El objetivo general de la presente investigación es estudiar las zonas de afectación del cantón Atacames ante la ocurrencia de tsunamis, desde una perspectiva integral, para evaluar el grado de amenaza, vulnerabilidad y estimar el riesgo de desastre; así como también generar alternativas de evacuación de la población afectada. Se investigaron las principales características de la zona costera del cantón Atacames: geología y geomorfología, características ambientales, cobertura y uso de suelo, la batimetría del fondo oceánico, conectividades, condiciones climatológicas y socioeconómicas. El valor turístico que representa el área de estudio y la amenaza latente de ocurrencia de tsunamis motivaron la realización de esta tesis. Se estudió el comportamiento de los tsunamis, desde su génesis, propagación y afectación en la costa contigua. Se describieron sus elementos y la clasificación de los tsunamis, su tamaño e intensidad. También se investigó la teoría social del riesgo aplicada a tsunamis para describir la amenaza como un proceso de construcción social, la vulnerabilidad y sus distintos enfoques, además del riesgo como categoría de análisis de eventos tsunamigénicos. La estimación de la amenaza se realizó a través de la zonificación de áreas inundadas, mediante un proceso que inició con la confección de un catálogo histórico de los eventos más importantes en el litoral ecuatoriano obtenido de bases de datos paramétricas y descriptivas de diferentes autores, asimismo la elaboración de una malla de muestreo de epicentros sísmicos derivada de la caracterización sismogenética de la zona de subducción y el estudio de peligrosidad sísmica disponible; luego el modelamiento de tsunamis a través del Centro de Alerta de Tsunamis del Ecuador para calcular la máxima amplitud de ola y tiempos de arribo. El análisis de la vulnerabilidad global se realizó a partir de la descripción y delimitación de las variables que se utilizaron como inputs para estudiar la vulnerabilidad socioeconómica y física, tales como conjunto etario frágil, pobreza según el método de necesidades básicas insatisfechas, discapacidad y accesibilidad a un sitio seguro. Este procedimiento permite destacar las zonas donde la población es más vulnerable por sus características socioeconómicas y físicas. Posteriormente se desarrolló el modelo geográfico multivariable para el análisis espacial de la vulnerabilidad global. Resultado final de la fase de predicción, se realizó la integración de la zonificación de la amenaza y vulnerabilidad global, ambas variables se combinaron a través de un proceso de algebra de mapas para la obtención del riesgo de las parroquias del cantón Atacames donde se estimó la probabilidad del impacto de este evento natural en la zona de estudio. Se desarrolló el análisis de rutas óptimas hacia puntos de encuentro seguros a lo largo de la red vial del cantón Atacames, a la vez se desarrolló un aplicativo WEB para dispositivos móviles y computadoras, con la información de la zona inundada, puntos de encuentro seguros, de manera que sirva como herramienta para la realización de simulacros y evacuación de la población durante la ocurrencia de tsunamis. / The objective of this research is to study the areas of involvement of Atacames City in the event of tsunamis, from a comprehensive perspective, to assess the degree of threat, vulnerability and estimate the risk of disaster; as well as generate alternative evacuations for the affected population. The main characteristics of the coastal area of Atacames City were investigated: geology and geomorphology, environmental characteristics, soil coverage and use, ocean bottom bathymetry, connectivity, climatic and socioeconomic conditions. The tourist value of this area and the latent threat of tsunami occurrence motivated the realization of this research. The behavior of tsunamis, from their genesis, spread and affectation on the adjoining coast, was studied. Its elements and tsunami classification, size and intensity were described. The social theory of risk applied to tsunamis was also investigated to describe the threat as a process of social construction, vulnerability, and its various approaches, as well as risk as a category of tsunami event analysis. The estimation of the threat was carried out through the zoning of flooded areas, through a process that began with the preparation of a historical catalogue of the most important events on the Ecuadorian coast obtained from parametric and descriptive databases of different authors, as well as the elaboration of a sampling mesh of seismic epicenters derived from the seismic characterization of the subduction zone and the study of seismic hazards available; then tsunami modeling through Ecuador's Tsunami Warning Center to calculate maximum wave amplitude and arrival times. The analysis of global vulnerability was based on the description and delimitation of variables that were used as inputs to study socioeconomic and physical vulnerability, such as fragile age set, poverty according to unmet basic needs method, disability, and accessibility to a safe site. This procedure allows to highlight the areas where the population is most vulnerable for its socioeconomic and physical characteristics. Subsequently, the multivariate geographic model for spatial analysis of global vulnerability was developed. The result of the prediction phase, the integration of the zoning of the threat and global vulnerability was carried out, both variables were combined through a process of algebra of maps to obtain the risk of the parishes of Atacames City where the probability of the impact of this natural event in the study area was estimated. The analysis of optimal routes to safe meeting points was developed throughout the road network of Atacames City, at the same time a WEB application was developed for mobile devices and computers, with information of the flooded area, safe meeting points, so that it serves as a tool for the realization of drills and evacuation of the population during the occurrence of tsunamis.

