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The present-day kinematics and deformation of the Arabian plate and the southern Red Sea region involves interaction of tectonic and non-tectonic processes including plate subduction, continental collision, seafloor spreading, intraplate magmatism, continental transform faulting, microplate rotation, hydrological loading cycles, and anthropogenic activity. Therefore, good constraints on the rates and directions of relative plate motion, plate boundary locations, and rheological properties in the area are essential to assess seismic and volcanic hazards in the region. In this thesis, I combine Global Navigation Satellite System (GNSS) measurements from over 200 stations with kinematic block modeling to provide updated estimates of the present-day motions of the Arabian plate and the southern Red Sea region. Using the non-rigid residual motions and changes in GNSS station baselines, I provide quantitative constraints on the internal deformation for the Arabian plate at different spatial scales. In addition, I use the GNSS station response to seasonal water exchange in the Red Sea to make inferences of the lithospheric elastic properties beneath Arabia. The GNSS-derived velocity field indicates coherent motion of both the Danakil block in the southern Red Sea and the Arabian plate at present. Current motions in the southern Red Sea region, however, are inconsistent with previous interpretations and require an additional plate boundary in the area. My updated fault slip rates improved earlier estimates limited by the number and spatial distribution of GNSS stations, particularly for the Arabian-Indian plate pair, for which slower right-lateral strike-slip motions are predicted. Non-rigid residual velocities within the Arabian plate interior indicate that large-scale internal deformations are compensated internally. However, at a smaller scale, I identify several localities accommodating significant strain, mostly related to anthropogenic activity. Ground response to surface mass loading associated with water transport in the Red Sea suggests that the Earth’s elastic structure beneath the Arabian plate is 20% to 30% less stiff than global averaged (i.e., AK135-F planetary model). Still, the lithosphere beneath both the Danakil block and the Arabian plate remains strong despite being affected by significant faulting and magmatism associated with the Nubian-Arabian-Eurasian plate interaction.

In historical, large-magnitude earthquakes, lateral spreading has been a very damaging type of ground failure. When a subsurface soil deposit liquefies, intact blocks of surficial soil can move downslope, or toward a vertical free face, even when the ground surface is nearly level. A lateral spread is defined as the mostly horizontal movement of gently sloping ground (less than 5% surface slope) due to elevated pore pressures or liquefaction in undelying, saturated soils. Here, lateral spreading is defined specifically to exclude liquefaction failures of steeper embankments and retaining walls, which can also produce lateral surface deformations. Lateral spreads commonly occur at waterfront sites underlain by saturated, recent sediments and are particularly threatening to buried utilities and transportation networks. While the occurrence of soil liquefaction and lateral spreading can be predicted at a given site, methods are needed to estimate the magnitude of the resulting deformations. In this research effort, an empirical model was developed for predicting horizontal and vertical surface displacements due to liquefaction-induced lateral spreading. The resulting model is called "EPOLLS" for Empirical Prediction Of Liquefaction-induced Lateral Spreading. Multiple linear regression analyses were used to develop model equations from a compiled database of historical lateral spreads. The complete EPOLLS model is comprised of four components: (1) Regional-EPOLLS for predicting horizontal displacements based on the seismic source and local severity of shaking, (2) Site-EPOLLS for improved predictions with the addition of data on the site topography, (3) Geotechnical-EPOLLS using additional data from soil borings at the site, and (4) Vertical-EPOLLS for predicting vertical displacements. The EPOLLS model is useful in phased liquefaction risk studies: starting with regional risk assessments and minimal site information, more precise predictions of displacements can be made with the addition of detailed site-specific data. In each component of the EPOLLS model, equations are given for predicting the average and standard deviation of displacements. Maximum displacements can be estimated using probabilities and the gamma distribution for horizontal displacements or the normal distribution for vertical displacements. / Ph. D.

