson5
1Department of Geography and Tourism, University of Iceland, Askja, Sturlugata 7, 101 Reykjavík, Icel, 2School of Environment, Earth & Ecosystems, The Open University, Milton Keynes MK7 6AA, UK, 3Icelandic Meteorological Office, Avalanche Centre, Suðurgata 12, 400 Ísafjörður, Iceland, 4Laboratoire de Planétologie et Géodynamique de Nantes UMR-CNRS 6112, 2, rue de la Houssinière, BP 92, 5Icelandic Institute of Natural History. Borgum við Norðurslóð, 602 Akureyri, Iceland
On the 20th of September 2012, a large debris slide occurred in the Móafellshyrna Mountain in the Tröllaskagi peninsula, central north Iceland. The slide initiated after an unusual warm and dry summer followed by a month of heavy precipitation. Furthermore, the slide originated after a seismic sequence. The main source of material was ice-rich talus deposits perched on a topographic bench. Blocks of ice-cemented deposits broke off the frontal part of the talus cone and fell onto the talus slope below. Further downslope, the landslide material became over-saturated, causing it to evolve into a debris slide. We estimate that the total volume of the debris slide is around 500,000 m3 and that its primary cause was intense precipitation. We cannot exclude the influence of the seismic sequence as a contributing factor. The presence of ice-cemented blocks in the slide deposits shows that thawing of ground ice could have played an important role as a triggering factor. Ice-cemented blocks of debris have been observed in the deposits of two other recent landslides in northern Iceland, in the Torfufell Mountain and the Árnesfjall Mountain. This suggests that discontinuous permafrost is degrading in Iceland, due to climate change. This study highlights that ground ice thaw could represent a new source of hazard in Iceland. The knowledge of the detailed distribution of mountain permafrost on the island is poorly constrained and should be a priority for future research.
Geomorphologic Evidence and Timeline Reconstruction of Holocene Jökulhlaups along the Hvítá River and Gullfoss, Iceland
1University of Texas at Austin
Gullfoss is one of Iceland’s most visited tourist sites, a two-tiered waterfall where the Hvítá River plunges 32 meters into the Hvítárgljúfur canyon. This system is one line of evidence for paleofloods that surged across the region ~9500 years BP. Over a span of 100-200 years, a series of floods drained the ice-dammed glacial lake Kjölur in the southwestern highlands. The largest events reached an estimated maximum peak discharge of 3 x 105 m3 s-1, ranking them among the largest known floods in Iceland and on earth. Most research on Icelandic jökulhlaups has focused on floods generated by volcanic and geothermal activity beneath the southernmost ice caps; but the little-studied Kjölur floods, not triggered by volcanogenic processes, may provide a better analog for most global glacial lake outburst floods. A pioneering study by Tómasson (1993) reconstructed the Kjölur paleofloods based on geomorphologic evidence and paleolake strandlines. This project builds on previous research by employing new methods to better constrain flood timing, magnitude, and routing. This presentation has three main goals: 1) present new and synthesized geomorphologic field evidence; 2) outline a sampling strategy for geochronological analyses; and 3) situate the Kjölur jökulhlaups in the broader context of catastrophic flood geomorphology in Iceland. This research will yield insight into drainage dynamics of ice-dammed proglacial lakes, which pose an increasing hazard worldwide due to rapid climate-driven glacial lake expansion. It has excellent potential to bridge the gap between academic research and public outreach through communication to a high number of international visitors.
Tómasson, H., 1993. Jökulstífluð vötn á Kili og hamfarahlaup í Hvítá í Árnessýslu. Náttúrufræðingurinn 62, 77-98.
A structural and InSAR study of the unstable rock slope in Oksfjellet, Troms
Marie Bredal1, Steffen G. Bergh2, Lars Harald Blikra3 and Tom Rune Lauknes4
1Geological Survey of Norway (NGU), 2UiT The Arctic University of Norway, 3Norwegian Water and Energy Directorate (NVE), UiT The Arctic University of Norway, 4Norut Northern Research Institute
Oksfjellet is one of many unstable rock slopes in Troms, Norway. Due to the hazard and risk posed by potential slope failures, it is important to obtain precise deformation measurements. In this study, a combination of field observations and InSAR data was analyzed to better understand the geological structures susceptible for sliding in Oksfjellet.
Field mapping in Oksfjellet revealed a ductile shear zone/thrust that is interpreted to have formed during the Caledonian nappe emplacement. Mapped fractures, trending NE-SW and NW-SE, coincides with regional Mesozoic brittle structures.
Satellite InSAR data (TerraSAR-X and Radarsat-2) revealed subsidence of the unstable slope at a rate of 4 ‒ 5 mm/year. Additionally, satellite InSAR data detected subsidence of a larger area, at a rate of less than 1 mm/year, that is thought to relate to active down-faulting. Results from Ground-Based InSAR revealed displacement estimates at rates of mm/day, indicating that seasonal changes related to water and ice influences the stability of the unstable rock slope.
