Este trabalho apresenta um estudo comparativo entre análises no domínio do tempo e análises espectrais, como forma de sugerir uma abordagem alternativa para o projeto de pontes de seção celular submetidas à ação de terremotos. Com esse propósito, desenvolveu-se um programa em linguagem JAVA para a geração de sismos artificiais, usando como base o Eurocode 8. A saída do programa foi utilizada para o desenvolvimento de um estudo de caso, que consiste em uma modelagem simplificada no software ADINA, de um vão de 21 m da Ponte Alverca, em Portugal. Após a extração e comparação de resultados dos dois métodos, é possível perceber que o método alternativo proposto - no domínio do tempo, que consiste na aplicação de acelerogramas artificiais ao modelo - possui resultados bastante coerentes com a análise espectral, além de ser mais recomendado se efeitos geométricos ou fisicamente não lineares forem considerados na modelagem. / This work presents a comparative study between time-domain analysis and spectral analysis, as a way of suggesting an alternative approach for treating cell section bridges subjected to earthquakes. To reach this goal, it was developed a program in JAVA language for the artificial earthquakes generation, using the Eurocode 8 as a basis. The program output was used for a case study that consists in a simplified modeling using ADINA software, of a twenty-one-meter-long span of Alverca Bridge, in Portugal. After the results extraction of both methods, it is possible to notice that the alternative method - in the time-domain, which consists of the application of artificial accelerograms to the model - has fairly consistent results with spectral analysis, not to mention that it is the most suitable one, in case geometrical or physical non-linearities are considered in the modelling.

Les interactions entre les processus tectoniques et l’érosion ont été peu étudiées à des échelles de temps courtes (< 1000 ans). Cependant, les séismes peuvent activement contribuer à l’érosion des chaînes de montagne en déclenchant de nombreux glissements de terrain. Des études récentes ont également montré que ces grands événements érosifs pourraient engendrer des changements de contraintes suffisants à proximité des failles actives pour modifier la sismicité régionale. Dans cette thèse, cette problématique a été abordée via une approche numérique. Dans un premier temps, le développement d’un modèle simple de glissements de terrain prenant en compte la topographie des versants a permis de démontrer le rôle des paramètres mécaniques (cohésion et friction), et de la forme des versants sur la distribution de taille des glissements de terrain. Ce modèle a été validé à l’aide de cas naturels de glissements de terrain co-sismiques. Dans un deuxième temps, le rôle de la forme finie des versants sur la probabilité de grands glissements de terrain a été démontrée en se basant sur des données. Enfin, dans un troisième temps, le potentiel effet d’un grand évènement érosif sur la sismicité a été exploré à l’aide d’un modèle numérique de cycle sismique dans lequel ont été implémentées des variations temporelles de la contrainte normale sur la faille. Les résultats mettent en évidence le rôle du volume de sédiments, mais aussi de leur temps d’export. En particulier, les paysages caractérisés par une hauteur unstable des versants importante pourraient, en favorisant de grands glissements de terrain, induire une érosion assez importante et rapide pour modifier de façon significative la sismicité régionale. / Interactions between tectonic processes and erosion have been poorly investigated at short time-scales (<1000 years). However, earthquakes can largely contribute to the erosion of mountain belts by triggering widespread landsliding. Moreover, recent studies have shown that such large erosional events could induce stress changes in the fault environment efficient enough to influence regional seismicity. In this thesis, this problematic is tackled through a numerical approach. Firstly, the development of a simple mechanical model accounting for the complexity and variability of natural hillslopes allowed to demonstrate the role of mechanical parameters (cohesion and friction), and of hillslope shape in the probability density function of landslide sizes. This model has been validated using natural cases of co-seismic landsliding. Secondly, the role of unstable hillslope height on large landslide probability has been demonstrated based on natural data, and the exponential distribution of this unstable height has ben shown. Finally, the potential effect of a large erosional event on seismicity has been explored with a numerical model of seismic cycle, in which has been implemented temporal normal stress variations. The results emphasize the role of eroded sediment volume, but also of the export time of sediments away from the mountain belt. In landscape with high unstable hillslopes, large landslides are favored and in turn, could induce fast an important enough erosion to modify regional seismicity.

