Marine glacial environments contain unique seafloor features resulting from the dynamic glacial processes. Studying these submarine geomorphological features can help us understand the glacial paleo-environments so that we can predict the likely responses of present day glaciers and ice sheets to future changes in the climate. This thesis details different approaches in understanding glacial seafloor features using acoustic systems. It focuses on the novel technique of automated mapping seafloor properties using the backscatter intensity collected by acoustic multibeam echosounder systems (MBES). The aim of this thesis is to assess the potential of this unexploited data source in characterizing different glacial landforms in the polar oceans. This is done by examining the voluminous backscatter data collected by Swedish icebreaker Oden from different cruises to the polar oceans and employing an automated backscatter processing technique, the ARA algorithm, to extract surficial sediment characteristics. The results from the sediment characterization are used together with outputs from other marine acoustical systems and sediment core data to understand formational processes of the glacial submarine features. Operational issues encountered in using this technology and its viability as a tool in characterization of glacial seafloor features are discussed and suggestions are given on the improvements needed to effectively implement the method in future studies. The final part of the manuscript is a paper, published in Geo-marine Letters, where I and my co-authors show a practical application of the acoustic systems ability to characterize geomorphological features of a mass-wasting event in the deepest part of the Arctic, the Molloy Hole.

Results from a series of 2D high resolution reflection seismic profiles collected at a quick-clay landslide site are presented. This study is a part of the “Integration of geophysical, hydrogeological and geotechnical methods to aid monitoring landslide in Nordic countries” project, sponsored by the (Geoscientists Without Borders) program of Society of Exploration Geophysicists (SEG). The study area is located on the shoreline of the Göta River, about 60 km north of Göteborg. The Göta River is the largest river in Sweden which runs from Lake Vänern to Göteborg, it follows the Götaälv Zone, which is an approximately 4 km wide fault zone dipping towards the west. The site is known for its quick-clay formation and landslides. The aim of this study is to image bedrock topography and the overburden layerings above it, within the overburden layers of specific interest are a coarse-grained layer and a quick-clay layer which is responsible for “quick-clay landslides”. The area was recently studied by the Swedish Geotechnical Institutes in a nation-wide project that dealt with investigating areas along the Göta River that are prone to landslides. The study area was investigated by various geotechnical (CPTU, CPTU-R soundings, laboratory measurements) and electrical resistivity investigations. Results from this investigation are used to interpret shallow seismic reflections and better understand the near surface geology. The seismic reflection data presented in this thesis were acquired along two profiles, 484 m and 384 m long (lines 2 and 3), in September 2011. A weight-drop and sledgehammer source was used to generate the seismic signal. A receiver spacing of 4 m and source spacing of 4-8 m was used. Power spectras of various sources and raw shots (before and after vertical stack) are also discussed. Processing of high resolution data was challenging in this area where the bedrock is very shallow. Therefore, stacked sections were very sensitive to stacking velocity; a great effort was made to obtain the velocity model. Pre-stack spectral whitening and band pass filtering after stack were the key steps for successful imaging. After carefully processing the data, we were able to image very shallow reflections and bedrock topography. A coarse-grained layer interpreted at 25-50 m depth, may be playing an important role in the formation of quick-clay and hence provide the triggering mechanism for landslides. The coarse layer potential to form quick-clays and its role in landslides, however, requires further investigation using other types of hydrogeological data, geotechnical data and geophysical well logging.