Based on structural measurements and displacement patterns detected by InSAR, the deformation in Oksfjellet is interpreted to be controlled by a complex interaction between ductile and brittle structures, following a common deep seated sliding surface between foliation/thrust and fractures. The combination of InSAR data and field mapping proved valuable in order to assess displacement patterns at different temporal and spatial scales. This contributed to an improved understanding of the evolution of the unstable rock slope in Oksfjellet.
The Kassen and Håkåneset rock slope instabilities along fjord lakes in Telemark show large postglacial gravitational strain but no present day deformation, Southern NorwayThe Kassen and Håkåneset rock slope instabilities along fjord lakes in Telemark show large postglacial gravitational strain but no present day deformation, Southern Norway
Kaja Krogh1, Reginald L. Hermanns2, Trond Eiken3, John Gosse4, Martina Bøhme2 and Ivana Penna2
1Norwegian University of Science and technology, Norway, 2Geological Survey of Norway, Trondheim, Norway, 3University of Oslo, Oslo, Norway, 4Dalhousie University, Halifax, Canada
The Kassen and Håkåneset rock slope instabilities lie along fjord lakes. The Kassen instability lies at the tip of a plateau dipping steeply towards Bandak lake. The instability stretches 2,5 km E-W. Its up to 100-m-high steep back scarp separates undeformed crystalline bedrock from strongly desintegrated rock mass breaking the slope in various compartments. In the central part a depression exists, that has descended an additional 25-50 m. Below that, bathymetric data reveal a 13.4-million-m3 large rock-avalanche deposit on the bottom of lake Bandak. Preliminary cosmogenic nuclide ages indicate that the top of the mountain melted out of the ice at 14.1 ka and was mainly active in the early part of the Holocene. Differently the top of the Håkåneset rock slope instability lies mid slope but similarly the up to 75-m-high back scarp separates strongly deformed and cracked rock mass from stable rock mass. Bathymetric data of Tinnsjø lake reveal that the instability extends down to ~330 m below lake level. At the foot both a 40-m-high pressure ridge within a terrace and several generations of slide scars within this terrace suggest that the instability reaches down to the lake bottom.
Kinematic feasibility tests at both locations show that simple failure modes are possible in the steepest slope parts but bi-planar sliding is feasible at both locations for larger compartments. Displacement rates determined by dGNSS show velocities below significance level (< 2mm/yr) for the past years suggesting that both rock slopes stabilized in comparison to the pronounced postglacial deformation.
Stability Analysis of Preikestolen (Rogaland county, Norway)
Katrine Mo1, Reginald Hermanns2, Martina Böhme3 and Pierrick Nicolet3
1Norwegian University of Science and Technology, 2Norwegian University of Science and Technology, Geological Survey of Norway, 3Geological Survey of Norway
The hike to Preikestolen is one of the most popular trails in Norway, with more than a hundred thousand visits each year. Despite the popularity, the stability of the rock formation is not yet determined. The Geological Survey of Norway (NGU) is now mapping potential unstable rock slopes in Rogaland County. Hence, Preikestolen is included as one of the main investigation objects. The master thesis “Stability analysis of Preikestolen” is a part of this project, and will be based on data collected by NGU in addition to student work.
In September 2017, the rock formation was scanned from four different angles with a ground based LiDAR scanner. These scans will be put together to create a detailed 3D model of Preikestolen. In addition, two 3D models will be created using photogrammetry. One model will be based on photos taken from helicopter and the other one from drone photos. These models will be compared to field data in order to test which remote sensing data give the closest results and can be used best as a standard method. Further, the 3D-models will be investigated in Coltop-3D to gather structural data measurements. These measurements will be used in combination with structural data from fieldwork to do a kinematic feasibility test. Further, the stress distribution in the rock formation will be modelled with RS2. To gather input data, several test are planned in the rock mechanics laboratory at NTNU. Eventually, all data will be discussed to give a final evaluation of the stability.
Assessment of risk posed by slope failures at a coastal cliff in Hyllestad municipality (Sogn og Fjordane, Norway)
Vegard Nes1, Reginald Hermanns2, Ivanna Penna2 and Jon Runar Drotninghaug1
In the last years, the Norwegian Geological Survey has been mapping unstable rock slopes in Sogn og Fjordane county. Several of them developed on fjord slopes, which implies that in addition to the direct impacts, the consequences related to displacement waves need to be addressed. In this context, slope instabilities along a 6 km coastal cliff in Aafjorden has been identified, and two of them are currently being monitored (NGU, 2017). The aim of this work is to give a complete overview of the unstable slopes present along the coastal cliff of Aafjorden, as well as their main controlling factors by including the results of a recent survey.
The mapping was completed through field work, and interpretation of photogrammetric models and a 1m resolution DEM. The mechanism of failures is based on site measurements as well as structure detection with COLTOP3D. Volume estimates of the unstable blocks were calculated using CloudCompare.
