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  • 201. Pease, Victoria
    et al.
    Koyi, Hemin
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Development of the Amerasia Basin: Insights from analogue modeling2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The tectonic development of the Amerasia Basin and its sub‐domains (the Canada Basin, the Makarov‐Povodnikov basins, the Alpha‐Mendeleev Ridges, and the Chukchi Plateau) has long been debated.  Recent studies confirm the conjugate relationship between the Alaskan and Canadian Arctic margins, in which counterclockwise rotation of Arctic Alaska from Arctic Canada resulted in the opening of the Canada Basin; although the northward extent of this spreading is debated, the tectonic development of the Canada Basin is ‘broadly’ understood.  The precise timing and the role of the Chukchi Plateau is also problematic.  In a series of two‐plate analogue models with properties homologous of homogeneous continental crust, we were able to model the development of the Amerasia basin and its sub‐domains (those not related to the HALIP).  In all models, a triangular (ocean) basin forms between the two ‘diverging’ plates, however, depending on the mode of opening and initial plate configuration transpressive, transtensive, and ‘pure’ strike‐slip structures are generated and account for the following first order observations: i) transcurrent margins of opposite motion, ii) curvature in the fossil ridge, and ii) asymmetry of the basin.  In addition, extension and clockwise rotation of the Chukchi Plateau (without compression) is achieved as part of the upper‐plate of a detachment system in which lower‐plate motion exceeds upper‐plate motion. Our results elucidate the development of sea‐floor spreading in the Amerasia Basin and are consistent with a rotational opening scenario.

  • 202. Pease, Victoria
    et al.
    Koyi, Hemin
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Development of the Amerasia Basin: Where are we now?2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    This contribution reviews our current understanding of the tectonic development of the Amerasia Basin and presents new analogue modelling results relating to its formation. The Amerasia Basin is separated into the Canada Basin and the Makarov-Povodnikov basins by the Alpha-Mendeleev Ridges. Published data supports a conjugate relationship between the Alaskan and Canadian Arctic margins, in which counterclockwise rotation of Arctic Alaska from Arctic Canada resulted in the opening of the Canada Basin. Thus the tectonic development of the Canada Basin is ‘broadly’ understood, although its precise timing and the role of the Chukchi Plateau remain disputed. This leaves the Amerasia Basin and we identify two significant barriers to understanding its tectonic development: i) The northward extent of the Canada Basin fossil spreading ridge, and ii) the role of LIP magmatism. In assessing the former, we constructed a series of two-plate analogue models with properties homologous of homogeneous continental crust and simulated extension between the plates around a common rotation axis. In all models, a triangular (ocean) basin forms between the two ‘diverging’ plates, however, depending on the mode of opening and initial plate configuration transpressive, transtensive, and ‘pure’ strike-slip structures can be generated. Plates with a fixed pole of rotation that move at the same rate produce a basin that widens away from the pole along a straight ridge, whereas models with a migrating pole of rotation produce a bend in the spreading ridge and this may explain the curved ridge observed in the Canada Basin. Both models produce strike-slip faults of reversed polarity in the region opposite the pole. If the spreading ridge extended to the Lomonosov Ridge (LR), a strike-slip fault boundary is generated ± associated transtensive/transpressive features. Two plates with different spreading rates generate asymmetric basins, which is also a component of the Amerasia Basin. These results elucidate the consequences of sea-floor spreading in the Amerasia Basin and constrain opening scenarios.

  • 203.
    Pease, Victoria
    et al.
    Stockholm University, Stockholm, Sweden.
    Koyi, Hemin
    Uppsala University, Uppsala, Sweden.
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Development of the Amerasia Basin: Where are we now?2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    This contribution reviews our current understanding of the tectonic development of the Amerasia Basin and presents new analogue modelling results relating to its formation. The Amerasia Basin is separated into the Canada Basin and the Makarov-Povodnikov basins by the Alpha-Mendeleev Ridges. Published data supports a conjugate relationship between the Alaskan and Canadian Arctic margins, in which counterclockwise rotation of Arctic Alaska from Arctic Canada resulted in the opening of the Canada Basin. Thus the tectonic development of the Canada Basin is ‘broadly’ understood, although its precise timing and the role of the Chukchi Plateau remain disputed. This leaves the Amerasia Basin and we identify two significant barriers to understanding its tectonic development: i) The northward extent of the Canada Basin fossil spreading ridge, and ii) the role of LIP magmatism. In assessing the former, we constructed a series of two-plate analogue models with properties homologous of homogeneous continental crust and simulated extension between the plates around a common rotation axis. In all models, a triangular (ocean) basin forms between the two ‘diverging’ plates, however, depending on the mode of opening and initial plate configuration transpressive, transtensive, and ‘pure’ strike-slip structures can be generated. Plates with a fixed pole of rotation that move at the same rate produce a basin that widens away from the pole along a straight ridge, whereas models with a migrating pole of rotation produce a bend in the spreading ridge and this may explain the curved ridge observed in the Canada Basin. Both models produce strike-slip faults of reversed polarity in the region opposite the pole. If the spreading ridge extended to the Lomonosov Ridge (LR), a strike-slip fault boundary is generated ± associated transtensive/transpressive features. Two plates with different spreading rates generate asymmetric basins, which is also a component of the Amerasia Basin. These results elucidate the consequences of sea-floor spreading in the Amerasia Basin and constrain opening scenarios.

  • 204.
    Peng, Tao
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Wang, Xiaowen
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    A Mobile-based Navigation Web Application: Finding the Shortest-time Path based on Factor Analysis2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With the economic growth, the number of motor vehicles has increased rapidly for the last decades, especially in developing countries like China and India. Availability of more vehicles makes it more convenient for people to travel and merchandise transport. The increase of the number of vehicles also brings stresses to public traffic and pollution to the environment. When the number of vehicles on the road is over the available space, it results in traffic congestion. The problem is being studied and there are several solutions to it, like building more roads, rebuilding the existing streets and enlarging the cities. Based on the traffic reason and the environment reason, the government and the institute of environmental protection appeal to the public to take public transport means instead of private cars. But the measure affects the utilization ofmotor vehicles.

    Global Positioning System (GPS) provides autonomous geo-spatial positioningand navigation service. Once the user enters the destination, the navigation service will show the shortest path from the location of the user to the destination. Following the guide makes the vehicles running purposively, and it is also favorable for traffic control and management.

    Theoretically, if the diver keeps the same driving mode, the shortest path will cost the shortest time, but in reality, the traffic environment is complex and the driving speed is variable thus the shortest path is probably not the fastest path. In this study, the hinder factors of the speed and traffic are fixed constructions on the road, like: turnings, hospitals, schools, residential areas, traffic lights and the user-controlled factor (sites of traffic jams, accidents, and temporary construction on the road). We take the hinderfactors of traffic and driving speed into consideration while providing the route plan, finding the shortest-time path, and showing the result as an online map via the web Geographic Information System (GIS) application. We show that reducing the travelling time of motor vehicles, makes the traffic flow more rapid and efficient. Alsoreducing the emission time of motor vehicles, diminishes the greenhouse effect.

    Beside these, the achievement of our study also shows that the public can take advantage of open source tools and data to build their GIS application to do spatial and data analysis.

  • 205.
    Raeesi, Mohammad
    et al.
    Bergen, Norway.
    Zarifi, Zoya
    Department of Earth Sciences, University of Western Ontario, London, Canada.
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Lantmäteriet, Gävle, Sweden.
    Boroujeni, Samar
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Tiampo, Kristy
    CIRES; Department of Geological Sciences, University of Colorado at Boulder, Boulder, CO, USA.
    Quantitative Analysis of Seismicity in Iran2017Ingår i: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 174, nr 3, s. 793-833Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use historical and recent major earthquakes and GPS geodetic data to compute seismic strain rate, geodetic slip deficit, static stress drop, the parameters of the magnitude–frequency distribution and geodetic strain rate in the Iranian Plateau to identify seismically mature fault segments and regions. Our analysis suggests that 11 fault segments are in the mature stage of the earthquake cycle, with the possibility of generating major earthquakes. These faults primarily are located in the north and the east of Iran. Four seismically mature regions in southern Iran with the potential for damaging strong earthquakes are also identified. We also delineate four additional fault segments in Iran that can generate major earthquakes without robust clues to their maturity.The most important fault segment in this study is the strike-slip system near the capital city of Tehran, with the potential to cause more than one million fatalities.

  • 206.
    Rashidi, Ahmad
    et al.
    International Institute of Earthquake Engineering and Seismology, Tehran, Iran.
    Khatib, Mohamad Mahdi
    Department of Geology, University of Birjand, Birjand, Iran.
    Nilfouroushan, Faramarz
    Lantmäteriet, Gävle, Sweden.
    Derakhshani, Reza
    Department of Geology, Shahid Bahonar University of Kerman, Kerman, Iran; Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands.
    Mousavi, Seyed Morteza
    Department of Geology, University of Birjand, Birjand, Iran.
    Kianimehr, Hossein
    International Institute of Earthquake Engineering and Seismology, Tehran, Iran; Iranian Seismological Center, Institute of Geophysics, University of Tehran, Tehran, Iran.
    Djamour, Yahya
    Geomatics College, National Cartographic Center of I.R., Tehran, Iran.
    Strain rate and stress fields in the West and South Lut block, Iran: Insights from the inversion of focal mechanism and geodetic data2019Ingår i: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 766, s. 94-114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The active tectonic deformation and hazardous earthquakes in the south and west of the Lut block have been investigated for a long time. In this study, we compute the geodetic and seismic strain rates using focal mechanism data from the Harvard CMT catalogue and various other sources including the published GPS velocities. Moreover, we also perform Focal Mechanism Stress Inversion (FMSI) to deduce a stress model for the region. Our study shows an expected correlation between the stress orientations, seismic and geodetic strain rates. Our results show that the south and west of the Lut block is generally exposed as a compressional strike-slip tectonic regime. The tectonic convergence in this area is taken up not only by motions along and across the faults but also by the rotation of those blocks which bounded by these faults. The maximum amount of rotation rate is observed where there are the main right lateral strike slip fault systems such as Sabzevaran, Gowk, Nayband, Bam, Kuhbanan, and Kahurak. The orientation of the mean stress direction, obtained from the FMSI results in the west and south of the Lut block, is approximated ~N19 E. In this area, faults are almost oblique relative to the tectonic motion direction. Moreover, there are right-lateral and left-lateral shears, in addition to the dip movements in different parts of the south and west of the Lut block. Our analyses show three main categories of the stress regimes including strike-slip faulting (43.2%), thrust faulting (38.6%), and unknown or oblique faulting (18.2%).