On September 16, 2015, a Mw 8.3 earthquake struck offshore of the north-central Chile coast with a fault-rupture length of approximately 150 km. The earthquake triggered a tsunami that impacted 500 km of coastline from Huasco (28.5°S) to San Antonio (33.5°S), registering as much as 4.5 m on the tide gauge at Coquimbo (30.0°S) with run-up heights >10 m at a few exposed locations between Limarí (30.7°S) and Coquimbo. The tsunami provided an invaluable opportunity to examine the nature of tsunami deposit evidence in a semi-arid, siliciclastic environment, where settings suitable for the preservation of tsunami sedimentation are scarce, thereby improving our ability to identify such evidence in the geologic record. Using before-and-after-tsunami satellite imagery and post-tsunami coastal surveys, we targeted one of the few low-energy depositional terrestrial environments in the tsunami-affected area that had a high potential to preserve the 2015 tsunami deposit and older events: the Pachingo marsh in Tongoy Bay (30.3°S). We employed field and laboratory methods to document the 2015 tsunami deposit and discovered sedimentological evidence of previous tsunami inundation of the site. The 2015 tsunami deposit and an older sand bed ~10 cm lower in the stratigraphy exhibit similar sedimentological characteristics. Both sand beds are composed of poorly to moderately sorted, gray-brown, fine- to medium-grained sand and are distinct from underlying and overlying organic-rich silty sediments. The sand beds are thinner (from ~20 cm to <1 cm) and finer (from medium- to fine-grained sand) at more inland locations, and fine upward. However, the older sand bed extends over 150 m farther inland than the 2015 tsunami deposit. To explore the differences in the offshore ruptures that generated the tsunamis that deposited each sand bed, we employed an inverse sediment transport model (TSUFLIND). Our field survey, sedimentological data, and modeling results infer that the older sand bed preserved at the Pachingo marsh field site was produced by a larger tsunami than the 2015 tsunami. Anthropogenic evidence (copper smelter waste) along with Cs137 and Pb210 dating constrains the magnitude and age of the older sand bed to the last 130 years. Based on historical analysis of recent tsunamis that impacted the Pachingo marsh region, we infer a widespread tsunami in 1922 is the best candidate for depositing the older sand bed at our site, providing first geologic evidence of pre-2015 tsunami inundation along the north-central Chile coast. / Master of Science / On September 16, 2015 a segment of the Chilean subduction zone ruptured off the coast of north-central Chile producing a magnitude 8.3 earthquake. The earthquake created a tsunami that impacted 500 km of coastline and created waves measuring 4.5 m on the tide gauge at Coquimbo (30.0°S) with waves reaching inland to heights >10 m at a few exposed locations. The 2015 event in north-central Chile provided a unique opportunity to study tsunami deposits in semi-arid, sand-dominated environment where preservation of tsunami deposits within coastal sediments is rare, helping improve our ability to identify this type of evidence in the sedimentary record. Using before-and-after-tsunami satellite imagery and post-tsunami coastal surveys, we targeted a marsh in the tsunami-affected area that was capable of preserving the 2015 tsunami deposit and older events: the Pachingo marsh in Tongoy Bay (30.3°S). We employed field and laboratory methods to document the 2015 tsunami deposit and discovered evidence of previous tsunami overwash at the site within the sediments of the marsh. Our field work observations and sedimentary data revealed that in addition to the 2015 tsunami deposit, the site contained an older, anomalous sand bed that we infer to be a tsunami based on its similarity to the modern deposit at the site. Our modeling results suggest that the older sand bed was deposited by a tsunami larger than the 2015 tsunami. Based on historical analysis of recent tsunamis that impacted the Pachingo marsh region, we infer a tsunami in 1922 is the best candidate for depositing the older sand bed at our site. This discovery provides the first evidence of tsunami sediments from pre-2015 tsunami inundation along the north-central Chile coast.

Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Casdcadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast. Anomalous sand sheets that have been characterized consist of well-sorted beach sand that fine up-section. The thickness of the deposits vary from 45 em to 0.2 em, and thin in the landward direction. Many of the sand layers include detrital caps. One to three detritus and mud lamina are intra-layered in the deposits. Marine diatoms and bromine, a marine tracer, increase in concentration at each of the sand layers.

Today, information sharing is critical to almost every institution and organization. There is no more pressing need for information sharing than during an international crisis, where multi-national military-civilian coordination is formed. Successful information technology implementation for international crises could be increased by analyzing prior relief efforts. The purpose of this thesis is to explore the role of information technology in enabling the sharing of actionable information among various organizations in relief efforts. At all levels of relief efforts, strategies to provide adequate help to the victims of disaster will rely on the development and distribution of actionable information. It is essential that participants strengthen their capacity to gather, share, analyze and disseminate such information. When using or developing information technology in relief operations, it is necessary to be aware of the obstacles related to information sharing. Due to the uniqueness of each relief operation, dependant on the various participants and nature of the disaster, it is difficult to define the problems, symptoms and possible solutions of each situation. Specifically, this thesis attempts to establish the requirements for the development of a Disaster Information Management System by examining both the universal problems in disaster relief operations and their possible solutions from within information technology.

The model equations for storm surge and tsunamis most commonly used are the shallow water equations with addition of appropriate source terms for bathymetry. Traditional approaches will need to resolve the mesh to discretize small-scale structure, which impacts the time-step size to be proportional to the size of cells. In this thesis, a novel approximate Riemann solver was developed in order to deal with the existence of barrier without restricting the time-step due to small cells. Because of the wave redistribution method and proper ghost cells setting, the novel Riemann solver maintained properties including mass and momentum conservation, the well-balancing properties and robustness at the wet-dry interface. The solver also preserves nonnegative water depth and prevents leakage. A modified h-box method is applied so the algorithm can overcome restrictions of small time-step sizes. The work has been done in the context of the GeoClaw platform with retaining the capabilities of GeoClaw solver. At the same time, the special developed Riemann solver extends the package to handle the sub-grid-scale effects of barriers. Incorporating the solver developed in this work into the GeoClaw framework has allowed to leverage GeoClaw’s ability to handle complex bathymetry and real applications.

Abstract not available

Reflection of an obliquely incident solitary wave at a vertical wall is studied experimentally in the laboratory wave tank. Precision measurements of water-surface variations are achieved with the aid of laser-induced fluorescent (LIF) technique and detailed temporal and spatial features of the Mach reflection are captured. During the development stage of the reflection process, the stem wave is formed with the wave crest perpendicular to the wall; this stem wave is not in the form of a Korteweg-de Vries (KdV) soliton but a forced wave, trailing by a continuously broadening depression wave. Evolution of stem-wave amplification is in good agreement with the Kadomtsev-Petviashvili (KP) theory. The asymptotic characteristics and behaviors are also in agreement with the theory of Miles (1977b) except those in the neighborhood of the transition between the Mach reflection and the regular reflection. The maximum fourfold amplification of the stem wave at the transition predicted by Miles is not realized in the laboratory environment: the maximum amplification measured in the laboratory is 2.92, which is however in excellent agreement with the numerical results of Tanaka (1993). The present laboratory study is the first to sensibly analyze validation of the theory; note that substantial discrepancies exist from previous (both numerical and laboratory) experimental studies. Agreement between experiments and theory can be partially attributed to the large-distance measurements that the precision laboratory apparatus is capable of. More important, to compare the laboratory results with theory, the corrected interaction parameter is derived from proper interpretation of the theory in consideration of the finite incident wave angle. Our laboratory data indicate that the maximum stem wave can reach higher than the maximum solitary wave height. The wave breaking along the wall results in the substantial increase in wave height and slope away from the wall. Extending the foregoing study on the reflection of a single solitary wave at a vertical wall, laboratory and numerical experiments are performed on two co-propagating obliquely incident solitary waves with different amplitudes that are reflected at the wall. The larger wave catches up with the smaller wave; hence the two waves collide with the strong interaction. The resulting wave pattern near the wall is complex due to the interaction among the two incident solitons and the two reflected solitons. The numerical predictions of the KP theory are in good agreement with the experimental results. Another comparison of the KP theory with laboratory experiments is demonstrated for one of the exact soliton solutions of the KP equation by Chakravarty and Kodama (2009). This solution is called the T-type solution by Kodama. The theoretically predicted formation of the 'box'-shape wave pattern in the vicinity of two-soliton intersection is realized in the laboratory tank. The agreement between the laboratory observation and the KP theory is found better for the cases with the larger wave amplitude a and smaller oblique angle ψ (i.e. tan ψ/(√3a cos ψ) < 0.6). Subtle and unavoidable differences among the analytical KP solution, the setup of numerical calculation, and the laboratory condition are discussed. / Graduation date: 2013

