Nesse trabalho será estudada a dinâmica de epicentros do modelo Olami-Feder- Christensen (OFC). Para isso, serão usados conceitos e ferramentas de redes complexas. Será analisado, em particular, o grafo de epicentros consecutivos do modelo, onde dois eventos subseqüentes são representados por uma aresta direcionada, cuja origem e vértice incidido representam os respectivos sítios no reticulado. A topologia desse grafo, que possui invariância de escala e correlação entre os graus, revela uma dinâmica característica, com atratores temporários, e quase-periodicidade. Essa dinâmica é comparada com a de terremotos reais, e as limitações do modelo são avaliadas. Em particular, foi constatado que a dinâmica governada por atratores temporários se encontra presente em terremotos reais, porém difere em pontos centrais da observada no modelo OFC. Além da análise da dinâmica dos epicentros, será feito um estudo sistemático de dois comportamentos não-triviais do modelo, o que foi necessário para a análise da dinâmica de epicentros: A identificação e caracterização de um \"efeito de borda\" no modelo, e uma separação de escalas de eventos de diferentes tamanhos, que considera tambémas suas distribuições espaciais. Esses resultados têm uma relevância importante o estudo do modelo de modo geral. Em particular, será retomada a análise da criticalidade do modelo, à luz desses critérios. / We study the dynamics of the epicenters of the Olami-Feder-Christensen model of earthquakes (OFC), using the concepts and tools of complex networks. In particular, we study the graph of consecutive epicenters, where two subsequent events represent a directed edge, and the source and target vertices represent the respective sites on the lattice. The topology of this graph, which exhibits scale-invariance and strong degree correlation, reveals a characteristic dynamics of temporary attractors and quasi-periodicity. This dynamics is compared to that of real seismicity, and the limitations of the model are assessed. The temporary attractor dynamics is also found in real earthquakes, however it differs from the one observed in the model in key points, which will be described in detail. Besides the analysis of the dynamics of the dynamics of epicenters, we systematically study two non-trivial behaviours of the OFC model, which was necessary for the study of the epicenters: The identification and characterization of a \"border effect\" in the model, and the separation of scales in the size of events, which takes into account their spatial distribution. These results have an important relevance to the study of the OFC model in general. In particular, we will revisit the analysis of the criticality of the model, which takes into account these criteria.

Rising incidents of earthquakes caused by human activity in the United States, known as induced earthquakes, is a growing concern. Induced earthquakes may occur when fluid and/or wastewater is injected several kilometers beneath the Earth’s surface into sedimentary rocks. Fluids and pressures can migrate from the sedimentary rocks, which are typically friendlier to fluid flow, into underlying less friendlier crystalline rocks along fluid pathways weakening and possibly reactivating preexisting faults. Understanding potential fluid pathways and/or barriers from the sedimentary rocks to crystalline rocks is crucial. I investigate the structure, composition, and heterogeneity of rocks near the contact between the sedimentary and crystalline rocks, known as nonconformities, and highlight their possible role in the transmission of fluids and porefluid pressures into the crystalline basement. To characterize nonconformities, we examined outcrop analogs and drillcore of nonconformities in New Mexico, Colorado, and Michigan. Geochemical, structural, and hydrological techniques were used to analyze the nonconformities at microscopic to megascopic scales. The nonconformities observed in this study consist of variably deformed, weathered, and altered igneous and metamorphic crystalline basement overlain by sedimentary rocks cut by outcrop- and map-scale faults. The nonconformity at the New Mexico sites includes a clay-rich weathered horizon atop deformed and jointed crystalline basement. Heterogeneity observed in the fracture and joint networks within the crystalline basement contributes to permeability heterogeneity and anisotropy. The crystalline basement adjacent to the nonconformity at the Colorado site is relatively fresh and unweathered and overlain by low permeability sandstones. The nonconformity and underlying slates in the Michigan drillcore are overprinted by hydrothermal alteration and carbonate mineralization, which provides evidence of hydrological communication between sedimentary and crystalline rocks. The nonconformities display a range of structural, hydrological, and geochemical styles and characteristics which vary over relatively small spatial extents. The geological and hydrogeological histories and complexities of nonconformity analogs provide valuable information to understand how fluids, past, and present, interact with the contact. This study introduces some of the factors that may control fluid flow adjacent to nonconformities and their possible significance to the interplay of deformation, fluid flow, and induced seismicity.