Our analysis shows that there are 8 unstable blocks with volumes up to 170 000 m3 along the coastal cliff of Aafjorden that can lead to considerable displacement waves, as already occurred in 1992 (Harbitz, 2001). The detachments are controlled by steep N-S and E-W striking joint sets in the western domain, and joint set dipping 70 degrees towards east in the eastern domain. The kinematics of the unstable blocks have exposed both potential toppling-failures and planar failures. Future work includes the risk assessment of all the potential scenarios, using the methodology developed by NGU (Hermanns, et al., 2013).
Harbitz, C. B., Domaas, U., Varlid, E. (2001) Rock slide generated tsunamis – probability and hazard zoning in Åfjorden, western Norway.
Hermanns, R. L., et al. (2013) Hazard and risk classification for large unstable rock slopes in Norway, Ital J Eng Geol Environ. doi, 10, pp. 2013-2006.
NGU (2017) Nasjonal database for ustabile fjellparti. Available at: http://geo.ngu.no/kart/ustabilefjellparti_mobil/ (Accessed: 06.10 2017).
Monitoring of surface processes in Gråfonnfjellet, Rauma municipality, Norway
Pierrick Nicolet1, Ivanna Penna1, Reginald Hermanns2, Odd Are Jensen3, Lena Rubensdotter1 and Silje Øren Skei4
1Norges Geologiske Undersøkelse, Trondheim, 2Norges Geologiske Undersøkelse, Trondheim; Norges Teknisk-Naturvitenskapelige Universitet (NTNU), 3Norges vassdrags- og energidirektorat, 4Norges Teknisk-Naturvitenskapelige Universitet (NTNU), Trondheim
Loose rock masses remain on the headscarps and after historic and prehistoric rock avalanches on Gråfonnfjellet mountain, Innfjorddalen, Norway. This material is remaining after at least three post-glacial rock avalanches that have been deposited in Innfjordalen (Scheiler et al. 2016). At this site, in addition to the rock avalanche deposits, a large colluvial fan can be observed (Skei 2016). The objectives of this work are to describe the source of sediments and the surface processes contributing to the development of the fan. This study takes advantage of permanent monitoring equipment (3 cameras and 1 meteorological station) and periodic measurements (LiDAR, photogrammetry, gigapixel pictures) to study the slope processes that are active nowadays. An area of intensively fractures rocks, that remains in the headscarp, is shown to be the main source of sediments. Indeed, 93 negative differences (e.g. missing blocs) have been observed between 2014 and 2016 on the gigapixel pictures in this area. In addition, 63 positive or composite differences (e.g. deposited bloc or sediments transported on a short distance) have been identified in the same area, which suggest that the sediments are often transported only on a short distance. Furthermore, the permanent camera placed in the valley permits to identify several snow avalanches that remobilize sediments down to the lower parts of the fan. During snow melt season or precipitation events, materials are transported in form of debris flows along two main channels. Further work is needed to better relate the observed events with the meteorological conditions.
Schleier, M., Hermanns, R. L., Gosse, J. C., Oppikofer, T., Rohn, J., Tønnesen, J. F., 2017. Subaqueous rock-avalanche deposits exposed by post-glacial isostatic rebound, Innfjorddalen, Western Norway. Geomorphology 289, pp. 117 – 133
Skei, S. O., 2016. Ulike skredprosessar sine samverknader på same skredvifte : korleis vert flaumskred som prosess påverka av andre skredprosessar på Gråfonnvifta, Innfjorddalen, Rauma kommune. Master thesis, NTNUTop
10.2. Open session Engineering and enviromental geology
The modelling of ice-marginal complexes and salt structures using 3D layer models
Thomas Breum Andersen1
1GEO, Geodata and Subsurface models, Maglebjergvej 1, 2800 Kgs. Lyngby
Among the most challenging geological structures to interpret and model in the Danish area are the ice marginal complexes with complex stacked internal structures and areas with salt domes intruding Neogene and Quaternary strata. The geology will reflect complex tectonics that must be interpreted and turned into a sequence of tectonic events in order to represent this in a 3D model.
The development of a reliable conceptual model is essential in this work and this conceptualization must encompass a thorough analysis of all data sources available including drillings, geophysics, geomorphology, previous investigations ect. representing a cross-discipline investigation.
The development of a geological 3D model that reflects the conceptual geology and tectonic structures requires special techniques when using layer models including sophisticated positioning of digitalization-points, interpolation and adjustment procedures in order to develop steeply dipping or vertical strata, faultlines or saltdomes that may be developed as true dome structures or horst structures.
Examples will be shown from well-known geological Danish geological sites as the Røsnæs Icemarginal complex, Thyborøn (Rønland Saltdiapir) and Suldrup Saltdiapir where these methods have been used in connection with ground water modelling projects and for geotechnical purposes. The modelling technique takes the layer-model method to its limits but this type of model can be integrated with the overall geology of an area fairly easy in contrast to a site specific voxel model.