Seismic hazard is used for national, regional, and local level to ensure safe constructions in specific areas. In the mining industry this information is valuable e.g. to  design infrastructure or rock support, to reduce the risk of rock burst and to minimise the risk of locating personnel in hazardous areas. Seismic hazard can be estimated by different approaches. Probabilistic Seismic Hazard Assessment (PSHA) is one approach to estimate the seismic hazard and is defined as the probability that an earthquake will occur within a certain area and time interval causing vibrations with an intensity larger than a given threshold.  This thesis contains an introduction to various aspects of PSHA and highlights some of the limitations with current assumptions and methods, together with a summary of my scientific contributions to PSHA. These contributions aim to improve PSHA in mines at different steps of the calculation chain. Their primary focus is on obtaining reliable input and output parameters (i.e. with uncertainties) at each step in the calculation chain, necessary for a reliable hazard assessment. This is done by adopting a Bayesian workflow, with comprehensive model validation, and where the underlying uncertainties are included for proper weighting of the covariates in each step. Additionally, it contains a collection of three papers (Paper A, Paper B and Paper C) focusing on these aspects. The short summary of these papers follows. Paper A Provides a path to reliable auto-processing of seismic events by describing how to capture the unknown and changing environment. It also highlights some of the human limitations with today's Routine Manual Processing (RMP) in terms of data truncation and discrepancies in processing results between individuals (e.g. in classification and hypocentre estimation). Additionally, the paper compares the automatic processing system BEMIS (developed by Wille Törnman and Jesper Martinsson) with RMP regarding event classification and hypocentre estimation when both approaches are subjected to the same data. This paper is an overview of the philosophy adopted in BEMIS, highlighting the strengths of using a Bayesian approach by: capturing, including, and propagating further the uncertainties in each step in the processing chain to obtain robust and valid estimates of the estimands of interest. Paper B Describes a fully automatic and robust Bayesian method to estimate precise and reliable model parameters describing the observed S-wave spectra. These model parameters are essential for determination of source parameters of an earthquake (e.g. source radius, seismic moment, magnitude etc). The model includes the observed noise and a combined empirical Green’s function. It captures source-, receiver-, and path-dependent terms in the description of the observed spectra by combining a physical source and attenuation model with a spatially and event-size dependent empirical compensation. The proposed method propagates estimation uncertainties along the entire processing chain starting from the hypocentre location and delivers reliable uncertainty description of the estimands. Paper C Describes the relationship between the recorded seismic activity and the: seismic decay time, planned production rate, production size and mining depth, for the seven largest orebodies in LKAB's iron ore mine in Malmberget. This relationship is described by a mine-wide Bayesian hieSavkararchical model and is an important part to individually customise the production rate for each orebody in the mine, make short-term predictions of future seismicity given planned productions, and to find out in what way the available predictors affect the seismicity. The model is validated using a comprehensive procedure and the results are precise and valid in terms of central tendency and dispersion.

