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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Deep Impact: Geo-Simulations as a Policy Toolkit for Natural Disasters

Naqvi, Asjad January 2017 (has links) (PDF)
Adverse post-natural disaster outcomes in low-income regions, like elevated internal migration levels and low consumption levels, are the result of market failures, poor mechanisms for stabilizing income, and missing insurance markets, which force the affected population to respond, and adapt to the shock they face. In a spatial environment, with multiple locations with independent but interconnected markets, these transitions quickly become complex and highly non-linear due to the feedback loops between the micro individual-level decisions and the meso location-wise market decisions. To capture these continuously evolving micro-meso interactions, this paper presents a spatially explicit bottom-up agent-based model to analyze natural disaster-like shocks to low-income regions. The aim of the model is to temporally and spatially track how population distributions, income, and consumption levels evolve, in order to identify low-income workers that are "food insecure". The model is applied to the 2005 earthquake in northern Pakistan, which faced catastrophic losses and high levels of displacement in a short time span, and with market disruptions, resulted in high levels of food insecurity. The model is calibrated to pre-crisis trends, and shocked using distance-based output and labor loss functions to replicate the earthquake impact. Model results show, how various factors like existing income and saving levels, distance from the fault line, and connectivity to other locations, can give insights into the spatial and temporal emergence of vulnerabilities. The simulation framework presented here, leaps beyond existing modeling efforts, which usually deals with macro long-term loss estimates, and allows policy makers to come up with informed short-term policies in an environment where data is non-existent, policy response is time dependent, and resources are limited.
482

Crustal deformation associated with great subduction earthquakes

Sun, Tianhaozhe 28 July 2017 (has links)
The slip behaviour of subduction faults and the viscoelastic rheology of Earth’s mantle govern crustal deformation throughout the subduction earthquake cycle. This Ph.D. dissertation presents research results on two topics: (1) coseismic and postseismic slip of the shallowest segment of subduction faults and (2) postseismic deformation following great subduction earthquakes controlled by mantle viscoelasticity. Topic 1: Slip behaviour of the shallowest subduction faults. By modelling high-resolution cross-trench bathymetry surveys before and after the 2011 Mw 9.0 Tohoku-oki earthquake, we determine the magnitude and distribution of coseismic slip over the most near-trench 40 km of the Japan Trench megathrust. The inferred > 60 m average slip and a gentle increase by 5 m towards the trench over this distance indicate moderate degree of net coseismic weakening of the shallow fault. Using near-trench seafloor and sub-seafloor fluid pressure variations as strain indicators in conjunction with land-based geodetic measurements, we determine coseismic-slip and afterslip distributions of the 2012 Mw 7.6 Costa Rica earthquake. Here, trench-breaching slip similar to the Tohoku-oki rupture did not occur during the earthquake, but afterslip extended to the trench axis and reached ~0.7 m over 1.3 years after the earthquake, exhibiting a velocity-strengthening behaviour. These two contrasting examples bracket a possibly wide range of slip behaviour of the shallow megathrust. They help us understand why large tsunamis are generated by some but not all subduction earthquakes. Topic 2: Postseismic deformation following great subduction earthquakes. Due to the asymmetry of megathrust rupture, with the upper plate undergoing greater coseismic tension than the incoming plate, viscoelastic stress relaxation causes the trench and land areas to move in opposite, opposing directions immediately after the earthquake. Seafloor geodetic measurements following the 2011 Tohoku-oki earthquake, modelled in this work, provided the first direct observational evidence for this effect. Systematic modelling studies in this work suggest that such viscoelastic opposing motion should be common to all Mw ≥ 8 subduction earthquakes. As the effect of viscoelastic relaxation decays with time and the effect of fault relocking becomes increasingly dominant, the dividing boundary of the opposing motion continues to migrate away from the rupture area. Comparative studies of ten 8 ≤ Mw ≤ 9.5 subduction earthquakes in this dissertation quantifies the primary role of earthquake size in controlling the “speed” of the evolution of this deformation. Larger earthquakes are followed by longer-lived opposing motion that affects a broader region of the upper plate. / Graduate
483

The Role of Education on Disaster Preparedness: Case Study of 2012 Indian Ocean Earthquakes on Thailand's Andaman Coast

