With the number of wind power units (WPUs) on the rise worldwide, it is inevitable that some of these would be exposed to natural disasters like tsunamis and it will become a necessity to consider their effects in the design process of WPUs. This study initially attempts to quantify the forces acting on an existing WPU due to a tsunami bore impact. Surge and bore heights of 2m, 5m and 10m are used to compute the forces using the commercially available full 3D Navier Stokes equation solver FLOW3D. The applicability of FLOW3D to solve these types of problems is examined by comparing results obtained from the numerical simulations to those determined by small scale laboratory experiments. The simulated tsunami forces on the WPU are input into a simplified numerical structural model of the WPU to determine its dynamic response. The tsunami force is also used to obtain base excitation which when applied on the WPU would be equivalent dynamically to the tsunami forces acting on it. This base excitation is useful to obtain the response of the WPU experimentally, the setup for which is available at University of California, San Diego's (UCSD) Large High Performance Outdoor Shake Table (LHPOST). The facility allows full scale experimental setup capable of subjecting a 65kW Nordtank wind turbine to random base excitations. A stress analysis of turbine tower cross section is performed in order to assess the structural integrity of the WPU. It has been determined that the WPU is unsafe for bore/surge heights above 5 m. It has also been postulated that the structural responses could be considerable in case of the taller multi megawatt wind power units of present day.

A key goal of tsunami research is to quantitatively reconstruct flow parameters from paleotsunami deposits in order to better understand the geohazards of coastal areas. These reconstructions rely on grain-size and thickness measurements of tsunami deposits, combined with simple models that allow an inversion from deposit characteristics to wave characteristics. I conducted flume experiments to produce a data set that can be used to evaluate inversion models for tsunami deposition under controlled boundary conditions. Key variables in the flume experiments are sediment grain-size distribution, flow velocity and depth, and depth of water ponded in the flume before the tsunami bore was released. Physical experiments were run in a 32 m-long outdoor flume at The University of Texas at Austin. The flume has a head box with a specialized mechanical lift gate that allows instantaneous release of water to create a bore. Various sediment mixtures (silt to very coarse sand) are introduced to the upstream end of the channel as a low dune positioned just below the lift gate. The bore entrained the sediment mixture, producing an unambiguous suspension-dominated deposit in the downstream half of the channel. Deposits were sampled for grain-size and thickness trends. The experimental results capture characteristics of many recent and paleotsunami deposits, including consistent fining in the transport direction. In addition to overall fining, trends in deposit sorting and coarse (D95) and fine (D10) fractions reveal the importance of sediment-source grain-size distribution on tsunami deposit attributes. / text

Ocean-island flank collapses are amongst the most dangerous of all landslide related hazards in the world, as they have the potential to trigger ocean-wide tsunamis that can cause damage and loss of life to communities thousands of kilometres from their source of origin. The implications for landslide-induced tsunami originating from high volcanic islands in the Pacific are serious; and consequent hazards to life, infrastructure, and emergency management need to be constantly reviewed, monitored, and investigated. Ta’u, the easternmost inhabited island in the Samoa Islands volcanic chain, exhibits a series of down-faulted benches on its southern flank; believed to be the remnant of catastrophic collapse involving ~30km³. An historical map of Ta’u, charted during the first United States exploring expedition into the Pacific Ocean (Charles Wilkes Expedition), suggests that the event was recent; having occurred less than 170 years ago. A collapse event of this magnitude would have generated a locally devastating tsunami, with possible impacts experienced at the regional level. However, there exists no written or oral record of such an event. It appears that half the island, involving an estimated 30km³, disappeared off the map less than 170 years ago without anybody noticing it. A number of key questions thus emerged. Did this event actually happen within the last 170 years, and if so, how and why could it have gone unnoticed? Is the event much older than the impression obtained from the literature? More importantly, what is the likelihood of a future collapse and subsequent tsunami, and what would the hazard impacts be at the local and regional levels? These questions formed the research basis for this thesis. Specific aims were developed to address the issues identified, and a range of inter-disciplinary scientific techniques using innovative methods and new datasets were implemented to achieve them. The results demonstrate that the collapse most likely occurred more than 170 years ago, raising serious debate on the accuracy of observations made during the Charles Wilkes Expedition. The results also show that the eruptive-hazard at the site exists. Given that the nature and frequency of active volcanism in the area is uncertain, the risk of a future collapse and subsequent tsunami in the medium-term is considered high. The inter-disciplinary approach to landslide-tsunami hazard investigation on an oceanic island presented in this thesis, can be developed and applied by disaster managers to similar hazard investigations on other oceanic islands. Ultimately, the increase in knowledge-base can be used as a tool for developing safer and more resilient coastal communities.

Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.

Within the scope of this thesis, a reliability based risk assessment, based on Monte Carlo simulation was used to analyse the safety levels of Esenk&ouml / y Fishery Harbor main breakwater, Sea of Marmara, Turkey. In the past, in reliability-based risk assessment methodology in Turkey, the design conditions were only wave characteristics, tidal range, storm surge, wave set-up and the structural system parameters. However in this study, the tsunami risk which was considered as a major design parameter is included in the computations. In this study, development of a structural stability criterion in coastal engineering was suggested to achieve a common definition of reliability including the tsunami risk. The model introduced in this study is a practical technique in the reliability-based risk assessment of breakwaters subject to tsunami risk. In order to determine the occurrence probability of design condition, which is a function of storm waves, tidal range, storm surge and tsunami height, the Monte Carlo simulation, was applied. From the reliability-based risk assessment model applied to Esenk&ouml / y Fishery Harbor as a pilot study in Turkey it was found that, inclusion of the tsunami risk increases the failure risk of the structure, and as lifetime of the structure increases, the impact of tsunami risk on the failure mechanism is more reflected. For Esenk&ouml / y Fishery Harbor main breakwater, tsunami was not the key design parameter when compared to storm waves. However, in regions with great seismic activity, tsunami risk may be very noteworthy depending on the frequency and the magnitude of the tsunami.

Tsunamis are characterized as shallow water waves, with long periods and wavelengths. They occur by a sudden water volume displacement. Earthquake is one of the main reasons of a tsunami development. Historical data for an observation period of 3500 years starting from 1500 B.C. indicates that approximately 100 tsunamis occurred in the seas neighboring Turkey. Historical earthquake and tsunami data were collected and used to develop two artificial neural network models to forecast tsunami characteristics for future occurrences and to estimate the tsunami return period. Artificial Neural Network (ANN) is a system simulating the human brain learning and thinking behavior by experiencing measured or observed data. A set of artificial neural network is used to estimate the future earthquakes that may create a tsunami and their magnitudes. A second set is designed for the estimation of tsunami inundation with relation with the tsunami intensity, the earthquake depth and the earthquake magnitude that are predicted by the first set of neural networks. In the case study, Marmara and Aegean regions are taken into consideration for the estimation process. Return periods including the last occurred earthquake in the Turkish seas, which was the izmit (Kocaeli) Earthquake in 1999, were utilized together with the average earthquake depths calculated for Marmara and Aegean regions for the prediction of the earthquake magnitude that may create a tsunami in the stated regions for various return periods of 1-100 years starting from the year of 2004. The obtained earthquake magnitudes were used together with tsunami intensities and earthquake depth to forecast tsunami wave height at the coast. It is concluded that, Neural Networks predictions were a satisfactory first step to implement earthquake parameters such as depth and magnitude, for the average tsunami height on the shore calculations.

