Uppsatsen analyserar hur främlingskap framställs i tre av Roberto Rossellinis filmer, ”Stromboli”, ”Europa ´51” och ”Viaggio in Italia”. Utgångspunkten är sociologi med inriktning på främlingskap där syftet är att avtäcka hur främlingen i varje film skildras, vad som utgör främlingskapet, om det löses och i så fall hur.  I min analys har jag tillämpat tematisk och narrativ analys av filmerna, vilka ställts i relation till uppsatsens teoretiska utgångspunkter utifrån Georg Simmel, Zygmunt Bauman, Julia Kristeva och Janet Wolff. Studien visar hur främlingskapets olika aspekter berörs och hanteras i filmerna. Klass, kultur och kön är tre avgörande och genomgående faktorer som frambringar främlingskap. Inledningsvis är huvudkaraktärerna en del av främlingskapet, men en medvetenhet väcks och en transformering av dem och deras relationer till de andra börjar. Främlingskapets lösningar finns i en aspekt som binder filmerna samman, nämligen religionen. Den hjälper huvudkaraktärerna att konfrontera det främmande hos dem själva och därmed avlägsna det som skrämt dem i mötet med den andre.

xvii, 171 p. : ill. (some col.) / Crystals influence the migration of gas through magma. At low concentrations, they increase the bulk fluid properties, especially viscosity. At concentrations close to maximum packing, crystals form a rigid framework and magma cannot erupt. However, erupted pyroclasts with crystal contents close to the packing concentration are common at mafic volcanoes that exhibit Strombolian behavior. In this dissertation, I study the influence of solid particles on gas migration. I apply my results to Stromboli volcano, Italy, type locality of the normal Strombolian eruptive style, where gas moves through an essentially stagnant magma with crystallinity ∼50%. Specifically, I investigate the effect of crystals on flow regime, gas content (Chapter II), bubble concentration (number densities), bubble shapes, bubble sizes (Chapter III), and bubble rise velocities (gas flux) (Chapter IV). I find that gas-liquid flow regimes are not applicable at high particle concentrations and should be replaced by new, three-phase (gas-liquid-solid) regimes and that degassing efficiency increases with particle concentration (Chapter II). In Chapter III, I show that crystals modify bubble populations by trapping small bubbles and causing large bubbles to split into smaller ones and by modifying bubble shapes. In Chapter IV, I model Stromboli's crystal-rich magma as a network of capillary tubes and show that bubble rise velocities are significantly slower than free rise velocities in the absence of particles. In each chapter, I use analogue experiments to study the effect of different liquid and solid properties on gas migration in viscous liquids. I then apply my analogue results to magmatic conditions using simple parameterizations and/or numerical modeling or by comparing the results directly to observations made on crystal-rich volcanic rocks. Chapter V proposes a mechanism for Strombolian eruptions and gas migration through the crystalrich magma in which the effect of crystals is included. This model replaces the current twophase "slug" model, which cannot account for the high crystallinity observed at Stromboli. There are three appendices in this dissertation: a preliminary study of the influence of particles on gas expansion, image analysis methods, and the numerical code developed in Chapter IV. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Katharine Cashman, Chairperson; Alan Rempel, Member; Mark Reed, Member; Raghuveer Parthasarathy, Outside Member

Strand et al. (2002) discovered small metal alloy grains rich in Cu, Co, and Sn (maximum size 150 µm) in vesicles of lava from Kilauea Volcano. These alloys are also found in basaltic rocks of several Italian volcanoes. To better understand the origin of these metal-rich grains, bombs from Stromboli Volcano were examined. Two bomb types were collected from Stromboli: pumiceous bombs and scoriaceous bombs. Bulk rock trace element geochemistry indicates that there are no significant differences in Cu, Co, or Sn (the three major components of the metal alloys) between the pumiceous and scoriaceous bombs. Comparison of olivine melt inclusion and matrix glass concentrations from these rocks shows that the pumiceous bombs are more primitive (melt inclusions: MgO 2.7-5.8 wt. %; matrix glass: MgO 5.1-6.50 wt. %) and are more S-rich (melt inclusions: maximum 0.13 wt. %; matrix glass: maximum 0.06 wt. % ) than the scoriaceous bombs. The melt inclusions and matrix glass in the scoriaceous bombs are more evolved (melt inclusions: MgO 3.0-4.3 wt. %; matrix glass: MgO 2.7-3.7 wt. %) and are S-poor (melt inclusions: maximum 0.06 wt. %; matrix glass: b.d.l. ). However, Cl concentrations in melt inclusions and matrix glass are more similar for both bomb types. Metal alloys were counted in thin section for each sample. The crystallized interiors of the bombs contain more metal grains than the glassy exteriors. Pumiceous bombs (from more primitive, S-rich magma) contain more metal grains of a larger size than the scoriaceous bombs (from more fractionated, S-poor magma). This indicates that S (and Cl) are probable transport ligands for the metals in the alloys. As S (and Cl) move through the glass of an erupted cooling bomb, they complex with volatile chalcophile metals (Cu, Co, and Sn). These vapor-phase metal sulfides and chlorides move to inflating vesicles. Here the sulfide and chloride complexes become reduced and metal alloys condense, as S and Cl escape as gas. Non-degassed primitive magma may provide more S (but not necessarily more metals) to create the higher abundance of alloys hosted by the vesicles of the pumiceous bombs.

