Η γεωφυσική διασκόπηση αποτελεί μια τεχνική διερεύνησης που χαρακτηρίζεται ως μη καταστροφική, με δυνατότητα εφαρμογής σε μεγάλη πλειονότητα προβλημάτων. Πραγματοποιήθηκε γεωφυσική έρευνα με εφαρμογή ηλεκτρικής χαρτογράφησης, ηλεκτρικής τομογραφίας, γεωραντάρ και καταγραφών εδαφικού θορύβου σε περιοχή της Πανεπιστημιούπολης. Σκοπός ήταν η λεπτομερής γεωφυσική διερεύνηση για τον εντοπισμό γεωλογικών ασυνεχειών στον ευρύτερο χώρο του Πανεπιστημίου. Οι προαναφερόμενες τεχνικές εφαρμόστηκαν στο πεδίο σε προκαθορισμένα γεωφυσικά δίκτυα (κάνναβοι) που απείχαν μεταξύ τους απόσταση 100 μέτρων, με σάρωση επάλληλων διατομών παράλληλα και κάθετα στην διεύθυνση του γεωμαγνητικού Βορρά. Ως πρώτη τεχνική επιλέχτηκε η ηλεκτρική χαρτογράφηση με χρήση της δίδυμης διάταξης και άνοιγμα ηλεκτροδίων 0.5-3 μέτρων, που απέδωσε την κατανομή της ηλεκτρικής αντίστασης του εδάφους επί οριζόντιου επιπέδου. Ως δεύτερη τεχνική εφαρμόστηκε η ηλεκτρική τομογραφία. Με χρήση 25 συνευθειακών ηλεκτροδίων σε απόσταση 1 μέτρου, μέσω της διάταξης Wenner-Schlumberger, επιτεύχθηκε η καταγραφή της κατανομής της φαινόμενης ειδικής αντίστασης επί κατακόρυφου επιπέδου και σε 8 διαφορετικά βάθη. Μέσω του ειδικού λογισμικού Res2DINV, υπολογίστηκε η τιμή της ειδικής ηλεκτρικής αντίστασης, με δημιουργία μαθηματικού προτύπου δύο διαστάσεων βασιζόμενο στα ελάχιστα τετράγωνα. Με την βοήθεια του ειδικού λογισμικού Geosoft Oasis Montaj, πραγματοποιήθηκε η επεξεργασία των δεδομένων της ηλεκτρικής χαρτογράφησης και της ειδικής ηλεκτρικής αντίστασης. Ως αποτέλεσμα ήταν η παραγωγή έγχρωμων χαρτών κατανομής της ηλεκτρικής αντίστασης, ενώ από την δεύτερη τεχνική παρήχθησαν οριζόντιες κατόψεις της ειδικής αντίστασης σε ορισμένο βάθος καθώς και τρισδιάστατη απεικόνιση αυτής. Οι γεωφυσικές έρευνες με χρήση του γεωραντάρ και των καταγραφών εδαφικού θορύβου χρησιμοποιήθηκαν επικουρικά για να ταυτοποιήσουν τα παραγόμενα αποτελέσματα των ηλεκτρικών μεθόδων γεωφυσικής διασκόπησης. Από την ερμηνεία των παραγόμενων χαρτών έγινε σαφής ο εντοπισμός της υπάρχουσας γεωλογικής ασυνέχειας στην παραπάνω περιοχή και κατασκευάστηκε τρισδιάστατο μοντέλο απεικόνισης κατανομής της ειδικής ηλεκτρικής αντίστασης. / Geophysical prospecting is a non catastrophic technique, which is applicable on a wide range of problems, including archaeological, environmental and geological problems. At Campus University of Patras, a detailed geophysical investigation applied in order to detect possible geological discontinuities, which produced serious problems at buildings and main roads of the Campus. As main technique used the electric mapping and electric imaging, which applied on already prepared geophysical grids by measuring parallel profiles with direction along and perpendicular to the geomagnetic north, while the two geophysical grids were 100 meters away each other. Firstly, an electric mapping procedure took place by using twin-probe array with four electrodes in distance between 0.5-3 meters. As a result was the recording of soil resistance on horizontal layer with constant depth. By processing the data through Geosoft Oasis Montaj software, the distribution of soil resistance was illustrated on color scale maps. Secondly, electric imaging technique applied with twenty-five equal space electrodes along straight lines, with one meter space by using the hybrid arrangement Wenner-Schlumberger. As a result was the recording of distribution of soil apparent resistivity on a vertical layer in eight separated depths. Resistivity calculated by processing imaging data with 2D mathematical algorithm based on least squares inversion (Res2Dinv). Further processing by Oasis Montaj, had as a result the production of horizontal slices and 3D maps, where the resistivity distribution was illustrated on separated depths, in color and grey schedule format. The combined geophysical investigation with the aid of ground penetrating radar and the HVSR (Horizontal to Vertical Spectral Ratio) technique confirmed the existence of geological discontinuity.