    We also calculated seismic and geodetic moment rates for this area, which indicate the seismic moment rate is relatively high between Bam and Shahdad where there are some segments of the Gowk fault.

  • 207.
    Ren, Zheng
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Case Studies on Fractal and Topological Analyses of Geographic Features Regarding Scale Issues2017Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Scale is an essential notion in geography and geographic information science (GIScience). However, the complex concepts of scale and traditional Euclidean geometric thinking have created tremendous confusion and uncertainty. Traditional Euclidean geometry uses absolute size, regular shape and direction to describe our surrounding geographic features. In this context, different measuring scales will affect the results of geospatial analysis. For example, if we want to measure the length of a coastline, its length will be different using different measuring scales. Fractal geometry indicates that most geographic features are not measurable because of their fractal nature. In order to deal with such scale issues, the topological and scaling analyses are introduced. They focus on the relationships between geographic features instead of geometric measurements such as length, area and slope. The scale change will affect the geometric measurements such as length and area but will not affect the topological measurements such as connectivity.

     

    This study uses three case studies to demonstrate the scale issues of geographic features though fractal analyses. The first case illustrates that the length of the British coastline is fractal and scale-dependent. The length of the British coastline increases with the decreased measuring scale. The yardstick fractal dimension of the British coastline was also calculated. The second case demonstrates that the areal geographic features such as British island are also scale-dependent in terms of area. The box-counting fractal dimension, as an important parameter in fractal analysis, was also calculated. The third case focuses on the scale effects on elevation and the slope of the terrain surface. The relationship between slope value and resolution in this case is not as simple as in the other two cases. The flat and fluctuated areas generate different results. These three cases all show the fractal nature of the geographic features and indicate the fallacies of scale existing in geography. Accordingly, the fourth case tries to exemplify how topological and scaling analyses can be used to deal with such unsolvable scale issues. The fourth case analyzes the London OpenStreetMap (OSM) streets in a topological approach to reveal the scaling or fractal property of street networks. The fourth case further investigates the ability of the topological metric to predict Twitter user’s presence. The correlation between number of tweets and connectivity of London named natural streets is relatively high and the coefficient of determination r2 is 0.5083.

     

    Regarding scale issues in geography, the specific technology or method to handle the scale issues arising from the fractal essence of the geographic features does not matter. Instead, the mindset of shifting from traditional Euclidean thinking to novel fractal thinking in the field of GIScience is more important. The first three cases revealed the scale issues of geographic features under the Euclidean thinking. The fourth case proved that topological analysis can deal with such scale issues under fractal way of thinking. With development of data acquisition technologies, the data itself becomes more complex than ever before. Fractal thinking effectively describes the characteristics of geographic big data across all scales. It also overcomes the drawbacks of traditional Euclidean thinking and provides deeper insights for GIScience research in the big data era. 

  • 208.
    Rosales, Oscar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Characterization of microbial growth in lignin-based residues and biodegradation of vanillin:: Optimizing factors for maximizing the extraction of a biodegradation compound of vanillin and investigating the potential for lipid accumulation.2017Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Vanillin (4-hydroxy-3methoxybenzaldehyde) is one of the most employed aromatic and flavoring additives in food and cosmetic industry. The industrial interest in vanillin could also apply to its biodegradation products. The microbial transformation of vanillin can open the possibility of new products with new areas of application for products related to vanillin. For example, vanillyl alcohol, vanillic acid and ferulic acid are currently used in the pharmaceutical or food industry. Some species reported to biodegrade vanillin into the related products vanillyl alcohol and vanillic acid, are: Brettanomyces anomalus and Saccharomyces cerevisiae. Moreover, certain microorganisms possess the ability to accumulate lipids when cultivated on different carbon sources, opening the possibility of microbial lipid production as another industrial application. The present investigation focuses on the optimization of extraction methods for vanillin biodegradation products, as well as identifying the isolates of a collection of microorganisms originating from the Faroe Islands that are amenable to being cultivated on a lignin-based media. Finally, the potential for microbial lipid accumulation was also studied. Two analytical methods, Thin-Layer Chromatography (TLC) and Gas Chromatography (GC) were employed for characterizing the biodegradation products obtained after 24 hours and 72 hours of culture in growth medium supplemented with 1 mM of vanillin. The results showed that after 24 hours of incubation, the model microorganism, strain FMYD002, had consumed some of the vanillin and transformed it into biodegradation products. TLC retention factors and GC chromatograms revealed that the main biodegradation product after 24 hours - when compared to a standard – is likely to be to vanillyl alcohol. Furthermore, vanillin and its biodegradation products were relatively temperature-stable based on a temperature test of supernatant from a 24-hour culture, however, when the 72-hour culture had been subjected to the highest temperature (60 °C) some spontaneous decomposition occurred. The biodegradation pattern of the 72-hour culture evidenced by TLC revealed two additional biodegradation products, one of which migrates in a similar fashion to vanillic acid. After 72 hours of incubation, the biodegradation product presumed to be vanillyl alcohol was no longer observed. Acidification tests showed that the best route for extraction of the product believed to be vanillyl alcohol is to adjust the extracted sample to a pH of 9. The cultivation test of the isolates in media prepared from different lignin-based residual products showed that 26 out of 60 initial strains grew regardless of the concentration of lignosulfonates and vanillin. Moreover, 17 strains grew in nitrogen-limited medium. Eight of the strains accumulated lipids. A preliminary categorization of isolates based on their colony morphology and capacity of growth on different substrates showed that to some extent, their morphology can predict the ability to grow on lignin- and vanillin-based media. This could help future scientists to easily screen for and select isolates with interesting activity for the ligno-cellulose industry.

  • 209.
    Sahlin, Eva A. U.
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Glasser, Neil F.
    Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, United Kingdom.
    Jansson, Krister N.
    Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden.
    Hambrey, Michael J.
    Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, United Kingdom.
    Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales2009Ingår i: Proceedings of the Geologists' Association, ISSN 0016-7878, Vol. 120, s. 245-255Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-Ilyn and Dyfi, acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Analyses of detailed digital elevation models, and interpretation of satellite images and aerial photographs, show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along late Caledonian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross-profiles and valley spurs typical of valleys formed by fluvial processes. Connectivity analysis of the Dyfi basin shows that it exhibits an almost completely dendritic pattern with connectivity alpha and beta values of 0.74 and 1.01, respectively, with little glacial modification of the preglacial fluvial valley pattern in the form of glacial valley breaching. Several examples of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds, have been identified in the Dyfi basin. The degree of preservation of the preglacial fluvial valley system within the Dyfi basin indicates limited modification by glacial processes, despite the area being subjected to glacier activity during the Late Devensian at least. It is possible that major parts of the basin were covered by cold-based or slow-moving ice, close to, or under, a migrating ice-divide, with the major ice drainage Occurring along the weaker zone of the Pennal Fault along which teh Dyfi valley is located, causing minor adjustments to the Surrounding interfluves and uplands. it is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. (C) 2009 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.

  • 210.
    Sahlin, Eva A.U.
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Glasser, Neil F.
    Institute of Geography and Earth Sciences, Aberystwyth University, Wales.
    The Geomorphological Map of Wales and its use in Geoconservation Assessment (poster)2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A geomorphological map is probably the most comprehensive way of illustrating the landform distribution, surface form, material, age, and the processes responsible for the landscape look. As such geomorphological maps are invaluable in the fields of geoconservation assessment, evaluation and management. It is therefore an oddity, as well as an inconvenience, that there is no systematic landform inventory or mapping of the geomorphology that is comparable to the surveys undertaken for geology or soils in the UK. For that purpose the project of “Developing a Geomorphological Map of Wales” was initiated by the Countryside Council for Wales (CCW) as part of a PhD project investigating the Quaternary glaciations of Wales.

    To develop a mapping methodology suitable for the Welsh landscape, three contrasting areas were selected to provide a wide range of geomorphological features. Aerial photography, satellite imagery, digital elevation models, and field investigations of landform/sediment associations, formed the foundation for landform interpretation, which were compiled in a GIS.

    Geomorphological maps of Cadair Idris, and the Central and North Cambrian Mountains were produced, scale 1:10 000 – 1:25 000. The maps form an extensive inventory of the geomorphological geodiversity, and were used for providing data to palaeoglaciological reconstructions and making geoconservation recommendations to the CCW. The recommended sites are of regional interest; their rareness, distinct morphology, interesting research and educational value makes them worthy of RIGS (Regional Important Geodiversity Sites) protection.

    A Geomorphological Map of Wales has the potential for wider practical, scientific and educational benefits, such as for governmental bodies, local authority planners, tourism, researchers, teachers, landowners and land managers. Without a full account of all the geomorphological components of a landscape, there can be no full understanding of the landscape history or the various landforming processes. Important geodiversity sites may be overlooked, badly managed or lost before their full potential are realised.

  • 211.
    Sahlin, Eva A.U.
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Glasser, Neil F.
    Institute of Geography and Earth Sciences, Aberystwyth University, Wales.
    Hambrey, Michael, J.
    Institute of Geography and Earth Sciences, Aberystwyth University, Wales.
    Jansson, Krister, N.
    Institutionen för naturgeografi och kvartärgeologi, Stockholms universitet.
    Connectivity analyses of valley patterns reveal Devensian glacial drainage activity in Mid-Wales (poster)2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Connectivity analyses of valley patterns from detailed digital elevation models, and interpretation of satellite images and aerial photographs show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along Silurian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross profiles and valley spurs typical of valleys formed by fluvial processes.