Muttarak, Raya, Pothisiri, Wiraporn January 2013 (has links) (PDF)
In this paper we investigate how well residents of the Andaman coast in Phang Nga province, Thailand, are prepared for earthquakes and tsunami. It is hypothesized that formal education can promote disaster preparedness because education enhances individual cognitive and learning skills, as well as access to information. A survey was conducted of 557 households in the areas that received tsunami warnings following the Indian Ocean earthquakes on 11 April 2012. Interviews were carried out during the period of numerous aftershocks, which put residents in the region on high alert. The respondents were asked what emergency preparedness measures they had taken following the 11 April earthquakes. Using the partial proportional odds model, the paper investigates determinants of personal disaster preparedness measured as the number of preparedness actions taken. Controlling for village effects, we find that formal education, measured at the individual, household, and community levels, has a positive relationship with taking preparedness measures. For the survey group without past disaster experience, the education level of household members is positively related to disaster preparedness. The findings also show that disaster-related training is most effective for individuals with high educational attainment. Furthermore, living in a community with a higher proportion of women who have at least a secondary education increases the likelihood of disaster preparedness. In conclusion, we found that formal education can increase disaster preparedness and reduce vulnerability to natural hazards.
484

Establishing a seismic retrofit policy : Implications for buildings with historical significance in the lower mainland of British Columbia

Keenan, Kathleen Marie 05 1900 (has links)
Earthquakes, such as the ones capable of affecting the Lower Mainland of British Columbia, can have a devastating effect on the environment that people live and work in. The purpose of this thesis is to examine methods of dealing with the hazards and problems created by existing, often historically significant, unreinforced buildings in earthquake-prone areas. Gaining an understanding of the complexity of this problem and the issues involved in establishing hazard mitigation policies gives insight into the policy-making process. The research indicates that a number of internal and external factors affect the formulation, adoption, and implementation of hazard mitigation policies. Despite limited awareness of the problem, low political salience of the issue, and limited resources in most communities, there are many steps that can be taken that will reduce the public's exposure to the risks created by unreinforced buildings and strengthen historically significant buildings that hold value, socially, economically, and culturally. Establishing more extensive mitigative measures, such as implementing a seismic retrofit policy, requires a decision-making process that must involve the people who live and work within that community. Each community, through a process of consultation with the stakeholders, needs to decide if it is in their interest to pursue hazard mitigation strategies to reduce the seismic risk. There is a need to integrate hazard mitigation strategies into the daily decision-making process of politicians and planners. The thesis concludes with some points for stakeholders to consider in designing policy to reduce the earthquake hazard that all the communities in the Lower Mainland of British Columbia face. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate
485

Experimental and Numerical Investigation of Liquid Storage Tanks Under Seismic Excitation

Bahreini Toussi, Iman January 2016 (has links)
Liquid storage tanks are a crucial type of structures. They are used to store various types of liquids and liquefied gases in different situations. In seismic regions, functionality of these structures after severe earthquakes is an important factor in their design. In earthquake-prone regions, the sloshing phenomena has an important role in the design procedure. Current design codes and guidelines (e.g. ACI 350.3 and ASCE 7) are based on analytical studies that in some cases can be inaccurate in prediction of forces and pressures. Since a long time ago scientists have studied the sloshing phenomena in liquid storage tanks with different methods including analytical, numerical and experimental studies. In the current study, rectangular ground-supported tanks are studied and the effect of seismic loading on them is investigated both experimentally and numerically. For the experimental tests, the tanks were placed on a shaking table and using high-speed HD cameras, tests were filmed and later analyzed frame by frame to capture the critical moments. To investigate the bi-lateral effect of base excitation on the tanks, they were oriented on the table with four different angles. In the numerical study, a computational fluid dynamics tool - OpenFOAM - was used to simulate the tank motion and finally the results were compared with the experiment in order to develop a reliable model.
486

A visualization of an experiment on a shake table

Penn, Michael January 1991 (has links)
A model to enable a graphics presentation of an experiment has been developed. The model was developed specifically for experiments run on a shake table for earthquake simulating tests but could be used for any experiment that involves movement and instrumentation. By integrating the results obtained from the instruments used during an experiment it is possible to display, on a computer screen, the motion of the model being tested. By use of visualization techniques it is possible to obtain a graphical representation of all the instruments being used and thereby producing a picture of the entire experiment. / Science, Faculty of / Computer Science, Department of / Graduate
487