In this study we investigate the interactions between two co-rotating vortices. These vortices are subject to rapid rotation and stable stratification such as are found in planetary atmospheres and oceans. By conducting a large number of simulations of vortex interactions, we intend to provide an overview of the interactions that could occur in geophysical turbulence. We consider a wide parameter space covering the vortices height-to-width aspect-ratios, their volume ratios and the vertical offset between them. The vortices are initially separated in the horizontal so that they reside at an estimated margin of stability. The vortices are then allowed to evolve for a period of approximately 20 vortex revolutions. We find that the most commonly observed interaction under the quasi-geostrophic (QG) regime is partial-merger, where only part of the smaller vortex is incorporated into the larger, stronger vortex. On the other hand, a large number of filamentary and small scale structures are generated during the interaction. We find that, despite the proliferation of small-scale structures, the self-induced vortex energy exhibits a mean `inverse-cascade' to larger scale structures. Interestingly we observe a range of intermediate-scale structures that are preferentially sheared out during the interactions, leaving two vortex populations, one of large-scale vortices and one of small-scale vortices. We take a subset of the parameter space used for the QG study and perform simulations using a non-hydrostatic model. This system, free of the layer-wise two-dimensional constraints and geostrophic balance of the QG model, allows for the generation of inertia-gravity waves and ageostrophic advection. The study of the interactions between two co-rotating, non-hydrostatic vortices is performed over four different Rossby numbers, two positive and two negative, allowing for the comparison of cyclonic and anti-cyclonic interactions. It is found that a greater amount of wave-like activity is generated during the interactions in anticyclonic situations. We also see distinct qualitative differences between the interactions for cyclonic and anti-cyclonic regimes.

The main aim of this thesis is to gain new knowledge about the lithospherical structure and tectonics of the Carpathian-Pannonian Basin region. We applied three different methods: 1Dautomatic modelling, 2D integrated geophysical modelling and 3D inversion to achieve this goal.These methods are similar concerning the used databases but differ by used processing andinterpretation. At first we apply 1D automatic modelling to get a very first overview of thestudied region. Secondly, we apply 2D integrated modelling of the lithosphere which combines the interpretation of surface heat flow, geoid, gravity, and topography data in the Carpathian-Pannonian Basin region and surrounding areas. This approach is able to constrain the complicated lithospheric structures of the studied region better than interpreting each data set onits own. We present four 2D integrated models of the lithosphere in the Carpathian-PannonianBasin region and surrounding areas. Finally, based on the 3D Inversion algorithm, we present the geophysical models of the lithosphere in the Carpathian-Pannonian region. The algorithm returns the density structure of the lithosphere from joint inversion of free air gravity, geoid andtopography data based on a Bayesian approach. The models are based on different input data sets and constrained by different a priori data. Based on our modelling we cannot confirm theextreme thinning (less than 70 km) of the Pannonian Basin lithosphere proposed by other authors.On the other hand, the results show the increasing trend of the lithospherical thickness of theCarpathian Arc from the Western Carpathians toward the Eastern Carpathians which confirms theprevious theories about the propagation of subduction process. We got some controversial resultsin the area of the Southern Carpathians. The results based on 3D inversion show extremely thinlithosphere in the area; on the other hand, the results based on 2D integrated modelling do notsupport such thinning. However both methods indicate that it is probable that the MoesianPlatform is bend and underthrusted underneath the Southern Carpathians. The south-eastern edge of the Pannonian Basin based on 3D inversion shows unexpected and surprisingly thinlithosphere. Since the area is quite large, we could exclude an effect of flexure, therefore this area might be potentially interesting for further investigation.

