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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.
11

Simulations de tsunamis générés par glissements de terrains aériens / Simulation of tsunami waves generated by subaerial landslide.

Viroulet, Sylvain 16 December 2013 (has links)
Les vagues de tsunami sont des ondes longues générées par des événements géophysiques impulsifs de la croûte terrestre, de volcans, d’impacts d’astéroïdes et de glissements de terrain. Si la majorité des tsunamis sont d'origine tectonique, l'effondrement en masse d'un relief côtier peut constituer une source importante de l’aléa tsunami. Après une brève introduction sur les différentes générations de tsunamis dans l'histoire et les enjeux de cette thèse, le chapitre 1 présente les principaux résultats bibliographiques sur la génération et la propagation de tsunamis, ainsi qu’un rappel sur l’établissement des équations s’appliquant à l’étude des vagues extrêmes. Le second chapitre est dédié à la présentation des différents codes numériques utilisés dans ce manuscrit, à savoir, Gerris et SPHysics. Le chapitre 3 s'intéresse à la génération de tsunami par l’impact d’un bloc solide. Les résultats expérimentaux sont comparés aux résultats numériques des deux codes. A partir de là, une étude systématique a été faite, menant à des lois d’échelles sur le temps d’arrivée et l’amplitude de la première vague générée. Dans le chapitre 4, les interactions entre le glissement de terrain et la vague générée sont étudiées expérimentalement à l'aide d'impact granulaire initialement sec dans l'eau. Une étude systématiques des différents paramètres met en lumière l'importance des propriétés du glissement sur la vague générée. Enfin, Le chapitre 5 est dédié à l’étude de l’effondrement du Cap Canaille à Cassis. Cette étude numérique utilise un modèle de génération et de propagation simplifié afin d'estimer le potentiel destructeur d'un éventuel effondrement majeur. / Tsunami waves are long waves generated by impulsive geophysical events of earth's crust, volcanoes, asteroids impacts or landslides. Even if most of the tsunamis are generated by submarine earthquakes, the massive collapse of coastal landscape may constitute an important source of tsunami hazard. After introducing historical tsunami events, chapter 1 presents a state-of-the-art on the generation and propagation of tsunami waves and the main equations dealing with extreme water waves. Chapter 2 presents the numerical codes used in this thesis: Gerris and SPHysics. Chapter 3 focuses on the generation of tsunami by a solid landslide. Experimental results are compared to numerical simulations obtained using both codes. From this results, we derive scaling laws on the arrival time and amplitude of the first generated wave. The chapter 4 deals with the interactions between the slide and the generated wave by taking into account the impact of an initially dry granular media into water. Systematic studies varying the different parameters exhibit the significance of the internal properties of the slide on the generated wave. Finally, chapter 5 is dedicated to the collapse of the Cap Canaille near Cassis. A idealized model for the generation and the propagation are used to estimate the hazard associated to such a massive collapse.
12

Spatial and Temporal Changes in Tsunami Risk Perception in Canterbury

DuBois, Jennifer Faith January 2007 (has links)
Risk perception for rare, low-probability hazards, such as tsunamis, tends to be low due to individual's unfamiliarity with them and the tendency to see them as synonymous with non-occurrence events. Visitors to an area tend to have even lower risk perception and knowledge of hazards, warning systems and appropriate actions to take during an event. Risk perception, however, can increase, if only temporarily, after a catastrophic event, such as the 2004 Boxing Day tsunami. To determine the changes in resident's knowledge and perception and the differences between those of residents and visitors two surveys were conducted. In the first survey interview style surveying was conducted at eleven locations in the coastal Christchurch and Banks Peninsula area of the Canterbury Region The questionnaire was composed of scaled, open, and closed ended questions and the main themes included knowledge of risk, preparation and warnings, what to do during a tsunami, and changes since the 2004 Boxing Day tsunami. The second survey of five coastal communities was conducted via a postal questionnaire and was aimed at obtaining residential views. Survey data was then analysed with Statistical Package for the Social Sciences (SPSS) statistical software. The residential data was compared with that of the non-residents to determine the differences in perception of residents and visitors. The residential information was then compared with survey data from the 2003 National Coastal Survey. Visitors knew less about general tsunami information such as when the last tsunami occurred and were less likely to believe that a tsunami could occur imminently. Non-residents reported less receipt of information and did considerably less information seeking. Differences in knowledge of warning systems were difficult to ascertain. The Boxing Day event certainly made an impact, increasing people's knowledge and awareness, though most likely only temporarily.
13

The Effects Of The Material Density And Dimensions Of The Landslide On The Generated Tsunamis

