Geophysical methods are frequently applied in conjunction with exploration efforts to increase the understanding of the surveyed area. Their purpose is to determine the nature of the geophysical response of the subsurface, which can reveal the lithological and structural character. By combining geophysical measurements with the drill core data, greater clarity can be achieved about the structures and lithology of the borehole. The purpose of the project was to give the student an opportunity to discover borehole logging operations and to have a greater understanding of the local geology, in particular the iron mineralizations in the apatite iron ore intersected by the boreholes. In order to do this, the student participated in performing a geophysical borehole survey and analyzing the results. These were combined with a drill core log in order to cross plot the results and increase understanding. / Geofysiska metoder används ofta i samband med prospektering för att öka förståelsen av området. Utförda från ytan ger de en relativt god tolkning av vad som kan finnas på djupet och är även kostnadseffektiva jämfört med provborrning. Borrhålsloggning sker däremot efter att själva hålet borrats och ändamålet är ofta att utöka förståelsen om området omedelbart kring det loggade hålet. Genom att kombinera geofysisk fältdata med tolkning av borrkärnan kan man erhålla en ökad förståelse för borrhålets strukturer och litologi. Syftet med det här projektet var att utöka studentens förståelse inom borrhålsloggning, samt att avgöra hur relevant metoden är för att identifiera järnmineraliseringar i apatitjärnmalmen som kännetecknar norra Bergslagen

In this study earthquake data is analyzed using a newly developed Migration Based Detection (MBD) algorithm (Wagner et al. 2017). A software environment suitable for manual analysis of large quantities of earthquakes (events) detected by the MBD algorithm is set up, and the MBD algorithm is applied to 13 days of seismic data from a network of 26 seismic stations in the geologically complex Hengill-area in southwest Iceland. A total of 859 event detections are produced and manually inspected. Out of these, 483 are considered true and/or uncertain, making the assessed number of false detections about 44%. A subset of 53 well defined true events are selected for event relocation using manual picking of first arrival P-waves. The relocation resulted in a mean difference of roughly 0.6 km for each coordinate in the horizontal plane and about 1.4 km in depth. Results of the study provide reference data that may aid further development of the MBD algorithm, as well as provide some insight into the performance of the MBD algorithm. The software environment tailored for analyzing events detected by the MBD algorithm may be used as a foundation for continued analysis of detected events. / I denna studie analyserades jordskalvsdata med hjälp av en nyligen utvecklad 'migration based detection'-algoritm (Wagner et al. 2017). En mjukvarumiljö skräddarsydd för manuell analys av stora kvantiteter av jordskalv detekterade av MBD-algoritmen iordningställdes, varpå MBD-algoritmen sedan applicerades på 13 dagar av seismisk data från ett nätverk av 26 seismiska stationer i det geologiskt sett komplexa Hengill-området i sydvästra Island. Totalt detekterades 859 jordskalv som genomgick manuell analys. Av dessa klassificerades 483 stycken som bekräftade eller troliga jordskalv, vilket resulterar i en uppskattad felmarginal om ca. 44 %. En delmängd om 53 väldefinierade jordskalv valdes ut för noggrannare analys av ursprungsplats och tidpunkt genom manuell plockning av P-fasankomst. Omlokaliseringen resulterade i en genomsnittlig differens om ca. 0.6 km i vardera koordinat i horisontalplanet och ca. 1.4 km i höjdled. Resultat från projektet kan användas som referensdata vid vidareutveckling av MBD-algoritmen samt ger viss insyn i prestandan hos MBD-algoritmen. Den iordningställda datormiljön kan användas som bas för vidare analys av jordskalv detekterade av MBD-algoritmen.