A implantação do Sítio Controlado de Geofísica Rasa (SCGR), do Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG), da Universidade de São Paulo (USP), é um marco na história da geofísica nacional. Trata-se do primeiro local de estudos controlados de geofísica rasa, instalado no Brasil. O SCGR está localizado próximo ao Instituto de Física, em frente ao IAG/USP, compreendendo uma área de 1500 m2 (50 m x 30 m). Nesta área, foram instalados diferentes alvos, com dimensões variadas e em diferentes profundidades, dispostos em sete linhas de 30 metros. Os alvos escolhidos tiveram como finalidade reproduzir uma pequena amostra dos principais objetos que são encontrados em ambiente urbano. O objetivo do estudo foi o de caracterizar os alvos instalados no SCGR, por meio da utilização de diferentes métodos geofísicos, com ênfase no método Ground Penetrating Radar (GPR), seguido dos métodos de eletrorresistividade e eletromagnético indutivo (EM-38). Esta caracterização consistiu em avaliar o desempenho e a confiabilidade dos métodos geofísicos, quando aplicados sobre alvos com propriedades físicas conhecidas. A coleta de dados foi realizada antes e depois da instalação do sítio controlado, permitindo, assim, a caracterização geofísica do meio (background) e dos alvos. Os resultados geofísicos foram apresentados na forma de perfis 2D e de cortes em profundidade em blocos volumétricos, Quase-3D. Os dados geofísicos do background evidenciam uma camada de aterro, com espessura de até 2,8 metros, repousando sobre sedimentos argilosos da planície de inundação do rio Pinheiros. O EM-38 possibilitou o mapeamento de todos os objetos metálicos enterrados até a profundidade máxima de 1,5 metro. A identificação de alguns alvos metálicos, enterrados na profundidade de 0,5 metro, também foi possível com os resultados de cargabilidade. Os dados de resistividade elétrica permitiram a identificação de um tubo metálico guia, enterrado no centro da área, a 0,5 metro de profundidade, e de alvos representativos de materiais geológicos. Os resultados de GPR permitiram o imageamento da maioria dos alvos implantados na área do SCGR, com melhor resolução aqueles que mostram maior contraste dielétrico. A pesquisa contribui para o refinamento dos métodos de campo aplicados aos problemas reais do cotidiano, principalmente, em estudos de geotecnia, planejamento urbano, arqueologia e meio ambiente. / The implantation of the Shallow Geophysical Test Site (SCGR) of the Astronomy, Geophysics and Atmospheric Sciences Institute (IAG), from University of Sao Paulo (USP), is a mark in national geophysical history. It is the first site Shallow geophysical study site installed in Brazil. This Test Site is located next to Physics Institute in front of IAG/USP, comprehending an area of 1500 m2 (50 m x 30 m). In this area, different targets were installed, with varied dimensions and different depths, buried in seven lines of 30 meters. Targets were chosen aiming at reproducing a small sample of main objects found in urban environment. The goal of the study was characterizing targets installed in SCGR by using different geophysical methods with emphasis in Ground Penetrating Radar (GPR), electric and inductive electromagnetic (EM-38) methods. This characterization consisted in evaluating the performance and reliability of geophysical methods, when applied in targets whose physical properties are well-known. Measurements were carried out before the targets installation in subsurface, in order to obtain data from land background or geologic horizons before disturbances. In a second stage, geophysical data were obtained after target installation. Geophysical results were shown in 2D profiles, and depth slices in volumetric blocks, Quasi-3D. Geophysical data from land background showed an earthwork layer, with thickness up to 2.8 meters, above loamy sediments of Pinheiros River. EM-38 enabled the mapping of all metallic targets buried until 1.5 meter of maxim depth. The identification of some metallic targets also buried in the depth of 0.5 meter was possible with chargeability results. Electric resistivity data allowed the identification of a metallic tube buried at the centre of the area, to 0.5 meter of depth, and of representative geological materials targets. GPR results identified of the majority of targets buried in SCGR with better resolution than those ones shown highest dielectric contrast. This research contributes for geophysical method refinement applied to everyday problems mostly in geotechnical, urban planning, archaeological and environmental studies.