La caractérisation des circulations thermo-convectives dans les milieux naturels est particulièrement étudiée pour ses applications industrielles, notamment en géothermie. Cette caractérisation correspond à deux enjeux liés à (i) la détection des remontées hydrothermales et (ii) la quantification de l'énergie évacuée par le système actif. La méthodologie proposée par cette thèse comporte ainsi deux volets. Le premier volet vise la localisation des systèmes actifs par caractérisation géophysique de sub-surface. Les techniques de prospection mises en œuvre sont la tomographie de résistivité électrique (TRE), la mesure in situ de température et la mesure de polarisation spontanée (PS). L'objet étudié dans cette thèse est la remontée hydrothermale située au niveau de la limite supérieure de l'effondrement de Rina Grande, au sommet du volcan Stromboli. L'approche géophysique de sub-surface comprend une cartographie spatiale (à l’échelle métrique) en TRE, PS et température et un suivi temporel des signaux PS et thermique. La cartographie spatiale nous renseigne sur l'extension spatiale du système hydrothermal (TRE) et le caractère actif des circulations (PS et température). Le modèle de résistivité électrique a été amélioré en tenant compte de la topographie, issue d'un Modèle Numérique de Terrain généré par photogrammétrie. Le traitement des données de surveillance montre qu'une relation linéaire lie le signal thermique et le signal PS, une relation qui ne peut être purement thermo-électrique. Le jeu de données temporel met l'accent sur la dynamique du système convectif et notamment la probable dépendance de la vigueur du système convectif avec les variations saisonnières de température atmosphérique. Le second volet vise à quantifier l'énergie évacuée par des systèmes thermo-convectifs à l'aide d'une approche numérique. L'approche géophysique met en évidence le fait que les zones endommagées telles que des limites structurales favorisent la circulation des fluides hydrothermaux. Ceci s'explique par le fait que fractures, failles ouvertes, zones d'altération etc. changent à petite échelle la perméabilité du milieu. L'approche numérique est donc vouée à la simulation 3D de l'écoulement et du transfert de chaleur dans des milieux poreux fracturés. Le travail s'est basé sur un code d'écoulement en milieux poreux fracturé pré-existant. Ce code a été adapté afin de résoudre le problème thermique. L'étude théorique vise à quantifier l'influence des paramètres du réseau de fractures sur l'énergie dissipée. L'influence de la densité de fractures, de la transmissivité de fractures et l'anisotropie du réseau de fractures sont évaluées. L'étude compare également les flux de chaleur dégagés par des modèles où les fractures sont insérées de manière discrète avec des modèles homogènes et de même propriétés macroscopiques (approche effective). Les résultats montrent que la validité de l'approche effective est fortement dépendante des paramètres du réseau de fracture. / The characterization of thermo-convective circulations in natural environments is particularly studied especially for geothermal applications. This characterization corresponds to two issues related to (i) the detection of the hydrothermal flows(ii) the quantification of the energy discharged by the active system. The methodology proposed by this thesis thus comprises two parts. The first component aims at locating active systems with geophysical methods. The prospecting techniques used are electrical resistivity tomography (ERT), in situ temperature measurement and self potential (SP) measurements. The object studied in this thesis is the hydrothermal system located at the upper limit of the Rina Grande sector collapse, at the top of the Stromboli volcano. The sub-surface geophysical approach includes spatial (metric) mapping in ERT, SP and temperature, and monitoring of SP and thermal signals. Spatial mapping informs us about the spatial extension of the hydrothermal system (ERT) and the active character of the circulations (SP and temperature). The model of electrical resistivity has been improved taking into account the topography, resulting from a Digital Elevation Model generated by photogrammetry. The treatment of the monitoring data shows that a linear relationship links the thermal and the PS signals, a relationship that can not be entirely due to thermoelectric effect. The temporal dataset focuses on the dynamics of the convective system and in particular the probable dependence of the vigor of the convective system on seasonal variations in atmospheric temperature.The second part aims at quantifying the energy released by thermo-convective systemsusing a numerical approach. The geophysical approach highlights the fact that damaged areas such as structural boundaries favor the circulation of hydrothermal fluids. This is due to the fact that fractures, open faults, alteration zones, etc. change the permeability of the medium on a small scale. The numerical approach is therefore dedicated to the 3D simulation of the flow and heat transfer in fractured porous media. The work is based on a pre-existing code in fracturing porous media, able to solve the flow problem. This code has been adapted to solve the thermal problem also. The theoretical study aims to quantify the influence of fracture network parameters on the released energy. The influence of fracture density, fracture transmissivity and fracture network anisotropy are evaluated. The study also compares the heat fluxes generated by models where the fractures are discretely inserted with homogeneous models with the same macroscopic properties (effective approach). The results show that the validity of the effective approach is highly dependent on the parameters of the fracture network.

Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.

Metallic bronze-Co-Ag alloys ranging from1-90 µm have been discovered in bomb and lava vesicles from the mafic volcanoes of Kilauea in Hawaii and Vesuvius, Stromboli and Etna in Italy. It is inferred that the metals for these alloys were transported (in part) as chloride complexes, and that the metal ratios in the alloys may be a function of S/Cl. Alloy compositions in each system are extremely heterogeneous with Co concentrations from 1% to 94%, Cu from 2% to 89%, Sn from 1% to 22% and Ag from 0.5% to 42%. Maximum abundances (in wt%) of other trace or minor elements are, Fe (3.0), Zn (0.11), As (0.50), Pd (0.05), Pt (0.05), Au (0.05), Hg (0.10) and Pb (.13) Spot analyses and element maps of alloy grains reveal that three major exsolved components exist. They are bronze, Co, and Ag. Kilauean alloys are dominantly Cu-Sn (bronze) with little Co and Ag while a systematic decrease in the bronze component and an increase in Co occurs in grains from Stromboli to Etna to Vesuvius. Element maps show a covariance of Cu and Sn while Co and Ag concentrations vary independently. Element maps of the alloys also reveal that chlorides are occasionally present in the same vesicles as the alloys. Sulphur content of the metal alloys rarely exceed about 0.4 wt%. Electron back-scatter diffraction (EBSD) was employed for lattice characterization of the exsolved phases and shows a FCC structure for the Cu-Sn section of the alloys. Cu-Sn alloys high in Sn are successfully indexed using the Cu6Sn5 pattern (hexagonal), even though the Sn:Cu ratio of our alloys is considerably lower than 5:6. Cu-Sn alloys containing significant subequal amounts of Co and Fe (≈5 wt% each) indexes as body-centered cubic (BCC). The presence of alloys suggests metal transport as complexes in a vapor phase before being reduced to native metals. Our current model for the origin of the alloys suggests that the metals are transported to vesicles as chlorides and then deposited as sulfides and/or native metals. Oxidation and removal of most of the S then occurs. This data suggests that in some circumstances Cu-Sn-Co and Ag are readily partitioned into escaping magmatic volatiles during quenching of mafic magma. Further examination into vesicle-hosted alloys may confirm that the ratio of Cu, Ag, Au, Zn, and Pb in vesicles reflects the ratio of available metals present in the magma and in subsequent ore deposits.

In der vorliegenden Arbeit werden verschiedene Randwertprobleme zur Beschreibung der Ausbreitung magnetotellurischer Felder mit Hilfe der Finite-Elemente-Methode numerisch gelöst. Die zwei- und dreidimensionalen Randwertprobleme zur Simulation des elektrischen oder des magnetischen Feldes, des magnetischen Vektorpotentials und des elektrischen Skalarpotentials, des magnetischen Vektorpotentials allein oder des anomalen magnetischen Vektorpotentials werden aus den Maxwell-Gleichungen hergeleitet. Auf Grundlage von Anwendung der Konvergenztheorie auf die Finite-Elemente-Lösung werden Konvergenzstudien für zweidimensionale Modelle des homogenen und des geschichteten Halbraums sowie für das dreidimensionale COMMEMI 3-D-2-Modell durchgeführt. Diese werden genutzt, um die Randwertprobleme hinsichtlich ihrer Effizienz zu bewerten. Außerdem liefern Konvergenzstudien eine Abschätzung des lokalen Fehlers der numerischen Lösung für ein realitätsnahes Modell des Vulkans Stromboli und seiner Umgebung, welches digitale Geländedaten enthält. / This thesis presents the numerical finite-element solution of different formulations of the magnetotelluric boundary value problem. Based on Maxwell\'s equations, the two-dimensional and three-dimensional boundary value problems are derived in terms of the electric or the magnetic field, the magnetic vector and the electric scalar potential, the magnetic vector potential only, or the anomalous magnetic vector potential. To evaluate their efficiency, convergence studies are performed for the two-dimensional models of the homogeneous and the layered halfspace as well as for the COMMEMI-3-D-2 model. Moreover, convergence studies yield estimates of the local error of the numerical solution for a close-to-reality model of Stromboli volcano incorporating digital terrain data.

