Thesis (Ph. D.)--Texas State University-San Marcos, 2006. / Vita. Appendix: leaves 102-102. Includes bibliographical references (leaves 106-112).

In order to improve our understanding of present and future coastal environmental change, we look into the past using sediment that accumulates in coastal environments. We have done this for two disparate systems: a back-barrier lagoon in southwestern Japan, and freshwater tidal marshes along the Hudson River, New York, USA. In Japan, we used a 2,500-year sediment record to investigate coastal flood risk from tsunamis and typhoons. This is a critical area of study to better understand the spatial and temporal variability of these hazards in Japan. In the Hudson River we looked at modern (since 1800) deposition of sediment in anthropogenically constructed embayments that have formed tidal wetlands in the last few centuries. A better understanding of the factors that have attributed to these successful tidal marsh systems in the past can help inform future management decisions in the face of future sea level rise. Studying the history of coastal systems using the sediment record is a valuable tool for assessing hazard risk and habitat loss in the present and future.

Global warming, which is one of the most serious consequence of climate change, can be expected to have different effects on the atmosphere, the ocean, icebergs, etc. Global warming has also brought secondary consequences into nature and human society directly. The most negative effect among the several effects of global warming is the rising sea level related to the large typhoons which can cause flooding on low-level land, coastal invasion, sea water flow into rivers and underground water, rising river level, and fluctuation of sea tides. It is crucial to recognize surge level and its return period more accurately to prevent loss of human life and property damage caused by typhoons. This study researches two topics. The first purpose of this study is to develop a statistical model to predict the return period of the storm surge water related to typhoon Maemi, 2003 in South Korea. To estimate the return period of the typhoon, clustered separated peaks-over-threshold simulation (CSPS) has been used and Weibull distribution is used for the peak storm surge height’s fitting. The estimated return period of typhoon Maemi’s peak total water level is 389.11 years (95% confidence interval 342.27 - 476.2 years). The second aim is related to the fragility curves with the loss data caused by typhoons. Although previous studies have developed various methods to mitigate damages from typhoons, the extent of financial loss has not been investigated enough. In this research, an insurance company provides their loss data caused by the wind speed of typhoon Maemi in 2003. The loss data is very important in evaluating the extent of the damages. In this study, the damage ratio in the loss dataset has been used as the main indicator to investigate the extent of the damages. The damage ratio is calculated by dividing the direct loss by the insured amount. In addition, this study investigates the fragility curves of properties to estimate the damage from typhoon Maemi in 2003. The damage ratios and storm induced wind speeds are used as the main factor for constructing fragility curves to predict the levels of damage of the properties. The geographical information system (GIS) has been applied to produce properties’ spatial wind speeds from the typhoon. With the damage ratios, wind speeds and GIS spatial data, this study constructs the fragility curves with four different damage levels (Level I - Level IV). The findings and results of this study can be basic new references for governments, the engineering industry, and the insurance industry to develop new polices and strategies to cope with climate change.

Master's thesis. / Format: PDF. Bibl.

published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Public Administration / Master / Master of Public Administration

published_or_final_version / abstract / toc / Chinese Historical Studies / Master / Master of Arts

published_or_final_version / abstract / toc / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