Baigiamajame magistro darbe kuriamas dviejų polių įgilinimo metu atsirandančių grunto masyvo deformacijų fizinis modelis, įvertinus užsienio šalių patirtį šioje srityje. Išnagrinėti pagrindiniai principai, kuriais remiantis buvo sudarytas fizinis modelis moreniniuose gruntuose. Pateikta eksperimentinės aikštelės fizinė geografinė padėtis, geologinė litologinė sandara, grunto fizikinės ir mechaninės savybės, hidrogeologinės sąlygos, modelio sudarymo metodika, laboratorinių bei lauko bandymų rezultatų analizė. Įvertinus teorinius ir praktiškai gautus fizinio modelio aspektus, pateikiamos baigiamojo darbo išvados ir siūlymai. / The thesis developed a two-pile įgilinimo the resulting array of soil physical deformation model, the assessment of foreign experience in this field. The main principles, which were drawn up in a physical model of morene soil. Submitted to the experimental site physical geographical location, geological lotological structure, soil physical mechanical characteristics, hydrogeological conditions, design methodologies, laboratory and field test results of the analysis. The assessment of the theoretical and practical aspects of the model obtained by physical, the conclusions and suggestions. The work consists of three parts: introduction, World of impact and interaction of soil physical models for review, installed by vibro pile and soil interaction physical model, the theoretical pile and soil interaction model, conclusions, references.

Persistent Scatterer Interferometric techniques are very powerful geodetic tools for land deformation monitoring that offer the typical advantages of the satellite remote sensing SAR (Synthetic Aperture Radar) systems : a wide coverage at a relatively high resolution. Those techniques are based on the analysis of a set of SAR images acquired over a given area. They overcome the decorrelation problem by identifying elements (in resolution cells) with a high quality returned SAR signal which remains stable in a series of interferograms. These techniques have been useful for the analysis of urban areas, where man-made objects produce good reflections that dominate over the background scattering, as well as in field areas where the density of infrastructures is more limited. Typically, PSI technique requires an approximate a priori temporal model for the detection of the deformation, even though characterizing the temporal evolution of a deformation is commonly one of the objectives of any study.This work is focused on a particular PSI technique, which is named Stable Point Network (SPN) and that it has been completely developed by Altamira Information in 2003. The work concisely outlines the main characteristics of this technique, and describes its main products: average deformation maps, deformation time series of the measured points, and the so-called maps of the residual topographic error, which are used to precisely geocode the PSI products. The main objectives of this PhD are the identification and analysis of the drawbacks of this processing chain, and the development of new tools and methodologies in order to overcome them. First, the performances of the SPN technique are examined and illustrated by means of practical cases (based on real test sites made with data coming from different sensors) and simulated scenarios.Thus, the main drawbacks of the technique are identified and discussed, such as the lack of automatic quality control parameters, the evaluation of the input data quality, the selection of good points for the measurements and the use of a functional model to unwrap the phases based on a linear deformation trend in time. Then, different enhancements are proposed. In particular, the automatic quality control of the coregistration procedure has been introduced through the analysis of the inter-pixel position of some natural point targets-like pixels identified within the images. The enhancements in the selection of the final points of measurements (the final PSI map) come by means of the analysis of the SAR signal signature of the strong targets presented within the image, in order to select only the center of the main lobe as point of measurement. The introduction of robustness within some critical steps of the technique is done by means of the analysis of the rotational of the estimates in close loops within a network of relative measurements, and by means of the implementation of a different integration methodology, which can be ran in parallel in order to compare it with the classical one. Finally, the main drawback of the technique, the use of a linear model for the detection of ground deformations, is addressed with the development of a new fitting methodology which allows possible change of trends within the analyzed time span. All those enhancements are evaluated with the use of real examples of applications and with simulated data. In particular, the new methodology for detecting non-linear ground deformations has been tested in the city of Paris, where a large stacking of ERS1/2 and ENVISAT SAR images are available. Those images are covering a very large time period of analysis at where some known non-linear ground deformations where occurring