Key words: 3D modelling, ice marginal complexes, saltdomes, tectonics, conceptual model, cross dicipline interpretation, modelling technique, Røsnæs, Thyborøn, Suldrup.
Geochemistry of deposited mine tailings in Repparfjorden, northern Norway, and their effect on bottom fauna.
Malin Andersson1, Tor Erik Finne1, Hilde Trannum2, Kristine Pedersen3, Anita Evenset3 and Paul Renaud3
1Geological Survey of Norway, 2The Norwegian Institute for Water Research, 3Akvaplan-niva
Submarine tailing disposal (STD) involves the discharge of mine tailings below the sea surface as an alternative to on-land deposits. Norway, a country with deep, sheltered fjords, is one of the few countries in the world where these disposal operations are in use. This study investigated a four decade old mine tailing deposit in Repparfjorden, originating from copper ore processing in the 1970’s. Bathymetry from this project revealed that the deposit is still presently almost intact. The issue is of interest as the mine is likely to reopen in 2019.
The mine tailings are, in relation to the natural materials lying under the tailings and on top, clearly enriched in the elements Au, Ba, Bi, Cr, Cu, Hf, Ni, Re and Zr, but also depleted in the elements: Be, Cd, Cs, In, Li, Nb, P, Pb, Rb, S, Sc, V and Zn, therefore establishing the chemical signature of the tailing material. To be able to compare geochemical results and execute fauna experiments, newly fabricated flotation tailings were produced. The old tailing deposit differs considerably from these, which could be due to differences in ore material or flotation process, or chemical changes during deposition. These differences make chemical predictions for a future deposit difficult.
The bottom fauna study revealed differences in the number of species and individuals present in the surface sediments depending on the influence of the tailings. Depending on the depth of tailings on top of surface sediments, a decrease in biomass amount was evident during a re-colonisation experiment.
Development of a direct tensile test method for microtextural fracture studies
Karin Appelquist1, Mathias Flansbjer2, Linus Brander1, Lovise Sjöqvist1, Jan Erik Lindqvist1 and Camilla Lindström1
1RISE CBI, 2RISE Mechanics Research
Traditional macroscale rock strength tests generally aim at characterizing and comparing different rock types in a standardized way. However, these methods rarely shed light on the crack development in relation to the material structure. Often the loading situation and specimen geometries are complex, resulting in difficulties identifying the contribution of different synchronous deformation processes. Examples are compressive loading tests, in which a combination of compression and shearing occur, and Los Angeles tests, in which crushing, abrasion, tension and shearing occur simultaneous. Due to this shortcoming, a new methodology which combine detailed cracking monitoring techniques with mechanical rock tests – allowing the examination of different isolated deformation mechanisms – is presented.
The methodology combines tensile stage testing of a rock specimen with continuous monitoring of the cracking processes by Digital Image Correlation and Acoustic Emission. After completion of tensile test, examination of microcracks and fractures by fluorescent transmission microscopy is conducted. This methodology enables the spatial and temporal visualization of the cracking processes within a rock sample, on micro- and mesoscale, linking the cracking processes (e.g. initiation, reactivation, propagation and bridging of microcracks, and the final development of the open fracture) to rock texture and microstructure. The methodology has been demonstrated on 28 samples from three granitic rocks of different textures and structures. The strength of the methodology is the increase in knowledge of critical parameters affecting cracking processes in rock materials and how these are related to the rock micro- and mesostructure.
Construction geological map of Stockholm- and example of geo-data recycling.
Phil Curtis1 and Claes Mellqvist1
The original construction geological map of Stockholm was produced during the 1970s and is still widely used today in the early planning stages of new infrastructure projects. Although it was digitized in 1997 it has not been updated since its original publication. The Geological Survey of Sweden (SGU) has been working on such an update that includes the incorporation of geological data from existing infrastructure projects from external sources such as (Swedish Transport Administration) Trafikverket and the construction industry. The new map is to be issued on the web in a 2D format for ease of use, however, much of the visualization and interpretation process has been performed in 3D and the results will be available for viewing on a separate website.
Weakness Zones in the Bedrock – Geophysical Studies in City Area
Taija Huotari1 and Marit Wennerström1
1Geological Survey of Finland
As the amount of underground building in city areas grows the need for information of bedrock under the ground surface is increasing. Problematic features for underground construction might be weakness zones in the bedrock. Information on the location, orientation and properties of weakness zones before starting construction will improve the schedule and cost estimates of the project, as well as usually reduces the construction costs. The potential of different geophysical methods were tested to detect weakness zones in the bedrock in the project called ‘Intrageo’ (Huotari & Wennerström, 2017). Further, the geophysical results were integrated with structural geological interpretation of weaknesses in the bedrock.