3 offprints in back pocket / 186 [26] xiv leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) from the Dept. of Physics, University of Adelaide, 1973

High seismic activity occurs along the Caribbean and the North American Plate boundary beneath the eastern part of Hispaniola. A large number of intermediate to deep earthquakes are clustered between the Puerto Rico Trench to the north and the Muertos Trench to the south suggesting the possibility of concurrent subduction from both north and south. The body wave inversion technique was used to analyze nine earthquakes, the largest teleseismically recorded events since the establishment of WWSSN (World Wide Standardized Seismograph Network) in 1963 in the geographic region between 72°W and 66°W latitude and 16°N and 21°N longitude. Their body-wave magnitude ranges from 5.6 to 6.1. Each event was inverted for strike, dip and slip of the two possible fault planes, as well as for the centroid depth, the total seismic moment and the source time function. In order to optimize the crustal structure parameters used in the body wave inversion method, a two-dimensional geophysical cross-section across Hispaniola was constructed by forward modeling of gravity and magnetics data. The inversion results are consistent and can be divided into groups according to the depth and the epicentral location of the events. The shallow events, with depths of 6 to 12 km, represent crustal deformation and show thrust mechanisms with large strike-slip component. The intermediate depth events range from 42 to 107 km in depth and occur to the south of eastern Hispaniola. They show clear thrust mechanisms with a consistent dip of the compressional P-axis at about 30° to the north and approximately north-south P-axis strike. The deep earthquakes occur between 110 and 177 km depth, have a steep-dipping tensional T-axis, and define another slab, possibly originating at the Puerto Rico Trench to the north. One m[subscript b]=6.l event, which occurred on 6/24/84, shows opposite orientations of the P- and T-axes from the surrounding intermediate events. It is interpreted as an interface event in the upper mantle. The southern subduction zone is well defined and indicates that the Muertos Trench is active, with the subducting plate dipping to the north beneath eastern Hispaniola. At a depth of about 110 km, the northward dipping slab collides with the almost vertical segment of the other slab. This deep vertical slab segment, extending to at least 200 km in depth, may be a remnant of an earlier subduction zone associated with the Puerto Rico Trench. Alternatively, it may be connected with a more gently dipping part of the slab towards the north or, even in some way, with subduction from the south. / Graduation date: 1990

Graduation date: 1994

Graduation date: 1997

Thesis (Ph.D.)--University of California, Los Angeles, 2004. / Includes bibliographical references.

This research, aimed at advancing the theory of environmental hazard adjustment processes by contrasting households from three cities in a high seismic hazard area with households from three other cities in a moderate seismic hazard area. It identified seven types of stakeholders namely, the risk area residents and their families (primary group), the news media, employers, and friends (secondary group), and federal, state, and local governments (tertiary group), and explained why they are relevant to the adoption of seismic hazard adjustments. It also addressed three key attributes— knowledge, trustworthiness, and responsibility for protection—ascribed to these multiple stakeholders and the relationships of these stakeholder attributes with risk perception, hazard intrusiveness, hazard experience, gender, resource adequacy, fatalism and hazard adjustment adoption. It was specifically concerned with the effects of nested interactions due to trust and power differentials among the seven stakeholders, with the self reported adoption of 16 earthquake protective measures at two points in time (1997 and 1999). Some of the key findings indicate that risk perception, gender, fatalism, city activity in earthquake management and demographic characteristics did not significantly predict hazard adjustment adoption. However, all stakeholder characteristics had significant positive correlations with risk perception and hazard adjustment, implying a peripheral route for social influence. Hazard intrusiveness, hazard experience, and stakeholder knowledge, trustworthiness, and responsibility affected the increased adoption of hazard adjustments by households. Particularly important are the peer groups’ (employers, friends and family) knowledge, trustworthiness and responsibility. These findings suggest, hazard managers cannot count only on the federal, state, and local government advisories put out through the news media to affect community decisions and thereby households’ decisions to take protective actions. Instead, hazard managers need to shift focus and work through peer group networks such as service organizations, industry groups, trade unions, neighborhood organizations, community emergency response teams, faith-based organizations, and educational institutions to increase the knowledge, trustworthiness and responsibility of all in the peer group. This will assure higher household hazard adjustment adoption levels, thus facilitating a reduction in post disaster losses and recovery time.