Prediction and control methodologies for ground deformation due to underground mining (commonly referred to as mine subsidence) provide engineers with the means to minimize negative effects on the surface. Due to the complexity of subsidence-related movements, numerous techniques exist for predicting mine subsidence behavior. This thesis focuses on the development, implementation, and validation of numerous enhanced subsidence prediction methodologies. To facilitate implementation and validation, the improved methodologies have been incorporated into the Surface Deformation Prediction System (SDPS), a computer program based primarily on the influence function method for subsidence prediction. The methodologies include dynamic subsidence prediction, alternative model calibration capability, and enhanced risk-based damage assessment. Also, the influence function method is further validated using measured case study data. In addition to discussion of previous research for each of the enhanced methodologies, a significant amount of background information on subsidence and subsidence-related topics is provided. The results of the research presented in this thesis are expected to benefit the mining industry, as well as initiate ideas for future research. / Master of Science

Deep soil mixing to construct stiff columns is one of the methods used today to improve performance of loose ground and remediate liquefaction problems. This research adopts a numerical approach to study seismic performance of soil-cement columnar reinforcements in loose sandy profiles. Different constitutive models were investigated in order to find a model that can properly predict soil behavior during seismic excitations. These models included NorSand, Dafalias-Manzari, Plasticity Model for Sands (PM4Sand) and Pressure-Dependent-Multi-Yield-02 (PDMY02) model. They were employed to predict behavior of soils with different relative densities and under different confining pressures during monotonic and cyclic loading. PDMY02 was identified as the most suitable model to represent soil seismic behavior for the system studied herein. The numerical aspects of the finite element approach were investigated to minimize the unintended numerical miscalculations. The focus was put on convergence tolerance, solver time-step, constraint definition, and, integration, material and Rayleigh damping. This resulted in forming a robust numerical configuration for 3-D nonlinear models that were later used for studying behavior of the reinforced grounds. Nonlinear finite element models were developed to capture the seismic response of columnar reinforced ground during dynamic centrifuge testing. The models were calibrated with results from tests with unreinforced profiles. Thereafter, they were implemented to predict the response of two reinforced profiles during seismic excitations with different intensities and liquefaction triggering. Model predictions were compared with recordings and the possible effects from the reinforcements were discussed. Finally, parametric studies were performed to further evaluate the efficiency of the reinforcements with different extension depths and area replacement ratios. The results collectively showed that the stiff elements, if constructed appropriately, can withstand seismic excitations with different intensities, and provide a firm base for overlying structures. However, the presence of the stiff elements within the loose ground resulted in stronger seismic intensities on the soil surface. The columns were not able to considerably reduce pore water pressure generation, nor prevent liquefaction triggering. The reinforced profiles, comparing to the free-field profiles, had larger settlements on the soil surface but smaller settlements on the columns. The results concluded that utilization of the columnar reinforcements requires great attention as these reinforcements may result in larger seismic intensities at the ground surface, while not considerably reducing the ground deformations. / Ph. D.