This thesis deals with rock magnetic measurements on Neogene dikes from the eastern fjords of Iceland. A vast amount of dikes generally striking north-north-east occur as swarms in the glacially eroded lava pile. They are considered as the underlying extensions of fissure swarms in active volcanic systems which like the dike swarms converge at central volcanoes. The dike swarms and associated central volcanoes are uncovered by ca. 1500 m of glacial erosion, leaving the upper parts of these igneous units bare. Two research papers have been prepared based on field studies and measurements of rock magnetism on carefully chosen occurrences of Icelandic dikes in order to test contradicting models of dike origin. The manuscripts are included in the thesis.The first is a detail study of a single composite dike, with a core of fine grained quartz-porphyry surrounded by dolerite margins. The core of the dike was sampled in three locations, separated by ~12 km and measured for magnetic remanence and anisotropy of magnetic susceptibility. Magma flow direction in this dike was interpreted using the mirror imbrication of the minor susceptibility axes from each margin of the quartz-porphyry core of the dike. The flow regime in all three locations showed a marked flow component from north to south, supported by field evidence in the form of parabolically aligned enclaves, and shear folds. Statistical procedures of bootstrapping was utilized to define the flow and handle imbrication in both the vertical and horizontal plane thus defining direction and inclination of flow. The main contribution of this paper was to prove that anisotropy of magnetic susceptibility used to infer flow direction may give consistent and reliable results, and to present new ways (to use old techniques) to define magma flow directions.The same technique used to infer flow in paper one has sub-sequentially been applied to a far larger set of mafic dikes, extending north-east from the exhumed Álftafjörður central volcano. The second paper documents that the flow regimes from the mafic dikes showed a predominantly horizontal flow from the central volcano, supporting tectonic models that suggest shallow magma chambers to be the source of the dikes. The thesis further discusses the results from these studies in comparison to other studies on Icelandic dikes where the magma flow is determined by the direction of the major susceptibility axis. / Denna avhandling behandlar magnetiska egenskaper hos regionala Isländska gångbergarter från de östra fjordarna i landet. Ett stort antal av dessa gångar går att finna i det glacialt eroderade landskapet från den Neogena perioden. Gångarna bildar långträckta stråk vilka i allmänhet stryker mot NNE. Dessa gångar anses vara en underjordisk fortsättning i den övre delen av jordskorpan, av de långsträckta förkastningssprickor vilka likt gångarna sammanstrålar mot centralvulkaner i nu aktiva vulkansystem. Gångarna och centralvulkanerna har bägge blivit avtäcka genom istida nednötning av berggrunden till en utsträckning av 1500 m, vilket lämnat de övre delarna av dessa magmatiska kroppar synliga i landskapet.Två manuskript har skrivits om dessa Isländska gångar. Det första manuskriptet omfattar en detaljerad studie av en kompositgång, bestående av en kärna av finkornig kvartsporfyr omgiven av dolerit. Kärnan i denna gång har blivit provtagen på tre ställen vilka åtskiljs från varandra av 12 km i längd. Provernas magnetiska susceptibilitet och anisotropin av denna har sedan analyserats. Riktning av fossilerat magmaflöde i denna gång har sedan bestämts från tolkningar av minimumaxeln hos den magnetiska susceptsellipsoiden och dess geometriska förhållande till gångens respektive sidor. Flödesriktningen i alla de tre provtagningsställena visade på en horizontell flödeskomponent från norr till syd, vilket stöds av fältrelationer i form av mafiska enklaver vilka lineerats av magmaflöde till formen av en paraboloid. Statistiska metoder användes för att definera flödesriktningen i det geometriska rummet vilket gett oss både riktning och lutning av flödet.Det huvudsakliga vetenskapliga bidraget från det första manuskriptet var att tydliggöra att magnetisk susceptibilitet kan användas för att ta fram flödesriktningar. Ny tillämpning av metodik för att bättre kvantifiera flöde introducerades också. Denna nygamla teknik har sedan använtes för att bestämma magmaflöden i ett betydligt större antal av mafiska gångar, vilka sträcker sig ut mot nordöst från den nu slocknade Álftafjörður-vulkanen. De flödesriktningar vilka definierades i de mafiska gångarna var företrädesvis horizontella, riktade bort från centralvulkanen. Detta stöder tektoniska modeller vilka söker förklara uppkomsten av de mafiska gångarna genom att härleda dem till intrusioner från ytliga magmakammare. Tilläggsvis har resultaten i dessa studier jämnförts med andra internationella studier vilka söker bestämma riktningen på magmaflöde genom användning av maximumaxeln i susceptibilitetsellipsoiden.