A caracterização geológica e geotécnica dos locais de implantação de aterros sanitários é fundamental, tanto para fornecer subsídios adequados ao projeto de instalação das células de deposição dos resíduos sólidos urbanos (RSU), quanto para que se conheçam as características da área antes de ser modificada pela obra. Neste sentido, o presente trabalho visou mostrar a contribuição que a geofísica, com o uso da técnica da eletrorresistividade e do potencial espontâneo, associado a informações de investigação geotécnica direta pode dar para o estabelecimento de um background da área de instalação do aterro sanitário da cidade de São Carlos-SP. Foram realizados 7 caminhamentos elétricos (CE) com o arranjo dipolo-dipolo com eletrodos espaçados de 10 metros e três sondagens elétricas verticais (SEV), utilizando o arranjo Schlumberger, com profundidade de investigação de até 100 metros. Para processamento dos modelos bidimensionais dos CE utilizou-se o programa RES2DINV, e enquanto que para as SEV foi utilizado o modelo unidimensional. A interpretação dos modelos geoelétricos foi aperfeiçoada pela confrontação com informações geológico-geotécnicas prévias da área, obtidas nos estudos de impacto ambiental (EIA/RIMA) e resultados de sondagens de simples reconhecimento (SPT), realizadas na fase de estudo para implantação do aterro sanitário. Com isso foi possível definir com clareza a profundidade do topo rochoso e das zonas de maior umidade nos CE e SEV. O conjunto de seções de CE foi georeferenciada com o auxílio de GPS de precisão, o que permitiu o tratamento espacial das informações e o estabelecimento dos mapas da superfície do topo rochoso, das zonas de fluxo de água subterrânea e da espessura dos materiais inconsolidados. O conjunto de informações obtido permitiu identificar locais possíveis para a instalação futura de poços de monitoramento, assim como os dados geoelétricos das várias camadas servirá como padrão para identificar eventuais contaminações do solo ou da água subterrânea no futuro. A identificação da presença do topo rochoso em pequena profundidade, em algumas áreas do aterro, permite o melhor planejamento das escavações para instalação das células de deposição do RSU. / The geological and geotechnical characterization of landfill implantation areas is crucial; even to provide appropriate subsidies of urban solid residues (USR) installation project of deposition cells and for knowing the characteristics of the area before being modified by the work. In this sense, the present work aimed to show the contribution that the geophysics, with the use of electrical resistivity technique and the spontaneous potential, associated with direct geotechnical investigation information can give to the establishment of a background of landfill installation area from São Carlos-SP city. Were performed 7 electrical imaging (EI) with the dipole-dipole array with electrodes spaced by 10 meters and three vertical electrical sounding (VES), using the Schlumberger array with depth research up to 100 meters. For processing of two-dimensional models of the EI was used the RES2DINV program and while for the vertical electrical sounding (VES)-was used one-dimensional model. Interpretation of geoelectric models was enhanced by the confrontation with geological and geotechnical information of prior area, obtained in the environmental impact assessment (EIA) and results of a simple reconnaissance probes, performed in the study phase for the landfill implementation. It was possible to clearly define the depth of the bedrock and the higher humidity areas in the EI and VES. The set of sections electrical Imaging (EI) was georeferenced with the aid of GPS accuracy that allowed the spatial treatment of Information and the setting maps of the bedrock surface, the groundwater flow zones and the thickness of the unconsolidated materials. The obtained set of information enabling identification of possible locations for the wells future monitoring installation, as well as the geoelectrical data from several layers will be use as a standard to identify possible contamination of the soil or groundwater in the future. The identification of bedrock presence in small depth, in some areas of landfill, allows better planning of excavation for installation of MSW deposition cells.