The investigations were carried out at Hannusjärvi and Finnoo in Espoo on the planned route for the 2nd phase of the West Metro, as well as in the area of the new underground wastewater treatment plant of HSY (Helsinki Region Environmental Services Authority) water services at Blominmäki, Espoo. Both investigation areas are located in the Helsinki metropolitan area in Finland. In 2nd phase West Metro targets the measurements were concentrated on tests of ground geophysical methods. The aim was to test different methods along the same survey profiles to perform integrated interpretation and to evaluate the usability of different methods. In Blominmäki tests concentrated on geophysical drill hole measurements and magnetic measurements with dense line spacing in the most fractured rock area. Petrophysical properties, as well as the rock type and structural features, were studied from drill core samples for the sake of comparison and verification.
Huotari, T. & Wennerström, M. (eds.) 2017. Integroitujen geofysikaalisten ja kallioperägeologisten tutkimusmenetelmien kehittäminen yhdyskuntarakentamisen tarpeisiin. Summary: Development of integrated geophysical and bedrock geological research methods for civil engineering. Geological Survey of Finland, Report of Investigation 231, 140 pages, 145 figures and 7 tables.
Digital archive for strong ground motions recorded in earthquake sequences
Evangelos Katsanos1 and Victor Ambo Boserup1
1Department of Civil Engineering, Technical University of Denmark
Numerous structures and infrastructures systems have been recorded to encounter extensive damages or total collapse due to successive earthquake ground motions occurred in short time spans. A list of recent earthquake sequences, found to be detrimental for both humans and the building stock, comprises of seismic events from Amatrice-Italy (2016) and Kumamoto-Japan (2016), Gorhka-Nepal (2015) and Tōhoku-Japan (2011). Nevertheless, the current seismic codes prescribe the structural design on the basis of a single “design” earthquake waiving the sequential seismic events that may increase the seismic vulnerability of structures. It is, thus, important to focus on this hazardous phenomenon in order, eventually, to mitigate its consequences. Over the last 15 years, the effects of earthquake sequences on the structural performance have been elucidated [1-3]. However, the use of real strong motions from successive ground shakings is commonly restricted to a single earthquake sequence event that may dominate (or bias) the structural response results . Additionally, the artificially-developed earthquake sequences may derive questionable seismic demand . Hence, this study is dedicated to compile a dataset including almost 7000 suitably selected strong ground motions, which were recorded worldwide during earthquake sequences and found of interest for studies addressing the structural response imposed by multiple earthquakes. The dataset compiled provides metadata related to seismological characteristics and strong ground motion parameters while, when necessary, the records were processed (i.e., base-line correction and frequency-based filtering). Finally, systematic analysis of the selected motions revealed trends on the basis of the several parameters associated with the successive earthquakes.
 Zhai C-H, Wen W-P, Chen Z, Li S, Xie L-L. Damage spectra for the mainshock-aftershock sequence-type ground motions. Soil Dynamics and Earthquake Engineering 2013; 45(1):1-12.
 Goda K. Nonlinear response potential of mainshock-aftershock sequences from Japanese earthquakes. Bulletin of the Seismological Society of America 2012; 102(5): 2139-2156.
 Ruiz-Garcia J, Negrete-Manriquez JC. Evaluation of drift demands in existing steel frames under as-recorded far-field and near-fault mainshock-aftershock seismic sequences. Engineering Structures 2011; 33:621-634.
 Hosseinpour F, Abdelnaby AE. Effect of different aspects of multiple earthquakes on the nonlinear behaviour of RC structures. Soil Dynamics and Earthquake Engineering 2017; 92:706-725.
 Goda K, Taylor CA. Effects of aftershocks on peak ductility demand due to strong ground motion records from shallow crustal earthquakes. Earthquake Engineering and Structural Dynamics 2012; 41(15): 2311-2330.
The quaternary history at the Horns Rev 3 site.
Joakim Stiel Korshøj1
In 2013 Geo was contracted to carry out pre investigations for Energinet, for the offshore windfarm Horns Rev 3. The pre investigations revealed a buried landscape, with dislocated floes of Miocene clays.
The Horns Rev 3 bank is composed of a rather complex sequence of Postglacial and glacial sediments, including glacial floes of Tertiary sediments. The area was not covered by ice during the Weichsel glaciation. The sea-level was approximately 120 m below current sea-level. The only deposits from Weichsel that is observed in the area is from meltwater rivers flowing in the lower lying areas. Two Postglacial units have been deposited during the Flandrian transgression. Deposits consist of non graded sand and organic clayey silt and clay . The deposits are generally loose/soft, locally the organic content is high, here they are described as organic clay (gyttja). Some smaller deposits of peat have been observed, one of which was dated by C14 determination. The peat layer was found in the bottom of the Postglacial sequence and was dated to between 8211 and 7791 years BC. In-between the meltwater deposits smaller till layers are seen, as well as floes of Tertiary sediments. Tertiary deposits have been found as floes interbedded in the meltwater deposits and two borings stopped in Tertiary deposits. Since drilling stopped in these layers, it is not possible to say if they are parts of folded Tertiary sediment by Saalian or earlier glaciations, floes or if the Tertiary sediments are in situ.
