Upward migration of earthquake hypocenters in Japan, Kurile–Kamchatka and Sunda subduction zones

It is shown by a special data processing analysis that there is upward migration of earthquake hypocenters in Japan, Kurile–Kamchatka and Sunda subduction zones. The total time of the migration appears to range from 3 years to 10 years. It leads to the estimation of average velocity ∼60–200 km/y. Probably it corresponds to upward movement of forcing agent like stress or deformation wave from depths of the upper mantle (600–700 km) to the level of lithosphere, possibly with subsequent initiation of fluid migration inside the crust to trigger shallow earthquakes. These findings may be helpful for the study of earthquake triggering and analysis of seismic precursors.