On two approaches to studying the aftershocks of a strong earthquake

The paper is devoted to comparing two approaches to the study of aftershocks. The methodological foundations of the traditional approach were laid many years ago. A new approach has emerged relatively recently. The two approaches differ from each other in the object, purpose and method of research. The differences are as follows. With the new approach, attention is focused not on aftershocks, but on the source of the earthquake. The evolution of the source is studied experimentally, and not the degradation of the frequency of aftershocks. Instead of a speculative selection of empirical formulas, the source deactivation coefficient is measured, variations in the coefficient are observed, and only on the basis of measurements and observations are conclusions drawn about the dynamics of the source. Thus, the divergence between the two approaches is doctrinal. The new approach turned out to be effective. Through targeted analysis of aftershock data, the Omori epoch and the phenomenon of bifurcation of the earthquake source were discovered. The purpose of further research is indicated. Keywords: earthquake source, Omori law, Hirano-Utsu law, logistic law, deactivation coefficient, bifurcation, master equation, methodology.Comment: 11 pages, 3 figure

On the proper time of the earthquake source

The concept of proper time, which is different from universal time, has been introduced into the physics of earthquakes. The global activity of strong earthquakes was chosen as the object of study. We consider the sequence of earthquakes as a random process of the Poisson type. Comparatively weak earthquakes are used as the underground clock, the ticking of which marks the course of proper time. The Poisson distribution is compared with the distributions for two sequences of strong earthquakes. One of the sequences is ordered by calendar time, and the second by proper time. The result of the test showed that the distribution of events ordered by proper time is closer to the Poisson distribution than the distribution of events ordered by calendar time. We explain this by non-stationarity, which is an immanent property of the Earth's lithosphere.Comment: 9 pages, 5 figure

Electromagnetic signals produced by elastic waves in the Earth’s crust

The paper describes the excitation of geoelectromagnetic-field oscillations caused by elastic waves propagating in the Earth’s crust and generated by natural and anthropogenic phenomena, such as earthquakes, explosions, etc. Two mechanisms of electromagnetic signal generation, i.e. induction and electrokinetics ones, are considered and a comparative analysis between them is carried out. The first mechanism is associated with the induction of Foucault currents due to movements of the Earth’s crust in the core geomagnetic field. The second mechanism is connected with movements of liquids filling pores and cracks of rocks. An equation is derived for describing in a uniform way these two manifestations of seismomagnetism. The equation is solved for body and surface waves. The study shows that a magnetic precursor signal is moving in the front of elastic waves

On the excitation of magnetic signals by Love waves

The polarization method for recognition of seismomagnetic waves against a noise background is presented. The method is applied to detection of magnetic oscillations accompanying the propagation of surface Love wave after a strong earthquake. A specific property of the Love waves is that theoretically the Tolman-Stewart effect is alone responsible for the magnetic field that penetrates into the Earth's surface. Data from the Mondy Magnetic Observatory and the Talaya Seismic Station suggest that the arrival time, duration, period,and polarization of magnetic signals conform with the idea of generation of alternating electric currents due to fluid vibrations in pores and fractures of rocks under the action of the inertial force associated with the Love wave propagation