La chaine de Taïwan représente l’une des zones les plus actives au monde. Depuis le début du XXe siècle, plus d’une vingtaine de séismes _Mw 7 ont affecté l’île. Cependant la probabilité d’occurrence de séismes plus importants (_Mw 8) est toujours matière à débat. Dans un tel contexte, il apparait donc important d’obtenir des enregistrements plus anciens pour évaluer l’occurrence de tels évènements. La paléosismologie marine, basée sur l’enregistrement des dépôts issus de la sédimentation gravitaire, apparait comme une alternative sérieuse afin d’illuminer l’histoire de la sismicité sur des périodes anciennes. Ce travail de thèse apporte de nouvelles contraintes sur l’histoire sismique au large, à l’est de Taïwan, au cours des derniers 3000 ans.La première partie de ce travail consiste à caractériser les systèmes sédimentaires récents. Cette étape fut essentielle pour la compréhension des processus, faciès sédimentaires et les facteurs de contrôle de la sédimentation qui régissent l’évolution de la pente sous-marine. Ces résultats ont montré que l’Est de Taïwan est caractérisé par une grande variabilité de processus et que les courants de turbidité dominent l’enregistrement sédimentaire.Les courants de turbidité sont générés par deux facteurs distincts : l’activité tectonique/sismique et l’activité climatique. La deuxième partie de ce travail est consacrée à l’approche paléosismique en utilisant les dépôts de turbidités comme marqueurs des paléoséismes. Pour ce faire, nous avons dans un premier temps testé et validé l’approche à l’échelle du siècle dernier. Ensuite une fois calibré, nous avons pu étendre les séries temporelles à l’échelle de l’Holocène. Nous avons daté les trois plus récents évènements turbiditiques autour de 2001 ± 3 AD, 1950 ± 5 AD et 1928 ± 10 AD. En utilisant des relations empiriques intégrant magnitude, distance et valeur du "peak ground acceleration", nous avons pu calibrer la source sismique et ainsi corréler ces trois turbidites à trois séismes instrumentaux : le séisme de Chengkong (12/10/2003) (Mw 6.8), le séisme de Taitung (11/24/1951) (Mw 7.1) et le séisme de Lutao (9/4/1935) (Mw 7.0). Au-delà du siècle dernier, les datations et modèles d’âges nous permettent d’établir une partie de la chronologie des évènements extrêmes sur une période de 3000 ans et d’estimer un temps de retour pour des évènements de l’ordre _Mw 7. Les résultats ont toutefois montré que ces temps de retour sont nettement supérieurs à ceux connus sur le siècle dernier, ce qui suggère que tous les séismes ne sont pas enregistrés par les dépôts sédimentaires marins. Ce travail de thèse a donc permis de montrer que les dépôts issus de la sédimentation évènementielle peuvent être considérés comme marqueurs de la sismicité et que cette approche peut constituer un outil complémentaire pour les études portant sur le risque sismique. / Taiwan is a young mountain belt, known as one of the most active area in the world. Since the beginning of the 20th century more than twenty _ Mw 7 earthquakes have struck the island. However, the occurrence of larger events (_Mw 8) is still a matter of debate. In this framework it is of key importance to obtain longer record in order to evaluate the occurrence of large past earthquakes. The sub-aqueous paleoseismology, based on the record of the sedimentary gravity deposits, appears as a serious alternative to approach this thematic and is a rapidly advancing field that has the potential to illuminate the long-term history of seismicity.The first part of this work was to investigate the present sedimentary systems off east Taiwan, essential to understand the morphosedimentary features, sedimentary facies and processes governing the evolution of the submarine slope, and the controlling factors of the recent sedimentation. Our results showed that the offshore slope east Taiwan is affected by a variety of sedimentary systems and processes, and that turbidity currents appear as the main erosional processes covering nearly 60% of the sedimentary record. Turbidity currents are generated by distinct controlling factors such as tectonic and climatic activity that enabled us to define twoend-members relative to turbidity currents initiation: Turbidity currents preconditioned by tectonic activity and triggered by earthquakes shaking and likely deposited into intra-slope basin and turbidity currents driven by climatic activity such as extreme floods or typhoons, generated in basin directly connected with onland rivers.The second part consisted to apply a paleoseismic approach, based on turbidites record, at two time-scales. First, we tested and validated the method by correlating turbidites deposits with instrumental earthquakes. Then, once calibrated we extended the time-series back in time. We dated the three most recent turbidites layers circa 2001 ± 3 AD, 1950 ± 5 AD and 1928 ± 10 AD. Using empirical relationship that link peakground acceleration, distance and magnitude to calibrate the seismic sources, we correlate these three turbidites with instrumental earthquakes: the Chengkong Earthquake 12/10/2003 (Mw 6.8), the 11/24/1951 Taitung Earthquake (Mw 7.1) and the 9/4/1935 Lutao Earthquake (Mw 7.0) respectively. Applying criteria to discriminating the different triggering mechanisms for turbidity current generation, we propose that earthquakes are the main triggering mechanisms. Dating and age modeling provided a part of the chronology of extreme events since the last 3000 years and allowed us to estimate return time for earthquakes Mw _ 6.8.This work represents a good starting-point for future investigations in order to better assess Holocene time series of extreme events.

The objective of this proposed research is to test whether interorganizational collaboration contributes to the ability of an organization to bounce back swiftly from disasters. The research questions are examined from the Institutional Collective Action (ICA) perspective. The general argument of this dissertation is that organizational resilience can be explained by interorganizational collaboration. The ICA framework, specifically, identifies two general network structures to explain strategies that can be adopted to minimize collaboration risks: bonding and bridging structures. This dissertation focuses on how governmental and nongovernmental organizations in South Korea collaborated. The data was collected from the southeastern tip of the Korean Peninsula in August of 2012, and January of 2013. The 2012 Typhoons devastated the area after the first data set was collected in August 2012, causing the loss of estimated US$ 730 million and 29 fatalities. Afterward, the second survey was administrated in January of 2013 to gauge respondents’ views on how organizations responded to the disasters. This dissertation consists of three essays. The first essay presents a brief overview and assessment of the current research on resilience. The second essay empirically tests the sources of organization resilience. The third essay examines the dynamic nature of interorganizational ties by employing stochastic actor-based models. The findings show how organizations prefer to not coordinate with other organizations even though this could reduce their strains during a disaster. The findings also suggest that organizations that operate in higher risk areas or participate in joint full-scale exercises before a disaster form interorganizational ties afterward.