O escudo Sul-riograndense tem sua importância econômica ligada às várias mineralizações de metais base e ouro como as áreas de Camaquã, Caçapava do Sul, Lavras do Sul e São Sepé. A região é objeto de estudos geológicos desde muito tempo e vários trabalhos já foram publicados a respeito, porém todos estes mostram grande complexidade tanto quanto à origem e evolução do escudo como para as ocorrências minerais nela presentes. O presente estudo utilizou um conjunto de análises multivariadas para dados aerogeofísicos e sensoriamento remoto em parte do Escudo do Rio Grande do Sul para verificar a contribuição destas técnicas para a otimização de recursos tanto financeiros quanto de tempo na execução dos projetos de pesquisa mineral naquela região. Os resultados mostraram que o uso destas técnicas contribui para a discriminação de grupos relacionados às litologias descritas para a área de pesquisa de forma muito mais clara que o uso das metodologias de forma individualizada. Embora não tenha revelado as assinaturas das ocorrências minerais pode ser utilizada para a discriminação destas dentro dos grupos formados pelas análises. / The Rio Grande do Sul Shield has its economic importance connected to the diverse gold and base metals mineralization that occurs in that area, such as Camaqua Basin, Cacapava, Lavras do Sul and São Sepé granitite intrusions. The region has been the subject of geological studies for a long time and several papers have been published about it, but they show great complexity for both the origin and evolution of the Shield and the mineral occurrences in it. The present study used a set of multivariate analysis for airborne geophysics and remote sensing data in part of the Rio Grande do Sul Shield, to verify the contribution of these techniques for the optimization of time and financial resources for the implementation of projects of mineral exploration. The results confirm that their use contribute to the discrimination of groups related to the described lithology in the area in a more clearly way that using these methodologies individually. Although the signatures of mineral occurrences have not been revealed, they can be used for their discrimination, based on the groups resultant from the analysis.

Ocean submesoscales are the subject of increasing focus in the oceanographic literature; with instrumentation now more capable of observing them in situ and numerical models now able to reach the resolution required to more fully capture them. Submesoscales are typified by horizontal spatial scales of O(1 − 10) km, vertical scales O(100) m and time-scales of O(1) day and are known to be associated with regions of high vertical velocity and vorticity. Occurring most commonly at density fronts at the ocean surface they can control mixed layer restratification and provide an important control on fluxes between the atmosphere and the deep ocean. This thesis sets out to better understand the fundamental physical processes underpinning submesoscale instabilities using a number of idealised process models. Linear stability analysis complemented by non-linear, high-resolution simulations will be used initially to explore the ways in which submesoscale instabilities in the mixed layer may compete and interact with one another. In particular, we will investigate the way in which symmetric and ageostrophic baroclinic instabilities interact when simultaneously present in a flow, with focus on the growth rates and energetic pathways of previously unexplored dynamic instabilities that arise in this paradigm; three-dimensional, mixed symmetric-baroclinic instabilities. Further, these non-linear simulations will allow us to investigate the transition to dissipative scales that can occur in the classical Eady model via a multitude of small-scale secondary instabilities that result from primary submesoscale instabilities. Finally, observational data, taken aboard the SMILES project cruise to the Southern Ocean, helps to motivate the consideration of a new dynamical paradigm; the Eady model with superimposed high amplitude barotropic jet. Non-linear simulations investigate the extent to which the addition of such a jet is capable of damping submesoscale growth. The causes of this damping are then investigated using linear analysis. With this approach eventually demonstrated as being unable to fully explain growth rate reductions, we introduce a new framework combining potential vorticity mixing by submesoscale instabilities with geostrophic adjustment, which relaxes the flow back to a geostrophic balanced state. This framework will help to explain, conceptually, how non-linear eddies control the linear stability of the flow.