Iron has been an essential element to human development and iron-oxide deposits are known to host minerals that are labelled as critical raw materials (CRMs), especially in the EU. Therefore, ensuring a sustainable supply of CRMs require access to both primary and secondary sources of their host deposits such as iron oxides. Blötberget is an old mining site in central Sweden rich in both primary and secondary iron-oxide resources (i.e. tailings) from centuries-long mining activities. Thus, this thesis focused on this site, to (1) improve the image of its iron-oxide mineralisation under the historical tailings area through the extraction and processing of 2D data from a wider and sparse 3D dataset, (2) characterise the tailings in terms of geometry delineation and geomechanical property estimation by generating P-wave velocity models of the tailings, and (3) improve the interpretation of existing results in the area through 3D visualisations and comparison. Results from this thesis work suggest possible depth and lateral extensions of the mineralisation for few hundreds of metres beyond what was known previously in the area. It is believed that about 10 Mt of primary iron-oxide resources could arguably be present under the tailing area while the tailings contain an estimated 1 Mt of secondary iron-oxide resources. Also, this thesis work findings indicate that the historical tailings are approximately 10 -12 m thick, 650 m long, and 300 m wide, and has a Vp/Vs ratio between approximately 3-4, indicating a poor geomechanical strength. Additionally, the depth to bedrock in this area was estimated to be 50 m at its deepest parts, with a morphology indicative of complex geological occurrence. Therefore, it is concluded, based on these results, that Blötberget has a good potential to ensure the supply of both iron ore and its constituent CRMs. / Järn har varit ett viktigt grundämne för mänsklig utveckling och järnoxidavlagringar är kända för att innehålla mineral som är märkta som kritiska råmaterial (KRM), särskilt inom EU. Därför kräver säkerställandet av en hållbar tillgång till KRM tillgång till både primära och sekundära källor till deras värdfyndigheter, till exempel järnoxid. Blötberget är en gammal gruvplats i mellersta Sverige som är rik på både primära och sekundära järnoxidresurser (dvs. gruvavfall) från en lång gruvverksamhet. Således fokuserade denna avhandling att (1) förbättra karaktäriseringen av järnoxidmineralisering i det historiska gruvområdet genom utvinning och bearbetning av 2D-data från ett glest 3D-dataset, (2) karakterisering av gruvavfall för avgränsning av geometri och uppskattning av geomekaniska egenskaper genom att generera P-vågshastighetsmodeller för gruvavfallsområdet, och (3) förbättra tolkningen av befintliga resultat i området genom 3D-visualiseringar. Resultat från denna avhandling tyder på möjliga djup och laterala förlängningar av mineraliseringen om några hundratals meter bortom vad som tidigare var känt i området. Det antas att cirka 10 Mt primära järnoxidresurser finnas under avfallssområdet medan gruvavfallet innehåller uppskattningsvis 1 Mt sekundära järnoxidresurser. Dessutom visar denna avhandling att det historiska gruvavfallet är cirka 10-12 m tjockt, 650 m långt och 300 m brett och har ett Vp/Vs -förhållande mellan cirka 3-4, vilket indikerar en låg geomekanisk hållfasthet. Dessutom beräknades djupet till berggrunden i detta område vara 50 m vid dess djupaste delar, med en morfologi som indikerar komplex geologisk förekomst. Därför dras slutsatsen, baserat på dessa resultat, att Blötberget har en god potential att säkerställa leveransen av både järnmalm och dess ingående KRM

The East African Rift System diverges in the Lake Natron Basin of Northern Tanzania and is a major zone of continental extension and crustal thinning with resulting in active tectonics and volcanism. The discovery of Acheulean technology in Olduvai Gorge and Peninj as well as the presence of significant volcanic centers, has made in the region subject to studies in various disciplines. However, lack of precise radiometric age constraints due to the complex geology of the region is a major drawback. The basin is bordered on the western side by an escarpment that contains thick sequences of volcanic (nephelinites, basanites, hawaiites, alkali basalts), volcaniclastic and lacustrine strata that predates 1.2 Ma. This thesis is based on 41 rock samples that were collected from two geological sections, the Endukai Kete (EK) and Waterfall (WF) sections and aims to establish a preliminary geomagnetic polarity time scale (GPTS) for the Natron Escarpment, together with establishing possible flow directions of the volcanic lavas within these sections. Nephelinites of EK section have an inferred NW-SE direction of flow, based on study of anisotropy of magnetic susceptibility. They record a normal polarity that most likely correspond to the Cobb Mountain Event (CMT; 1.187-1.208 Ma), although there is an 80-ka discrepancy between the CMT event and the dated lavas. The most probable source is the Mosonik that erupted nephelinitic lavas 1.28 Ma ago. The palagonitic tuff layer below the nephelinites displays reverse polarity and a NE-SW direction of flow. Due to the absence of approximately 200 m strata within the basanite series of the section, regional lithological correlation is used to constrain the GPTS pattern. Hajaro Beds of the Peninj Group to the north of the escarpment, postdates the Olduvai Event (1.71 to 1.86 Ma) and lacustrine strata of the escarpment for EK and WF sections are deposited over the same unconformity and share depositional similarities. Therefore, the lacustrine strata are correlative to Hajaro beds and the normal event observed within the basanite series of both sections is attributed to the Réunion Event (2.116 – 2.137 Ma). The establishment of a preliminary magnetostratigraphic sequence presented in this thesis demonstrate that the rift escarpment in northern Tanzania is suitable for paleomagnetic dating. Future studies should be conducted to establish a more detailed and constrained magnetostratigraphic section, which will be of great use in this part of the African Rift where radiometric dating has been challenging.

