A record of a tsunami event riding on the usual tide signal was recorded by a floating‐type tidal gauge installed in the port of Yafo, Israel. The tsunami was triggered by an earthquake in the Aegean Sea on 9 July 1956. This paper presents a retrieval of tsunami waves from the record. At the first stage of the study an attempt had been undertaken to reproduce the 1956 tsunami assuming a coseismic nature of its generation source. Although these simulations resulted in tsunami waves with their amplitude close to that obtained from the record measured at Yafo, they did not contain significant spectral energy components with periods of ∼15 min as appear in the spectra of 1956 tide‐gauge records. When landslide movement, triggered by the main shock and/or by the largest aftershock, is suggested as a source of these tsunami waves, the spectra of the resulted marigram obtained in the proximity to Yafo contain harmonics with frequencies very close to those measured. This corroborates the landslide nature of the tsunamigenic source responsible for generation of higher‐frequency (relative to the tidal waves) energy components. The peak periods determined via spectral analysis of the recent tide‐gauge records (1 year and longer) in the absence of tsunami events vary from 50 to 60 min. Similar periods have been revealed in a special numerical study dealing with longwave propagation toward the coast of Israel, thus confirming that their origin is related to continental shelf resonance. These resonance periods differ significantly from those found for the 1956 tsunami.

Catastrophic tsunamis that flooded the ocean coast in the past had taken many human lives and destroyed the infrastructure of the coastal areas in the Pacific and elsewhere. Recent tragic events in the Indian Ocean motivated governments to develop new and improve the existing tsunami warning systems capable to mitigate the impact of catastrophic events. In the future, regional tsunami warning systems will be integrated into a network including both the systems currently being developed and the existing warning systems (in the past, tsunami warning systems had been deployed to protect the coastal areas in Japan, USA, Russia, Australia, Chile and New Zealand). The present study, conducted by the Institute of Computational Technologies in collaboration with other research institutes in Novosibirsk, is directed to the design of a new generation of the tsunami warning system for the Pacific coast of Kamchatka. The main purpose of the present study is to develop the computational methodology allow us to build a database of potential tsunamigenic sources that impose the imminent tsunami risk for the eastern coast of Kamchatka Peninsula. In the first stage of the project, a set of basic model sources of tsunamigenic earthquakes is defined. These model sources are used to calculate the initial water elevation in the source area that are used as initial conditions for dynamic modeling of tsunami propagation in the selected geographical region near the Kamchatka east coast. The next stage is the modeling of propagation and transformation of tsunami waves on the way from the source area towards the coast. This information is presented as a decision support system intended for use by persons on duty who are responsible for initiating tsunami mitigation procedures such as evacuation of people and sending ships away from the dangerous harbors and bays. The project involves numerical solution of a large number of instances of wave hydrodynamics problems. At the same time, interpretation of the results requires non-trivial postprocessing and development of a specialized information systems. Numerical calculation of tsunami propagation in the ocean with a real bathymetry for multiple combinations of the model earthquake sources with high spatial resolution constitutes the major part of the computational requirements of the project. The amount of computation resources needed for numerical modeling of tsunami propagation implies the use of high performance computers and may require adaptation of numerical algorithms to specific computing platforms. In the future, this approach may be extended to other tsunamigenic areas in the Pacific and the Indian oceans. In the latter case, we plan to consider the problem of defining the extension of the coastal zone that is the subject for flooding by tsunami waves. This would require to perform run-up calculation. To achieve the necessary accuracy in reproducing of tsunami behavior in the coastal areas, we will need to take into account such features of the coastal area as small rivers, lakes and swamps. This will significantly increase the amount of computational resources needed both during the development of numerical models and algorithms and in the production runs.