    The connectivity analyses show that the Dyfi basin exhibits a purely dendritic pattern with little glacial modification of the preglacial fluvial valley pattern in form of valley breaching. It is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. This suggests a complex glacial drainage history, where cold-based ice was not only confined to the interior uplands, but also covered low-altitude areas previously believed to be a major drainage conduit for the Welsh Ice Cap. This indicates that Late Devensian glacial erosion was not as intense as previously believed and larger areas might have been overlain by cold-based ice.

  • 212.
    Sahlin, Eva A.U.
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Glasser, Neil F.
    Institute of Geography and Earth Sciences, Aberystwyth University, Wales.
    Jansson, Krister N.
    Institutionen för naturgeografi och kvartärgeologi, Stockholms Universitet.
    Hambrey, Michael J.
    Institute of Geography and Earth Sciences, Aberystwyth University, Wales.
    Evidence for cold-based ice at low altitudes: Preservation of a preglacial fluvial valley system in the Dyfi basin, Wales (poster)2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Coastal valleys in the west part of mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Analysis of detailed digital elevation models and interpretation of satellite images and aerial photographs show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along Silurian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross profiles and valley spurs typical of valleys formed by fluvial processes. Connectivity analysis of the Dyfi basin shows that it exhibits a nearly dendritic pattern with connectivity α and β values of 0.74 and 1.01 respectively, with little glacial modification of the preglacial fluvial valley pattern in the form of valley breaching. It is proposed that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. Several examples have been identified of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds. The degree of preservation of the pre-glacial fluvial valley system within the Dyfi basin indicates limited modification by glacial processes, despite the area being subjected to Late Devensian glacier activity. It is possible that major parts of the basin were covered by cold-based or slow-moving ice close to or under a migrating ice divide, with the major ice drainage occurring along the weaker zone of the Pennal Fault, causing minor adjustments to the surrounding interfluves and uplands.

  • 213.
    Samuelsson, Karl
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Spatial analyses of people's experiences in urban landscapes2019Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    För att begränsa städers negativa påverkan på global hållbarhet förordas ofta kompakta stadsmiljöer. För att säkra stadsbors välbefinnande krävs emellertid stora och tillgängliga naturområden. Denna konflikt måste lösas för att nå en stadsutveckling som bidrar till både lokal och global hållbarhet.

    Denna avhandling består av två studier av Stockholm som tillämpar rumslig analys av människors upplevelser, då dessa är viktiga indikatorer för välbefinnande. Den undersöker hur tillgänglighet till olika miljöfaktorer är relaterade till positiva och negativa upplevelser. Vidare tillämpar den resiliensprinciper för att undersöka vilka upplevelser som samexisterar på områdesskala.

    Stadsmiljön har betydande påverkan på människors upplevelser. Vissa vanliga indikatorer inom stadsplanering visar svaga samband med upplevelser, medan andra mindre vanliga har större effekter. Sammansättningar av upplevelser på områdesskala uppvisar genomgående mönster, både rumsligt och i förhållande till resiliensprinciper. Många områden innehåller en mångfald av positiva upplevelser, medan ett fåtal domineras av negativa upplevelser.

    Resultaten visar att relationer mellan människa och miljö bör ta en mer central plats i stadsplaneringen, då detta erbjuder möjligheter att förbättra stadsbors upplevelser. Resiliensprinciper kan fungera som tumregler inom stadsplaneringen för en stadsutveckling som inte äventyrar människors upplevelser. Metoden som utvecklats här kan appliceras i andra städer, då den kan identifiera specifika platser för omvandling, men också leda till djupare förståelse för samspelet mellan stadsmiljöer och människors upplevelser i olika sammanhang.

  • 214.
    Samuelsson, Karl
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Colding, Johan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap. Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Sweden.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap. Stockholm Resilience Centre, Stockholm University, Sweden.
    Urban resilience at eye level: spatial analysis of empirically defined experiential landscapes2019Ingår i: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 187, s. 70-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An unresolved issue in creating resilient cities is how to obtain sustainability benefits from densification while not eroding the capacity of social-ecological systems to generate wellbeing for urban dwellers. To understand how different relationships between urban form and wellbeing together play out, we analysed geocoded experiential data (1460 experiences from 780 respondents) together with variables of the physical environment. Through statistical and spatial analysis, we operationalised resilience principles to assess what urban environments provide “resilience at eye level” – a diversity of experiences and a level of connectivity between them that limit adverse outcomes. We found 8 typologies of experiential landscapes – distinct compositions of 11 categories of experiences. Our analysis shows that typologies with experiences supportive of wellbeing are diverse and exist in environments that balance residents and workplaces, avoid extreme spatial integration and/or density and have accessible nature. Typologies with many experiences hindering wellbeing fail in one or several of these respects. Our findings suggest that resilience principles can act as a guiding heuristic for urban densification that does not compromise human wellbeing.

  • 215.
    Samuelsson, Karl
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Giusti, Matteo
    Stockholm Resilience Centre, Stockholm University, Sweden.
    Peterson, Garry D.
    Stockholm Resilience Centre, Stockholm University, Sweden.
    Legeby, Ann
    School of Architecture, KTH Royal Institute of Technology, Sweden.
    Brandt, S. Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre, Stockholm University, Sweden.
    Impact of environment on people’s everyday experiences in Stockholm2018Ingår i: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 171, s. 7-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to construct urban environments that limit negative impacts for global sustainability while supporting human wellbeing, there is a need to better understand how features of the environment influence people’s everyday experiences. We present a novel method for studying this combining accessibility analysis and public participatory GIS (PPGIS). Seven environment features are defined and accessibility to them analysed across Stockholm municipality. We estimate the probabilities of positive and negative experiences in places based on these environment features, by using spatial regression to extrapolate from the results of an online PPGIS survey (1784 experiences of 1032 respondents). Six of the seven studied environment features have significant impact on experiential outcome, after accounting for spatial autocorrelation among the data. The results show that number of residents and proximity of nature environments and water, all common quality indicators in urban planning and research, have weak statistically significant effects on people’s experiences. However, areas dominated by large working populations or proximity to major roads have very low rates of positive experiences, while areas with high natural temperature regulating capacities have very high rates, showing that there are considerable qualitative differences within urban environments as well as nature environments. Current urban planning practices need to acknowledge these differences to limit impacts on the biosphere while promoting human wellbeing. We suggest that a good way to start addressing this is through transformation of negatively experienced urban areas through designs that integrate closeness to urbanity with possibilities to have nature experiences on a daily basis. 

  • 216.
    Santhi Pechsiri, Joseph
    et al.
    KTH, Department of Industrial Ecology.
    Sattari, Amir
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Garza Martinez, Paulina
    KTH, Department of Industrial Ecology.
    Xuan, Liu
    A Review of the Climate-Change-Impacts’ Rates of Change in the Arctic2010Ingår i: Journal of Environmental Protection, ISSN 2152-2197, E-ISSN 2152-2219, Vol. 1, nr 1, s. 59-69Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate Change is a global phenomenon that has a global scale impact. The current trend of climate change towards the warming of the globe has resulted in various changes in the geological, climatology, social, economical, and biological processes worldwide. Temperature of the globe has increased due to various factors, but anthropogenic plays a major contribution through the heavy input of Greenhouse gases. One of the world’s most remote regions that have been affected by most of the anthropogenic stresses on environmental services is the Arctic Region. The Arctic Region has shown various drastic changes and has shown to be effected by various anthropogenic activities that take place elsewhere. These changes include the ozone hole (resulting from ozone degrading compound emitted heavily by anthropogenic demands ), the accumulation of various persistent and volatile pollutants (i.e. POPs) , and the meltdown of the polar ice (among others) . These drastic changes are well perceived and well projected for future preparations. However, the question still remains if these impacts would only accelerate change. This paper aims to discuss if these changes are accelerating or happening at a constant rate. In addition, this paper aims to only focus on changes due to global warming and climate changes phenomenon.

  • 217.
    Sarady, Maria
    et al.
    Department of Social and Economic Geography, Uppsala University.
    Sahlin, Eva A. U.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    The influence of snow cover on ground freeze-thaw frequency, intensity, and duration: An experimental study conducted in coastal northern Sweden2016Ingår i: Norsk Geografisk Tidsskrift, ISSN 0029-1951, E-ISSN 1502-5292, Vol. 70, nr 2, s. 82-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact of snow cover on seasonal ground frost and freeze-thaw processes is not yet fully understood. The authors therefore examined how snow cover affects seasonal ground frost in a coastal setting in northern Sweden. Air and soil temperatures were recorded in a paired-plot experiment, both with and without snow cover, during the frost season 2012–2013. The frequency, duration, and intensity of the freeze-thaw cycles during the frost season were calculated. The results showed that the freeze-thaw frequency was 57% higher at the soil surface and the intensity 10 °C colder in the spring of 2013, when the ground lacked snow cover. Furthermore, the duration of the seasonal freeze-thaw cycle was 30 days longer on average in cases where there was natural snow accumulation. The correlation between air and ground surface temperatures weakened with increased snow-cover depth. The authors conclude that continued increases in air temperature and decreases in snow in coastal northern Sweden might alter freeze-thaw cycles and thus affect natural and human systems such as geomorphology, ecology, spatial planning, transport, and forestry.