Les techniques d'interférométrie sur réflecteurs persistants, ou points stables (PSI), sont des outils particulièrement efficaces pour le suivi des déformations du sol et offrent les avantages typiques des systèmes de télédétection radar à synthèse d'ouverture (RSO) : une large couverture spatiale combinée à une résolution relativement élevée. Ces techniques sont basées sur l'analyse d'un jeu d'images RSO acquises sur une zone donnée. Elles permettent de régler le problème de décorrélation grâce à l'identification d'éléments particuliers (au sein de la cellule de résolution) dont la rétrodiffusion radar est de haute qualité et stable sur toute une série d'interférogrammes. Ces techniques sont fort efficaces (utiles ?) pour l'analyse de zones urbaines où les constructions constituent de bons réflecteurs avec une réflexion supérieure à celle du sol ; il en va de même pour des zones de campagne où la densité d'infrastructures est plus limitée. La technique PSI requiert un modèle temporel approximatif a priori pour la détection des déformations, bien que la caractérisation de l'évolution temporelle de la déformation soit communément l'un des objectifs des études. Le travail réalisé porte sur une technique PSI particulière, appelée Stable Point Network (SPN), Réseau de Points Stables, qui a été totalement développée par Altamira Information en 2003. Le travail présente de manière concise les caractéristiques de la technique et décrit les principaux produits générés : carte moyenne de déformation, séries temporelles de déformation des points mesurés, et les cartes de résidu d'erreur topographique utilisées pour géocoder de façon précise les produits PSI. Le principal objectif de cette thèse est l'identification et l'analyse des points faibles de la chaîne de traitement SPN et le développement de nouveaux outils et méthodologies pour résoudre les problèmes identifiés. Dans un premier temps, les performances de la technique SPN sont examinées et illustrées sur des cas pratiques (basés sur des sites test réels et à partir de données provenant de différents capteurs) et à l'aide de simulations. Les principaux points faibles de la technique sont identifiés et commentés, notamment le manque de paramètres automatiques de contrôle qualité, l'évaluation de la qualité des données d'entrée, la sélection de bons points pour la mesure ainsi que l'utilisation d'un modèle fonctionnel pour le déroulement de phase (franges interferometriques) basé sur une tendance linéaire de la déformation dans le temps. Différentes solutions sont ensuite envisagées. Nous nous intéressons tout particulièrement au contrôle qualité automatique dans la procédure de coregistration, en utilisant l'analyse du positionnement inter-pixel de certains points naturels, comme par exemple des pixels identifiés dans les images. L'amélioration de la sélection finale des points de mesure (carte PSI) s'obtient grâce à l'analyse de la signature du signal radar des cibles les plus puissantes présentes au sein de l'image, afin de sélectionner uniquement le centre du lobe principal du point de mesure. D'autres développements apportent plus de robustesse dans des étapes clefs, ainsi l'analyse du rotationel des estimations en lien étroit avec un réseau de mesures relatives, ou l'implémentation d'une méthodologie différente pour l'intégration qui peut être lancée en parallèle afin d'être comparée avec l'intégration classique. Enfin le principal inconvénient de la technique, c'est-à-dire l'utilisation d'un modèle linéaire de détection des déformations du sol fait l'objet d'un développement d'une nouvelle méthode d'ajustement qui permet des changements de tendance durant la période de temps considérée(...) / Persistent Scatterer Interferometric techniques are very powerful geodetic tools for land deformation monitoring that offer the typical advantages of the satellite remote sensing SAR (Synthetic Aperture Radar) systems : a wide coverage at a relatively high resolution. Those techniques are based on the analysis of a set of SAR images acquired over a given area. They overcome the decorrelation problem by identifying elements (in resolution cells) with a high quality returned SAR signal which remains stable in a series of interferograms. These techniques have been useful for the analysis of urban areas, where man-made objects produce good reflections that dominate over the background scattering, as well as in field areas where the density of infrastructures is more limited. Typically, PSI technique requires an approximate a priori temporal model for the detection of the deformation, even though characterizing the temporal evolution of a deformation is commonly one of the objectives of any study.This work is focused on a particular PSI technique, which is named Stable Point Network (SPN) and that it has been completely developed by Altamira Information in 2003. The work concisely outlines the main characteristics of this technique, and describes its main products: average deformation maps, deformation time