In der vorliegenden Arbeit werden verschiedene Randwertprobleme zur Beschreibung der Ausbreitung magnetotellurischer Felder mit Hilfe der Finite-Elemente-Methode numerisch gelöst. Die zwei- und dreidimensionalen Randwertprobleme zur Simulation des elektrischen oder des magnetischen Feldes, des magnetischen Vektorpotentials und des elektrischen Skalarpotentials, des magnetischen Vektorpotentials allein oder des anomalen magnetischen Vektorpotentials werden aus den Maxwell-Gleichungen hergeleitet. Auf Grundlage von Anwendung der Konvergenztheorie auf die Finite-Elemente-Lösung werden Konvergenzstudien für zweidimensionale Modelle des homogenen und des geschichteten Halbraums sowie für das dreidimensionale COMMEMI 3-D-2-Modell durchgeführt. Diese werden genutzt, um die Randwertprobleme hinsichtlich ihrer Effizienz zu bewerten. Außerdem liefern Konvergenzstudien eine Abschätzung des lokalen Fehlers der numerischen Lösung für ein realitätsnahes Modell des Vulkans Stromboli und seiner Umgebung, welches digitale Geländedaten enthält. / This thesis presents the numerical finite-element solution of different formulations of the magnetotelluric boundary value problem. Based on Maxwell\'s equations, the two-dimensional and three-dimensional boundary value problems are derived in terms of the electric or the magnetic field, the magnetic vector and the electric scalar potential, the magnetic vector potential only, or the anomalous magnetic vector potential. To evaluate their efficiency, convergence studies are performed for the two-dimensional models of the homogeneous and the layered halfspace as well as for the COMMEMI-3-D-2 model. Moreover, convergence studies yield estimates of the local error of the numerical solution for a close-to-reality model of Stromboli volcano incorporating digital terrain data.

Etude de systèmes hydrothermaux de volcans actifs : Misti (Pérou) et Stromboli (Italie) ; Approches géophysiques et géochimiques. Ce mémoire présente une nouvelle méthodologie d'étude des systèmes hydrothermaux appliquée aux volcans Misti (Pérou) et Stromboli (Italie), par couplage de méthodes géophysiques (Polarisation Spontanée : PS) associées aux circulations d'eau et géochimiques (gaz du sol : CO2) associées aux remontées de gaz. A l'échelle de l'édifice volcanique, l'analyse des relations PS/altitude sur des profils radiaires permet de réaliser une cartographie précise des variations des processus d'électrofiltration au sein de l'édifice correspondant à des variations latérales de lithologie (ex: Misti). La méthode des gaz du sol couplée à la méthode PS a montré que des phénomènes de scellage coïncident avec l'extension des systèmes hydrothermaux (ex : Misti et Stromboli). Ces phénomènes ont été identifiés par des concentrations en CO2 proches des valeurs atmosphériques à l'intérieur du système hydrothermal délimité en PS, et par un dégazage significativement plus élevé à l'extérieur du système hydrothermal. Dans le cadre des études réalisées à Stromboli, nous avons mis en évidence que les limites structurales d'origine volcanique, relativement superficielles, telles que des limites de caldeira ou de cratère, constituent des zones préférentielles de drainage des fluides. A plus de 300 mètres des cratères actifs, ce phénomène se matérialise par une corrélation négative entre minima PS et pics de CO2, indiquant des descentes hydriques associées à des remontées de gaz, alors qu'à proximité des sources thermiques, une corrélation positive entre maxima PS et pics de CO2 prend le pas sur la précédente, indiquant à la fois des remontées de gaz et de vapeur d'eau. Toutefois, dans les deux cas, ces anomalies toujours localisées le long de limites structurales sont particulièrement réduites (40-80 m de largeur) et nécessitent pour être mises en évidence un pas d'échantillonnage resserré (<= 20 m). A l'échelle de l'édifice du Stromboli, les failles régionales, exemples de structures plus profondes, se manifestent uniquement par des anomalies de CO2. Près des zones actives, l'analyse des anomalies PS de courte longueur d'onde (5-10 m) permet de suivre le cheminement du réseau hydrique superficiel drainant les fluides depuis les anomalies thermiques en direction du minimum topographique.