Underground mining of the Kirunavaara iron mineralization is causing large-scale deformation of the hangingwall of the orebody. To understand and possibly even predict this deformation, a good understanding of the elastic and mechanical properties of the rocks in the hangingwall is necessary. This thesis presents results from the study of Anisotropy of magnetic susceptibility (AMS), magneto-mineralogy, fracture frequency (FF), and rock quality (RQD). If a link can be found between AMS and the rock mechanical parameters FF and RQD, AMS may serve as a cheap tool for a rough indicator of rock mechanical properties. Two parallel reflection seismic profiles were shot within the town of Kiruna in order to locate deformation zones and lithological boundaries in the hangingwall. This work was done in cooperation with Uppsala University. AMS, FF and RQD data was obtained from three drillcores in the hangingwall and 13 outcrops. The drillcores are located along the southernmost of the seismic profiles. The AMS study showed that the magnetic fabric varies very much between rock types, and even within what has previously been thought of as homogeneous porphyry. Based on the magnetic fabric, 5 sub-groups of porphyries (group I-V) were identified. Results of the magneto-mineralogy study further indicate that magnetite controls the magnetic susceptibility of not just the porphyries, but all the rock types in the Kirunavaara hangingwall. The only exception is the paramagnetic type IV porphyry. Data from outcrops show a decrease in the dip of the magnetic foliation plane (F) and the degree of magnetic anisotropy (Pj) towards the east, and this was confirmed by data from drillcores. The decrease in dip also corresponds to previous studies of the structural geology in the area. For the porphyries, a qualitative correlation was found between the FF and the magnetic shape parameter (T), but no solid correlation could be established between the RQD and Pj, F or T. The magnetic data suggests that the rocks in the uppermost part of the Kirunavaara hangingwall (down to 151-185m) have been subjected to shearing while deeper rocks (below 151-185m) show signs of folding. This sub-horizontal layering is also observed in the magneto-mineralogy and RQD-data. A possible explanation is that the porphyries of the Kirunavaara hangingwall originate from (at least) two different lava-flows, the resultant rocks having a different mineralogical composition and thus different magnetic and rock mechanical properties. Five seismic reflectors, corresponding to five lithological boundaries, were located, and their strike and dip calculated. What appears to be the upper part of the Kirunavaara mineralization was also mapped, as a bonus. Tomographic modelling of first arrivals indicates the position of low velocity (deformation) zones in the near-surface, down to 200m.

As a part of a 4D modeling project, two studies with different scopes were conducted in the central Skellefte district (CSD), northern Sweden. The aim of the studies is to create a basis for a better understanding of the spatial relationship between geological structures and mineralization and to construct a 3D and 4D geology model of the area.In the first study, we used geo-electrical data to define the geological structures at depth down to 430 m. The inversion of the resistivity and Induced Polarization (IP) data indicated a number of lithological contacts, which required further constraints prior to constructing the final 3D model.Hence we measured petrophysical properties including density, magnetic susceptibility, resistivity and IP of 154 samples, selected from drill-holes in vicinity of the resistivity/ IP profiles, to constrain the model. Forward resistivity models were then acquired using the resistivities measured on drillcores, to test the response of different geological scenarios in 3D after inversion. The gravity and magnetic response of the resistivity/ IP models was then calculated to constrain the models down to 1.5 km depth. The models were then modified, until reaching a consistency between geo-electrical and potential field data. The result indicated the possibility of three sulphide mineralization zones within the highly conductive parts at depth ≤ 500 m. The result also helped to determine the geometry of the contact between sedimentary rocks of the Vargfors basin and volcanic rocks of the Skellefte Group.In the second study, we tested geological models based on interpretation of reflection- seismic data using potential field data (down to 5 km depth) as well as electrical data (down to 430 m depth). The gravity and magnetic data especially benefitted the interpretation where no reflector is indicated, or poor-quality reflectors could not contribute to the understanding of major lithological contacts along the main faults and shear zones in the CSD. Moreover, the gravity and magnetic data, add significant information to reveal the spatial relationship between the Skellefte volcanics, metasedimentary rocks of the Vargfors Group and two intrusive structures of TIB gabbro-diorite and granitic rocks, which were poorly indicated on the reflection-seismic profiles. The results further indicate that joint interpretation of the integrated geophysical techniques can provide remarkable information regarding geometry of structures, which is a base for constructing 3D and 4D geological models.

