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Situated in an active tectonic region, Santiago de Chile, the country´s capital with more than six million inhabitants, faces tremendous earthquake hazard. Macroseismic data for the 1985 Valparaiso and the 2010 Maule events show large variations in the distribution of damage to buildings within short distances indicating strong influence of local sediments and the shape of the sediment-bedrock interface on ground motion. Therefore, a temporary seismic network was installed in the urban area for recording earthquake activity, and a study was carried out aiming to estimate site amplification derived from earthquake data and ambient noise. The analysis of earthquake data shows significant dependence on the local geological structure with regards to amplitude and duration. Moreover, the analysis of noise spectral ratios shows that they can provide a lower bound in amplitude for site amplification and, since no variability in terms of time and amplitude is observed, that it is possible to map the fundamental resonance frequency of the soil for a 26 km x 12 km area in the northern part of the Santiago de Chile basin. By inverting the noise spectral rations, local shear wave velocity profiles could be derived under the constraint of the thickness of the sedimentary cover which had previously been determined by gravimetric measurements. The resulting 3D model was derived by interpolation between the single shear wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed further to check if any correlation between the shear wave velocity in the uppermost 30 m (vs30) and the slope of topography, a new technique recently proposed by Wald and Allen (2007), exists on a local scale. While one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated vs30 exists, whereas a better link is found between vs30 and the local geology. When comparing the vs30 distribution with the MSK intensities for the 1985 Valparaiso event it becomes clear that high intensities are found where the expected vs30 values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin. Using the attained knowledge on the basin characteristics, simulations of strong ground motion within the Santiago Metropolitan area were carried out by means of the spectral element technique. The simulation of a regional event, which has also been recorded by a dense network installed in the city of Santiago for recording aftershock activity following the 27 February 2010 Maule earthquake, shows that the model is capable to realistically calculate ground motion in terms of amplitude, duration, and frequency and, moreover, that the surface topography and the shape of the sediment bedrock interface strongly modify ground motion in the Santiago basin. An examination on the dependency of ground motion on the hypocenter location for a hypothetical event occurring along the active San Ramón fault, which is crossing the eastern outskirts of the city, shows that the unfavorable interaction between fault rupture, radiation mechanism, and complex geological conditions in the near-field may give rise to large values of peak ground velocity and therefore considerably increase the level of seismic risk for Santiago de Chile. / Aufgrund ihrer Lage in einem tektonisch aktiven Gebiet ist Santiago de Chile, die Hauptstadt des Landes mit mehr als sechs Millionen Einwohnern, einer großen Erdbebengefährdung ausgesetzt. Darüberhinaus zeigen makroseismische Daten für das 1985 Valparaiso- und das 2010 Maule-Erdbeben eine räumlich unterschiedliche Verteilung der an den Gebäuden festgestellten Schäden; dies weist auf einen starken Einfluss der unterliegenden Sedimentschichten und der Gestalt der Grenzfläche zwischen den Sedimenten und dem Festgestein auf die Bodenbewegung hin. Zu diesem Zweck wurde in der Stadt ein seismisches Netzwerk für die Aufzeichnung der Bodenbewegung installiert, um die auftretende Untergrundverstärkung mittels Erdbebendaten und seismischem Rauschen abzuschätzen. Dabei zeigt sich für die Erdbebendaten eine deutliche Abhängigkeit von der Struktur des Untergrunds hinsichtlich der Amplitude der Erschütterung und ihrer Dauer. Die Untersuchung der aus seismischem Rauschen gewonnenen horizontal-zu-vertikal-(H/V) Spektral-verhältnisse zeigt, dass diese Ergebnisse nur einen unteren Grenzwert für die Bodenverstärkung liefern können. Weil jedoch andererseits keine zeitliche Veränderung bei der Gestalt dieser Spektralverhältnisse festgestellt werden konnte, erlauben die Ergebnisse ferner, die Resonanzfrequenz des