On distribution of earthquakes relative to the density boundary in stratification of Earth’s crust (case study in selected areas of the North-East of Russia)

Purpose. Identify patterns in position earthquake hypocenters relative density stratification in the borders of the earth's crust. Methods. The methods of the new interpretative gravity anomalies by interpreting the gravity field is determined by the power of the earth's crust, forming the anomaly in the gravity field (Bouguer). In this border area forms a surface that separates two sector of the earth's crust. In its upper part, in the sector above the fixed surface, observed density change substance at the transition from one block to another in the horizontal direction. At the bottom of the density change laterally absent due to quasi-homogeneous state of substance, determined probably deep metamorphism of the substance under the influence of elevated temperatures and pressures. The catalog of earthquakes Magadan region contain information about events registered in its territory with 1753 for some of them appreciate the depth of the hypocenter. 3D models of the earth's crust, built a new interpretational techniques gravity for two different seismic activity in their areas: the active south-eastern part of the zone of junction of Ayan-Yuryakhsk anticlinorium and Inyali-Debinsk synclinorium (south-eastern flank Cherski seysmo belts) and passive South west part Omolon array allowed on a quantitative basis to trace patterns in the distribution of earthquake hypocenters relative density stratification border. Results. The found similar areas with different seismic activity: earthquake hypocenters gravitate to areas of abrupt change in terrain borders density stratification. This hypocenters are concentrated in the upper crust, ranging mostly above this boundary. Earthquakes recorded deeper this boundary are energy class К 9. Originality. For the first time introduced the concept of "a density separation boundary in the crust" and quantified its relief for specific areas. For the first time on a quantitative basis the regularities in the distribution of earthquake hypocenters relative density stratification boundaries of the earth's crust. Practical significance. Laws in the distribution of earthquake hypocenters relative density features of the earth's crust a certain area can act as an additional way to assess the seismic hazard of a particular territory.