Dû à leur impact destructeur et meurtrier, il est important de comprendre la dynamique des tsunamis afin d'améliorer les modèles de prévention et d'alerte. Le peu de données disponibles in situ rend la génération des tsunamis peu connue. Les modèles de générations, notamment la génération sismique qui est considérée ici, simplifient les phénomènes mis en jeu. De nombreux effets sont négligés, parmi eux la cinématique de déformation du fond. Deux paramètres temporels peuvent être définis pour d écrire ce mouvement: la vitesse de propagation de rupture vp qui est propre à l' évènement sismique, et le temps d' élévation tr. Respectivement, ces paramètres caractérisent le mouvement horizontal et vertical. Une étude linéaire et théorique, puis non-linéaire et numérique, révèle un phénomène de résonance pour de courts tr et des vp de l'ordre de la célérité des ondes longues. Dans ces conditions, l'amplitude des vagues générées est amplifié e par rapport à celle de la déformation du fond marin, et des phénomènes dispersifs apparaissent. Pour illustrer ce phénomène, le cas du tsunami de 1947, qui frappa la Nouvelle Zélande, est simulé avec les modèles de Saint-Venant puis de Boussinesq du système Telemac2D. Rejoignant la théorie, l'influence de vp est nettement observable tandis que les faibles valeurs de tr ont un impact limité. Bien que des effets dispersifs soient attendus durant cet évènement, ils ne sont pas observés avec le modèle numérique. En parallèle de cette étude sur les échelles temporelles, cette thèse a permis de contribuer à la validation des modèles numériques du système Telemac dans le cadre du projet TANDEM. Ainsi, les modèles issus de Telemac2Det Telemac3D sont testés sur des cas tests représentant la génération, la propagation ou le run-up d'un tsunami. Il s'avère que dans la plupart des cas, les modèles numériques proposent de résultats très corrects. Cependant, on note une certaine dépendance aux paramètres numériques pour les cas délicats comme celui de la propagation d'une onde solitaire. En plus des cas idéalisés, le modèle de Saint-Venant de Telemac2D est utilisé pour modéliser l'évènement de Tohoku-Oki de 2011, pour lequel les résultats sont satisfaisants / The impact of tsunamis on mankind is well known. During recent years, several events showed us the disasters they can trigger which reiterate the importance of understanding their dynamics. Due to the lack of in-situ data, the generation is the least known aspect of tsunamis. As a result, simplified models of the source are used for numerical tsunami modeling, as for seismic generation for which the traditional approach neglects several phenomena, among which is the kinematic deformation of the sea floor. This motion canbe characterized by two temporal parameters: the rupture velocity vp and a hydraulic rise time tr. The novelty here, is to investigate both parameters simultaneously and to extend the linear theoretical development to a non-linear numerical study. From these works, a resonance zone is identified for small tr and vp close to the long wave celerity. For these particular values, the waves are amplified beside the sea floor deformation and dispersive effects develop. To illustrate this theory, the 1947 New Zealand tsunami is simulatedwith the Non-Linear Shallow Water and Boussinesq models of Telemac2D. This seismic event corresponds to a tsunami earthquake with slow kinematics of deformation. Four generation models, with different values of vp and tr are compared. The impact of vp on the generated wave amplitudes is strong whereas the influence due to tr is significantly smaller. Additionally, it was found that the expected dispersive effects did not develop during the numerical modeling. Meanwhile, in the scope of the TANDEM project, the validation of the Telemac system is performed through test cases, covering: generation, propagation and run-up of tsunamis. Globally, the models from the Telemac system match the validation data, however we note a reliance on numerical parameters for sensitive cases as the propagation of a solitary wave. Finally, the Non-Linear Shallow Water model of Telemac2D is used to simulate the Tohoku-Oki tsunami that hit Japan in 2011. Thenumerical model succeeds in representing this real event incorporating all the stages of tsunami life, from generation to flooded areas. Some limitations in using the method were found, which one discussed in detail within the present manuscript

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 410-414).