  • 218.
    Schewenius, Maria
    et al.
    Stockholm Resilience Centre.
    Colding, Johan
    Stockholm Resilience Centre; The Beijer Institute, Royal Swedish Academy of Sciences.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre.
    Social-Ecological Integrated Planning and Design2017Ingår i: Dreams and Seeds: The role of campuses in sustainable urban development / [ed] Schewenius, M., Keränen, P., al Rawaf, R., Stockholm: Stockholm Resilience Centre; Metropolia University of Applied Sciences , 2017, 1, s. 47-49Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 219.
    Schmidinger, Helen
    et al.
    Uppsala universitet.
    Brandt, S. Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Närområdesexkursioner och inre motivation för bättre lärande: en studie i svenska gymnasieskolan2015Ingår i: Nordidactica: Journal of Humanities and Social Science Education, ISSN 2000-9879, Vol. 2015, nr 1, s. 22-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports results from two locally based geography excursions at two secondary schools in Sweden, in order to study how the pupils’ own experience from the local neighborhood, intrinsic motivation, and flow interact during the learning process to see if these parameters affect their understanding and knowledge of the studied objects. The methods used were observations during the excursions, as well as interviews and questionnaires afterwards. The results show that the pupils believe that they learn more when studying objects in their natural environment, i.e. outside their classroom. Furthermore, the results show that intrinsic motivation may be difficult, but not impossible, to achieve, and also that there are good opportunities for attaining flow. If the pupils can see patterns and structures of the objects and processes studied, they will start understand and gain knowledge. This process will increase chances for intrinsic motivation, which will further increase understanding and knowledge, and attaining flow. Once achieved, a spiral process of continued flow, continued intrinsic motivation, and increasing knowledge may be maintained.

  • 220.
    Schmidinger, Helen
    et al.
    Uppsala universitet.
    Molin, Lena
    Uppsala universitet.
    Brandt, S. Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Excursions in school – past and present from Swedish and Anglo-Saxon perspectives2014Ingår i: European Journal of Geography, ISSN 1792-1341, Vol. 5, nr 4, s. 87-101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this article is to present the results from a review of literature on geography excursions and field studies and to discuss their development over time, focusing on purpose, content, method, and execution. The scope was limited to Swedish and Anglo-Saxon literature, produced after the year 1900. The results show that excursions and field studies have since long been important methods in school teaching, not only in the subject geography. One of the purposes of using excursions and field studies in teaching is to facilitate the learning process of pupils and students. Several authors arguing that learning improved when the objects are studied in the real world. We can see that a continuous process of change has altered contents as well as conduction of the excursions. The previous instrumental orientation has moved toward more pupil-participating work methods. Today preparation is a keyword in most texts on excursions, and the perspectives have been broadened.

  • 221. Schreurs, G.
    et al.
    Buiter, S.
    Burberry, C.
    Callot, Jean-Paul
    Cavozzi, C.
    Cerca, M.
    Cristallini, E.
    Cruden, A.
    Chen, J. H.
    Cruz, L.
    Daniel, J.M.
    Garcia, V. H.
    Gomes, C.
    Grall, C.
    Guzmán, C.
    Nur Hidayah, T.
    Hilley, G.
    Lu, C.Y.
    Klinkmüller, M.
    Koyi, H.
    Uppsala universitet, Berggrundsgeologi.
    Macauley, J.
    Maillot, B.
    Meriaux, C.
    Nilfouroushan, Faramarz
    Uppsala universitet, Berggrundsgeologi.
    Pan, C. C.
    Pillot, D.
    Portillo, R.
    Rosenau, M.
    Schellart, W. P.
    Schlische, R.
    Take, A.
    Vendeville, B.
    Vettori, M.
    Vergnaud, M.
    Wang, S. H.
    Withjack, M.
    Yagupsky, D.
    Yamada, Y.
    Quantitative comparisons of analogue models of brittle wedge2010Konferensbidrag (Refereegranskat)
  • 222.
    Schreurs, Guido
    et al.
    Institute of Geological Sciences, University of Bern, Bern, Switzerland.
    Buiter, Susanne J. H.
    Geodynamics Team, Geological Survey of Norway, Trondheim, Norway; The Centre for Earth Evolution and Dynamics, University of Oslo, Blindern, Oslo, Norway.
    Boutelier, Jennifer
    Department of Geology, University of Toronto, Toronto, Ontario, Canada.
    Burberry, Caroline
    Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Callot, Jean-Paul
    IFP Energies Nouvelles, Rueil Malmaison, Cedex, France.
    Cavozzi, Cristian
    NEXT – Natural and Experimental Tectonics Research Group, Department of Physics and Earth Sciences, “Macedonio Melloni”, University of Parma, Parma, Italy .
    Cerca, Mariano
    Universidad Nacional Autonoma de Mexico, Centro de Geociencias, Juriquilla, Queretaro, Mexico.
    Chen, Jian-Hong
    Department of Geosciences, National Taiwan University, Taipei, Taiwan.
    Cristallini, Ernesto
    Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
    Cruden, Alexander R.
    Department of Geology, University of Toronto, Toronto, Ontario, Canada.
    Cruz, Leonardo
    Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, USA.
    Daniel, Jean-Marc
    IFP Energies Nouvelles, Rueil Malmaison, Cedex, France.
    Da Poian, Gabriela
    Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
    Garcia, Victor H.
    Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
    Gomes, Caroline J. S.
    Departamento de Geologia, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
    Grall, Céline
    IFP Energies Nouvelles, Rueil Malmaison, Cedex, France.
    Guillot, Yannick
    Université Lille-Nord de France, Laboratoire Géosystèmes, Villeneuve d’Ascq, Cedex, France.
    Guzmán, Cecilia
    Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
    Nur Hidayah, Triyani
    Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA.
    Hilley, George
    Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, USA.
    Klinkmüller, Matthias
    Institute of Geological Sciences, University of Bern, Bern, Switzerland.
    Koyi, Hemin A.
    Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Lu, Chia-Yu
    Department of Geosciences, National Taiwan University, Taipei, Taiwan.
    Maillot, Bertrand
    Laboratoire Géosciences et Environnement Cergy, Université de Cergy-Pontoise, Neuville-sur-Oise, Cergy-Pontoise, Cedex, France.
    Meriaux, Catherine
    School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia.
    Nilfouroushan, Faramarz
    Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Pan, Chang-Chih
    Department of Geosciences, National Taiwan University, Taipei, Taiwan.
    Pillot, Daniel
    IFP Energies Nouvelles, Rueil Malmaison, Cedex, France.
    Portillo, Rodrigo
    Universidad Nacional Autonoma de Mexico, Centro de Geociencias, Juriquilla, Queretaro, Mexico.
    Rosenau, Matthias
    Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany.
    Schellart, Wouter P.
    School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia.
    Schlische, Roy W.
    Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA.
    Take, Andy
    Department of Civil Engineering, Queen's University, Kingston, Ontario, Canada.
    Vendeville, Bruno
    Université Lille, Laboratoire d’Océanologie et de Géosciences, Lille, France.
    Vergnaud, Marine
    IFP Energies Nouvelles, Rueil Malmaison, Cedex, France.
    Vettori, Matteo
    NEXT – Natural and Experimental Tectonics Research Group, Department of Physics and Earth Sciences “Macedonio Melloni”, University of Parma, Parma, Italy.
    Wang, Shih-Hsien
    Department of Geosciences, National Taiwan University, Taipei, Taiwan.
    Withjack, Martha O.
    Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA.
    Yagupsky, Daniel
    Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
    Yamada, Yasuhiro
    Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan.
    Benchmarking analogue models of brittle thrust wedges2016Ingår i: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 92, s. 116-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variabilityamong analogue models and to appraise the reproducibility and limits of model interpretation. Fifteenanalogue modeling laboratories participated in this benchmark initiative. Each laboratory received ashipment of the same type of quartz and corundum sand and all laboratories adhered to a stringentmodel building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sievestructure, sifting height,filling rate, and details on off-scraping of excess sand followed prescribedprocedures.Our analogue benchmark shows that even for simple plane-strain experiments with prescribedstringent model construction techniques, quantitative model results show variability, most notably forsurface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variabilityin model results is related to slight variations in how sand is deposited in the sandbox. Small changes insifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities,which will affect the mechanical properties of the sand, and will result in lateral and vertical differencesin peak and boundary friction angles, as well as cohesion values once the model is constructed. Initialvariations in basal friction are inferred to play the most important role in causing model variability.Our comparison shows that the human factor plays a decisive role, and even when one modeler re-peats the same experiment, quantitative model results still show variability. Our observations highlightthe limits of up-scaling quantitative analogue model results to nature or for making comparisons withnumerical models. The frictional behavior of sand is highly sensitive to small variations in material stateor experimental set-up, and hence, it will remain difficult to scale quantitative results such as number ofthrusts, thrust spacing, and pop-up width from model to nature.

  • 223.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Lim, Nancy J.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Color map design for visualization in flood risk assessment2017Ingår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 31, nr 11, s. 2286-2309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Visualizations of flood maps from simulation models are widely used for assessing the likelihood of flood hazards in spatial planning. The choice of a suitable type of visualization as well as efficient color maps is critical to avoid errors or bias when interpreting the data. Based on a review of previous flood uncertainty visualization techniques, this paper identifies areas of improvements and suggests criteria for the design of a task-specific color scale in flood map visualization. We contribute a novel color map design for visualizing probabilities and uncertainties from flood simulation ensembles. A user study encompassing 83 participants was carried out to evaluate the effects of this new color map on user’s decisions in a spatial planning task. We found that the type of visualization makes a difference when it comes to identification of non-hazardous sites in the flood risk map and when accepting risks in more uncertain areas. In comparison with two other existing visualization techniques, we observed that the new design was superior both in terms of task compliance and efficiency. In regions with uncertain flood statuses, users were biased toward accepting less risky locations with our new color map design.