Mon sujet de thèse concerne les propriétés acoustiques et sismiques des formations non consolidées. Ce sujet est très mal connu, depuis la surface d'une part parce que la physique des milieux non consolidés est encore mal connue, et en forage d'autre part parce que ces milieux ne sont pas stables mécaniquement. Toute mesure en forage demande donc la pose d'un tubage et la réalisation des mesures à travers ce tubage. Dans le cadre de ma thèse, on appliquera premièrement ces mesures aux domaines du stockage de CO2 dans les formations géologiques, et ensuite à celui des glissements de terrains. Dans ce cadre, des mesures ont été réalisées sur les sites de Maguelone et de Svelvik pour le stockage géologique du CO2, et de Lodève pour les glissements de terrain.Le site expérimental Maguelone (France) a fait l'objet de la surveillance géophysique de la surface et en forages pendant les expériences d'injection de gaz dans un réservoir souterrain de roches clastiques peu profonde. En particulier, les profils sismiques verticaux (PSV) et les logs Sonique (derrière un tubage PVC) ont été enregistrés dans deux puits situés à quelques mètres du puits d'injection, avant, pendant et après une série d'injections de gaz. Les premieres arrivées pour les PSV ont été obtenues par le pointage (picking), et interprétées en termes de modèles de vitesses sismiques. Les données Sonique, après les avoir comparées avec les autres mesures pétrophysiques et géophysiques, ont été traitées et analysées en termes de vitesses et amplitudes. Avant l'injection, la comparaison des vitesses sismiques et d'amplitude entre les expériences dans un seul puits (MAG1), met en évidence l'impact de l'injection de gaz sur les propriétés élastiques des sédiments détritiques poreux au niveau du site d'injection, ce qui indique une augmentation de la saturation en gaz en face des couches sableuses et de couches de gravier. En tout, time-lapse VSP et les sonic logs, fournissent un moyen pour détecter et surveiller l'injection et le stockage de gaz dans des réservoirs géologiques, conduisant à une vue sur la dynamique du sous-sol au cours du temps. L'objectif du projet de CO2FieldLab (Svelvik Site_ Norvège) était de démontrer que les méthodes de surveillances adéquates peuvent être déployées pour documenter les risques de fuites de CO2 dans des réservoirs souterrains. Pour ce faire, une expérience d'injection peu profonde dans le sédiment perméable a été conçu et réalisé à Svelvik (Norvège) en Septembre 2011. L'objectif était de produire une fuite de CO2 afin d'évaluer la sensibilité relative de plusieurs outils de surveillance des émissions de CO2 géochimiques et géophysiques. Cette étude a mis en évidence le potentiel des méthodes acoustiques pour la surveillance et la détection de faible profondeur le stockage du CO2 et de la migration. Dans chacun des sites de l'étude, les séries de techniques ont été utilisées avec succès pour monitorage le stockage du CO2 et de la migration dans les réservoirs peu profonds, ces techniques se combinent les approches géophysiques et géochimiques. Sur le site de Lodève, mon travail s'est focalisé sur l'analyse de diagraphies et d'images ultrasoniques de parois obtenues sur seulement 20 mètres en trou nu dans la zone de déformation d'un glissement de terrain actif dans cette région. Des profils sismiques de surface ont également été enregistrés. Par contre, du fait de l'instabilité mécanique du forage, une légère déformation élastique ovale du forage a été mise en évidence aussi bien sur les images en distance qu'en amplitude. En utilisant la méthodologie utilisée traditionnellement pour l'analyse de déformations cassantes en forage (appelées "breakouts"), on note que la direction d'ovalisation correspond à la direction de plus grande pente du flanc de colline affectée par le glissement traversé par le forage entre 60 et 70 mètres, dans l'intervalle où les images ont été enregistrées. / The objective of My thesis concerns the acoustic and seismic properties of unconsolidated formations. This topic is poorly known, from the surface -of one hand- because the physical of unconsolidated environments is still poorly understood, and in the well on the other hand where these environments are not mechanically stable. Therefore any downhole measure requests the installation of a casing and taking measurements through this casing. In my thesis, these measurements were used for the geological storage of CO2, and then in the landslide. In this context, measures have been carried out on sites Maguelone and Svelvik for the geological storage of CO2, and in the Lodeve site for landslides.The Maguelone experimental site (France) has been the subject of surface and downhole geophysical monitoring of gas injection experiments in a shallow subsurface clastic reservoir. In particular, vertical seismic profiles (VSP) and downhole SONIC logs (through PVC liners) were recorded in two holes located within meters of the gas injection hole, before, during and after a series of gas injections. VSP first-arrival times were obtained by picking, and interpreted in terms of seismic velocity models. The sonic data, once compared to other logs and core petrophysical measurements, have been processed and analyzed in terms of velocities and amplitudes. Before injection. The comparison of seismic velocities and amplitude between experiments for a single hole brings out the impact of gas