Tsunami investigation is a fundamental component of coastal hazard mitigation and risk reduction. Recent history reveals that such hazards can influence rapid changes in global cultural dynamics through extensive loss of life (e.g. 2004 Indian Ocean Tsunami), lifeline destruction (e.g. 2011 Tohoku Tsunami) and property damage (e.g. 2014 Chile Tsunami), affecting the mobilization of regional and global humanitarian and financial resources. The 2009 South Pacific Tsunami (2009 SPT) in the Samoan Islands, which had devastating local impacts, provided the opportunity to better understand tsunami characteristics and subsequent hazard potential in this region. Lessons were learned from the impacts of this event in the context of local and regional tsunami mitigation. Equally a number of questions emerged. What is the long-term tsunami hazard in the Samoan region? What is the future risk of near-field events of similar or greater magnitude? What evidence is there in the geohazard chronology record? If there is evidence, what does it imply with regard to risk reduction in Samoa and the broader Pacific? These questions formed the research basis for this thesis. Specific aims and objectives were devised to address the challenges and concerns identified. A range of inter-disciplinary techniques were used to yield innovative information to achieve them. Proxy characteristics (e.g. loss on ignition, grain size, elemental ratio, geochronology, resonance modeling) associated with the 2009 SPT and identified 1990 and 1991 Cyclones Ofa and Val deposits, respectively, provided unique analogues for identifying and distinguishing tsunami and cyclone signatures in the deeper Samoan geologic record. A tsunami and cyclone geochronological model spanning the last 3,000 years or so was developed. Estimation of tsunami frequency of similar or greater magnitude events than the 2009 SPT likely originating from the near-field Northern Tongan Subduction Arc (NTSA) source was also made possible. The results suggest a minimum 87 year recurrence interval of 2009 SPT-type tsunami intensities or stronger associated with a likely NTSA origin. Assessment of the contemporaneity between identified tsunamis and cyclones in the geologic record with anomalous and/or enigmatic sequences in the ethno-archaeological, oral and indigenous records provided likely indicators of the possible extent of associated hazards. Further, the discovery and association of anthropogenically-formed charcoal contemporaneous with earliest colonization in the Samoan archipelago, with the oldest tsunami identified, likely substantiates an approximate 3,000 year hazard history. Evidence of a landslide-generated tsunami which occurred during the Last Glacial Maximum (LGM), as well as non-related hypotheses concerning inland high-elevation calcareous deposits of cultural significance, were considered within the broader long-term tsunami hazard context. Knowledge gaps associated with landslide-generated tsunami processes and their hazard potential in this region were identified. The possibility of calcareous deposits found in a central highland location in these islands being of a potential tsunami or coastal marine origin is dismissed. This research demonstrates that an intrinsic tsunami hazard history covering the last 3,000 years exists in the Samoan Islands. Directions for future studies that build on the findings presented here are offered. The principal research outcomes achieved provide a basis for future refinement. Nonetheless, the thesis can be used in its present form as a guide for similar investigations, as well as in long-term coastal risk and mitigation at the local level. The techniques used and information obtained can also be developed and applied to analogous coastal environments in other countries to assist broader long-term regional and global tsunami risk reduction.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Bibliographical references: p. 275-293.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 13, 2009) Includes bibliographical references (p. 108-109).

Magíster en Ciencias, Mención Geología / Gran parte de la costa de Chile es periódicamente afectada por grandes tsunamis producidos por terremotos en el contacto de subducción de las placas de Nazca y Sudamericana. A pesar de esto los estudios de depósitos de paleotsunamis a lo largo de la costa hiperárida del Desierto de Atacama en el norte de Chile son casi inexistentes. Este trabajo presenta resultados de la investigación de registros de paleotsunamis en la región de Taltal, ubicada en la mayor laguna sísmica del Norte Grande chileno, al sur de la zona de ruptura del último gran terremoto y tsunami de magnitud Mw~8.8 de 1877, y al norte de la zona de ruptura del último gran terremoto y tsunami Mw~8.5 de 1922 en la región de Atacama. A través de la excavación de calicatas y trincheras en la costa, cercanas a sitios arqueológicos, se identificaron capas de arena y gravas constituyendo depósitos anómalos con material arqueológico retrabajado, que contrastan con el resto de los depósitos de origen arqueológico o sedimentario. De los perfiles geológicos se recolectaron muestras de sedimentos, las que fueron sometidas a análisis de tipo sedimentológico, geocronológico, geomorfológico, geoquímico, biológico y arqueológico. Se pudieron identificar al menos dos depósitos de tsunamis fechados en torno a 4491±27 y 1498±17 Cal. B.P. Los estratos que conforman estos sedimentos se caracterizan por presentar un contacto basal erosivo, disminución del espesor hacia el continente, gradación normal e inversa, estructuras sedimentarias de flujos turbulentos de alta velocidad, e incremento relativo de Ca, Fe, Ti y/o Sr. A su vez muestran material biológico, como pequeños gastrópodos y lapas típicos de ambientes rocosos en la zona intermareal, que no son encontrados habitualmente en las capas arqueológicas como producto del consumo humano. También, en el área se registraron grandes bloques de roca en algunos casos alineados y depositados distantes de la línea de costa, los que podrían ser indicativos de tsunamis recientes. A partir de los resultados de este análisis se discute sobre la génesis y diferencia entre los depósitos de paleotsunamis y otro tipo de eventos catastróficos que afectan a esta costa como aluviones y tormentas. A través de la comparación de estos registros junto con los resultados de un análisis histórico de los maremotos que afectaron también esta zona en 1877 y 1922, se concluye que el área de Taltal ha sido impactada por grandes tsunamis durante el Holoceno, mayores que los registrados localmente como producto de los eventos históricos ya mencionados. / Proyecto FONDECYT 1161547

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN / Bibliography: leaves 198-206. / by Robert Pfahler Comer. / Ph.D.