L’explosion du nombre et de la variété des données géodésiques, sismologiques et tsunami disponibles est une opportunité exceptionnelle pour produire de nouveaux modèles de la source sismique. Mais ces données n’apportent pas toutes la même information et sont soumises à différentes sources d’incertitudes, rendant la solution au problème inverse non-unique. Dans cette thèse, nous utilisons une méthode d’échantillonnage bayésien pour produire de nouveaux modèles de glissement moins assujettis au sur-ajustement des données et permettant une estimation réaliste de l’incertitude associée aux paramètres estimés. Nous l’appliquons à l’étude du glissement dans trois contextes tectoniques différents : le séisme de Landers (1992, Mw=7.3), la zone de subduction équato-colombienne où s’est produit le séisme de Pedernales (2016, Mw=7.8), et le séisme intra-plaque de Tehuantepec (2017, Mw=8.2). À travers ce travail, nous démontrons l’importance de la considération rigoureuse des incertitudes et les atouts de l’approche bayésienne pour l’étude des différentes phases du cycle sismique. / The explosion in the amount and variety of available geodetic, tsunami, and seismological observations offers an outstanding opportunity to develop new seismic source models. But these data are sensitive to different sources of uncertainty and provide heterogeneous information, which makes the solution of the inverse problem non-unique.In this thesis, we use a Bayesian sampling method to propose new slip models, which benefit from an objective weighting of the various datasets by combining observational and modelling errors. These models are less affected by data overfit and allow a realistic assessment of posterior uncertainties. We apply this method to the study of slip processes occurring in three different tectonic contexts: the Landers earthquake (1992, Mw=7.3), the Ecuador-Colombia subduction zone which hosted the Pedernales earthquake (2016, Mw=7.8), and the intraslab Tehuantepec earthquake (2017, Mw=8.2). Through these analyses, we demonstrate how the study of the seismic cycle can benefit from rigorous uncertainty estimates and Bayesian sampling.

Em geral, os desenvolvimentos na literatura e em códigos de construção voltados para projeto sísmico tem grande ênfase em edifícios civis e seu respectivo comportamento dinâmico. Entretanto, em diversas ocasiões, faz-se necessário o projeto e dimensionamento de equipamentos ou estruturas de geometria e comportamento distintos dos de um edifício usual. Contudo, são encontradas em diferentes normas afirmações e advertências de que as informações lá contidas aplicam-se inteiramente a essas estruturas ou construções similares. Nesses documentos, emitidos por vários países para aplicação em seus respectivos territórios, são estabelecidos procedimentos e métodos. Ademais, opções para análise são propostas, com base em diversos fatores como o tipo de estrutura resistente, a função da edificação, os custos relacionados, a importância da obra e as características geológicas do local de construção. Nesse trabalho, foi realizado o estudo de estruturas para máquinas de fabricação de papel, de modo analítico e por meio do método dos elementos finitos, com respeito a projeto sísmico. Esses equipamentos consistem de pórticos metálicos suportados por estruturas civis, e que suportam rotores por cuja superfície passa o papel durante operação. Os métodos usualmente presentes em normas, força horizontal equivalente, análise espectral e análise transiente com históricos de acelerações no tempo foram aplicados, e suas respostas comparadas e comentadas. Buscou-se como resultado uma melhor compreensão das considerações e dos métodos mais adequados para essas estruturas, assim como das eventuais variações ocasionadas pela sua aplicação. / Usually, the progresses in codes and technical literature regarding seismic analyses are aimed at civil buildings and their dynamic behavior. Nevertheless, frequently, the dimensioning and construction of equipments or structures with distinct geometry and behavior are required. In numerous codes, though, statements that the comprised information should be fully applied solely to buildings and similar constructions are found. In these codes, issued by many countries for the application in their respective territories, there are procedures and criteria established for seismic design. Moreover, applicable analysis methods are presented, and the selection of which one to employ is based on details as type of resistant systems, intended occupation, rebuilding costs, significance and the geological features of the erection site. In this work, the study of structures for paper production machines is presented, regarding seismic analysis and employing analytical and the finite element methods. These machines consist of metallic frames supported by civil structures and supporting rotors, whose surfaces are in contact with the paper web. The methods usually found in codes, equivalent lateral force, spectrum analysis and transient with acceleration time history were considered, and their results compared and commented afterwards. A better understanding of the more appropriate methods and input parameters for these structures was intended, as well as of any eventual deviation caused by their use.