  • 224. Shahpasandzadeh, M.
    et al.
    Nilfouroushan, Faramarz
    Uppsala universitet, Berggrundsgeologi.
    Koyi, H.
    Uppsala universitet, Berggrundsgeologi.
    Kinematics of structures and active tectonics of an active orogenic belt, Alborz Mountains, northern Iran: New insights from scaled analogue modeling2010Konferensbidrag (Refereegranskat)
  • 225.
    Shahpasand-zadeh, Majid
    et al.
    Department of Earth Sciences, Kerman Graduate University of Technology, Kerman, Iran.
    Koyi, Hemin
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    The significance of switch in convergence direction in the Alborz Mountains, northern Iran: insights from scaled analogue modelling2017Ingår i: Interpretation, ISSN 2324-8858, E-ISSN 2324-8866, Vol. 5, nr 1, s. SD81-SD98Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The switch in direction of convergence between Central Iran and the Eurasian plate isbelieved to have a significant impact on the structural style in the Alborz Mountains, in northof Iran. To understand the deformation pattern and investigate the influence of the SouthCaspian Basin (SCB) kinematics since the middle Miocene on the structural styles and activetectonics of the Alborz Mountains, a series of scaled analogue models were prepared, wherepassively layered loose sand simulating the sedimentary units were subjected toorthogonal and subsequently oblique shortening by a rigid indenter. Model resultsshow that during the shortening an arcuate-shape foreland-vergent imbricate stack forms infront of the indenter. The orthogonal shortening is characterized by a prevailing right-lateraland left-lateral oblique-slip motion in the east and west of the model, respectively. This shiftin kinematics contradicts the proposed pre-neotectonic (orthogonal) model of the Alborz.However, during oblique shortening, model results show that deformation is mainlyaccommodated by left-lateral transpression within the sand wedge and by its internaldeformation. Oblique shortening is consistently accommodated by continued left-lateralmotion on the WNW-trending oblique thrusts, whereas the east-west trending thrusts and thepre-existing ENE-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults.Precise monitoring of the model surface also illustrates partitioning of shortening into theforeland-vergent left-lateral thrusting in the south and hinterland-vergent back thrusting in thenorth. These model results are generally consistent with field observations and GPS data ofstructure and kinematics of the Alborz Mountains.

  • 226.
    Shen, Lin
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    GIS-based Multi-criteria Analysis for Aquaculture Site Selection2010Självständigt arbete på grundnivå (kandidatexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The pearl oyster Pinctada martensii or Pinctada fucata is the oyster for produce the South China Sea Pearl, and the production of pearl oyster Pinctada martensii plays a key role for the economic and social welfare of the coastal areas. To guarantee both rich and sustainability of providing pearl oyster productions, addressing the suitable areas for aquaculture is a very important consideration in any aquaculture activities. Relatively rarely, in the case of site selection research, the researchers use GIS analysis to identify suitable sites in fishery industry in China. Therefore, I decided to help the local government to search suitable sites form the view of GIS context. This study was conducted to find the optimal sites for suspended culture of pearl oyster Pinctada martensii using GIS-based multi-criteria analysis. The original idea came from the research of Radiarta and his colleagues in 2008 in Japan. Most of the parameters in the GIS model were extracted from remote sensing data (Moderate Resolution Imaging Spectroradiometer and Landsat 7). Eleven thematic layers were arranged into three sub-models, namely: biophysical model, social-economic model and constraint model. The biophysical model includes sea surface temperature, chlorophyll-α concentration, suspended sediment concentration and bathymetry. The criteria in the social-economic model are distance to cities and towns and distance to piers. The constraint model was used to exclude the places from the research area where the natural conditions cannot be fulfilled for the development of pearl oyster aquaculture; it contains river mouth, tourism area, harbor, salt fields / shrimp ponds, and non-related water area. Finally those GIS sub-models were used to address the optimal sites for pearl oyster Pinctada martensii culture by using weighted linear combination evaluation. In the final result, suitability levels were arranged from 1 (least suitable) to 8 (most suitable), and about 2.4% of the total potential area had the higher levels (level 6 and 7). These areas were considered to be the places that have the most suitable conditions for pearl oyster Pinctada martensii for costal water of Yingpan.

  • 227.
    Shoshtari, Salahaldin
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    DETERMINATION OF FREE STAND-ALONE PHOTOVOLTAIC POTENTIAL IN GERMANY BY GIS-BASED SITE RANKING2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this study is to find potential areas suitable for energy production using renewable sources. For this aim, accurate assessments are necessary. The assessments include geographical suitability, closeness of infrastructure and observing local and regional framework concerning the use of renewable sources together with environmental protection. In addition, economical factor is considered in such an assessment. In this study, the Photovoltaic (PV) production potential for Germany is considered. An accurate and complete data set is necessary in order to achieve reliable results. In addition, a powerful database management and strong analysis tools are required. Geographical Information System (GIS) is a tool for finding suitable sites for the photovoltaic production.Using GIS, energy generation planners are able to visualize solar densities throughout the considered area. In addition, they can find the optimal and most economical sites by the combination of solar potential with the information about land. In this study, data sources consist of meteorological and geographical conditions. Furthermore, all analyses have been performed using Arc GIS Desktop. This study demonstrates the possible places for photovoltaic plants and indicates suitable candidates according to weights and factors in multi criteria analysis. The solar radiation data is from year 1995 to 2005. Land cover data is according to Corine 2000 and the more detailed Raumordnungskataster (Rok) for Weser-Ems. Numerical results are reliable from a comparison point of view. This study demonstrates the sensitivity of the defined criteria with respect to electricity production. In particular, this study is useful to see the capabilities of GIS for site selection regarding photovoltaic plants.The purpose of this study is to find potential areas suitable for energy production using renewable sources. For this aim, accurate assessments are necessary. The assessments include geographical suitability, closeness of infrastructure and observing local and regional framework concerning the use of renewable sources together with environmental protection. In addition, economical factor is considered in such an assessment. In this study, the Photovoltaic (PV) production potential for Germany is considered. An accurate and complete data set is necessary in order to achieve reliable results. In addition, a powerful database management and strong analysis tools are required. Geographical Information System (GIS) is a tool for finding suitable sites for the photovoltaic production.Using GIS, energy generation planners are able to visualize solar densities throughout the considered area. In addition, they can find the optimal and most economical sites by the combination of solar potential with the information about land. In this study, data sources consist of meteorological and geographical conditions. Furthermore, all analyses have been performed using Arc GIS Desktop. This study demonstrates the possible places for photovoltaic plants and indicates suitable candidates according to weights and factors in multi criteria analysis. The solar radiation data is from year 1995 to 2005. Land cover data is according to Corine 2000 and the more detailed Raumordnungskataster (Rok) for Weser-Ems. Numerical results are reliable from a comparison point of view. This study demonstrates the sensitivity of the defined criteria with respect to electricity production. In particular, this study is useful to see the capabilities of GIS for site selection regarding photovoltaic plants.

  • 228.
    Sjö, Maria
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Tähtikivi, Annelie
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Geomorfologisk kartläggnng av Kungsbäckens avrinningsområde2006Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    År 2015 ska alla avrinningsområden i EU-länderna vara fastställda. Anledningen till detta är att år 2000 trädde ett vattendirektiv i kraft. Syftet med direktivet är att skapa en helhetssyn för vattenresurserna i Europa och för att få en enhetlig och övergripande lagstiftning. I Sverige har SMHI redan bestämt vattendelare och avrinningsområden för ett stort antal områden i landet, men i och med direktivet har det blivit ett krav. En helhetssyn på vattenresurser tillsammans med kunskaper om geologi är en förutsättning för en hållbar utveckling och ett effektivt tillvaratagande av naturresurserna. Inom samhällsplaneringen spelar geologin en tämligen betydande roll. Vid exempelvis planering av nya bostadsområden är det av stor vikt att veta markens egenskaper.

    Syftet med detta examensarbete var att fastställa Kungsbäckens avrinningsområde samt att göra en geomorfologisk undersökning av området. Arbetet syftade även till att redogöra för några fluvialmorfologiska förekomster kring del av Kungsbäcken - från utloppet vid Gavleån vid Stora Vall till viadukten vid Regementsvägen. Genom att utföra studien som en kombination av naturgeografi och GIT påvisas möjligheterna att utföra olika typer av analyser och beräkningar utifrån de naturresurser som finns i ett område och den moderna tekniken. Vidare kommer resultatet från denna studie att delges SMHI. De kan därmed få nytta av materialet när de, på uppdrag av Naturvårdsverket, skall utföra en kartläggning av Kungsbäckens avrinningsområde.

    För att möjliggöra en geomorfologisk kartläggning av Kungsbäckens avrinningsområde och fastställa dess gränser studerades initialt tillgängligt material såsom tidigare studier, litteratur, terrängkarta, jord- och bergartskartor samt flygfotografier. Vid genomförandet av fastställningen av områdets gränser nyttjades bland annat SMHI:s tidigare gjorda gränser, en av oss gjord analog analys, utifrån tryckta terrängkartan 13H SV samt en flödesmodellering av en i studien gjord höjdmodell över området. Därefter gjordes fältstudier till tre stycken områden med osäkra områdesgränser, vilka framkom av ovan nämnda analyser. Med hjälp av flödesriktningsinstrument och okulär besiktning kunde gränserna då fastställas. Även fältstudier av geomorfologiskt intresse har utförts, såsom studie av ändmoräner och hällar.

    Med hjälp av genomförda fältstudier, analyser, digitalisering och litteraturgranskning har gränserna för Kungsbäckens avrinningsområde bestämts samt beräknats till en area av 105,4 km2. Områdets geomorfologiska kartläggning har resulterat i en karta där de olika förekomsterna finns redovisade (se bilaga 1, karta i A3-format). Förutom detta finns olika begrepp och naturfenomen beskrivna i rapporten samt nyttan med denna typ av studie.

  • 229.
    Sjöberg, Lars
    et al.
    Division of Geodesy and Satellite Positioning KTH.
    Abrehdry, Majid
    Division of Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    Division of Geodesy and Satellite Positioning KTH.
    The observed geoid height versus Airy's and Pratt's isostatic models using matched asymptotic expansions2014Ingår i: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 49, nr 4, s. 473-490Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isostasy is a key concept in geodesy and geophysics. The classical isostatic models of Airy/Heiskanen and Pratt/Hayford imply that the topographic mass surplus and ocean mass deficit are balanced by mountain roots and anti-roots in the former model and by density variations in the topography and the compensation layer below sea bottom in the latter model. In geophysics gravity inversion is an essential topic where isostasy comes to play. The main objective of this study is to compare the prediction of geoid heights from the above isostatic models based on matched asymptotic expansion with geoid heights observed by the Earth Gravitational Model 2008. Numerical computations were carried out both globally and in several regions, showing poor agreements between the theoretical and observed geoid heights. As an alternative, multiple regression analysis including several non-isostatic terms in addition to the isostatic terms was tested providing only slightly better success rates. Our main conclusion is that the geoid height cannot generally be represented by the simple formulas based on matched asymptotic expansions. This is because (a) both the geoid and isostatic compensation of the topography have regional to global contributions in addition to the pure local signal considered in the classical isostatic models, and (b) geodynamic phenomena are still likely to significantly blur the results despite that all spherical harmonic low-degree (below degree 11) gravity signals were excluded from the study.