Earthquake and submarine mass failure are the most frequent causes of tsunami waves. While the process of the tsunami generation by earthquakes is reasonably well understood, the generation of tsunami waves during submarine mass failure is not. Estimates of the energy released during a tsunamigenic earthquake and respective tsunami wave draw a clear picture of the efficiency of the tsunami-generating process. However for submarine landslides, this is not as straightforward because the generation process has never been recorded in nature making energy inferences very difficult. Hence the efficiency of submarine landslide as tsunami generators is yet to be conclusively determined. As the result of this uncertainty, different equations, derived from experimental data or theory, result in leading-wave amplitude that vary over 6 orders of magnitude for the same initial slide conditions. To arrive at more robust estimates of the leading-wave characteristics and associated runup, the spatiotemporal dynamics of the coupling between the slide body and water column needs to be investigated. The duration the water surface deformation is coupled with the slide motion is an essential question to shed light on the energy transfer. A parametric study is conducted with the state of-the-art hydrocode iSALE in order to shed light on this complex geophysical event. The mass, viscosity, and depth of submergence are the particular slide parameters varied and their relationship to runup and decoupling time is analyzed.

Thesis (Ph. D.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Tsunamis are gravity water waves that are generated by impulsive disturbances such as submarine earthquakes, landslides, volcanic eruptions, underwater explosions or asteroid impacts. Submarine earthquakes are the primary tsunami source, but landslides may generate tsunamis exceeding tectonic tsunamis locally, in both wave and runup heights. The field data on landslide tsunami events are limited, in particular regarding submarine landslide dynamics and wave generation. Tsunamis generated by three-dimensional deformable granular landslides are physically modeled in the NEES (Network of Earthquake Engineering Simulation) 3D tsunami wave basin (TWB) at Oregon State University in Corvallis, Oregon. A novel pneumatic landslide tsunami generator is deployed to simulate natural landslide motion on a hill slope. The instrumentation consists of various underwater, above water and particle image velocimetry (PIV) cameras, numerous wave and runup gauges and a multi-transducer acoustic array (MTA). The subaerial landslide shape and kinematics on the hill slope and the surface elevation of the offshore propagating tsunami wave and runup on the hill slope are measured. The evolution of the landslide front velocity, maximum landslide thickness and width are obtained along the hill slope. The landslide surface velocity distribution is obtained from the PIV analysis of the subaerial landslide motion. The shape and the size of the submarine landslide deposit are measured with the MTA. Predictive equations are obtained for the tsunami wave amplitude, wave period and wavelength in terms of the non-dimensional landslide parameters. The generated 3D tsunami waves propagate away from the landslide source as radial wave fronts. The amplitudes of the leading tsunami waves decay away from the landslide source in radial and angular direction. The wave celerity of the leading tsunami wave may be approximated by the solitary wave speed while the trailing waves are slower due to the dispersion effects. The energy conversion rate between the landslide and the generated wave is estimated. The observed waves are weakly non-linear in nature and span from shallow water to deep water depth regime. The unique experimental data serves the validation and advancement of numerical models of tsunamis generated by landslides. The obtained predictive equations facilitate initial rapid tsunami hazard assessment and mitigation.