Inversion and appraisal for the one-dimensional magnetotellurics problem

Dosso, Stanley Edward January 1990 (has links)
The method of magnetotellurics (MT) uses surface measurements of naturally-occurring electromagnetic fields to investigate the conductivity distribution within the Earth. In many interpretations it is adequate to represent the conductivity structure by a one-dimensional (1-D) model. Inferring information about this model from surface field measurements is a non-linear inverse problem. In this thesis, linearized construction and appraisal algorithms are developed for the 1-D MT inverse problem. To formulate a linearized approach, the forward operator is expanded in a generalized Taylor series and second-order terms are neglected. The resulting linear problem may be solved using techniques of linear inverse theory. Since higher-order terms are neglected, the linear problem is only approximate, and this process is repeated iteratively until an acceptable model is achieved. Linearized methods have the advantage that, with an appropriate transformation, a solution may be found which minimizes a particular functional of the model known as a model norm. By explicitly minimizing the model norm at each iteration, it is hypothesized that the final constructed model represents the global minimum of this functional; however, in practice, it is difficult to verify that a global (rather than local) minimum has been found. The linearization of the MT problem is considered in detail in this thesis by deriving complete expansions in terms of Fréchet differential series for several choices of response functional, and verifying that the responses are indeed Fréchet differentiable. The relative linearity of these responses is quantified by examining the ratio of non-linear to linear terms in order to determine the best choice for a linearized approach. In addition, the similitude equation for MT is considered as an alternative formulation to linearization and found to be inadequate in that it implicitly neglects first-order terms. Appropriate choices of the model norm allow linearized inversion algorithms to be formulated which minimize a measure of the model structure or of the deviation from a (known) base model. These inversions construct the minimum-structure and smallest-deviatoric model, respectively. In addition, minimizing I₂ model norms lead to smooth solutions which represent structure in terms of continuous gradients, whereas minimizing I₁ norms yield layered conductivity models with structural variations occurring discontinuously. These two formulations offer complementary representations of the Earth, and in practice, a complete interpretation should consider both. The algorithms developed here consider the model to be either conductivity or log conductivity, include an arbitrary weighting function in the model norm, and fit the data to a specified level of misfit: this provides considerable flexibility in constructing 1-D models from MT responses. Linearized inversions may also be formulated to construct extremal models which minimize or maximize localized conductivity averages of the model. These extremal models provide bounds for the average conductivity over the region of interest, and thus may be used to appraise model features. An efficient, robust appraisal algorithm has been developed using linear programming to extremize the conductivity averages. For optimal results, the extremal models must be geophysically reasonable, and bounding the total variation in order to limit unrealistic structure is an important constraint. Since the extremal models are constructed via linearized inversion, the possibility always exists that the computed bounds represent local rather than global extrema. In order to corroborate the results, extremal models are also computed using simulated annealing optimization. Simulated annealing makes no approximations and is well known for its inherent ability to avoid unfavourable local minima. Although the method is considerably slower than linearized analysis, it represents a general and interesting new appraisal technique. The construction and appraisal methods developed here are illustrated using synthetic test cases and MT field data collected as part of the LITHOPROBE project. In addition, the model construction techniques are used to analyze MT responses measured at a number of sites on Vancouver Island, Canada, to investigate the monitoring of local changes in conductivity as a precursor for earthquakes. MT responses measured at the same site over a period of four years are analyzed and indicate no significant changes in the conductivity (no earthquakes of magnitude greater than 3.0 occurred in this period). Conductivity profiles at a number of sites are also considered in an attempt to infer the regional structure. Finally, a method of correcting linearized inversions is developed. The corrections consist of successively approximating an analytic expression for the linearization error. The method would seem to represent a novel and practical approach that can significantly reduce the number of linearized iterations. In addition, a correspondence between the correction steps and iterations of the modified Newton's method for operators is established. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
488

Seismic Risk Assessment of Unreinforced Masonry Buildings Using Fuzzy Based Techniques for the Regional Seismic Risk Assessment of Ottawa, Ontario