This thesis examines how 18 University of Canterbury students based in Christchurch experienced housing insecurity during the three years after a series of major earthquakes from late 2010 and throughout 2011. I adopted a qualitative exploratory approach to gather students’ accounts and examine their experiences which were analysed using constructivist grounded theory methods. Three core categories were identified from the data: mobility, recreating security, and loss. Mobility included the effects of relocation and dislocation, as well as how the students searched for stability. Recreating security required a renewed sense of belonging and also addressed the need to feel physically safe. Lastly, loss included the loss of material possessions and also the loss of voice and political representation. The theory that emerged from these findings is that the extent to which students were able to control their mobility largely explained their experiences of housing insecurity. When students experienced a loss of control over their mobility they effectively addressed this by being resourceful and drawing on existing forms of capital. This resourcefulness generated a new form of capital, here called security capital, which represents a conceptual contribution to existing debates on students’ experiences of homelessness in a disaster context.

Seismic site response analysis allows an engineer to assess the effect of local soil conditions on the ground motions expected during an earthquake. In seismic site response analysis, an input ground motion on rock is propagated through a site specific soil column. The computed response at the surface is dependent on both the input ground motion and the soil properties that characterize the site. However, there is uncertainty in both the input ground motion and the soil properties, as well as natural variability in the soil properties across a site. To account for the uncertainty in the input ground motions, engineers use a suite of motions that are selected and scaled to fit a scenario input motion. This study introduces a semi-automated method to select and scale the input motions to fit a target input motion and its variability. The proposed method is intended to replace tedious trials of combinations by hand with combinations performed by a computer. However, as in the traditional selection methods, the final selection of the combination is done by the engineer.The effect of the selected ground motion combination on the computed surface response spectrum from the site response analysis, and its variability, was investigated in this study. The results show by using a combination with as few as five motions, the median surface response spectrum can be predicted with an error of 10%. Additionally, the manner used to scale the input motions does not impact the accuracy of the median surface response spectrum, as long as the median response spectrum of the input combination agrees with the target input response spectrum. However, if the standard deviation of the surface response spectrum is to be considered (e.g., to develop median plus one standard deviation spectra), a input combination of at least 20 motions is recommended and the combination must be scaled such that the standard deviation of the input combination matches the standard deviation of the input target spectrum. Monte Carlo simulations were used to assess the impact of soil property variability on surface spectra computed by seismic site response. The results from this study indicate that by accounting for the variability of the shear-wave velocity profile of a site can cause a significant decrease in the median surface response spectrum, as well as a slight increase in the standard deviation of the surface response spectrum at periods less than the site period. By considering the variability of the nonlinear properties (shear modulus reduction and damping ratio) the median response spectrum decreased only slightly, but the standard deviation increased in a manner similar to the increase observed when considering the variability of the shear-wave velocity profile. Simultaneously considering the variability of the shear-wave velocity profile and nonlinear properties resulted in a median surface response spectrumsimilar to the median surface response spectrumcomputed with considering the variability of the shear-wave velocity alone. However, the standard deviation of the surface response spectrum was larger than the standard deviation computed by independent consideration of the variability of the shear-wave velocity or nonlinear properties.