ИСТИНА

The strength of a tsunami is usually determined with use of Soloviev–Imamura tsunami intensity scale. Relationship between the tsunami intensity and the earthquake moment-magnitude exhibits a large spread between the data. Therefore, the moment-magnitude is not a reliable measure of tsunamigenic potential of an earthquake. Since the main effect responsible for tsunami generation is the displacement of water by co-seismic bottom deformation the total volume displaced in the tsunami source may turn out to be a better measure of the tsunamigenic potential than the moment-magnitude. The main purpose of this study is to examine relationship between the tsunami intensity and the displaced water volume in tsunami source. In recent years, the calculation of bottom deformation in a tsunami source with use of earthquake slip distribution or Finite Fault Model (FFM) was introduced into practice. In comparison with a single rectangular fault model, FFM provides more precise reproducing of bottom deformation in near-field zone, i.e. within the source area. In particular, such a precise determining of tsunami source results in a reasonable coincidence of in-situ measured (e.g. by DARTs) and simulated tsunamis in the open ocean. In this study, we consider a few tens recent tsunamigenic earthquakes, those for which USGS, Caltech or UCSB provides slip distribution data. Using these data and the Okada formulae, we calculate co-seismic bottom deformations which allow us to determine the volume of water displaced in each tsunami source. First, the displaced water volume is considered as a function of earthquake moment-magnitude. Then, the relative role of vertical and horizontal deformations in displacement of water is discussed. Ultimately, we obtain and discuss dependence that relates the Soloviev–Imamura tsunami intensity and the displaced water volume.