In contrast to the oceans, deformation in the continental lithosphere is distributed over broad regions. This dissertation is composed of three separate but related studies investigating the kinematics and dynamics of such deformation. The first two studies look at the Makran subduction zone, and the third focusses on deformation in South East Tibet. The first study is an investigation of the 11 May 2013 M w 6.1 Minab earthquake which occurred at the western end of the Makran subduction zone, adjacent to the transition to continent-continent collision in the Zagros mountains. Seismological, geodetic and field results are used to study the source parameters and slip distribution of this earthquake, and demonstrate that the earthquake was left-lateral and occurred on a fault striking ENE–WSW; approximately perpendicular to previously studied faults in the adjacent Minab-Zendan-Palami fault zone. Geological and geomorphological observations of similar faults in the vicinity are used to infer that vertical-axis rotations allow a series of such faults to accommodate ∼15–19 mm/yr of N–S right-lateral shear. The dynamic implications for the transition between subduction and continental collision are discussed. The second study looks at the Makran region as a whole. First, the shape and depth of the interface with the Arabian plate is constrained by modelling the depths and mechanisms of earthquakes across the region, and combining these with additional seismological constraints. These constraints on the subduction interface are used to investigate elastic strain accumulation on the megathrust in the western Makran, which has important implications for seismic and tsunami hazard in the region. Second, the kinematics at the northern edge of the Makran accretionary prism are investigated using a combination of geodetic and geomorphological observations, addressing the long-standing tectonic problem of how the right-lateral shear taken up by strike-slip faulting in the Sistan Suture Zone in eastern Iran is accommodated at the zone’s southern end. Finally, the kinematics and dynamics of the accretionary prism are investigated. By considering the kinematics of the 2013 Balochistan and Minab earthquakes, local gravitational and far-field compressive forces in the Makran accretionary prism are inferred to be balanced. This force balance allows the mean shear stress and effective coefficient of friction on the Makran megathrust to be calculated, 5–35 MPa and 0.01–0.03 respectively. The final part of this thesis focusses on the temporal evolution of topography in South East Tibet. Recently published paleoaltimetry results based on stable-isotope geochemistry are used to provide constraints on vertical motions. These demonstrate that uplift is much slower than had previously been suggested from thermochronometric data. Numerical modelling of the time evolution of a gravitationally-driven fluid is used to investigate the effect of lateral rheological contrasts on the shape and evolution of topography. In such a flow, material at the surface can be transported hundreds of kilometres, an effect which should be accounted for in paleoaltimetric analysis. Lateral rheological contrasts, analogous to the relatively undeforming Sichuan Basin and Central Lowlands of Myanmar, can reproduce the main features of the present-day topography, GPS velocity field and earthquake-derived strain rate without the need for a low-viscosity lower-crustal channel.

On October 8th 2005 the villages surrounding Chinati bazaar in Bagh district of Pakistani-administered Kashmir (PaK) were hit by an earthquake measuring 7.6 on the Richter scale that affected the lives of more than 3.5 million people in PaK and Khyber Pukhtunkhwa. In this thesis I attempt to understand, through the stories and narratives of the people of Chinati bazaar, how they lived through, made sense of, and dealt with the earthquake and its aftermath. I use participant observation and conversations to tell the stories of those affected by the earthquake in their own voices as much as possible. The storytellers of the bazaar lived through two types of events: the earthquake itself and the post-earthquake rehabilitation and reconstruction process. The latter brought with it both positive and negative impacts: if, on the one hand, it brought progress and a new hope that life could be ‘Built Back Better', on the other hand, it brought a different type of suffering – one that led to a loss of honour and dignity, resulted in social upheavals, and led to the exclusion and marginalization of certain groups. In this thesis I focus on both these ‘events'. Through these stories I build an argument about post-disaster discourses of change. I argue that while the narratives of the storytellers of Chinati bazaar posit the earthquake as a point of rupture in their confabulated stories, from which the collective memory of the bazaar dates its movement towards becoming modern and global, these changes have their origins instead in ‘bigger' stories of modernisation and globalisation that predate the earthquake and that highlight and emphasise more continuous processes of change that have been occurring over a longer period of time. In this thesis I analyse how these two competing discourses of rupture and dramatic change on the one hand, and slow, continuous change on the other, play out in the lives of the storytellers of Chinati Bazaar.