Ocean-island flank collapses are amongst the most dangerous of all landslide related hazards in the world, as they have the potential to trigger ocean-wide tsunamis that can cause damage and loss of life to communities thousands of kilometres from their source of origin. The implications for landslide-induced tsunami originating from high volcanic islands in the Pacific are serious; and consequent hazards to life, infrastructure, and emergency management need to be constantly reviewed, monitored, and investigated. Ta’u, the easternmost inhabited island in the Samoa Islands volcanic chain, exhibits a series of down-faulted benches on its southern flank; believed to be the remnant of catastrophic collapse involving ~30km³. An historical map of Ta’u, charted during the first United States exploring expedition into the Pacific Ocean (Charles Wilkes Expedition), suggests that the event was recent; having occurred less than 170 years ago. A collapse event of this magnitude would have generated a locally devastating tsunami, with possible impacts experienced at the regional level. However, there exists no written or oral record of such an event. It appears that half the island, involving an estimated 30km³, disappeared off the map less than 170 years ago without anybody noticing it. A number of key questions thus emerged. Did this event actually happen within the last 170 years, and if so, how and why could it have gone unnoticed? Is the event much older than the impression obtained from the literature? More importantly, what is the likelihood of a future collapse and subsequent tsunami, and what would the hazard impacts be at the local and regional levels? These questions formed the research basis for this thesis. Specific aims were developed to address the issues identified, and a range of inter-disciplinary scientific techniques using innovative methods and new datasets were implemented to achieve them. The results demonstrate that the collapse most likely occurred more than 170 years ago, raising serious debate on the accuracy of observations made during the Charles Wilkes Expedition. The results also show that the eruptive-hazard at the site exists. Given that the nature and frequency of active volcanism in the area is uncertain, the risk of a future collapse and subsequent tsunami in the medium-term is considered high. The inter-disciplinary approach to landslide-tsunami hazard investigation on an oceanic island presented in this thesis, can be developed and applied by disaster managers to similar hazard investigations on other oceanic islands. Ultimately, the increase in knowledge-base can be used as a tool for developing safer and more resilient coastal communities.

Thesis (M.A.)--University of Delaware, 2008. / Principal faculty advisor: Joel Best, Dept. of Sociology & Criminal Justice. Includes bibliographical references.

Tsunamis are among the most devastating and complex natural disasters, affecting coastal regions worldwide. Tsunami waves are generated through many natural phenomena, such as earthquakes, landslides, and volcanic eruptions. The waves travel at high speeds away from the source, potentially affecting multiple countries with very little warning. Over the past several decades, tsunamis such as the 2004 Indian Ocean, the 2010 Chilean, and the 2011 Tohoku Tsunami served as reminders of the potential devastation of these natural disasters, resulting in tragic loss of life and billions of dollars in damages. Forensic engineering field investigations and subsequent analysis of these events have demonstrated that infrastructure in these tsunami-prone regions was not adequately prepared for the extreme forces associated with a tsunami. As a result, there has been an increased research emphasis worldwide on the planning and design of infrastructure located in tsunami-prone areas to be better prepared for such future events. The present study aims to experimentally investigate and analyze the motion of debris carried by an inundating tsunami flood. One of the previous challenges involved in the evaluation of debris motion during such events was a lack of experimental methods that could non-invasively, quickly and accurately track the motion of debris at high velocities. This study introduces two innovative methods of tracking the debris. The first one used a novel camera-based tracking algorithm, while the second used Bluetooth and Inertial Measurement Unit sensors to track the debris within the inundating tsunami flood. The study outlines, for the first time, the technology and methods involved in the two tracking methods as it used both dry-test and wet-test experiments to evaluate the applicability of these methods in coastal and hydraulic engineering. This study used these two methods to evaluate the motion of debris from experiments conducted in a new Tsunami Wave Basin commissioned recently at Waseda University (Tokyo, Japan). The study examined the effect of the initial positioning of the debris, particularly focusing on the spreading area of the debris (determining thus their maximum displacement and the spreading angle of the debris). The results showed that an increase in the number of the debris resulted in an increase in the spreading angle of the debris and a decrease in the displacement of the debris. The increased number of debris also added significantly more variation in the final resting position of the debris due to the increased debris-debris collisions. The initial orientation of the debris also affected debris motion, particularly influencing the peak velocity of the debris and the distance from the initial debris resting position to where the peak velocity was observed.

Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.