The Influence of Isostatic Equilibrium on the Formation of the Sources of Tsunamigenic Earthquakes

摘要

The hypothesis is proposed that tsunamigenic earthquakes in subduction zones, where the thrust geodynamic setting is dominant, are caused by the development of subvertical Riedel megashears (R' megas-hears), which are not typical of shear settings. The gravity and GPS monitoring data for the 2011 Tohoku earthquake indicate isostasy, which was manifested in a tendency towards the smoothing of the relief contrasts between the island arc and deep trench. It is this isostatic factor that produces the sources of tsunamigenic earthquakes.