Several laterally extensive candidate tsunami deposits are preserved along coastlines facing the eastern Java Trench, indicating it has experienced mega-thrust earthquakes in the past. We investigated 37 coastal sites in Bali, Lombok, Sumba and Timor islands, many of which preserve course sand and pebble layers that overlie sharp basal contacts with scour marks into the mud, fine upward in grain size, and have bimodal grain size distributions. Other unique features are the common occurrence of marine fossils and concentrations of heavy minerals. The occurrence of these high-energy deposits interlayered with clay-rich units indicates the coarse clastics are anomalous because they were deposited in what is normally a very low-energy depositional environment. The lateral extent and paucity of thin, coarse clastic layers with marine organisms are inconsistent with local stream flood event, and the proximity to the equator of the sites diminishes the possibility of marine flood events from cyclones. The sparse, but consistent, the occurrence of at least two candidate tsunami deposits at depths of 1 and 2 meters over 950 km along the strike of the Java Trench may reveal that mega-thrust earthquakes have occurred there and generated giant tsunamis in the recent past.Five widely scattered imbricated boulder deposits are also found on Bali, Lombok, and Sumba. The boulders consist of slabs of hardpan up to 2.5 m in length and 80 cm thick that was torn from a near-shore seabed and stacked on top of one another. Some of the boulders were carried over the erosional coastal bank and deposited up to 100 meters inland. Comparisons with imbricated boulder ridges formed during the 1994 tsunami in east Java indicate that these deposits are from one or multiple tsunamis sourced by the Java Trench.Experiments in effective ways to communicate and implement tsunami disaster mitigation strategies have led us to train local communities about the 20-20-20 rule. If coastal communities experience more than 20 seconds of shaking from an earthquake, even if it is not intense, they should evacuate the coast. The time delay between the earthquake and arrival of tsunami waves is around 20 minutes, which is the time window for evacuation. Some tsunami waves may be as high as 20 meters, which is the target elevation for evacuation. Adopting the 20-20-20 rule could save thousands of lives throughout the region, especially in Bali where nearly 1 million people inhabit likely tsunami inundation zones.

We studied a paleoseismic trench that was excavated across the Banning strand of the San Andreas Fault by Petra Geosciences (33.9172°, -116.538°). The trench exposed a ~40 m wide fault zone in interbedded alluvial sand gravel, silt and clay deposits. We present the first paleoseismic record for the Banning strand of the southern San Andreas Fault. The most recent event occurred sometime between 730 and 950 cal BP, potentially coincident with rupture of the San Gorgonio Pass thrust. We interpret that five earthquakes have occurred since 3.3-2.5 ka and eight earthquakes have likely occurred since 7.1-5.7 ka. It is possible that additional events may have occurred without being recognized, especially in the deeper section the stratigraphy, which was not fully exposed across the fault zone. We calculate an average recurrence interval of 380 - 640 yrs based on four complete earthquake cycles between earthquakes 1 and 5. The average recurrence interval is thus equivalent to or less than the elapsed time since the most recent event on the Banning strand. The recurrence interval is similar to the San Gorgonio Pass (450-1850 years) but longer than that for the Mission Creek strand (~220 years).

