It is suggested that the eruption of the Sarycheva Peak volcano on 11 June 2009 may have been related to strong earthquakes which occurred in the Middle Kuril Islands from 2006 through 2009 (Figure 1), geodynamic processes (such as tectonic activation, subduction, and friction of contacting blocks), tectonic stresses, melting of rocks, rising of the melting substance, gases and fluids. The publication discusses the earthquake hypocenters profile along the Kuril Islands (Figure 2), the seismogeological depth profile of volcanoes of the Kuril Islands that was published by T.K. Zlobin (Figure 3), and positions of the magmatic chamber and the seismogenic zone of the SenHelens volcano from the publication by S. Carey (Figure 4). The map of earthquake epicenters for the Middle Kuril Islands is constructed on the basis of the NEIC catalogue (Figure 5). A corresponding depth profile showing earthquake hypocenters is constructed (Figure 6). An aseismic area is detected underneath the Matua Island (Sarychev Peak volcano); it is almost 30 km wide and about 200 km thick. In the Middle Kuril Islands, magma lifting and eruption were facilitated by stretching of the lithosphere (Fi gure 7), occurrence and activation of breaks, fractures and faults due to earthquakes which occurred from 2006 though 2009, and lifting of gas and fluids (Figure 8). The eruption was possible by explosion upon instant injection of fluids into the po rous space due to considerable shear stresses, which occurred after the earthquakes, and the reaction of dehydration. It can also result from supply of volcanic gases and fluids, according to the vacuumexplosion fluid dynamics model.

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The catastrophic Simushir earthquake occurred on 15 November 2006 in the Kuril-Okhotsk region in the Middle Kuril Islands which is a transition zone between the Eurasian continent and the Pacific Ocean. It was followed by numerous strong earthquakes. It is established that the catastrophic earthquake was prepared on a site characterized by increased relative effective pressures which is located at the border of the low-pressure area (Figure 1). Based on data from GlobalCMT (Harvard), earthquake focal mechanisms were reconstructed, and tectonic stresses, the seismotectonic setting and the earthquakes distribution pattern were studied for analysis of the field of stresses in the region before to the Simushir earthquake (Figures 2 and 3; Table 1). Five areas of various types of movement were determined. Three of them are stretched along the Kuril Islands. It is established that seismodislocations in earthquake focal areas are regularly distributed. In each of the determined areas, displacements of a specific type (shear or reverse shear) are concentrated and give evidence of the alteration and change of zones characterized by horizontal stretching and compression. The presence of the horizontal stretching and compression zones can be explained by a model of subduction (Figure 4). Detailed studies of the state of stresses of the Kuril region confirm such zones (Figure 5).