Untergrundes für ein 26 km x 12 km großes Gebiet im Nordteil der Stadt zu bestimmen. Unter Zuhilfenahme von Informationen über die Dicke der Sedimentschichten, welche im vorhinein schon durch gravimetrische Messungen bestimmt worden war, konnten nach Inversion der H/V-Spektralverhältnisse lokale Scherwellengeschwindigkeitsprofile und nach Interpolation zwischen den einzelnen Profilen ein dreidimensionales Modell berechnet werden. Darüberhinaus wurde mit den verfügbaren Daten untersucht, ob auf lokaler Ebene ein Zusammenhang zwischen der mittleren Scherwellengeschwindigkeit in den obersten 30 m (vs30) und dem Gefälle existiert, ein Verfahren, welches kürzlich von Wald und Allen (2007) vorgestellt wurde. Da für jede lithologische Einheit eine starke Streuung für die seismischen Geschwindigkeiten gefunden wurde, konnte kein Zusammenhang zwischen dem Gefälle und vs30 hergestellt werden; demgegenüber besteht zumindest ein tendenzieller Zusammenhang zwischen vs30 und der unterliegenden Geologie. Ein Vergleich der Verteilung von vs30 mit den MKS-Intensitäten für das 1985 Valparaiso-Erdbeben in Santiago zeigt, dass hohe Intensitätswerte vor allem in Bereichen geringer vs30-Werte und dicker Sedimentschichten auftraten. Weiterhin ermöglichte die Kenntnis über das Sedimentbeckens Simulationen der Bodenbewegung mittels eines spektralen-Elemente-Verfahrens. Die Simulation eines regionalen Erdbebens, welches auch von einem dichten seismischen Netzwerk aufgezeichnet wurde, das im Stadtgebiet von Santiago infolge des Maule-Erdbebens am 27. Februar 2010 installiert wurde, zeigt, dass das Modell des Sedimentbeckens realistische Berechnungen hinsichtlich Amplitude, Dauer und Frequenz erlaubt und die ausgeprägte Topographie in Verbindung mit der Form der Grenzfläche zwischen den Sedimenten und dem Festgestein starken Einfluss auf die Bodenbewegung haben. Weitere Untersuchungen zur Abhängigkeit der Bodenerschütterung von der Position des Hypozentrums für ein hypothetisches Erdbeben an der San Ramón-Verwerfung, welche die östlichen Vororte der Stadt kreuzt, zeigen, dass die ungünstige Wechselwirkung zwischen dem Verlauf des Bruchs, der Abstrahlung der Energie und der komplexen geologischen Gegebenheiten hohe Werte bei der maximalen Bodengeschwindigkeit erzeugen kann. Dies führt zu einer signifikanten Zunahme des seismischen Risikos für Santiago de Chile.

Cratonic basins cover more than 10% of Earth's continental surface area, yet their origin remains enigmatic. In this thesis a suite of new and legacy geophysical and geological data are integrated to constrain the origin of the Parnaíba basin, a cratonic basin in Northeast Brazil. These data include a 1400 km long, deep (20 s two-way travel time) seismic reflection profile, five +/- 110 km offset wide-angle split-spread receiver gathers, gravity anomaly, and well data. In the centre of the basin, the depth to pre-Paleozoic basement is ~ 3.3 km, a zone of midcrustal reflectivity (MCR) can be traced laterally for ~ 250 km at depths between 17-25 km and Moho depth is ~ 42 +/- 2 km. Gravity and P-wave modelling suggests that the MCR represents the upper surface of a high density (2985 kg m³) and V_p (6.7 - 7.0 km s^-1) lower crustal body, likely of magmatic origin. Backstripping of well data shows a concave up decreasing tectonic subsidence, similar in form to that commonly observed in rift-type basins. It is shown, however, that the seismic and gravity data are inconsistent with an extensional origin. It is shown that an intrusive body in the lower crust that has loaded and flexed the surface of the crust, combined with sediment loading, provides a satisfactory fit to the observed gravity anomaly, sediment thickness and basin shape. A buried load model is also consistent with seismic data, which suggest that the Moho is as deep or deeper beneath the basin centre than its flanks and accounts for at least part of the tectonic subsidence through a viscoelastic stress relaxation that occurs in the lithosphere following load emplacement. Comparative analysis of the Michigan and Congo basins shows gravity data from these basins is also consistent with a lower crustal mass excess, while subsidence analysis shows viscoelastic stress relaxation may also contribute to their early subsidence histories. However, unlike Parnaíba, both of these basins appear to have been subjected to secondary tectonic processes that obscure the primary 'cratonic basin' subsidence signals. Parnaíba basin, therefore, offers an excellent record for the investigation of cratonic basin formation.