injection on the elastic properties of the porous clastic sediments at the injection site, suggesting an increase in gas saturation in front of the sandy and gravel-rich layers. . In all, time-lapse VSP and sonic logging through PVC provide a means to detect and monitor gas injection and storage in geological reservoirs, leading to a view on subsurface dynamics over time. The objective of the CO2FieldLab project (Svelvik site_ Norway) was to demonstrate that adequate monitoring methods can be deployed to document potential leaks of CO2 from subsurface reservoirs. For this, a shallow injection experiment through permeable sediment was designed and conducted at Svelvik (Norway) in September 2011. The goal was to produce a CO2 leak in order to assess the relative sensitivity of several geochemical and geophysical CO2 monitoring tools. This study highlighted the potential of acoustic methods for shallow monitoring and detecting of the CO2 storage and migration. In each of the study sites, the series of techniques have been successfully used to monitor CO2 storage and migration in the shallow reservoirs, these techniques combine geophysical and geochemical approaches On the Lodeve site, my work focused on the well logging analyzes especially the ultrasonic images obtained 20 meter only of the hole in the deformation zone un active landslide in the region. A slight elastic deformation oval of the hole was demonstrated both the distance and amplitude images. Using the methodology traditionally used for the analysis of the breakouts, we have noted that the ovalisation direction corresponds to the direction of slope of the hillside affected by slipping, traversed by the well between 60 and 70 meters of depth, the interval were the image ultrasonic recorded.

L’étude archéologique d’un site est réalisée sur la base d’une fouille, qui est une étude précise sur une ouverture restreinte. En amont de cette opération, la prospection géophysique offre la possibilité de localiser une zone susceptible d’apporter des informations majeures par une cartographie détaillée du site. Ces travaux de thèse se focalisent sur un protocole original de prospection magnétique pour détecter des structures pluri-métriques à pluri-décimétriques et une démarche méthodologique pour estimer la conservation d’un niveau d’occupation archéologique. Ces développements ont été réalisés pour apporter un maximum d’information sur l’occupation anthropique et cibler une zone de fouille suivant la problématique archéologique associée au site. Dans les zones littorales et suivant la période chronologique considérée, l’environnement associé à une occupation était différent. La modification relativement rapide des environnements côtiers résulte de la remontée du niveau marin depuis la fin du dernier maximum glaciaire. Dans le cadre d'une étude paléoenvironnementale associée à un site, l’objectif de la prospection géophysique est similaire à celle effectuée pour une fouille : localiser une zone d’implantation des carottages paléoenvironnementaux. La démarche méthodologique développée dans ces travaux est basée sur une approche paléogéographique de l’environnement à partir de prospections géophysiques multi-méthodes et multi-échelles. Des prospections électromagnétiques (Slingram), des sections électriques et des diagraphies électriques (direct-push) apportent une représentation cartographique et stratigraphique des contrastes géophysiques de la subsurface. Deux zones d’étude ont été sélectionnées pour tester et mettre en place ces démarches méthodologiques, le site néolithique du Pontet (Charente-Maritime) et les ports antiques de Narbonne. Ces deux sites sont dans des contextes archéologiques, géographiques et géologiques différents. / Archaeological study of a site is based on an excavation which is a comprehensive study on a restricted gap. Before excavation, geophysical survey supplies the possibility to locate an area likely to provide details by detailed mapping of the site. This PhD work focus on an original magnetic survey protocol to detect pluri-metric and pluri-decimetric structures and a methodological approach to estimate the conservation of an archaeological level occupation. These developments have provided maximum information on anthropogenic settlement and to target excavation zone according to the archaeological problem of the site. In coastal zones and according to the considered chronological period, the environment of the settlement was different. The relatively rapid change in coastal environments results from the rise of sea level since the end of the last glacial maximum. As part of a paleoenvironmental study of a site, the objective of geophysical survey is similar to that for excavation : locating an area to paleoenvironmental coring. The methodological approach developed in this work is based on a paleogeographic approach to the site environment using multi-method and multi-scale geophysical surveys. Electromagnetic survey (Slingram), electrical tomography and direct-push electrical resistivity logging provide a cartographic and stratigraphic representation of the geophysical contrasts of the subsurface. Two study areas were selected to test and implement these methodological approaches, the Neolithic site of Le Pontet (Charente-Maritime) and the ancient harbours of Narbonne. These two sites are in different archaeological, geographical and geological contexts.