Amidst the global climate action movement, geologic carbon storage (GCS) has emerged as a pivotal strategy for mitigating atmospheric CO2 levels, offering environmental and economic opportunities. This thesis targets the Bunter Sandstone Formation within the Rødby structures in Denmark, focusing on seismic Profile 1. Profile 1 is chosen as it crosses over the existing domal structure, and this will enable to investigate the closure or the extension of the domal structure, and also to evaluate its capacity for CO2 sequestration. Utilizing 2D Reflection Seismic Imaging and collaborating with the Geological Survey of Denmark and Greenland (GEUS), the study employs advanced seismic techniques to analyse the Triassic period sandstone formation.  The seismic data for Profile 1 was acquired during June-July 2023 as part of GEUS's national GCS projects by Uppsala University’s Geophysics Program, utilizing the SeisMoveTM dual-element recording system. A total of 991 shots were recorded by 1030 wireless recorders in a fixed geometry, enhancing the signal-to-noise ratio through vertical stacking of repeated shot records. The data acquisition parameters were carefully selected based on similar projects involving pilot and upscaling work conducted in Denmark prior to the Rødby survey. These parameters were influenced by experiences gained during previous successful applications in Denmark and similar environments, ensuring the retrieval of high-resolution seismic reflection images across a wide depth range. The results reveal the presence of a potential new domal structure within the Rødby region, which could substantially influence the area's capacity for carbon storage. The new possible domal structure extend toward east of the survey area and this discovery suggests the need for further investigations to comprehensively assess the extent of this new structure. Therefore, this study enhances the understanding of the Rødby region's subsurface geology; and by advancing the application of carbon capture and storage technologies, this study aligns with Denmark's climate initiatives and contributes to global climate change mitigation efforts. / Mitt i den globala klimatrörelsen har geologisk kollagring (GCS) dykt upp som en viktig strategi för att minska atmosfärens CO2-nivåer, vilket erbjuder miljömässiga och ekonomiska möjligheter. Denna avhandling är inriktad på Bunter-sandstensformationen i Rødby-strukturerna i Danmark, med fokus på seismisk profil 1. Profil 1 valdes eftersom den korsar den befintliga konvexa strukturen, och detta gör det möjligt att undersöka formationens omfattning, och detta i sin tur gör det möjligt att undersöka stängningen eller utvidgningen av domalstrukturen och att utvärdera dess kapacitet för CO2-bindning. Att använda och I samarbete med Danmarks och Grönlands geologiska undersökning (GEUS) använder studien avancerade seismiska tekniker för att analysera sandstensformationen från triasperioden. Seismic data for Profile 1 were collected during June-July 2023 as part of GEUS's national GCS project of Uppsala University's Geophysics program, using the SeisMoveTM dual-element recording system. A total of 991 images were recorded by 1030 wireless recorders in a fixed geometry, improving the signal-to-noise ratio by vertically stacking repeated takes. The data collection parameters were carefully selected based on similar pilot and scale-up projects carried out in Denmark prior to the Rødby survey. These parameters were chosen based on experience from previous successful applications in Denmark and similar environments, ensuring the recording of high-resolution seismic reflection images over a wide depth range. The results show that there is a potential new structure in the Rødby region, which could significantly affect the area's carbon storage capacity. The new possible convex structure extends to the east of the study area and this discovery indicates the need for further investigations to make a comprehensive assessment of the extent of this new structure. Therefore, this study increases the understanding of the underground geology of the Rødby region. By promoting the application of carbon capture and storage (CCS) technologies, this study is in line with Denmark's climate initiative and contributes to global climate change mitigation efforts.