Insel, Isil 01 September 2009 (has links) (PDF)
In this thesis study / mechanism and modeling of tsunamis generated by landslides are investigated. Landslide parameters affecting the surface wave characterisics are studied. In order to understand occurance of this kind of tsunamis, among many historical tsunamis, the ones that are triggered by landslides are detected and studied. The generation of the landslide generated tsunamis are modeled using TWO-LAYER model, which solves nonlinear long wave equations simultaneously within two interfacing layers with necessary boundary conditions at the sea bed, interface and water surface. The model is applied to one of the possible landslides at offshore Yalova in the Sea of Marmara. Two of the controlling parameters, which are the density and the thickness of the slid material, are analysed and a sensitivity analysis is performed to determine the level of their effects on the evolution and amplitude of the tsunami source. Furthermore, the propagation and coastal amplification of the landslide generated waves are investigated using the tsunami simulation and visualization code NAMI DANCE. The results are presented, compared and discussed.
14

Database Development For Tsunami Warning System In Mediterranean Basin By Tsunami Modeling

Onat, Yaprak 01 June 2011 (has links) (PDF)
Wider awareness, proper preparedness and effective mitigation strategies need better understanding of tsunamis and tsunami hazard assessment. Tsunami assessment study covers the exchange and enhancement of available earthquake and tsunami data, development of bathymetric and topographic data in sufficient resolution, selection of possible or credible tsunami scenarios, selection and application of the valid and verified numerical tools for tsunami generation, propagation, coastal amplification, inundation and visualization. From this point of view, this thesis deals with all these components of tsunami hazards assessment. The database of 38 different seismic sources is generated and applied to Eastern Mediterranean Basin by using numerical code called NAMI DANCE. Furthermore, the simulation results are compared and discussed. In the thesis, the difficulties in defining seismic source parameters, the effect of dip and rake (slip) angle on seismic generated tsunamis are evaluated. Moreover, the performance of the numerical code, the accuracy of results, the efficiency of the numerical methods in the application to Mediterranean Basin Tsunamis and the comparisons of simulations in nested domains for Bodrum, Kas and Iskenderun are given as case studies. According to the study, north-west and south-west of Turkey may have tsunami risk more than other regions. The maximum wave amplitudes, which may be expected to occur near the shore, are found more than 4 m. However, maximum positive wave amplitude observed in history is approximately 8 m. The arrival time of first wave to hit the coasts vary in a range of 15 to 60 minutes depending on the closeness of the location to the sources&rsquo / epicenter.
15

Risk analysis of coastal flooding due to distant tsunamis

Gica, Edison. January 2005 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 410-414).
16

Klockan 10.31 på morgonen i Khao Lak & The Impossible : Fakta och fiktion i två katastrofskildringar. / At 10.31 in the morning in Khao Lak & The Impossible : Fact and fiction in two disaster books.

Pettersson, Susanna January 2013 (has links)
This essay is about "factionstexter", a combination between fact and fiction, and the problems that can occur when reading them. I present previous resarch on this subject and I focused on docu drama and dramadoc. Bo G Jansson is the researcher I used most frequently in this essay. He describes various types of faction texts in film, television and literature. Annette Årheim´s thesis stands for the didactic portion of the essay. She has done interviews with students about texts with a reality background and presents how they read these and it shows that it is problematic. The essay also includes an analysis where I discuss two different faction texts, the book At 10.31 in the morning in Khao Lak and the movie The Impossible. These are both stories written after the tsunami disaster in the Indian Ocean on Boxing Day 2004. I try to categorize the different texts and I anayze the narrative technique, focalization and also the text´s paratextuality. I also compare them thematically. Finally I do a didactic discussion where I give suggestions on how to work with faction texts in the classroom.
17

Spatial and Temporal Changes in Tsunami Risk Perception in Canterbury

DuBois, Jennifer Faith January 2007 (has links)
Risk perception for rare, low-probability hazards, such as tsunamis, tends to be low due to individual's unfamiliarity with them and the tendency to see them as synonymous with non-occurrence events. Visitors to an area tend to have even lower risk perception and knowledge of hazards, warning systems and appropriate actions to take during an event. Risk perception, however, can increase, if only temporarily, after a catastrophic event, such as the 2004 Boxing Day tsunami. To determine the changes in resident's knowledge and perception and the differences between those of residents and visitors two surveys were conducted. In the first survey interview style surveying was conducted at eleven locations in the coastal Christchurch and Banks Peninsula area of the Canterbury Region The questionnaire was composed of scaled, open, and closed ended questions and the main themes included knowledge of risk, preparation and warnings, what to do during a tsunami, and changes since the 2004 Boxing Day tsunami. The second survey of five coastal communities was conducted via a postal questionnaire and was aimed at obtaining residential views. Survey data was then analysed with Statistical Package for the Social Sciences (SPSS) statistical software. The residential data was compared with that of the non-residents to determine the differences in perception of residents and visitors. The residential information was then compared with survey data from the 2003 National Coastal Survey. Visitors knew less about general tsunami information such as when the last tsunami occurred and were less likely to believe that a tsunami could occur imminently. Non-residents reported less receipt of information and did considerably less information seeking. Differences in knowledge of warning systems were difficult to ascertain. The Boxing Day event certainly made an impact, increasing people's knowledge and awareness, though most likely only temporarily.
18