O estudo de bacias sedimentares é de grande importância econômica, já que podem servir de reservatórios naturais de água, hidrocarbonetos e minérios valiosos. Neste sentido, avanços significativos vêm sendo feitos na área da engenharia computacional, motivados principalmente pela indústria petrolífera, buscando uma melhor compreensão dos mecanismos envolvidos na formação das bacias, a fim de otimizar custos e minimizar riscos na exploração das mesmas. O objetivo deste trabalho é a modelagem da formação, compactação e deformação de bacias sedimentares abordando exclusivamente os fenômenos mecânicos envolvidos. A simulação pode ser dividida em três fases características: a deposição dos sedimentos, sua compactação devido às forças gravitacionais e alívio de poro-pressões, e as deformações impostas por movimentos tectônicos extensionais e compressivos. Os estudos são realizados a partir de um modelo constitutivo poroelastoplástico em grandes deformações, levando em conta os acoplamentos hidro-mecânico e elástico-plástico. A simulação numérica é realizada através do método dos elementos finitos. Um algoritmo desenvolvido em Fortran é utilizado para realizar simulações bidimensionais da bacia em estado plano de deformação. São apresentados para diferentes momentos os fenômenos de subsidência da rocha sedimentar no caso de movimentos tectônicos extensionais, e de inversão da bacia (uplift) para o caso de movimentos tectônicos compressivos. São analisados e comparados todos os casos: compactação gravitacional e compactação segundo esforços de origem tectônica. / The study of sedimentary basins is of great economic importance, since they can serve as natural reservoirs of water, hydrocarbons and valuable minerals. In this context, motivated mainly by the oil industry, significant advances have been made in the area of computational engineering, seeking a better understanding of the mechanisms involved in the formation of basins in order to optimize costs and minimize risks in their exploration. This work is devoted to modeling of purely mechanical aspects of the formation, compaction and deformation of sedimentary basins. The simulation can be divided into three characteristic phases: the sediments deposition, its compaction due to gravitational forces and pore pressure dissipation, and its deformations imposed by extensional and compressive tectonic motion. The poromechanical constitutive law is formulated in the framework of finite irreversible strains, accounting for hydromechanical and elasticity-plasticity couplings. The numerical simulation is performed using the finite element method. An algorithm developed in Fortran code is used to perform two-dimensional simulations in plane strain state. Two phenomena are presented for different basin ages: the sedimentary rock subsidence, in the case of extensional tectonics, and the basin inversion (uplift), in the case of compressive tectonics. Different analyses and comparisons are made for all cases: gravitational compaction and tectonic-driven compaction.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / O presente estudo baseou-se na análise do conteúdo orgânico do furo de sondagem rasa do poço 9-FBA-69-BA localizado na Bacia do Recôncavo. Foram utilizadas 126 amostras para análise de COT e 35 pares de lâminas para as análises palinológicas e palinofaciológicas. As análises palinofaciológicas mostraram que os componentes orgânicos particulados são dominados por material orgânico amorfo em praticamente toda a seção. Representantes alóctones estão pontualmente presentes e representados por fitoclastos, grãos de pólen e esporos. Os resultados de COT mostram valores percentuais acima de 1% em praticamente todo o intervalo estudado. Através da observação à luz de microscopia branca transmitida e luz incidente, foi possível individualizar três palinofácies distintas para a seção, levando-se em conta os tipos e o grau de preservação da matéria orgânica. A análise do ICE (Índice de Coloração dos Esporos) apresenta valores de maturação entre 4,5 a 5, caracterizando um grau de maturação térmica próximo da janela de geração de hidrocarbonetos. A associação palinoflorística mostra uma baixa diversidade de representantes, onde dentre os 292 palinomorfos com 28 gêneros e 11 espécies de grãos de pólen e esporos, 167 são representados somente pela espécie Classopollis classoides. Baseado na associação palinoflorística presente e na análise litológica do poço podemos inferir que a sedimentação ocorreu em um paleoambiente fluvial deltaico- lacustre, sob um clima árido a semiárido visto a abundante presença de formas Rimuladas. Apesar da não detecção das formas guias diagnósticas de idade, que definem as palinozonas do arcabouço palinoestratigráfico válido para seções cretáceas brasileiras, a associação palinológica recuperada, com formas típicas do eocretáceo (Classopollis classoides, Araucariacites australis, Equisetosporites sp.), aliado a presença da espécie Vitreisporites pallidus, e ausência de formas do neocretáceo, nos permitiu posicionar a seção na palinozona Vitreisporites pallidus considerada de idade Aratu / The present study was based on analysis of the organic content of the shallow survey of well 9-69-BA-FBA located in the Recôncavo Basin. 