series of the measured points, and the so-called maps of the residual topographic error, which are used to precisely geocode the PSI products. The main objectives of this PhD are the identification and analysis of the drawbacks of this processing chain, and the development of new tools and methodologies in order to overcome them. First, the performances of the SPN technique are examined and illustrated by means of practical cases (based on real test sites made with data coming from different sensors) and simulated scenarios.Thus, the main drawbacks of the technique are identified and discussed, such as the lack of automatic quality control parameters, the evaluation of the input data quality, the selection of good points for the measurements and the use of a functional model to unwrap the phases based on a linear deformation trend in time. Then, different enhancements are proposed. In particular, the automatic quality control of the coregistration procedure has been introduced through the analysis of the inter-pixel position of some natural point targets-like pixels identified within the images. The enhancements in the selection of the final points of measurements (the final PSI map) come by means of the analysis of the SAR signal signature of the strong targets presented within the image, in order to select only the center of the main lobe as point of measurement. The introduction of robustness within some critical steps of the technique is done by means of the analysis of the rotational of the estimates in close loops within a network of relative measurements, and by means of the implementation of a different integration methodology, which can be ran in parallel in order to compare it with the classical one. Finally, the main drawback of the technique, the use of a linear model for the detection of ground deformations, is addressed with the development of a new fitting methodology which allows possible change of trends within the analyzed time span. All those enhancements are evaluated with the use of real examples of applications and with simulated data. In particular, the new methodology for detecting non-linear ground deformations has been tested in the city of Paris, where a large stacking of ERS1/2 and ENVISAT SAR images are available. Those images are covering a very large time period of analysis at where some known non-linear ground deformations where occurring

L'activité des volcans andésitiques, tels que le Mont St Helens (États-Unis), Montserrat (Antilles) ou encore le Merapi (Indonésie), alterne entre des périodes relativement calmes, avec coulées de lave et formation d'un dôme, et des événements explosifs parfois très violents. Prévoir les transitions entre ces deux régimes est essentiel pour assurer la sécurité des populations voisines, mais demeure actuellement un vrai défi. Or les données expérimentales et les observations de terrain montrent que l'explosivité du magma est étroitement liée à son contenu en gaz. L'objectif de cette thèse est d'améliorer notre compréhension de l'évolution de ce contenu en gaz et de son influence sur l'activité volcanique, en nous appuyant sur des simulations numériques, l'analyse de données expérimentales ainsi que sur l'interprétation de données de déformation enregistrées au Merapi.Une part importante de ce travail réside dans le développement et l'amélioration de modèles d'écoulement en 2D pour prendre en compte le dégazage dans la partie supérieure du conduit, en régime transitoire. Nous présentons un modèle d'écoulement du gaz en temps qui tient compte des pertes en gaz aux bords du conduit et à sa sortie, selon les conditions présentes dans la roche encaissante et le dôme. Nous proposons également une adaptation des modèles de conduit permettant de coupler complètement l'écoulement du gaz avec celui du magma pour étudier l'évolution des conditions dans le conduit en régime transitoire. À partir de simulations de l'évolution du dégazage lors de l'emplacement d'un dôme, nous identifions les para-mètres contrôlant les pertes en gaz. Nos résultats montrent que ces pertes sont extrêmement sensibles à l'évolution de la perméabilité du magma et des gradients de pression autour du conduit en réponse au poids du dôme. La perméabilité du dôme a quant à elle peu d'influence. Au cours de la croissance du dôme, les pertes en gaz diminuent en profondeur. En haut du conduit, la pression du gaz augmente de quelques dizaines de MPa. Ces effets sont associés à une augmentation de l'explosivité du magma et de l'aléa volcanique en cas d'effondrement du dôme.Bien que la perméabilité du magma exerce un fort contrôle sur la perte de gaz, comme l'ont montré nos résultats, son évolution dans le conduit est peu contrainte. Les lois de perméabilité utilisées actuellement ne sont pas en accord avec l'ensemble des mesures réalisées sur des échantillons de magmas riches en silice. Dans le but d'améliorer notre compréhension du développement de la perméabilité dans le conduit, nous avons cherché à éclaircir le lien