Modeling of generation, propagation and runup of tsunami waves caused by oceanic impacts

Weiß, Robert. Unknown Date (has links) (PDF)
University, Diss., 2005--Münster (Westfalen).
19

Localized Scour Around Structures Under Transient Flow Conditions

Mehrzad, Razieh 08 April 2021 (has links)
In recent years, extreme natural phenomena such as tsunamis or storm surges have affected populated coastal regions around many coastal regions around the world and with particular impact for countries bordering the Indian, Pacific and Atlantic Oceans. Such extreme events caused significant loss of life and extensive damage to coastal communities. Field surveys conducted from the 1992 Nicaragua Tsunami to the relatively recent 2011 Tohoku Japan Tsunami have recorded lots of evidence of scour around damaged buildings and bridge foundations. It is documented that scouring is one of the significant causes of coastal structural damages. In post-tsunami forensic engineering surveys of India and Thailand following the 2004 Great Sumatra Andaman tsunami, researchers were able to document local scour occurrences not only at buildings located close to shore, but also hundreds of meters inland. (Yeh and Li 2008, Nistor et al. 2012 and Li et al. 2012). The most damaging 2011 Tohoku Tsunami provided an outstanding opportunity to document (Chock et al., 2013) a variety of failure modes of infrastructure including coastal and onshore structures. This research program encompassed a comprehensive experimental and numerical investigation and analysis for the scour mechanism and vortex structures due to inland-propagating tsunami-like bores on a dry or flooded horizontal mobile bed, representing comprehensive tsunami-induced scour study. The primary objective of this thesis was to investigate the influence of different parameters on the bore propagation characteristics and how they affect the scouring process. To achieve this objective, a series of hydraulic bores consistent with the dam-break wave theory were generated. Extensive experiments were conducted to perform parametric analysis on both bore propagation and local scour (e.g., influence of structure size, bore height, bed initial condition, bed material size and second tsunami wave). The secondary objective involved development of a numerical model to simulate local scour and predict the threedimensional (3D) flow pattern around a structure induced by tsunami–like bore. The open source TelemacMascaret numerical model was used to determine flow characteristics adjacent to the structure and the associated bed evolution and resulting local scour. The 3D hydrodynamic Telemac model couples internally with the sediment transport module SISYPHE to solve bed evolution equations. The efficiency of the numerical model was assessed and compared quantitatively and qualitatively with the results of the physical experiments. The studies show a longer duration of a turbulent bore induced more scour depth compared to that generated by solitary or long waves. The short duration and very turbulent nature of the bores induced rapid scour. It was shown that the location of maximum scour depth and sediment deposition pattern downstream of the structure are well captured by the numerical model, however; magnitude of scour depth is underpredicted compared to that of the experimental work. It was found that the ASCE (2016) prescriptions on estimating scour underpredicts the maximum scour depth and thus, the use of the ASCE (2016) provisions, may lead to undesirable underestimations of maximum scour depth. The results of this study have contributed to the American Society of Civil Engineers (ASCE) 7 Chapter 6, which is the first standard written in mandatory language in the world, which specifically prescribes guidance for the design of tsunami resilient critical infrastructure using also a probabilistic framework for the determination of the extent of coastal inundation.
20

High-Fidelity Numerical Simulation of Shallow Water Waves

Zainali, Amir 09 December 2016 (has links)
Tsunamis impose significant threat to human life and coastal infrastructure. The goal of my dissertation is to develop a robust, accurate, and computationally efficient numerical model for quantitative hazard assessment of tsunamis. The length scale of the physical domain of interest ranges from hundreds of kilometers, in the case of landslide-generated tsunamis, to thousands of kilometers, in the case of far-field tsunamis, while the water depth varies from couple of kilometers, in deep ocean, to few centimeters, in the vicinity of shoreline. The large multi-scale computational domain leads to challenging and expensive numerical simulations. I present and compare the numerical results for different important problems --- such as tsunami hazard mitigation due to presence of coastal vegetation, boulder dislodgement and displacement by long waves, and tsunamis generated by an asteroid impact --- in risk assessment of tsunamis. I employ depth-integrated shallow water equations and Serre-Green-Naghdi equations for solving the problems and compare them to available three-dimensional results obtained by mesh-free smoothed particle hydrodynamics and volume of fluid methods. My results suggest that depth-integrated equations, given the current hardware computational capacities and the large scales of the problems in hand, can produce results as accurate as three-dimensional schemes while being computationally more efficient by at least an order of a magnitude. / Ph. D.

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