On the structure and seismotectonics of the Kuril arc-trench system

Based on the new regional catalog of focal mechanisms for 396 strong (M ≥ 6.0) earthquakes in the Kuril-Okhotsk region and Japanese one in part for the period of 1964–2009 and with the data of seismic continuous profiling and multichannel common-depth point sounding by reflection method used, the peculiarities of the structure and seismotectonics of the Kuril arc-trench system have been analyzed. Additionally, the features of the Benioff and Tarakanov opposite seismofocal zones, associated with the Kuril arc-trench system, are studied. It is shown that the Benioff zone is a deep thrust through which the Kuril Arc (or Eurasian tectonic forefront) has thrust on the Pacific Plate by up to 50–70 km for the last 0.5–1.0 Ma (Pasadenian global phase of folding and orogeny). The thrusting process formed the middle and lower parts of the Pacific Ocean slope, the tectonic couple of Pegasus regional nappe and accretionary prism, the ramp structure of the Kuril Trench, and probably the opposite seismofocal zones.