A implantação do Sítio Controlado de Geofísica Rasa (SCGR), do Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG), da Universidade de São Paulo (USP), é um marco na história da geofísica nacional. Trata-se do primeiro local de estudos controlados de geofísica rasa, instalado no Brasil. O SCGR está localizado próximo ao Instituto de Física, em frente ao IAG/USP, compreendendo uma área de 1500 m2 (50 m x 30 m). Nesta área, foram instalados diferentes alvos, com dimensões variadas e em diferentes profundidades, dispostos em sete linhas de 30 metros. Os alvos escolhidos tiveram como finalidade reproduzir uma pequena amostra dos principais objetos que são encontrados em ambiente urbano. O objetivo do estudo foi o de caracterizar os alvos instalados no SCGR, por meio da utilização de diferentes métodos geofísicos, com ênfase no método Ground Penetrating Radar (GPR), seguido dos métodos de eletrorresistividade e eletromagnético indutivo (EM-38). Esta caracterização consistiu em avaliar o desempenho e a confiabilidade dos métodos geofísicos, quando aplicados sobre alvos com propriedades físicas conhecidas. A coleta de dados foi realizada antes e depois da instalação do sítio controlado, permitindo, assim, a caracterização geofísica do meio (background) e dos alvos. Os resultados geofísicos foram apresentados na forma de perfis 2D e de cortes em profundidade em blocos volumétricos, Quase-3D. Os dados geofísicos do background evidenciam uma camada de aterro, com espessura de até 2,8 metros, repousando sobre sedimentos argilosos da planície de inundação do rio Pinheiros. O EM-38 possibilitou o mapeamento de todos os objetos metálicos enterrados até a profundidade máxima de 1,5 metro. A identificação de alguns alvos metálicos, enterrados na profundidade de 0,5 metro, também foi possível com os resultados de cargabilidade. Os dados de resistividade elétrica permitiram a identificação de um tubo metálico guia, enterrado no centro da área, a 0,5 metro de profundidade, e de alvos representativos de materiais geológicos. Os resultados de GPR permitiram o imageamento da maioria dos alvos implantados na área do SCGR, com melhor resolução aqueles que mostram maior contraste dielétrico. A pesquisa contribui para o refinamento dos métodos de campo aplicados aos problemas reais do cotidiano, principalmente, em estudos de geotecnia, planejamento urbano, arqueologia e meio ambiente. / The implantation of the Shallow Geophysical Test Site (SCGR) of the Astronomy, Geophysics and Atmospheric Sciences Institute (IAG), from University of Sao Paulo (USP), is a mark in national geophysical history. It is the first site Shallow geophysical study site installed in Brazil. This Test Site is located next to Physics Institute in front of IAG/USP, comprehending an area of 1500 m2 (50 m x 30 m). In this area, different targets were installed, with varied dimensions and different depths, buried in seven lines of 30 meters. Targets were chosen aiming at reproducing a small sample of main objects found in urban environment. The goal of the study was characterizing targets installed in SCGR by using different geophysical methods with emphasis in Ground Penetrating Radar (GPR), electric and inductive electromagnetic (EM-38) methods. This characterization consisted in evaluating the performance and reliability of geophysical methods, when applied in targets whose physical properties are well-known. Measurements were carried out before the targets installation in subsurface, in order to obtain data from land background or geologic horizons before disturbances. In a second stage, geophysical data were obtained after target installation. Geophysical results were shown in 2D profiles, and depth slices in volumetric blocks, Quasi-3D. Geophysical data from land background showed an earthwork layer, with thickness up to 2.8 meters, above loamy sediments of Pinheiros River. EM-38 enabled the mapping of all metallic targets buried until 1.5 meter of maxim depth. The identification of some metallic targets also buried in the depth of 0.5 meter was possible with chargeability results. Electric resistivity data allowed the identification of a metallic tube buried at the centre of the area, to 0.5 meter of depth, and of representative geological materials targets. GPR results identified of the majority of targets buried in SCGR with better resolution than those ones shown highest dielectric contrast. This research contributes for geophysical method refinement applied to everyday problems mostly in geotechnical, urban planning, archaeological and environmental studies.