ИСТИНА

Increase in precision and resolution of the satellite GRACE monthly gravity models and accumulation of more than 10-years time- series of such models, enabled us to reveal earlier unexplored processes in the areas of major ( ) earthquakes. Gravity time variations in the regions of giant earthquakes (Sumatra-2004, Chile-2010, Tohoku-2011) showed coseismic gravity jump followed by long post-seismic changes reaching almost the same amplitude [e.g. Mikhailov et al., 2014]. The coseismic gravity jumps resulting from the smaller events are almost unnoticeable [Mikhailov et al., 2004, deViron et al., 2008]. However, we have established a long steady growth of gravity anomalies after a number of such events [Mikhailov et al., 2016]. The detailed analysis of the growth of the positive gravity anomaly after 15/11/2006 Simushir earthquake is presented. The growth started a few months after the event synchronously with the seismic activation on the downdip extension of the coseismic rupture and the approximately simultaneous change in the direction and average velocity of horizontal surface displacements at the regional GPS sites. It indicates that this earthquake induced postseismic creep in a huge area extending to the depths below 100 km. The total displacement since 03/2007 up to 07/2012 is estimated at 3.0 m in the upper part of the plate contact and 1.5 m in its lower part up to a depth of 100 km. The released total energy is equivalent to the earthquake of Mw = 8.5. Such processes have not been previously revealed by the ground-based techniques. Hence, the time series of the GRACE gravity models are an important source of the new data on the locations and evolution of the locked asperities of subduction zones and their seismic potential.