The effect of giant tsunamis such as the Indian Ocean Tsunami in 2004 and the Great East Japan Earthquake Tsunami in 2011 has been devastating. In this study, a numerical simulation of the tsunami has been developed to estimate the physical characteristics of tsunamis and their effect on human society. Several laws and equations have been introduced for the simulation of tsunami propagation in the ocean, tsunami refraction, and tsunami run-up on land under a stable computational condition with acceptable accuracy. Our proposed method has been accepted as the world standard since 1997 and has been widely distributed to many countries through UNESCO.¹⁾ Computer graphic animations prepared by using the results of numerical simulation have been effectively used in public education and to increase the understanding of behaviors of the tsunami on the earth. When the numerical prediction of tsunami becomes possible with sufficient accuracy, then their results can be used to predict future damages and prevent the occurrence of a disaster. Data in the past were collected and expressed in terms of a newly introduced tsunami intensity which is related to the locally observed tsunami heights.

A comprehensive geochemical study of the Chelyabinsk meteorite reveals further details regarding its history of impact-related fragmentation and melting, and later aqueous alteration, during its transit toward Earth. We support an ∼30 Ma age obtained by Ar-Ar method (Beard et al., 2014) for the impact-related melting, based on Rb-Sr isotope analyses of a melt domain. An irregularly shaped olivine with a distinct O isotope composition in a melt domain appears to be a fragment of a silicate-rich impactor. Hydrogen and Li concentrations and isotopic compositions, textures of Fe oxyhydroxides, and the presence of organic materials located in fractures, are together consistent with aqueous alteration, and this alteration could have pre-dated interaction with the Earth’s atmosphere. As one model, we suggest that hypervelocity capture of the impact-related debris by a comet nucleus could have led to shock-wave-induced supercritical aqueous fluids dissolving the silicate, metallic, and organic matter, with later ice sublimation yielding a rocky rubble pile sampled by the meteorite.