General Information on Tsunami Waves, Seaquakes and Other Catastrophic Phenomena in the Ocean -- Physical Processes at the Source of a Tsunami of Seismotectonic Origin -- Role of the Compressibility of Water and of Non-linear Effects in the Formation of Tsunami Waves -- The Physics of Tsunami Formation by Sources of Nonseismic Origin -- Propagation of a Tsunami in the Ocean and Its Interaction with the Coast -- Methods of Tsunami Wave Registration -- Seaquakes: Analysis of Phenomena and Modelling. There has been significant progress in tsunami research, monitoring and mitigation within the last decade. This book summarizes the state-of-the-art knowledge on tsunamis. It presents a comprehensive overview of tsunamis, seaquakes and other catastrophic ocean phenomena. It describes up-to-date models of tsunamis generated by a submarine earthquake, landslide, volcanic eruption, meteorites impact, and moving atmospheric pressure inhomogeneities. Models of tsunami propagation and run-up are also discussed. The book investigates methods of tsunami monitoring including satellite altimetry and the study of paleotsunamis. Non-linear phenomena in tsunami source are discussed in the context of their contribution to the wave amplitude and intensification of the vertical exchange in ocean. The book is intended for scientists, researchers and specialists in oceanography, geophysics, seismology, hydro-acoustics, geology, geomorphology, including the engineering and insurance industries.