Seismic hazard models for Alaska require estimates of the size and frequency of prehistoric megathrust earthquakes. However, observations that place limits on the size of subduction paleoearthquakes along the Alaska-Aleutian subduction zone are scarce. To help place bounds on the along-strike extent of prehistoric Alaska-Aleutian subduction ruptures, we present stratigraphic and microfossil evidence of repeated tsunami inundation over the last ~400 years at Sitkalidak Island, located 0.5 km off the coast of south-central Kodiak Island. Peat cores collected from an estuary in southern Sitkalidak Island reveal three anomalous, laterally continuous sand beds with sharp upper and lower contacts preserved within a coastal peat sequence. The microfossil and lithostratigraphic characteristics of the sand beds, including the presence of anomalous marine planktonic diatoms, high fragmentation of diatoms, and upward fining sand sequences, indicate high-energy marine incursions consistent with tsunami inundation. Radiocarbon dating constrains the deposition of the sand beds to AD 1964, AD 1788, and ~400 cal yr B.P. The peat core stratigraphy and dates are consistent with tidal wetland stratigraphic records observed at sites ~90 km to the west at Sitkinak Island, and ~80 km to the east at Middle Bay, Kodiak Island. Diatom results from Sitkalidak Island suggest decimeter-scale subsidence during the deposition of the 1964 CE and 1788 CE sand bed. Deformation concurrent with the 1964 and 1788 ruptures along with the presence of a sand bed associated with the ~400 cal yr BP rupture at Sitkalidak help better define the western and eastern rupture limits, and thus the permissible maximum magnitudes, of past Alaska-Aleutian subduction zone ruptures. / Master of Science / The Alaska-Aleutian subduction zone experiences frequent great earthquakes over magnitude 8 which often produce far-reaching tsunamis. Seismic hazard models that help coastal communities predict and prepare for future hazards require estimates of the size and frequency of prehistoric earthquakes. Data for prehistoric earthquake events in the western region of the subduction zone is scarce. To help address the lack of prehistoric data and understand the rupture path and magnitude of past Alaska-Aleutian earthquakes, we present stratigraphic and microfossil evidence of repeated tsunami inundation over the last ~400 years at Sitkalidak Island, located 0.5 km off the coast of south-central Kodiak Island, Alaska. Sediment cores collected from a marsh in southern Sitkalidak Island record three laterally continuous sand beds with sharp stratigraphic contacts preserved within a coastal peat. Diatom microfossil and grain-size characteristics of the sand beds indicate high-energy marine incursions consistent with chaotic tsunami inundation. Radiocarbon dating places the age of sand bed deposition to AD 1964, AD 1788, and ~400 cal yr B.P. The sediment core stratigraphy and dating correlates well with sites investigated ~90 km to the west and ~80 km to the east. Diatom results from Sitkalidak Island point to small, decimeter scale coseismic subsidence during the deposition of the AD 1964 and AD 1788 sand beds. Land-level change concurrent with the 1964 and 1788 earthquakes along with the presence of a sand bed associated with the ~ 400 cal yr B.P. earthquake found at Sitkalidak Island help better define the earthquake rupture limits and maximum magnitudes of past Alaska-Aleutian subduction zone earthquakes.

ter have most of their energy held in the region of the water column near to the surface. Tsunamis are extremely long waves with long periods that can range from five minutes to several hours. Due to their very long wavelengths, tsunamis travel at the shallow water wave celerity which is equal to the square root of the gravitational acceleration times the water depth. The speed of a tsunami in the open ocean can reach in excess of 500 miles per hour. Tsunamis are also characterized by low wave height when moving through oceanic depths and are often hard to recognize when seen out in the deep ocean. As tsunamis approach the coastal region, they are affected by the rapid decrease in water depth. / US Navy (USN) author.

This dissertation presents the detailed results of investigations of the geomorphological and sedimentary processes associated with five Holocene tsunamis reported to have occurred in the Aegean Sea region of Greece. This research considers the effects of the widely quoted and archeologically important Minoan tsunami of the 17th century B.C.; the central southern Aegean tsunami of 66 A.D.; a hugely destructive tsunami reported to have followed a massive earthquake on the 21st July 365 A.D.; a tsunami of volcanic origin which affected the island of Thira on 29th September 1650 A.D.; and the destructive southern Aegean tsunami of 9th July 1965 A.D. The last account is believed to be the first systematic investigation of the geomorphology and sedimentology of a modern Aegean tsunami. This research is primarily concerned with the investigation of Holocene coastal sedimentary sequences in order to identify any geological traces of the former tsunamis and it is hoped that this evidence can be used to supplement the fragmentary historic accounts. This dissertation also considers whether microfossils can be used in the identification of individual stratigraphic horizons associated with tsunami-deposited sediments and investigates whether it is possible to determine the generative origins of individual tsunamis on the basis of the sediments associated with them. Whilst the findings of this research are not intended to provide a definitive account of the tsunamis considered, they do provide important evidence where the prevailing geological conditions of the Aegean Sea region would otherwise combine to limit the data available. Furthermore, it is believed that the results of this investigation do contribute to existing knowledge and will be of value to archaeologists seeking to explore the relationships between archaeological sites, landscape evolution and environmental change.