entre perméabilité, conditions d'écoulements, et caractéristiques géométriques du réseau de bulles connectées. Nous proposons une formulation du seuil de percolation, moment exact où le magma devient perméable compatible avec un grand nombre d'échantillons naturels et expérimentaux. Nous présentons aussi une nouvelle loi de perméabilité en accord avec la plupart des observations existantes, que nous avons intégrée à notre modèle 2D de dégazage. Nos résultats montrent qu'en fonction du nombre de bulles dans le magma et de la distribution de leurs tailles, l'importance des pertes en gaz et par conséquent les conditions d'écoulement dans le conduit varient d'effusives à explosives.Enfin, afin d'évaluer l'utilité des données de déformation pour suivre l'évolution des conditions d'écoulement, nous utilisons des modèles d'écoulement simples couplés à de la déformation élastique en 3D pour retrouver la déformation observée au sommet du Merapi peu avant l'éruption de 2006. Bien que ces modèles permettent de mieux comprendre les déplacements observés, le peu de données, associé à la complexité géologique et rhéologique du sommet, ainsi qu'à celle des processus physiques intervenant dans le conduit font qu'il est difficile de contraindre les conditions d'écoulement grâce à la déformation dans ce cas précis. / At silicic volcanoes, such as Mount St Helens (United States), Montserrat (British West Indies), or Merapi (Indonesia), periods of relative quiescence, with lava flows and dome emplacement, alternate with explosive, sometimes very violent events. Forecasting the effusive/explosive transitions, which is essential for the safety of nearby populations, remains currently a real challenge. However, experimental as well as field observations provide evidence that magma gas content is a major clue for understanding explosivity. This thesis, based on numerical simulations, experimental samples analysis, as well as on the interpretation of ground deformation data recorded at Merapi volcano, aims at improving our understanding of gas loss evolution, and its impact on the eruptive regime.A major part of this work consisted in developing and improving 2D axisymmetric conduit flow models for integrating gas loss in transient conditions. We provide a time-dependent model for gas flow in the upper conduit, that accounts for gas loss both at the conduit walls and at its top, depending on conditions in the surrounding rock and dome. We also propose an adaptation of conduit flow models allowing for full coupling between magma and gas flow in 2D that should be used to further investigate flow conditions evolution during transient regimes. From time-dependent gas flow simulations in the case of an effusive dome emplacement, we identify controlling parameters for gas loss. Our results provide evidence that gas loss is extremely sensitive to the evolution of magma permeability and of pressure gradients around the conduit due to dome loading, whereas, contrary to the common idea, dome permeability has almost no influence. Along with dome growth, gas loss decreases at depth, thus causing an increase in the magma gas content. At the top of the conduit, this results in an increase in gas pressure by a few tens of MPa, thus increasing the likelihood of magma explosivity and hazard in the case of a rapid decompression due to dome collapse.Although magma permeability plays a major role for gas extraction, as revealed by our results, its evolution within the conduit is poorly constrained. Currently used permeability laws fail in reassembling the whole dataset of permeability measurements from natural and experimental silicic samples. In order to improve our understanding of permeability development in the conduit, we worked on linking permeability and flow conditions with geometrical parameters that characterise the connected bubble network, based on experimental samples analysis. We propose an expression for the percolation threshold, i.e. the very moment when magma becomes permeable, that succeeds in classifying a wide dataset of natural and experimental samples. We also develop a new permeability law that reassembles most of the existing observations, and implement it within our gas flow 2D model. Results show that depending on the number of bubbles within the magma and on their size distribution, gas loss and then magma flow conditions evolve from effusive to explosive conditions.Eventually, we evaluate the applicability of monitoring flow conditions from observed ground deformation by using simplified conduit flow models, coupled with elastic deformation in 3D, to interpret ground deformation recorded in the near field at Merapi a few days before the 2006 eruption. Although conduit flow models provide important clues for interpreting observed displacements, the sparsity of field observations together with the complexity of the volcano summit geology, rheology and processes happening in the conduit make it very complex to constrain flow conditions from observed deformation.