  • 230.
    Sjöberg, Lars
    et al.
    Royal Institute of Technology (KTH), Stockholm, Sweden .
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    A study on the Fennoscandian post-glacial rebound as observed by present-day uplift rates and gravity field model GOCO02S2013Ingår i: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 48, nr 3, s. 317-331Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Repeated absolute gravity measurements in Fennoscandia have revealed that the on-going post-glacial rebound can be regarded as a pure viscous flow of mantle mass of density 3390 kg/m3 towards the central part of the region caused by a gravity/uplift rate of −0.167 μGal/mm. Our model estimates the rebound induced rates of changes of surface gravity and geoid height to have peaks of −1.9 μGal/yr and 1.6 mm/yr, respectively, the former being consistent with absolute gravity observations. The correlation coefficient of the spherical harmonic representations of the geoid height and uplift rate for the spectral windows between degrees 10 and 70 is estimated to −0.99±0.006, and the maximum remaining land uplift is estimated to the order of 80 m. Both the (almost) linear increase of relaxation time with degree and the linear relation between geoid height and uplift rate support a model with mass flow in the major part of the mantle and disqualify the model with a flow in a thin channel below the crust. The mean viscosity of the flow in the central uplift region is estimated to 4×1021 Pa s.

  • 231.
    Sjöberg, Lars E.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. KTH Royal Institute of Technology, Stockholm, Sweden.
    Gravity Inversion and Integration: Theory and Applications in Geodesy and Geophysics2017Bok (Övrigt vetenskapligt)
    Abstract [en]

    This book contains theory and applications of gravity both for physical geodesy and geophysics. It identifies classical and modern topics for studying the Earth. Worked-out examples illustrate basic but important concepts of the Earth’s gravity field. In addition, coverage details the Geodetic Reference System 1980, a versatile tool in most applications of gravity data.

    The authors first introduce the necessary mathematics. They then review classic physical geodesy, including its integral formulas, height systems and their determinations. The next chapter presents modern physical geodesy starting with the original concepts of M.S. Molodensky. A major part of this chapter is a variety of modifying Stokes’ formula for geoid computation by combining terrestrial gravity data and an Earth Gravitational Model.

    Coverage continues with a discussion that compares today’s methods for modifying Stokes’ formulas for geoid and quasigeoid determination, a description of several modern tools in physical geodesy, and a review of methods for gravity inversion as well as analyses for temporal changes of the gravity field.

    This book aims to broaden the view of scientists and students in geodesy and geophysics. With a focus on theory, it provides basic and some in-depth knowledge about the field from a geodesist’s perspective.

  • 232.
    Sjöberg, Lars E.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Royal Institute of Technology, Stockholm, Sweden.
    Isostasy - Geodesy2016Ingår i: Encyclopedia of Geodesy / [ed] Grafarend, Erik, Springer , 2016Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Isostasy (Greek isos “equal,” stasis “stand still”) is a term in geology, geophysics, and geodesy to describe the state of mass balance (equilibrium) between the Earth’s crust and upper mantle. It describes a condition to which the mantle tends to balance the mass of the crust in the absence of external forces.

  • 233.
    Sjöberg, Lars E.
    et al.
    Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Tenzer, Robert
    School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan, China .
    On Gravity Inversion by No-Topography and Rigorous Isostatic Gravity Anomalies2015Ingår i: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 172, nr 10, s. 2669-2680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss some theoretical aspects and practical consequences of using traditional versus “new”/rigorous formulations of the Bouguer and isostatic gravity anomalies/disturbances. In principle, the differences between these two concepts are in the definition of the so-called secondary indirect topographic effect (SITE) on the gravity data. Although we follow the tradition to call this effect SITE, we show that it is formally a direct topographic effect (DITE), needed to remove all topographic signal, but in practice not regarded as such. Consequently, there is a need for a no-topography gravity anomaly, which removes all topographic effects, leaving the below-crust Earth transparent for gravity inversion. Similarly, a rigorous isostatic gravity anomaly includes also a compensation effect for the SITE. By using a simple topographic model, we confirm a theoretically found ratio of 2/(n + 1) between the magnitudes of the SITE and DITE by wavelength (spherical harmonic degree n), both for the Bouguer and isostatic gravity anomalies. Finally, global gravity inversions are applied by utilizing the Vening Meinesz-Moritz isostatic model to determine the Moho geometry using the Bouguer gravity disturbances/anomalies and the no-topography gravity anomalies, and the results are compared. The numerical results confirm our theoretical findings that the Bouguer gravity disturbances and the no-topography gravity anomalies provide very similar results. A comparison of these gravimetrically computed Moho depths with the CRUST1.0 seismic model shows rms agreements of 4.3 and 4.5 km, respectively. This is a significant improvement when compared to the Moho result obtained by using the Bouguer gravity anomalies, yielding the rms difference of 7.3 km for the CRUST1.0 model. These results confirm a theoretical deficiency of the classical definition of the Bouguer and isostatic gravity anomalies, which do not take into consideration the SITE effects on the topography and its compensation. 

  • 234. Sorbi, Mohammad Reza
    et al.
    Nilfouroushan, Faramarz
    Uppsala universitet, Berggrundsgeologi.
    Zamani, Ahmad
    Seismicity patterns associated with the September 10th, 2008 Qeshm earthquake, South Iran2012Ingår i: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 101, nr 8, s. 2215-2223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The b value of the Gutenberg-Richter relation and the standard deviate, Z, were calculated to investigate the temporal and spatial variations in seismicity patterns associated with the September 10th, 2008 (Mw=6.1) Qeshm earthquake. The temporal variations of b value illustrate a distinct dramatic drop preceding the Qeshm earthquake and the spatial changes in b value highlight a zone with an abnormally low b value around the epicenter of this event. The Cumulative number and Z value as a function of time shows a precursory seismic quiescence preceding the 2008 Qeshm earthquake that observed for one year in a circle with R=50 km around its epicenter. The spatial distribution map of the standard deviate, Z, also exhibits an obvious precursory seismic quiescence region before the 2008 Qeshm event around the epicenter of this event. Interestingly, the precursory seismic quiescence region is approximately consistent with low b value anomaly region and both have E-W to NE-SW trend. These two precursory anomalies took place in relatively large regions, which were possibly relevant to the preparation zone of the 2008 Qeshm event.

  • 235. Steffen, Holger
    et al.
    Ganas, Athanassios
    Kapetanidis, Vasilis
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Lidberg, Martin
    Lantmäteriet, Gävle, Sweden.
    WP10 Members, EPOS
    The EPOS GNSS strain rate product (Y2018) – status and open questions2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Geodetic strain rate as derived from Global Navigation Satellite System (GNSS) station velocities is the rate of deformation in the crust (distance change combined with rotations and elevation changes) within a corresponding time. GNSS-derived strain rates are of great importance for Solid Earth Sciences, for example, in seismotectonic and geodynamic studies for comparison to stress fields and rates of earthquake occurrence or interpretation of plate motion characteristics, i.e. in plate boundary areas. Within the EU Horizon 2020 project EPOS-IP (European Plate Observing System-Implementation Phase) WP10 (GNSS thematic core services) a series of GNSS-derived strain rates products for Europe is envisaged. The project is currently in the last steps of the Implementation Phase before reaching the Operational Phase in 2020. We will present the status of the planned strain-rate product. This includes an overview of anticipated data input and output, methods for strain rate calculation and suggestions for the strain rate data portal. We will also raise a few open questions that we would like to discuss and for which we anticipate fruitful feedback from the EUREF community.

  • 236.
    Sun, Xiaowei
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    An Urban Morphological Study on Swedish Cities from a Topological Perspective2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Streets provide the framework of a city and they are necessary for human life. Some underlying patterns of street networks cannot be directly recognized by people. In this study, topological analysis of urban street networks was adopted to build up new insight into urban morphology. Space syntax, which has been integrated into GIS, was applied for the analysis of spatial configuration, and fifty Swedish cities were chosen as samples to uncover various urban patterns. Street connectivity was the focus of the analysis and axial lines were the main analytical tools. The aim of this study was to hierarchically represent the cities’ streets and classify the sample cities into different types by urban morphology.

    Street data for Swedish cities were collected from OpenStreetMap. ArcGIS 10, with the Axwoman extension, provided a platform to carry out the topological analysis. Natural roads, axial lines and space syntax parameters were generated automatically with the functions of Axwoman. Hierarchical levels of streets were visually represented and the underlying pattern of each city was gotten from the hierarchical representation. Based on street hierarchy, the fifty sample cities were classified into nine groups, wherein cities of the same group had uniform hierarchical levels. Using the hierarchical pattern of each group’s axial lines, the nine city groups were further reclassified into three types.

    It was found that, for the street network of most sample cities represented with axial lines, not more than 40% of their streets have connectivity larger than the average value. The hierarchical representation also revealed that streets with high connectivity, which provide greater accessibility, were only minorities in the sample cities. Moreover, minor streets with high connectivity were almost distributed in city centers.

    In some of the studied cities, axial lines made better representation of the hierarchical patterns of streets, while in others, it did not provide a suitable way of uncovering urban patterns compared to natural roads. A limitation of axial lines manifested in this study was that it chopped curved roads into several segments, thus, disrupting the continuity of streets.

    In general, axial lines can provide a way to uncover urban patterns. They have meaningful effect to city residents and these patterns can help people gain better understanding of the urban structure. In addition, the hierarchical patterns of streets can be used to model pedestrian and traffic flows, predict crime occurrences, and make spatial plans. The hierarchical representation of streets can also contribute to people’s wayfinding performance.