Risks of arsenic exposure through agriculture
Kirsti Loukola-Ruskeeniemi1, Juha Kaija1, Timo Tarvainen1, Tarja Hatakka1, Riitta Keiski2, Auli Turkki2, Jana Pinka3, Isabel Jordan3, Fabienne Battaglia4, Marina le-Guedard5, Celia Jones6, Prosun Bhattacharya7, Sirpa Kurppa8, Ingo Müller9, Grzegorz Siebielec10 and Jose Solis Veliz11
1Geological Survey of Finland, 2University of Oulu, Finland, 3GEOS Ingenieurgesellschaft mbH, Germany, 4BRGM, France, 5LEB Aquitaine Transfert, France, 6Kemakta, Sweden, 7Kungliga Tekniska Högskolan, Sweden, 8Natural Resources Institute Finland, 9LfULG, Germany, 10Institute of Soil Science and Plant Cultivation, Poland, 11National University of Engineering, Peru
Arsenic is a toxic and carcinogenic semi-metal which can enter into agricultural soil and water due to human activities or from natural deposits. AgriAs Water JPI project started 1st April 2017 and evaluates arsenic contamination in Europe focusing in two study areas with intense anthropogenic pollution. Research institutes, universities and companies from five EU countries participate in the project. AgriAs summarizes national and European databases (e.g., Tarvainen et al. 2013) and develops recommendations and guidelines for sustainable management of arsenic risks in agricultural areas. The French study site is a historical area of destruction of WWI chemical weapons located in a sensitive zone for agriculture and groundwater. The German site is characterized by 800 years of mining. Arsenic removal technologies will be developed and demonstrated in both areas. Biological tools will be applied to manage ecological, environmental and human risks. Dissemination activities will follow the procedures of the successful LIFE + project ASROCKS which developed guidelines for rock aggregate production in arsenic-rich areas (e.g., Parviainen et al. 2015). In the first stakeholder workshop organized in Freiberg in September 2017, interaction and discussions between farmers, authorities and researchers were active.
The authors thank EU and the Academy of Finland, Agence Nationale de la Recherche, Bundesministerium für Ernährung und Landwirtschaft and Forskningsrådet FORMAS for funding, in the frame of the AgriAs Consortium financed under the ERA-NET WaterWorks2015 Cofunded Call. This ERA-NET is an integral part of the 2016 Joint Activities developed by the Water Challenges for a Changing World Joint Programme Initiative.
Parviainen, A. et al. 2015. Arsenic in bedrock, soil and groundwater – the first arsenic guidelines for aggregate production established in Finland. Earth-Science Reviews 150, 709–723.
Tarvainen, T. et al. 2013. Arsenic in agricultural and grazing land soils of Europe. Applied Geochemistry 28, 2–10.
2,5D Open Source Modeling of Rock Aggregate Resources in the Helsinki Metropolitan Area
1University of Helsinki
The objective of this study is to develop a method of appraising rock aggregate resources, using open data and open source tools. The availability of aggregates in Finland is mostly determined by competing land use and restrictions on extraction. Therefore, it is important to determine the extent of available resources, especially near areas of high demand.
The study area consists of the 14 municipalities in the Helsinki metropolitan area, a total of 3841 km2. The data used are open access, provided by GSF and NLS. These are combined in a GIS to identify locations where extraction of aggregates is possible. Geology, limitations and the highest and lowest point of possible extraction are detrmined. These are used to estimate the available resources and locate the economically feasible sites. Data used include a digital elevation model and layers on geology and land use.
The results show that competing land use has sterilized most aggregate locations in the area. Remaining locations are concentrated on the edges. However, some potential sites remain. Field evaluations and comparison to previous studies show that the method is sound and able to locate possible localities.
The model is fast in coarsely determining aggregate volume. It is highly suitable for focusing expert fieldwork. Land use in the area continues to sterilize new locations. To avoid economic and ecological damage, a plan should be implemented for securing this resource. This may include the reserving of locations, reducing use, checking legislation on production and recycling used aggregates.
Developing of Geothermal District Heating solutions for 4 towns in Poland
Kirsti Midttømme1, Beata Kępińska2, Leszek Pająk3, Baldur Pétursson4, Jan Kocbach5, Ingvar Henne5, Usman Dar6, Jørgen. B Skauge6, Óskar P. Einarsson7 and Friðfinnur K Daníelsson8
1Christian Michelsen Research (CMR), 2Mineral and Energy Economy Research Institute, Polish Academy of Sciences (MEERI PAS), 3MEERI PAS, 4Orkustofnun, 5CMR, 6Sweco Norge, 7Verkis, 8Alvarr
Poland possesses proper geothermal energy to supply low-emission thermal energy. Polish, Icelandic and Norwegian experts collaborate to develop geothermal district heating solutions for four towns in Poland. Three of the towns, Konstantynów Łódzki, Sochaczew, and Poddębice, are located in sedimentary rocks central Poland in the Permian-Mesozoic Szczein –Lodz Miechow. The last town, Lądek Zdrój is situated in crystalline rocks in Sudet Mountains close to the boundary to Czech Republic. The town is one of the oldest Polish health resorts using thermal water.
