ИСТИНА

Our work is devoted to the memory of the outstanding Japanese scientist. In 1896, Fusakichi Omori discovered the law of the aftershocks evolution that bears his name. We propose a new approach to processing and analyzing the flow of aftershocks after the main shock of a strong earthquake. It is based on the nonlinear differential equation of aftershocks, which has the form of a shortened Riccati equation. The coefficient s in front of the quadratic term of the aftershock equation has the meaning of the deactivation factor of the earthquake source after the formation of the main discontinuity. For s = const, the aftershocks equation is completely equivalent to the hyperbolic law of Omori. A hypothesis has been put forward that the known deviations of the frequency of aftershocks from the hyperbolic law are due to the nonstationarity of the earthquake source after the formation of a main discontinuity in the continuity of rocks. The relaxation model of the source in which the deactivation coefficient s(t) depends on time is proposed. By using aftershocks equation, we posed and solved the inverse problem of physics of the earthquake source. This allowed us to determine the deactivation factor s(t) by using the observation of the frequency of aftershocks. We compiled the atlas of aftershocks after a series of strong earthquakes. The atlas contains a description of the parameters, the original sequence of aftershocks, and the function s(t) for each event. The analysis of the atlas showed a rich variety of the evolution forms of the earthquake source after the main shock. Our work was partially supported by the Program 28 of the Presidium of RAS, and RFBR project 18-05-00096.