  • 237.
    Sun, Xiaowei
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Comparative Analysis of Urban Morphology: Evaluating Space Syntax and Traditional Morphological Methods2013Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis examines the urban morphology of fifty cities using spatial syntax analysis. The analysis compares the urban street networks of European, USA, Islamic and East Asian cities. Street connectivity was the main metric and natural roads were the basis for the analysis. The aim of the study was to analyze determine how sensitive space syntax methods are for uncovering the hierarchical patterns of urban street networks and examining their scale-free and small-world properties.

    Street data was collected from OpenStreetMap. ArcGIS 10 with the Axwoman extension was used to study the hierarchical levels of street networks. Matlab provided the platform to examine the scale-free property of street data. Pajek software was used to measure the small-world behavior. Based on the hierarchical representation, the fifty sample cities were classified into different groups and their scale-free and small-world properties were studied.

    From a traditionally morphological perspective, it was found that some cities in Europe have a close-knit cellular and organic urban morphology. Cities in the USA exhibit gridiron patterns on the whole. Some Islamic cities have special urban structure with houses grouped around the cul-de-sac lanes. Several of the East Asian cities studied also have grid forms. According to the space syntax analysis, urban street networks that have a connectivity value greater than the average value were less than 40%. The results showed that for most cities, the street connectivity distribution follows a power-law distribution and exhibits scale-free properties. Urban street networks of all sample cities were found to have a small-world property.

    Space syntax cannot detect all of the morphological patterns recognized in traditional morphological studies. The method can, however, efficiently quantify the spatial configuration of a large sample. Space syntax’s topological and scaling metrics thus provide a way to compare urban street networks. These metrics can thus help classify cities according to their street patterns but also contribute to an understanding of human behavior within and thus the design of urban spaces. For example, an urban street network with a small-world property could have high efficiency for traffic flows at local and global levels and should be considered in further study.

  • 238. Tavakoli, F.
    et al.
    Walpersdorf, A.
    Authemayou, C.
    Nankali, H. R.
    Hatzfeld, D.
    Tatar, M.
    Djamour, Y.
    Nilfouroushan, Faramarz
    solid earth Geology.
    Cotte, N.
    Distribution of the right-lateral strike-slip motion from the Main Recent Fault to the Kazerun Fault System (Zagros, Iran): Evidence from present-day GPS velocities2008Ingår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 275, s. 342-375Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    GPS measurements across the Kazerun Fault System in the Zagros mountain belt provide first instantaneous velocities on the different segments. These results are closely consistent with the geological fault slip rates (over 150 ka), implying stable velocities over a longer period. The present-day strike–slip motion is distributed from the Main Recent Fault to the N-trending Kazerun Fault System along a preferential en-echelon fault zone included in a more distributed fan-shape fault pattern. The Hormuz salt decoupling layer cannot be the only cause of a sedimentary spreading because seismicity attests these faults are rooted in the basement. The Dena fault (3.7 mm/yr) transfers the MRF fault slip mainly to the Kazerun (3.6 mm/yr) and slightly to the High Zagros and Sabz Pushan faults (1.5 mm/yr), and the Kazerun fault further to the Kareh Bas fault (3.4 mm/yr). Total geological horizontal offsets associated with GPS slip rates help inferring precise fault slip onset ages. The successive onsets deduced by this approach imply that the right-lateral strike-slip activity of the MRF has propagated in time southeastward to the Dena segment, and then to the Kazerun segment and to the Kareh Bas fault.

  • 239. Taymaz, Tuncay
    et al.
    Nilfouroushan, Faramarz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Yolsal-Çevikbilen, Seda
    Eken, Tuna
    Co-seismic Crustal Deformation of the 12 November 2017 Mw 7.4Sar-Pol-Zahab (Iran) Earthquake: integration of analysis based on DInSAR and seismological observations2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The November 12, 2017 Mw 7.4 earthquake that trembled near the border region between Halabjah (Iraq) andSarpol-e Zahab (Iran) is the largest ever-recorded earthquake in the Zagros Mountains since 1900. The epicenterlocation of the event suggests that the NNW trending Mountain Front Fault (MFF) has been responsible for theearthquake though it was not associated with surface faulting. Analysis of teleseismic P- and SH- body-waveformsdata indicate a well-constrained rupture propagated along the dip direction of the fault plane with an effectiverupture area of 80km long, 70km wide and focal depth of 192 km ENE dipping low-angle thrust faulting with asmall strike-slip component that produced little uplift in the region (Strike: 358o; Dip: 16o, Rake: 149o and SeismicMoment (Mo): 1.828x1020 N.m. with maximum displacement (Dmax) of 6.9m at hypocenter, and rupture velocity(Vr) of 3.2 km/s). The source rupture duration is about 45s, but the main moment release is observed in the first10s. Focal mechanism solution of the event indicates a NNW trending plane dipping 16 degrees ENE. This isin agreement with the dip direction of the MFF and the distribution of aftershocks covering an area some 50-70km wide. We explore its details in astonishment, if it is proved, that the Zagros Mountain Front fault (MFF) wasresponsible then it might have become curved at depth (?)To measure the co-seismic crustal deformation around the epicenter, we processed the ascending and descendingSentinel-1 SAR images, collected before and after the earthquake, by SNAP software and generated the interferogramsof surface deformation. The Differential InSAR (DInSAR) results show an upward and downward displacementsof 90 cm and 30 cm around the epicenter respectively. Furthermore, we investigate the differencebetween strike derived from seismological and that inferred from DInSAR satellite observations, and its possiblecauses.We do not have “best” or “right” rupture model yet, but just models satisfying for specific data sets. The aftermathof earthquakes like the 2017 Halabjah (Irak)-Sarpol-e Zahab (˙Iran) provides excellent opportunity to evaluate ourunderstanding of earthquakes and their hazards in the earthquake prone regions.

  • 240.
    Tenzer, Robert
    et al.
    The Key Laboratory of Geospace Environment and GeodesySchool of Geodesy and Geomatics, Wuhan UniversityWuhanChina.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Samhällsbyggnad. Division of Geodesy and Satellite Positioning.
    Comparative Study of the Uniform and Variable Moho Density Contrast in the Vening Meinesz-Moritz’s Isostatic Scheme for the Gravimetric Moho Recovery2014Ingår i: IGFS 2014, Proceedings of the 3rd International Gravity Field Service (IGFS), Shanghai, China, 30 June - 6 July 2014 / [ed] Shuanggen Jin, Riccardo Barzaghi, Springer, 2014, s. 199-207Konferensbidrag (Refereegranskat)
    Abstract [en]

    In gravimetric methods for a determination of the Moho geometry, the constant value of the Moho density contract is often adopted. Results of gravimetric and seismic studies, however, showed that the Moho density contrast varies significantly. The assumption of a uniform density contrast thus might yield large errors in the estimated Moho depths. In this study we investigate these errors by comparing the Moho depths determined globally for the uniform and variable models of the Moho density contrast. These two gravimetric results are obtained based on solving the Vening Meinesz-Moritz’s inverse problem of isostasy. The uniform model of the Moho density contrast is defined individually for the continental and oceanic lithosphere to better reproduce the reality. The global data of the lower crust and upper mantle retrieved from the CRUST1.0 seismic crustal model are used to define the variable Moho density contrast. This seismic model is also used to validate both gravimetric solutions. Results of our numerical experiment reveals that the consideration of the variable Moho density contrast improves the agreement between the gravimetric and seismic Moho models; the RMS of differences is 5.4 km (for the uniform density contrast) and 4.7 km (for the variable density contrast).

  • 241.
    Tenzer, Robert
    et al.
    Institute of Geodesy and Geophysics, School of Geodesy and Geomatics, Wuhan University, Wuhan, China.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Reference crust-mantle density contrast beneath Antarctica based  on the Vening Meinesz-Moritz isostatic inverse problem and CRUST2.0 seismic model2013Ingår i: Earth Science Research, ISSN 1927-0542, E-ISSN 1927-0550, Vol. 17, nr 1, s. 7-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The crust-mantle (Moho) density contrast beneath Antarctica was estimated based on solving the Vening Meinesz-Moritz isostatic problem and using constraining information from a seismic global crustal model (CRUST2.0). The solution was found by applying a least-squares adjustment by elements method. Global geopotential model (GOCO02S), global topographic/bathymetric model (DTM2006.0), ice-thickness data for Antarctica (assembled by the BEDMAP project) and global crustal model (CRUST2.0) were used for computing isostatic gravity anomalies. Since CRUST2.0 data for crustal structures under Antarctica are not accurate (due to a lack of seismic data in this part of the world), Moho density contrast was determined relative to a reference homogenous crustal model having 2,670 kg/m3 constant density. Estimated values of Moho density contrast were between 160 and 682 kg/m3. The spatial distribution of Moho density contrast resembled major features of the Antarctic’s continental and surrounding oceanic tectonic plate configuration; maxima exceeding 500 kg/m3 were found throughout the central part of East Antarctica, with an extension beneath the Transantarctic mountain range. Moho density contrast in West Antarctica decreased to 400-500 kg/m3, except for local maxima up to ~ 550 kg/m3 in the central Antarctic Peninsula.

  • 242.
    Tenzer, Robert
    et al.
    National School of Surveying, University of Otago, Dunedin, New Zealand.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Reformulation of the Vening-Meinesz Moritz Inverse Problem of Isostasy for Isostatic Gravity Disturbances2012Ingår i: International Journal of Geosciences, ISSN 2156-8359, E-ISSN 2156-8367, Vol. 3, nr 5A, s. 918-929Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The isostatic gravity anomalies have been traditionally used to solve the inverse problems of isostasy. Since gravity measurements are nowadays carried out together with GPS positioning, the utilization of gravity disturbances in various regional gravimetric applications becomes possible. In global studies, the gravity disturbances can be computed using global geopotential models which are currently available to a relatively high accuracy and resolution. In this study we facilitate the definition of the isostatic gravity disturbances in the Vening-Meinesz Moritz inverse problem of isostasy for finding the Moho depths. We further utilize uniform mathematical formalism in the gravimetric forward modelling based on methods for a spherical harmonic analysis and synthesis of gravity field. We then apply both mathematical procedures to determine globally the Moho depths using the isostatic gravity disturbances. The results of gravimetric inversion are finally compared with the global crustal seismic model CRUST2.0; the RMS fit of the gravimetric Moho model with CRUST2.0 is 5.3 km. This is considerably better than the RMS fit of 7.0 km obtained after using the isostatic gravity anomalies.