A 10 MWth geothermal district heating plant was established in Poddebice in 2013, substituting fossil energy. The geothermal well of 2101 m depth is extracting water of 70 °C from Lower Cretaceous sandstones. Maximum flow rate is 252m3/h. The water is discharged into the Ner river and it is a challenge to satisfy the requirement of a maximum temperature of 35°C on the water discharged. There is also a need for better understanding of the effect of long-term geothermal exploitation
A new geothermal well of 2800m depth extracting water of 70 C from Lower Jurassic is planned as an additional energy source for Konstantynów Łódzki incooperated in the existing Łódź district heating system.
The authorities in Sochaczew plans a geothermal district heat pump solutions utilizing water of 40°C from Lower Cretaceous sandstone.
A new geothermal well of 2500 m depth is planned in Lądek Zdrój producing water of 70°C from fracture zones.
The joint Polish/Icelandic/Norwegian project was funded by EEA Grant.
Geological studies of the possible Helsinki–Tallinn undersea tunnel route
Keijo Nenonen1 and Ossi Ikävalko1
1Geological Survey of Finland
Geological Survey of Finland (GTK) and Estonian geological Survey (EGS) conducted geological studies and acoustic-seismic surveys of the possible linings for an undersea railway tunnel between Helsinki and Tallinn.
The surveys provided a detailed overview of the geological structure of the sea floor basement and deposits between Finland and Estonia. A new finding was that the crystalline Proterozoic basement sea floor continues all the way to Naissaar and to the shallows near the Estonian coast. A thick layer (100-150 m) of soft sedimentary rocks from Cambrian – Ordovician age (sandstones, claystone and limestones) covers the hard granitic bedrock on the city of Tallinn area. Presently ongoing FinEst Link project between Finland and Estonia examines the possibilities of building a 100 km long railway tunnel. The geological findings provides new and useful information for further detailed engineering geological surveys.
The FinEst link project examines the technical and economic feasibility of the undersea tunnel and the logistic solutions in addition to its cost-effectiveness and economic, environmental and social impacts. Results are to be expected during the present year 2018. The viability of planning the tunnel can be assessed only after receiving these results.
The research work on the feasibility of the tunnel project was enabled by EU funding under the Interreg Central Baltic programm. The project is led by the Helsinki-Uusimaa Regional Council in cooperation with the City of Helsinki, the Finnish Transport Agency, the City of Tallinn, the Estonian Ministry of Economic Affairs and Communications and the Harju County Government
Alvi, K. 2017. Acoustic-seismic survey along the proposed railway tunnel route options, between Helsinki and Tallinn. Merenmittauslupa T- 037-16 22.7.2016 (AM13753). Report: Helsiki –Uusimaa regional council, Geological Survey of Finland, 24 p.
Ikävalko, O., Vähäaho, I and Suuroja S. 2013. Soil and bedrock conditions to be expected in Tallin-Helsinki tunnel construction. STATENS VEGVESENS RAPPORTER Nr. 213,Strait Crossings 2013 16. – 19. June 2013 Bergen, Norway p. 790 -799.
Nenonen, K. ja Ikävalko, O., 2012. Tunneli läpi harmaan kiven Tallinnaan , with .English summary; A Tunnel connection to Tallinn trough the hard grey bedrock. Geologi 64:75–80.
Suuroja, S., Suuroja, K., Ploom, K., Kask, A. & Soosalu, H., 2012. Tallinn – Helsinki ‐tunnel soil‐ and bedrock construction conditions. Compilation of a geological database for the possible Tallinn‐Helsinki tunnel area (in Estonian EEZ). Geological Survey of Estonia, Department of Geophysics, Marine and Environmental Geology, Department of Geological mapping. Report. Tallinn, pp. 19.
Nyt borearkiv ser dagens lys – Øget adgang til private borearkiver
Mikkel Wendelboe Toft1
Geo har skabt en ny online adgang til viden om undergrunden. Formålet er at sikre at fagfolk på tværs af organisationer kan arbejde med bedst muligt udgangspunkt så projekterne bliver løst mest effektivt og med mindst risiko. I dette oplæg vil vi fortælle om strategien bag frigivelsen af virksomhedens data, samt om de tekniske problemstillinger som vi bliver mødt af under udviklingen af et sæt helt nye services. Desuden perspektiveres der mod potentialet ved af tilgængeliggøre andre virksomheders data. Initiativet er blandt andet motiveret af Statens beslutning om at stille sit kortgrundlag gratis til rådighed, hvilket har skabt helt nye forudsætninger i markedet. Vi har udviklet en række værktøjer som, via bagvedliggende 3D modeller af undergrunden, kan lave virtuelle boringer, udstille 3D jordartskort i fladesnit, samt gøre det muligt at lave hurtige og brugervenlige profilsnit af høj kvalitet. Ved at udstille værktøjerne online, søger vi at skabe maksimal tilgængelighed, og mulighed for høj brugervenlighed. Et interessant potentiale i tendensen med åbning af adgangen til data i de private virksomheder, er værdien ved sammenstilling af data fra andre kilder. En sammenstilling gør det muligt eksempelvis at se relationen mellem registreret jordforurening, arealanvendelse eller befæstelsesgrad, og den overfladenære geologi. Mulighederne for anvendelse er utallige, og når først brugeren i særlige fagdomæner får adgang, så vurderer vi at anvendelsesmulighederne vil spire frem.