126 samples for TOC and 35 pairs of blades were used for palynological and palynofacies analysis. The palynofacies analysis showed that particulate organic components are dominated by amorphous organic material in almost any section. Alien representatives are occasionally present and represented by phytoclasts, pollen grains and spores. The results of TOCshows percentages above 1% in almost the entire range studied. Through observation with white transmitted light and UV lightmicroscopy, it was possible to distinguish three distinct palynofacies section, considering the type and the degree of preservation of the organic material. The analysis of SCI (Spores Color Index) has maturation values between 4.5 to 5, featuring a degree of thermal maturation close to the window of hydrocarbons generation. The palynoflora association shows a low diversity of representatives, where among 292 palynomorphs with 28 genera and 11 species of pollen grains and spores, 167 are represented only by the species Classopollis classoides. Based on the present palynoflora association and the lithological analysis of the well, we can infer that sedimentation occurred in a fluvial-lacustrine deltaic paleoenvironment, under an arid to semi-arid atmosphere represented by the presence of abundant forms Rimuladas. Despite the non-detection of diagnostic forms of age guides, which define the palynozones of the paleostratigraphic framework valid for the Brazilian section of the lower Cretaceous (Classopollis classoides, Araucariacites australis, Equisetosporites sp.), the palynoflora recovered association indicates that these deposits are part of the Vitreisporites pallidus palynozone considered of age Aratu

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / O presente estudo baseou-se na análise do conteúdo orgânico do furo de sondagem rasa do poço 9-FBA-69-BA localizado na Bacia do Recôncavo. Foram utilizadas 126 amostras para análise de COT e 35 pares de lâminas para as análises palinológicas e palinofaciológicas. As análises palinofaciológicas mostraram que os componentes orgânicos particulados são dominados por material orgânico amorfo em praticamente toda a seção. Representantes alóctones estão pontualmente presentes e representados por fitoclastos, grãos de pólen e esporos. Os resultados de COT mostram valores percentuais acima de 1% em praticamente todo o intervalo estudado. Através da observação à luz de microscopia branca transmitida e luz incidente, foi possível individualizar três palinofácies distintas para a seção, levando-se em conta os tipos e o grau de preservação da matéria orgânica. A análise do ICE (Índice de Coloração dos Esporos) apresenta valores de maturação entre 4,5 a 5, caracterizando um grau de maturação térmica próximo da janela de geração de hidrocarbonetos. A associação palinoflorística mostra uma baixa diversidade de representantes, onde dentre os 292 palinomorfos com 28 gêneros e 11 espécies de grãos de pólen e esporos, 167 são representados somente pela espécie Classopollis classoides. Baseado na associação palinoflorística presente e na análise litológica do poço podemos inferir que a sedimentação ocorreu em um paleoambiente fluvial deltaico- lacustre, sob um clima árido a semiárido visto a abundante presença de formas Rimuladas. Apesar da não detecção das formas guias diagnósticas de idade, que definem as palinozonas do arcabouço palinoestratigráfico válido para seções cretáceas brasileiras, a associação palinológica recuperada, com formas típicas do eocretáceo (Classopollis classoides, Araucariacites australis, Equisetosporites sp.), aliado a presença da espécie Vitreisporites pallidus, e ausência de formas do neocretáceo, nos permitiu posicionar a seção na palinozona Vitreisporites pallidus considerada de idade Aratu / The present study was based on analysis of the organic content of the shallow survey of well 9-69-BA-FBA located in the Recôncavo Basin. 