<p>Thermophysical properties (dissociation enthalpy, heat capacity, metastability) and compositional properties (hydrate number, free water and fractionation) of natural gas hydrate were studied experimentally on samples that contained large amounts of ice. Methods for continuous hydrate production and sampling, and for quantification of the properties were developed. Hydrate was produced from a natural gas of ethane (5 %mol) and propane (3 %mol) in methane.</p><p>A low temperature scanning calorimetry method was developed to measure dissociation enthalpy, heat capacity, hydrate number and free water (ice). During the analysis, the hydrate samples were pressurized to 1.7 MPa with methane and the system operated between the hydrate equilibrium curves of methane and the hydrate forming natural gas. A sample conditioning procedure eliminated thermal effects of desorption as the ice melted. Desorption occurred since the samples were produced and refrigerated to 255 K under a natural gas pressure of 6-10 MPa, but were analyzed and melted under a methane pressure of 1.7 MPa.</p><p>A low temperature isothermal calorimetry method was developed to quantify the metastability properties. Metastability was confirmed for temperatures up to 268 K and quantified in terms of the low dissociation rate.</p><p>Fractionation data were obtained in the range 3.0 to 7.5 MPa and for subcoolings between 2 and 16 K. High pressure and large subcooling is desirable to suppress fractionation. A fractionation model was proposed. The model coincides with the van der Waals-Platteeuw model for zero subcooling. No fractionation is assumed for hypothetical hydrate formation at infinite driving force (subcooling). Between these two extremes an exponential term was used to describe the fractionation. The model predicted fractionation with an accuracy of about 1%abs corresponding to 1-10%rel.</p>

Thermophysical properties (dissociation enthalpy, heat capacity, metastability) and compositional properties (hydrate number, free water and fractionation) of natural gas hydrate were studied experimentally on samples that contained large amounts of ice. Methods for continuous hydrate production and sampling, and for quantification of the properties were developed. Hydrate was produced from a natural gas of ethane (5 %mol) and propane (3 %mol) in methane. A low temperature scanning calorimetry method was developed to measure dissociation enthalpy, heat capacity, hydrate number and free water (ice). During the analysis, the hydrate samples were pressurized to 1.7 MPa with methane and the system operated between the hydrate equilibrium curves of methane and the hydrate forming natural gas. A sample conditioning procedure eliminated thermal effects of desorption as the ice melted. Desorption occurred since the samples were produced and refrigerated to 255 K under a natural gas pressure of 6-10 MPa, but were analyzed and melted under a methane pressure of 1.7 MPa. A low temperature isothermal calorimetry method was developed to quantify the metastability properties. Metastability was confirmed for temperatures up to 268 K and quantified in terms of the low dissociation rate. Fractionation data were obtained in the range 3.0 to 7.5 MPa and for subcoolings between 2 and 16 K. High pressure and large subcooling is desirable to suppress fractionation. A fractionation model was proposed. The model coincides with the van der Waals-Platteeuw model for zero subcooling. No fractionation is assumed for hypothetical hydrate formation at infinite driving force (subcooling). Between these two extremes an exponential term was used to describe the fractionation. The model predicted fractionation with an accuracy of about 1%abs corresponding to 1-10%rel.

A geophysical investigation on the northern part of Utö was carried out between 2020 and 2021 to asses the extent of the iron ore (BIFs) and the iron bearing sulfides that have been surveyed and mined in the past. The survey using analog field equipment combined magnetometry, gravimetry, susceptibility, leveling, density, and thin-section microscopy. Magnetic measurement reduction method was done through SGU’s communicated advice and modeling software was used. Additionally, an in depth literature analysis was performed to understand the historical context of mine operations to aid interpretation. The results of the multidisciplinary analysis show a number of observations. The interpolated local magnetic anomaly and the gravimetric results fit well with current SGU magnetic and Bouguer anomaly maps. The crosscutting magnetic profile between Nyköpingsgruvan and Långgruvan remains anomalously high despite the volume of removed ore. Susceptibility results confirmed past reports of localities where iron bearing sulfides were found and provide evidence to early ore formation and fluid mobilization. The 2D Bouguer anomaly profile revealed deformation structures reported in literature and also suggests a possible volume of remaining iron ore. Rediscovered meta-tuffite and ignimbrite rock samples were collected and petrological analysis infers a high resolution lithology. Newly discovered literature and material of previous geophysical surveys determined iron ore depths up to 1000 meters. Despite the amount of survey data the results are concluded to be coarse in resolution but can be improved.