The Arabian-Nubian Shield is an excellent natural laboratory to study crust formation processes during the Neoproterozoic. It is one of the largest juvenile tracts of continental crust formed during this time. It diachronously evolved between the breakup of Rodinia (c.780 Ma) and amalgamation of Gondwana (c.550 Ma). New SIMS zircon U-Pb, whole-rock Sm-Nd isotopic and geochemical data are presented. The results are used to establish the geochronology of the Abas terrane and constrain its crustal evolution. The U-Pb data show bimodal age distribution: an older age group c. 790-760 Ma, which corresponds to the arc-forming stage of the ANS and a younger group c. 625-590 Ma, belonging to post-collisional episode in the region. The oldest sample in the post-collisional tectonomagmatic group is slightly deformed indicating that pervasive deformation in the area was decaying by c. 625 Ma. The inherited zircons documented range in age from Meso-to-Paleoproterozoic. Although few, these inherited zircons indicate that crust material of that age was assimilated during the Neoproterozoic magmatic events. The U-Pb geochronologic also resolved the temporal transition from high-K calc-alkaline to alkaline magmatism in the post-collisional suits. This transition commonly marks the end of orogeny. Almost all samples studied exhibit a strongly enriched initial εNd compositions and Nd model ages that predate the crystallization ages of the rocks by several hundred million years. These features highlight the sharp contrast in the magmatic sources between the Abas granitoids and the rest of the ANS, which is dominantly juvenile except that of the Afif terrane of Saudi Arabia. This suggests that the Abas terrane of Yemen had a distinctive crustal evolution history compared to the rest of the shield and these features provide evidence for the presence of pre-Neoproterozoic crust at depth in this region.

There was a large radar campaign during 2007 and 2008, the International Polar Year (IPY),and at that time the EISCAT Svalbard Radar was operated and measured the ionosphere continuouslyat most times. This report presents statistical results from an electron enhancementpoint of view. Until now there has been some research into the field and results based on theions in the ionosphere, and the enhancements we refer to as Naturally enhanced ion acousticlines (NEIALs). Plasma line data from May 2007 to February 2008 has been analysed inorder to find and classify enhancements as NEIALs have been classified but with respect tothe electron distribution instead of the ion distribution. A method of detection was developedin order to differentiate the enhancements from the background with a relation between theminimum and maximum power of each measured dump. Results show that there is a largedifference between the downshifted plasma lines and the upshifted plasma lines, both has arange distribution peak at 180 km and the upshifted plasma line has another peak at 230 kmwhich the downshifted plasma line does not. The occurrence rate of the enhancements was1.64 % for the downshifted plasma line and 4.69 % for the upshifted plasma line. Threedifferent types of enhancements are classified using the variance distribution for the peakfrequency of that detected dump, Single, Profile, and Diffuse. The Single enhancements havea bit different spectral, range, and time of day distributions than of the Profile and Diffusedistributions. The Diffuse classifications are mostly wrong classifications and aliasing and itis very similar to Profile enhancements as seen by its distribution.

The Fennoscandian Shield as a part of a large Precambrian basement area is located in northern Europe and hosts economically important mineral deposits including base metals and precious metals. Regional geophysical data such as potential field and magnetotelluric data in combination with other geoscientific data contain information of importance for an understanding of the crustal and upper mantle structure. Knowledge about regional-scale structures is important for an optimized search for mineralisation. In order to investigate in more detail the spatial distribution of regional electrically conductive structures and near-surface mineral deposits, complementary magnetotelluric measurements have been done within the Precambrian Shield in the north-eastern part of the Norrbotten ore province. The potential field data provided by the Geological Survey of Sweden have been included in the current study. Processing of magnetotelluric data was performed using a robust multi-remote reference technique. The dimensionality analysis of the phase tensors indicates complex 3D structures in the area. A 3D crustal model of the electrical conductivity structure was derived based on 3D inversion of the data using the ModEM code. The final inversion 3D resistivity model revealed the presence of strong crustal conductors with the conductance of more than 3000 S at depth of tens of kilometres within a generally resistive crust. A significant part of the middle crust conductors is elongated in directions that coincide with major ductile deformation zones that have been mapped from airborne magnetic data and geological fieldwork. Some of these conductors have near-surface expression where they spatially correlate with the locations of known mineralisation. Processing and 3D inversion of the regional magnetic and gravity field data were performed, and the structural information derived from these data by using an open-source object-oriented package code written in Python called SimPEG. In this study, a new approach is proposed to extract and analyse the correlation between the modelled physical properties and for domain classification. For this, a neural net Self-Organizing Map procedure (SOM) was used for data reduction and simplification. The input data to the SOM analysis contain resistivity, magnetic susceptibility, and density model values for some selected depth levels. The domain classification is discussed with respect to geological boundaries and composition. The classification is furthermore applied for prediction of favourable areas for mineralisation. Based on visual inspection of processed regional gravity and magnetic field data and a SOM analysis performed on higher-order derivatives of the magnetic data, an interpretation of a sinistral fault with 52 km offset is proposed. The fault is oriented N10E and can be traced 250 km from Karesuando at the Swedish-Finish border southwards to the Archaean-Proterozoic boundary marked by the Luleå-Jokkmokk Zone.