126 samples for TOC and 35 pairs of blades were used for palynological and palynofacies analysis. The palynofacies analysis showed that particulate organic components are dominated by amorphous organic material in almost any section. Alien representatives are occasionally present and represented by phytoclasts, pollen grains and spores. The results of TOCshows percentages above 1% in almost the entire range studied. Through observation with white transmitted light and UV lightmicroscopy, it was possible to distinguish three distinct palynofacies section, considering the type and the degree of preservation of the organic material. The analysis of SCI (Spores Color Index) has maturation values between 4.5 to 5, featuring a degree of thermal maturation close to the window of hydrocarbons generation. The palynoflora association shows a low diversity of representatives, where among 292 palynomorphs with 28 genera and 11 species of pollen grains and spores, 167 are represented only by the species Classopollis classoides. Based on the present palynoflora association and the lithological analysis of the well, we can infer that sedimentation occurred in a fluvial-lacustrine deltaic paleoenvironment, under an arid to semi-arid atmosphere represented by the presence of abundant forms Rimuladas. Despite the non-detection of diagnostic forms of age guides, which define the palynozones of the paleostratigraphic framework valid for the Brazilian section of the lower Cretaceous (Classopollis classoides, Araucariacites australis, Equisetosporites sp.), the palynoflora recovered association indicates that these deposits are part of the Vitreisporites pallidus palynozone considered of age Aratu

O estudo de bacias sedimentares é de grande importância econômica, já que podem servir de reservatórios naturais de água, hidrocarbonetos e minérios valiosos. Neste sentido, avanços significativos vêm sendo feitos na área da engenharia computacional, motivados principalmente pela indústria petrolífera, buscando uma melhor compreensão dos mecanismos envolvidos na formação das bacias, a fim de otimizar custos e minimizar riscos na exploração das mesmas. O objetivo deste trabalho é a modelagem da formação, compactação e deformação de bacias sedimentares abordando exclusivamente os fenômenos mecânicos envolvidos. A simulação pode ser dividida em três fases características: a deposição dos sedimentos, sua compactação devido às forças gravitacionais e alívio de poro-pressões, e as deformações impostas por movimentos tectônicos extensionais e compressivos. Os estudos são realizados a partir de um modelo constitutivo poroelastoplástico em grandes deformações, levando em conta os acoplamentos hidro-mecânico e elástico-plástico. A simulação numérica é realizada através do método dos elementos finitos. Um algoritmo desenvolvido em Fortran é utilizado para realizar simulações bidimensionais da bacia em estado plano de deformação. São apresentados para diferentes momentos os fenômenos de subsidência da rocha sedimentar no caso de movimentos tectônicos extensionais, e de inversão da bacia (uplift) para o caso de movimentos tectônicos compressivos. São analisados e comparados todos os casos: compactação gravitacional e compactação segundo esforços de origem tectônica. / The study of sedimentary basins is of great economic importance, since they can serve as natural reservoirs of water, hydrocarbons and valuable minerals. In this context, motivated mainly by the oil industry, significant advances have been made in the area of computational engineering, seeking a better understanding of the mechanisms involved in the formation of basins in order to optimize costs and minimize risks in their exploration. This work is devoted to modeling of purely mechanical aspects of the formation, compaction and deformation of sedimentary basins. The simulation can be divided into three characteristic phases: the sediments deposition, its compaction due to gravitational forces and pore pressure dissipation, and its deformations imposed by extensional and compressive tectonic motion. The poromechanical constitutive law is formulated in the framework of finite irreversible strains, accounting for hydromechanical and elasticity-plasticity couplings. The numerical simulation is performed using the finite element method. An algorithm developed in Fortran code is used to perform two-dimensional simulations in plane strain state. Two phenomena are presented for different basin ages: the sedimentary rock subsidence, in the case of extensional tectonics, and the basin inversion (uplift), in the case of compressive tectonics. Different analyses and comparisons are made for all cases: gravitational compaction and tectonic-driven compaction.