| Abstract
|
:
|
This thesis provides a synthetic understanding and an extensive analysis on megathrust earthquake generated tsunamis, with emphasis on the application of numerical modeling. In the present thesis, the tsunami characteristics are first depicted as a special hydrodynamic phenomenon. Further, a detailed literature review on the recent developments in tsunami numerical modeling techniques and on their applications is presented. A common approach in modeling the generation, propagation and inundation of tsunamis is discussed and used in the thesis. Based on the assumption of a vertical displacement of ocean water that is analogous to the ocean bottom displacement during a submarine earthquake, and the use of a non-dispersive long-wave model to simulate its physical transformation as it radiates outward from the source region. A general analysis of the Indian Ocean Tsunami of December 26th, 2004 is provided; and tsunami generation and propagation is conducted for this tsunami, as well as for tsunamis occurring in the Arabian Sea and Northwest Pacific Ocean, near the coast of the Vancouver Island. The analyses are based on geological and seismological parameters collected by the author. In this paper the author uses the collected bathymetry and earthquake information, plus tide gauge records and field survey results, and focuses on the theoretical assumptions, validation and limitation of the existing numerical models. Numerical simulations are performed using MIRONE, a tsunami modelling software developed based on the nonlinear shallow water theory. Through numerical modeling of three tsunami scenarios, e.g. December 26, 2004 Indian Ocean Tsunami, November 28, 1945 Arabian Sea Tsunami and the potential Cascadia Tsunami, a vivid overview of the tsunami features is provided as discussed. Generally, the results fairly agree with the observed data. The GEOWARE software is used to compute the tsunami travel time necessary to calibrate the results from MIRONE, using different numerical techniques. Several sensitivity analyses are conducted so that one can understand how oceanic topography affects tsunami wave propagation, determine how smoothing the topography affects the simulated tsunami travel time, and interpret the tsunami wave-height patterns as seen in the model simulations. The model can predict reasonably the tsunami behaviour, and are thus useful for tsunami warning system (tsunami mitigation and preparedness); and coastal population and industry can prepare for such possible catastrophic events.
|