The investigation to understand the subsurface and its features has long been asubject of interest for various fields, including fields such as archaeology and infras-tructure projects. However, traditional excavation methods are often costly and time-consuming. In their place, alternative techniques such as borehole drilling, which isitself expensive, and ground-penetrating radar (GPR), which produces a good butdistorted image, have gained popularity. Nonetheless, the limitations of each methodimpede them from meeting the requirements of subsurface exploration. This Mas-ter’s thesis introduces an approach combining these two methods to overcome theirlimitations and enhance their accuracy to understand the subsurface.This thesis aims to demonstrate the feasibility and effectiveness of integratingborehole drilling and GPR for subsurface exploration. Specifically, the integrationof borehole with GPR-profiles will be examined to enhance their practicality andaccuracy, meaning that this thesis will investigate the utilization of borehole datato update and adjust GPR-profiles, thereby providing more precise and informativedata for further analysis.The findings of this work indicate that combining borehole drilling and GPR-profiling to improve and update the accuracy of the GPR-profiles is entirely feasibleand results in a substantially improved subsurface exploration capability. Further,the outcomes of this thesis suggest that the integrated approach can generate amore precise representation of the underground structure. Ultimately, the proposedintegration of borehole drilling and GPR-profiling presents a promising approach toenhance the accuracy and efficiency of subsurface exploration and has the potentialto be valuable in a wide range of fields.i

Ground motions caused by earthquakes may be strong enough to cause destruction of infrastructure and possibly casualties. If such past destructive earthquakes are analysed, the gained information could be used to develop earthquake warning systems that predicts and possibly reduce the damage potential of further earthquakes. The Swedish National Seismic Network (SNSN) runs an automated early warning system that attempts to predict the damage of an earthquake that just got recorded, and forward the predictions to relevant government agencies. The predictions are based on, e.g. earthquake magnitude, source depth and an estimate of the size of affected human population. The purpose of this thesis is to introduce an additional parameter: earthquake intensity, which is a measure of the intensity with which the ground shakes. Based on this, a new earthquake hazard scheme, the Intensity Based Earthquake Classification (IBEC) scheme, is created. This scheme suggests alternate methods, relative to SNSN, of how earthquake classifications can be made. These methods will use an intensity database established by modelling scenario earthquakes in the open-source software ShakeMap by the U.S. Geological Survey. The database consists of scenarios on the intervals: 4.0 ≤ Mw ≤ 9.0 and 10 ≤ depth ≤ 150 kilometre, and covers the whole intensity scale, Modified Mercalli Intensity, 1.0 ≤ Imm ≤ 10.0. The IBEC classification scheme also enabled the creation of the 'Population-to-Area' criterion. It improves prediction of earthquakes that struck isolated cities, located in e.g. valleys in large mountainous areas and deserts. Even though such earthquakes are relatively uncommon, once they occur, they may cause great damage as many cities in such regions around the world often are less developed regarding resistance to ground motions. / Markrörelser orsakade av jordbävningar kan va starka nog att skada vår infrastruktur och orsaka dödsoffer. Genom att analysera forna destruktiva jordbävningar och utveckla program som försöker att förutsäga deras inverkan så kan den potentiella skada minskas. Svenska Nationella Seismiska Nätet (SNSN) driver ett automatiserat tidigt varningssystem som försöker förutsäga skadorna som följer en jordbävning som precis spelats in, och vidarebefodra denna information till relevanta myndigheter. Förutsägelserna är baserade på, t.ex. jordbävnings-magnitud och djup samt uppskattning av mänsklig population i det påverkade området. Syftet med denna avhandlingen är att introducera ytterligare en parameter: jordbävnings-intensitet, som är ett mått av intensiteten i markrörelserna. Baserat på detta skapas ett jordbävnings-schema kallat Intensity Based Earthquake Classification (IBEC). Detta schema föreslår alternativa metoder, relativt SNSN, för hur jordbävnings-klassificering kan göras. Dessa metoder använder sig av en intensitets-databas etablerad genom modellering av jordbävning-scenarios i open source-\linebreak programmet ShakeMap, skapat av U.S. Geological Survey. Databasen består av scenarior över intervallen 4.0 ≤ Mw ≤ 9.0 och 10 ≤ djup ≤ 150 kilometer, vilka täcker hela intensitetsskalan, Modified Mercalli Intensity, 1.0 ≤ Imm ≤ 10.0. IBECs klassificeringsschema har även möjliggjort skapandet av "Population-mot-Area"-kriteriet. Detta förbättrar förutsägelsen av jordbävningar som träffar isolerade städer, placerade i t.ex. dalgångar i stora bergskjedjor och öknar. Även om denna typ av jordbävningar är relativt ovanliga så orsakar dom ofta enorm skada då sådana här städer ofta är mindre utvecklade rörande byggnaders motstånd mot markrörelser.