On November 6, 1988, two strong earthquakes (Mw: 7.0 and 6.8) separated by about 13 minutes occurred in Yunnan Province, China. The aftershocks located by Kunming Telemetered Seismic Network form a lineament approximately 120 km long and 20 km wide with the long dimension oriented approximately N30°W. The epicenter of the first event lies about 30 km from the southern terminus of the aftershock zone while the epicenter of the second event is 60 km further to the northwest. Field investigations indicate that the surface fault ruptures associated with the first and second shock and a variety of ground deformations. We analyze teleseismic data recorded by the GDSN network to determine the rupture process of these two mainshocks (referred to as Ml and M2) and the two largest aftershocks (referred to as Al and A2). Inversion of long-period body waves gives the following centroid source parameters for Ml: strike 154°±4°, dip 86°±1°, slip 181°±1°, centroid depth shallower than 15 km (least-misfit centroid depth 12 km), and seismic moment 4.5-4.9 X 10²⁶ dyn cm (least-misfit seismic moment 4.6 X 10²⁶ dyn cm). The source time function, further constrained by broadband seismograms, indicates that the source duration for this event is 12 seconds. Due to signal interference with Ml, body wave inversion techniques cannot be applied to M2. The Rayleigh waves provide a better look at this event. In order to identify the energy contributions from the two events, group velocity analysis was performed on the surface wave trains. The energy from the individual events was then isolated based on their dispersion patterns. The amplitude spectra in the period range of 100 to 66 s were inverted for the source parameters. The inversion constrains the strike of M2 precisely (155°±3°), however, dip and slip angles were not well resolved by the inversion. Similar Rayleigh wave amplitude spectra and radiation patterns of Ml and M2, however, suggest that they had very similar mechanisms and centroid depths. On the average, the amplitude spectra of M2 are smaller than those of Ml by a factor of 2.2, indicating the seismic moment of M2 is 2.1 X 10²⁶ dyn cm. The two largest aftershocks, Al (Mw 6.1) and A2 (Mw 5.3), which occurred at the southern terminus of the aftershock zone, were analyzed by modeling teleseismic and strong ground motion data. Teleseismic body wave inversion gives source orientation of Al: strike 165°±2.5°, dip 90°±1.5°, slip 178°±0.5°, centroid depth shallower than 12 km (least-misfit centroid depth 7 km from broadband waveform inversion), and seismic moment 1.5-1.6 X 10²⁵ dyn cm. The inversion of A2 gives the source orientation and centroid depth very similar to those of Al. The seismic moment for this event is 1.3-1.6 X 10²⁴ dyn cm. Modeling of strong ground motion seismograms adds more constraints on centroid depths and source time functions of Al and A2. To minimize the effect of scattering caused by upper crustal heterogeneity, we confined our analysis to frequencies lower than 1 Hz. A crustal model, with a low velocity sedimentary layer, was found that predicts common features of observed strong ground motion seismograms for both events. Derived source orientation is consistent with that found from teleseismic body wave inversion. The centroid depths of Al and A2 were constrained to be between 4 and 12 km. A source duration of 7 s and 2 s was obtained for Al and A2, respectively. Derived rupture parameters of Ml and M2, aftershock distribution, field investigations, geological information and concepts of geometrical barriers and fault asperities, indicate that the preexisting fault intersections played the key role in rupture terminations and initiations. The 12 s source duration of Ml and about 60 km long zone of ground deformation along the strike suggest that Ml rupture was bilateral. The rupture initiated near a fault intersection and propagated to NNW and SSE along the strike. The SSE propagating rupture was terminated by a preexisting fault which intersects the ruptured fault 30 km to the south. The aftershock Al and A2 as well as a dense group of small aftershocks were associated with the termination of the SSE segment. The NNW propagating rupture was also terminated by a NE striking preexisting fault on which several of the largest aftershocks appear to have occurred. This NE striking fault right-laterally offsets the fault on which Ml and M2 occurred forming a geometrical barrier for the rupture. M2 presumably nucleated near this barrier and unilaterally ruptured about 25 km toward NNW where it was terminated by a well documented preexisting fault. / Graduation date: 1992

Accurate earthquake prediction is a difficult, unsolved problem that is central to the ambitions of many geoscientists. Understanding why earthquakes occur requires a profound understanding of many interrelated processes; our planet functions as a massive, complex system. Scientific visualization can be applied to such problems to improve understanding and reveal relationships between data. There are several challenges inherent to visualizing seismic data: working with large, high-resolution 3D and 4D data sets in a myriad of formats, integrating and rendering multiple models in the same space, and the need for real-time interactivity and intuitive interfaces. This work describes a product of the collaboration between computer science and geophysics. TerraVis is a real-time system that incorporates advanced visualization techniques for seismic data. The software can process and efficiently render digital elevation models, earthquake catalogs, fault slip distributions, moment tensor solutions, and scalar fields in the same space. In addition, the software takes advantage of stereoscopic viewing and head tracking for immersion and improved depth perception. During reconstruction efforts after the devastating 2010 earthquake in Haiti, TerraVis was demonstrated as a tool for assessing the risk of future earthquakes.