Development of a database for stratigraphic information on Quaternary deposits at the Geological Survey of Norway (NGU)
Louise Hansen1, Bo Nordahl1, Alexandra Jarna1 and Inger-Lise Solberg1
1Geological Survey of Norway
A National database for superficial deposits have existed in Norway for decades and is developed and hosted by the Geological Survey of Norway. The database is the basis for web services presenting Quaternary map information at different scales and associated products and services (www.ngu.no). The maps are used in society for various purposes from research to public planning. Stratigraphic information has previously only been presented as a somewhat complicated text strings locally on analogue Quaternary maps, or in associated reports/articles. There has, till now, not been any database to receive stratigraphic information in a structured way. As there is a growing need in the Norwegian society for subsurface geological information there is also a need for the development of a stratigraphic database. A prototype of a stratigraphic database is presented. An important aspect of the database is that it can host varied types of stratigraphic information from different sources. The newly developed National Database for Ground investigations (NADAG) is a potential source for valuable stratigraphic information from e.g. linked drill reports. Well organized and standardized stratigraphic information in a digital format is needed for extending the present day geological map products into the subsurface, and for further analyses and modeling. Possible web solutions are presented.
Provenance and Contamination History of the Paraná Delta, Argentina
Jane Ihrfors1, Matilda Schütz1, Rodney Stevens1, Juan Pablo Milana2 and Claudio Parcia3
1University of Gothenburg, 2Universidad Nacional de San Juan, 3Universidad Nacional de San Martin
This is a sedimentological and geochemical study documenting sediment provenance and contamination of the Paraná Delta front during the last 150 years. The Paraná river system is a pristine landscape home to several endangered species and South Americas second largest drainage basin containing some of the world’s largest wetlands. The basin has been cultivated for a long time but with an expanded human activity during the last century with increased deforestation and industrialisation. Therefore, studies in the Paraná could give an indication on how the Amazons will be affected by increased human impact. Previous studies of the delta front have mapped and dated beach ridges (Medina et al, 2013). A transect sampled perpendicular to these provides a historical record of the delta progression and development. The aim is to see how the change of climate and human activity in the catchment area have affected the sediment provenance at the delta front. The samples are analysed using methods to identify the mineral composition in the clay and sand fractions to reveal their provenance and roughly estimating each sub-basin’s sediment supply to the delta front. Sediment geochemical trends over the sampled timeline, with a particular emphasis on heavy metal contents, are interpreted in terms of provenance and contamination, which in turn are linked to human impact through deforestation, afforestation, population growth, urbanisation and industrial activity. In general, the delta-forming processes themselves need to be re-evaluated on the Paraná Delta since these are also affected by changing climate and increasing human impact.
Medina, R., & Codignotto, J. (2013). Evolucion del delta del rio Parana y su posible vinculacion con el calentamiento global. Revista Del Museo Argentino De Ciencias Naturales (1999), 15(2), 191-200.
Investigations of clay deposits as barrier for a final repository for Denmark’s low- and intermediate level radioactive waste in subsurface to 500 m depth.
Bertel Nilsson1, Peter Gravesen1, Stig A. Schack Petersen1 and Merete Binderup1
1Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen, Denmark
The Danish radioactive waste from the research station Risø must be stored on Danish land territory (exclusive Greenland). The radioactive waste is consisting of the waste from the decommissioning of the nuclear facilities at Risø, and the radioactive waste produced in Denmark from hospitals, universities and industry.
The Geological Survey of Denmark and Greenland has until 2011 been responsible for the geological studies of near-surface areas (100-200 meter depth) for the repository. The task has been to locate and recognize non-fractured clays or Precambrian bedrocks with low permeability which can isolate the radioactive waste from the surroundings. Six potential areas have been located based on the most favorable conditions in relation to geology, hydrogeology, nature protection and climate change conditions.
Five of the six localities Paleogene and Neogene clays are considered as suitable as the last barrier in the repository based at these criteria: 1.The clay layer shall be at least 50-100 m thick, 2. The clay layers shall have a continuous horizontal distribution in the selected area. 3. The clay layers shall be low permeable without fractures and with very low groundwater content. 4. The selected area shall be without groundwater and drinking water interests. The last locality was located in Precambrian basement rocks.
In 2018 new technical studies will be carried out to determine possible future locations for a deep geological final repository at ~500 meter depth. As the existing data and previous studies do not make it possible to conclude where a deep repository can be placed.Top