  • 243.
    Tenzer, Robert
    et al.
    School of Geodesy and Geomatics, Wuhan University, Wuhan, China .
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Theoretical deficiencies of isostatic schemes in modeling the crustal thickness along the convergent continental tectonic plate boundaries2016Ingår i: Journal of Earth Science, ISSN 1674-487X, E-ISSN 1867-111X, Vol. 27, nr 6, s. 1045-1053Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of global and regional studies often show significant disagreement between the Moho depths determined using seismic and isostatic models. In this study, we estimate the differences between these two models in central Eurasia. The Vening Meinesz-Moritz (VMM) inverse problem of isostasy is utilized to determine the isostatic Moho depths. The estimated VMM Moho depths are then corrected for the sediment density contrast. The application of this correction improves the agreement between the isostatic and seismic Moho models. The existing discrepancies between the isostatic and seismic models are finally modeled by applying the non-isostatic correction, which accounts for the unmodelled mantle density heterogeneities and other geodynamic processes, which are not taken into account in classical isostatic models. Our results reveal that the non-isostatic correction still cannot fully describe mechanisms affecting the Moho geometry along the convergent continent-tocontinent tectonic plate boundaries occurring beneath Himalayas despite an overall good performance of the applied method. 

  • 244.
    Tenzer, Robert
    et al.
    University of Otago.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Cheinway, Hwang
    Chang, Emmy Tsui-Yu
    Moho Interface Modeling Beneath the Himalayas, Tibet and Central Siberia Using GOCO02S and DTM2006.02013Ingår i: Terrestrial, Atmospheric and Oceanic Science, ISSN 1017-0839, E-ISSN 2223-8964, Vol. 24, nr 4, s. 581-590Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We apply a newly developed method to estimate the Moho depths and density contrast beneath the Himalayas, Tibet and Central Siberia. This method utilizes the combined least-squares approach based on solving the inverse problem of isostasy and using the constraining information from the seismic global crustal model (CRUST2.0). The gravimetric forward modeling is applied to compute the isostatic gravity anomalies using the global geopotential model (GOCO02S) and the global topographic/bathymetric model (DTM2006.0). The estimated Moho depths vary between 60 - 70 km beneath most of the Himalayas and Tibet and reach the maxima of ~79 km. The Moho depth under Central Siberia is typically 50 - 60 km. The Moho density contrast computed relative to the CRUST2.0 lower crustal densities has the maxima of ~300 kg m-3 under Central Tibet. It substantially decreases to 150 - 250 kg m-3 under Himalayas and north Tibet. The estimated Moho density contrast under central Siberia is within 100 - 200 kg m-3.

  • 245.
    Tenzer, Robert
    et al.
    Key Laboratory of Geospace Environment and Geodesy, Wuhan University, Wuhan, China; he New Technologies for the Information Society, University of West Bohemia, Plzen, Czech Republic.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. the Royal Institute of Technology, Stockholm, Sweden.
    Chen, Wenjin
    University of Trieste, Trieste, Italy.
    Sjöberg, Lars E.
    the Royal Institute of Technology, Stockholm, Sweden.
    Global Isostatic Gravity Maps From Satellite Missions and Their Applications in the Lithospheric Structure Studies2017Ingår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 10, nr 2, s. 549-561Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent satellite gravity missions provide information on the Earth’s gravity field with a global and homogenous coverage. These data have been utilized in geoscience studies to investigate the Earth’s inner structure. In this study, we use the global gravitational models to compute and compare various isostatic gravity data. In particular, we compile global maps of the isostatic gravity disturbances by applying the Airy-Heiskanen and Pratt-Hayford isostatic theories based on assuming a local compensation mechanism. We further apply the Vening Meinesz-Moritz isostatic (flexural) model based on a more realistic assumption of the regional compensation mechanism described for the Earth’s homogenous and variable crustal structure. The resulting isostatic gravity fields are used to analyze their spatial and spectral characteristics with respect to the global crustal geometry. Results reveal that each of the applied compensation model yields a distinctive spatial pattern of the isostatic gravity field with its own spectral characteristics. The Airy-Heiskanen isostatic gravity disturbances provide a very smooth gravity field with no correlation with the crustal geometry. The Pratt-Hayford isostatic gravity disturbances are spatially highly correlated with the topography on land, while the Vening-Meinesz Moritz isostatic gravity disturbances are correlated with the Moho geometry. The complete crust-stripped isostatic gravity disturbances reveal a gravitational signature of the mantle lithosphere. These general characteristics provide valuable information for selection of a particular isostatic scheme, which could be used for gravimetric interpretations, depending on a purpose of the study.

  • 246.
    Tenzer, Robert
    et al.
    University of Otago, National School of Surveying.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Gladkikh, Vladislav
    University of Otago, National School of Surveying.
    Signature of the upper mantle density structure in the refined gravity data2012Ingår i: Computational Geosciences, ISSN 1420-0597, E-ISSN 1573-1499, Vol. 16, nr 4, s. 975-986Artikel i tidskrift (Refereegranskat)
  • 247.
    Tenzer, Robert
    et al.
    Institute of Geodesy and Geophysics, School of Geodesy and Geomatics, Wuhan University, Wuhan, China .
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Royal Institute of Technolog (KTH), Division of Geodesy & Geoinformation, Stockholm, Sweden.
    Sjöberg, Lars E.
    Royal Institute of Technolog (KTH), Division of Geodesy & Geoinformation, Stockholm, Sweden.
    Comparison of various isostatic marine gravity disturbances2015Ingår i: Journal of Earth System Science, ISSN 0253-4126, E-ISSN 0973-774X, Vol. 124, nr 6, s. 1235-1245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present and compare four types of the isostatic gravity disturbances compiled at sea level over the world oceans and marginal seas. These isostatic gravity disturbances are computed by applying the Airy– Heiskanen (AH), Pratt–Hayford (PH) and Vening Meinesz–Moritz (VMM) isostatic models. In addition, we compute the complete crust-stripped (CCS) isostatic gravity disturbances which are defined based on a principle of minimizing their spatial correlation with the Moho geometry. We demonstrate that each applied compensation scheme yields a distinctive spatial pattern in the resulting isostatic marine gravity field. The AH isostatic gravity disturbances provide the smoothest gravity field (by means of their standard deviation). The AH and VMM isostatic gravity disturbances have very similar spatial patterns due to the fact that the same isostatic principle is applied in both these definitions expect for assuming a local (in the former) instead of a global (in the latter) compensation mechanism. The PH isostatic gravity disturbances are highly spatially correlated with the ocean-floor relief. The CCS isostatic gravity disturbances reveal a signature of the ocean-floor spreading characterized by an increasing density of the oceanic lithosphere with age. 

  • 248.
    Tenzer, Robert
    et al.
    Wuhan University, China, Hubei, China.
    Bagherbandi, Mohammad
    Division of Geodesy and Satellite Positioning, KTH.
    Sjöberg, Lars
    Division of Geodesy and Satellite Positioning KTH.
    Novak, Pavel
    University of West Bohemia, Czech Republic, Plzeň, República Checa.
    Isostatic crustal thickness under the Tibetan Plateau and Himalayas from satellite gravity gradiometry data2015Ingår i: Earth Sciences Research Journal, ISSN 1794-6190, E-ISSN 2339-3459, Vol. 19, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The global gravity and crustal models are used in this study to determine the regional Moho model. For this purpose, we solve the Vening Meinesz-Moritz's (VMM) inverse problem of isostasy defined in terms of the isostatic gravity gradient. The functional relation between the Moho depth and the second-order radial derivative of the VMM isostatic potential is formulated by means of the (linearized) Fredholm integral equation of the first kind. Methods for a spherical harmonic analysis and synthesis of the gravity field and crustal structure models are applied to evaluate the gravity gradient corrections and the respective corrected gravity gradient, taking into consideration major known density structures within the Earth's crust (while mantle heterogeneities are disregarded). The resulting gravity gradient is compensated isostatically based on applying the VMM scheme. The VMM inverse problem for finding the Moho depths is solved iteratively. The regularization is applied to stabilize the ill-posed solution. The global geopotential model GOCO-03s, the global topographic/bathymetric model DTM2006.0 and the global crustal model CRUST1.0 are used to generate the VMM isostatic gravity gradient with a spectral resolution complete to a spherical harmonic degree of 250. The VMM inverse scheme is used to determine the regional isostatic crustal thickness beneath the Tibetan Plateau and Himalayas (compiled on a 1x1 arc-deg grid). The differences between the isostatic and seismic Moho models are modeled and subsequently corrected for by applying the non-isostatic correction. Our results show that the regional gravity gradient inversion can model realistically the relative Moho geometry, while the solution contains a systematic bias. We explain this bias by more localized information on the Earth's inner structure in the gravity gradient field compared to the potential or gravity fields.

  • 249.
    Tenzer, Robert
    et al.
    University of Otago, National School of Surveying.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Vajda, Peter
    Geophysical Institute of the Slovak Academy of Sciences.
    Depth-dependent density change within the continental upper mantle2012Ingår i: Slovak Academy of Sciences. Geophysical Institute. Contributions to Geophysics and Geodesy, ISSN 1338-0540, Vol. 42, nr 1, s. 1-13Artikel i tidskrift (Refereegranskat)
  • 250.
    Tenzer, Robert
    et al.
    Wuhan Univ, Peoples R China.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet. Royal Inst Technol KTH, Stockholm, Sweden.
    Vajda, Peter
    Slovak Acad Sci, Slovakia.
    Global model of the upper mantle lateral density structure based on combining seismic and isostatic models2013Ingår i: Geosciences Journal, ISSN 1598-7477, Vol. 17, nr 1, s. 65-73Artikel i tidskrift (Refereegranskat)
23456 201 - 250 av 274
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