京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第19158号 / 地環博第133号 / 新制||地環||27(附属図書館) / 32109 / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)教授 ｼｮｳ ﾗｼﾞﾌﾞ, 教授 岡﨑 健二, 教授 清野 純史, 准教授 小林 広英, 准教授 西前 出 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第21240号 / 地環博第176号 / 新制||地環||35(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 岡﨑 健二, 准教授 小林 広英, 准教授 西前 出 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

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In 1852, a five-minute long earthquake hit the Banda Arc region that was felt over most of Indonesia. It caused uplift of new islands and sent a tsunami across the Banda Sea that reached a height of 8 meters at Banda Neira and was also registered at Ambon, Saparua and other islands. Records of the 1852 earthquake at multiple locations provide the constraints needed to reconstruct the disastrous event through earthquake intensity analysis and numerical modeling of the tsunami. Using tsunami heights and arrival times as the major constraints, best fit numerical models of the tsunami were constructed using Clawpack. These models indicate that the earthquake was most likely a mega-thrust event along the Tanimbar Trough with a Mw of around 8.4. At least 10-15 meters of elastic strain energy has accumulated along the Tanimbar Through since the 1852 event, and the population in the region has increased exponentially. When another event occurs ≥ that in 1852, there will be many more people and treasure in harms way.

Tsunamis have caused severe damage to coastal communities and associated infrastructure over the past decades. Thus, researchers deemed necessary to investigate and better understand the mechanisms loading associated with tsunami waves and the inundation caused by them. Over the past few years, researchers have demonstrated that the dam-break waves are hydrodynamically similar to the onshore propagation of tsunami inundation; hence, dam-break waves are now widely used to investigate tsunami impacts. Various studies related to dam-break waves have been conducted to investigate their characteristics: the kinematic behavior, including free surface profiles, wave height, wave front velocity, and dynamics including the impact pressure and associated force. Most dam-break experiments have been conducted on a horizontal bed, in a tank or a flume, while few studies had employed sloped surfaces. However, natural and artificial beaches usually have slopes ranging from 0-degrees to 20-degrees (or more). In this study, downstream slopes are considered to investigate the influence of slope effects on the kinematic behaviors and associated hydrodynamic loadings due to dam-break waves. The Volume of Fluid method (VOF) code of the OpenFOAM and the Smoothed Particle Hydrodynamics (SPH) code of the DualSPHysics were applied to reproduce the results of physical tests and provide a comparison with the experimental results. First, existing boundary treatment methods in the SPH were studied and compared to a self-developed code in order to select the best performing method by checking the flow behaviors. In the second part of the thesis, experimental investigation of the impact of dam-break induced surges over a horizontal bed against a vertical wall was conducted by analysing the rapidly varying correlation between the wave height and the associated dynamic pressure. In the third part of this study, three different downstream slopes were added in the experimental setup to investigate the beach effects on the kinematics of dam-break flow, including the free surface profiles, wave height, wave front location and its velocity. In the last part, the impact dynamic pressure on the vertical straight wall from the horizontal and sloped cases were captured to investigate the slope effects on the hydrodynamic loading. The impact force integrated from the dynamic pressure was determined with a simplified calculation formula. In addition, the physical experiments were also reproduced by the numerical models of OpenFOAM and DualSPHysics to compare and investigate their accuracy and to analyze the differences between the physical tests and numerical simulations.

This study examined mental health outcomes for widowed Tamil women in Sri Lanka to identify any associations between type of spousal loss and several outcomes, including internalized stigma as a result of widowhood, anxiety symptoms, depressive symptoms, and posttraumatic stress symptoms. A sample of 381 Tamil female widows living in Eastern Sri Lanka were surveyed in 2016 to understand their experiences in a post-disaster and post-war context. Type of spousal loss was separated into seven categories: war-related death, death as a result of tsunami, illness-related deaths, accidental death, suicide, disappearance, and other. Path analysis was used to assess whether type of spousal loss predicts variations in symptom outcomes, controlling for time they have been bereaved, number of children, social problems, and perceived sense of community. The Conservation of Resources (COR) theory (Hobfoll, 1989) was used to conceptualize how spousal loss is connected to distress symptoms and to explain the findings. Analysis revealed that the only types of spousal loss which associated with significant variation in symptom distress were spousal loss as a result of accident and "other" causes. Specifically, accidental causes of spousal death were associated with lower levels of depression, and "other" causes of death were associated with lower levels of depression and anxiety as compared to all other causes of death. In addition, the control variables of sense of community and social problems predicted significant variation in symptom distress such that higher levels of sense of community were associated with lower levels of depression, anxiety, and posttraumatic stress symptoms, and social problems were associated with higher levels of all measured types of mental health distress symptoms.

The Sultanate of Oman is a rapidly modernizing country with a significant length of its coastline slated for development. Much of the coastline is still in its natural state and basic studies describing the sedimentary systems need to be conducted in order to plan effectively for their sustainable development and to monitor changes in them with time. For such purposes, sediment samples (surface and sub-surface), elevation data, and serial sediment cores were collected at Sur Lagoon during three field seasons. The research objectives, procedures, results, and analyses for Sur lagoon are presented in three chapters. The first chapter compares textural facies, identified on the basis of particle-size distribution (PSD) of surface sediments from Sur Lagoon and evaluated using multi-variate cluster analysis, for their value in recognizing modem sedimentary environments. Clustering the full PSD size spectrum (0.0375- 1888 μm) shows that facies identification is possible is closely tied to surface elevation, particle-size decreasing with increasing elevation above mean sea level. This analytical technique should be tested under different conditions to assess further its utility. The second chapter discusses the taphonomically distinct and laterally extensive (> 1 km2) bivalve shell bed deposited by a tsunami on November 28th, 1945. Taphonomic characteristics of this unit are compared to those of the shell-rich tsunamite from Caesarea, Israel, and resulted in the identification of three generic, tsunamigenic-specific traits in shell beds: 1) thickly bedded and laterally extensive shell deposit, 2) presence of allochthonous articulated bivalves not in life position, and 3) extensive angular fragmentation. When these three traits are found together, a tsunamigenic origin should be considered for the shell bed. The third chapter analyzes the PSD of the tsunamite in eight sediment cores for digested and undigested samples. Cluster analysis of the PSD extended the upper or lower tsunamite contacts in four cores, but in general, the tsunamite thickness is consistent with the previously identified shell beds (Chapter 3). The tsunamigenic processes that resulted in the deposition of the shell bed were complex, and deposition occurred during run-up, flooding, and backwash stages of the tsunami, incorporating marine, lagoonal, and terrestrial (wadi) sediment into the tsunamite. The results of this study provide baseline sedimentological data for an understudied region of the world. New applications of cluster analysis of PSD and taphonomic analysis have the potential to identify previously unknown tsunamites in the geological record, and lithological facies using textural analysis. / Thesis / Doctor of Philosophy (PhD)

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