Siilinjärvi located in eastern Finland is presently the only phosphate mine with significant phosphorus production in western Europe. Phosphate rock and phosphorus are known as a critical raw material for the European Union due to their economic importance and being prone to the supply risks. Securing their sustainable exploration as well as extraction is hence important. At Siilinjärvi, the phosphate rocks appear within a major Archean alkaline and carbonatite system deformed by several shear zones and intruded by dike systems. By understanding their spatial and temporal relationships an improved exploration and extraction of the ore is possible, which in turn will contribute to the sustainable extraction of this critical material. In October 2018 a novel in-tunnel seismic survey was conducted in the Siilinjärvi open-pit mine. The objective of the study was to employ an in-tunnel seismic survey intersecting several major shear zones running on the eastern side of the main pit, with the idea of characterising its geometry and relationship with the mineralization. The use of the existing mine infrastructure (a water-drainage tunnel) makes the acquisition of the data quite novel in open-pit mines. The water-drainage tunnel nearly in the bottom of the pit crosscutting several major shear zones and dikes was used to enable bench-tunnel seismic data acquisition. High-quality data were acquired using 144 receivers inside the tunnel, with the sources located both inside the tunnel (Bobcat-mounted vertical drophammer) and on the surface (combined explosives and Bobcat-drophammer). Results obtained show at least two reflections interpreted to originate from subvertical shear zones intersecting the tunnel illustrating the importance of such surveys for shear-zone imaging and site characterization. Based on a careful study of a number of shot records, delay in arrival times and partial amplitude lose, these reflections are interpreted to be backscattered surface-waves generated from the shear zones. / Siilinjärvi i östra Finland är just nu den enda fosfatgruvan med en betydande fosforproduktion inom den Europeiska Unionen. Fosfater och fosfor är viktigt för EU på grund av deras ekonomiska betydelse och begränsade tillgång. Den fosforbärande bergarten i Siilinjärvi befinner sig i ett stort Arkeiskt alkalisk och karbonatit-komplex som är deformerad av flera skjuvzoner och intruderat gångsystem. En förbättring av sökandet och utvinnandet av denna viktiga malm skulle vara möjligt genom en ökad förståelse för de spatiala och temporala relationerna i komplexet. Syftet med denna studie var att tillämpa en ny seismisk undersökning, baserad på existerande infrastruktur i gruvan, för en bättre geologisk förståelse och därmed en förbättrad exploatering. En innovativ seismisk undersökning av tunnlar gjordes i Siilinjärvis dagbrott oktober 2018. En vattendräneringstunnel nästan i botten av brottet som korsar fem skjuvzoner användes för att mäta seismiskt tunnel-data. Hög kvalitativ data samlades in genom att använda 144 mottagare inuti tunneln med källor lokaliserade både inuti tunneln, i form av en vertikal dropphammare monterad på en Bobcat, och på ytan i form av en kombination av sprängning och Bobcatmoterad dropphammare. Två reflektioner tolkades att ha sitt ursprung från subvertikala skjuvzoner som korsar tunneln vilket visar på vikten av dessa typer av undersökningar för skjuvzons detektion och områdes karaktärisering.