El Sabbagh, Amid January 2014 (has links)
Unreinforced masonry construction is considered to be the most vulnerable forms of construction as demonstrated through recent earthquakes. In Canada, many densely populated cities such as (Vancouver, Montreal and Ottawa) have large inventories of seismically vulnerable masonry structures. Although measures have been taken to rehabilitate and increase the seismic resistance of important and historic structures, many existing unreinforced masonry structures have not been retrofitted and remain at risk in the event of a large magnitude earthquake. There is therefore a need to identify buildings at risk and develop tools for assessing the seismic vulnerability of existing unreinforced masonry structures in Canada. This thesis presents results from an ongoing research program which forms part of a multi-disciplinary effort between the University of Ottawa’s Hazard Mitigation and Disaster Management Research Centre and the Geological Survey of Canada (NRCAN) to assess the seismic vulnerability of buildings in dense urban areas such as Ottawa, Ontario. A risk-based seismic assessment tool (CanRisk) has been developed to assess the seismic vulnerability of existing unreinforced masonry and reinforced concrete structures. The seismic risk assessment tool exploits the use of fuzzy logic, a soft computing technique, to capture the vagueness and uncertainty within the evaluation of the performance of a given building. In order to conduct seismic risk assessments, a general building inventory and its spatial distribution and variability is required for earthquake loss estimations. The Urban Rapid Assessment Tool (Urban RAT) is designed for the rapid collection of building data in urban centres. This Geographic Information System (GIS) based assessment tool allows for intense data collection and revolutionizes the traditional sidewalk survey approach for collecting building data. The application of CanRisk and the Urban RAT tool to the City of Ottawa is discussed in the following thesis. Data collection of over 13,000 buildings has been obtained including the seismic risk assessment of 1,465 unreinforced masonry buildings. A case study of selected URM buildings located in the City of Ottawa was conducted using CanRisk. Data obtained from the 2011 Christchurch Earthquake in New Zealand was utilized for verification of the tool.
489

Geographies of responsibility: the cultural logic of 21st century weather emergencies

Ambrose, Jennifer Marie 01 December 2014 (has links)
Geographies of Responsibility: The Cultural Logic of 21st Century Weather Emergencies analyzes the role of narrative in contemporary severe weather events. The speed and diversity of media through which we now communicate "the weather" significantly impact how U.S. communities experience these events and their possible social, cultural, and political meanings. This project explores four weather emergencies, covering physical geographies of the far northwest, Great Plains, mid-Atlantic, and Caribbean, that were circulated and reframed via a range of media--from newspapers to television, social, and new media--who discussed these events, and to what ends. Chapter 1 examines reporting on the 2004 Alaska wildfires directed at U.S. national and Alaska state communities to explore the importance of the "nation" as a continuing relevant relative spatial scale. Chapter 2 investigates the 2007 Greensburg tornado and subsequent "green" (re)development of the town. Chapter 3 analyzes the 2010 "Snowmageddon" blizzards in Washington, D.C., which initiated "playful" acts that highlighted how urban economic realities and historical social geographies of race are embedded in particular urban sites. Chapter 4 explores the 2010 Haiti earthquake, which evoked economies of responsibility across multiple scales of mobilization that reiterated the cultural and historical "weather map" laid down by Hurricane Katrina. These mass mediated weather events each mobilized attention and response through narratives that evoked an emergency to communities across multiple geographic scales put into relationships with one another through storylines far more complex than an analysis of how "global" and local weather systems co-create each other.
490

A SIMPLIFIED SEISMIC ASSESSMENT PROCEDURE FOR BRIDGES IN INDIANA

Leslie S Bonthron (9074318) 27 July 2020 (has links)
<p>The potential for damaging earthquakes in Indiana from the New Madrid Seismic Zone (NMSZ) has been known for 200 years. However, the identification of the Wabash Valley Seismic Zone (WVSZ) has increased the awareness of the seismic risk in Indiana. The Indiana Department of Transportation (INDOT) has been preparing for the occurrence of a large event by reducing the vulnerability of its bridge network, specifically in the Vincennes district. To facilitate the work of the State of Indiana, in this thesis the development of a simplified assessment procedure for the bridges typical in Indiana is presented. The thesis also includes a proposed simplified assessment tool, Indiana Seismic Assessment Tool (INSAT) to rapidly assess the vulnerability of INDOT’s bridges. To understand the behavior and vulnerabilities typical to bridges in Indiana, a set of 100 representative bridges was chosen for a detailed seismic assessment. The assessment is completed using information from the bridge drawings and 100 synthetic ground motion time-histories. The results of the detailed assessment, found in the SPR 4222 final report, are used to develop trends in mass and stiffness across bridge types, to identify vulnerability thresholds for application in the simplified assessment, and to validate the simplified assessment procedure.</p><p> </p><p>The simplified seismic assessment procedure presented in this thesis and INSAT leverage information found in BIAS. However, in its current state, BIAS does not contain enough information to perform a robust seismic assessment. Eight data items are recommended for implementation into BIAS in order to carry out a simplified assessment. These eight data items are the substructure type, the abutment type, the number of elements, the element height, length, and width, the deck thickness, and a height ratio flag. While some of these items can be estimated, the best version of the simplified assessment utilizes all of the recommended data items and leads to an 87% agreement between the vulnerability classifications of the simplified assessment and the detailed assessment.</p>

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