arXiv subjects

A. V. Guglielmi

Publications and source records attributed to A. V. Guglielmi.

At least 37 records · Page 2Linked to original sources

arXiv2024

Energy flows in the earthquake source before and after the main shock

We proceeded from general physical concepts based, on the one hand, on the Umoff-Poynting theorem, and on the other, on the phenomenological theory of earthquakes, and formulated the following question: What are the directions of energy flows in the earthquake source before and after the formation of a main rupture in it? A non-standard technique for experimental research of this issue has been developed. The epicentral zone of the main shock is considered as a kind of track detector, and foreshocks and aftershocks are considered as marks (tracers) marking the propagation in the source of some factor that has energy and stimulates the excitation of foreshocks and aftershocks in a stressed-strained rock mass. By processing and analyzing a large volume of observation data, it was found that over time, foreshocks, on average, approach the epicenter of the main shock, while aftershocks, on the contrary, move away from the epicenter. A method is indicated for verifying the result by studying the magnitude dependence of foreshock convergence and aftershock divergence. Keywords: foreshock, aftershock, main rupture, evolution equation, nonlinear diffusion waves, fault length.

physics.geo-ph↗

arXiv2023

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.

physics.geo-ph↗

arXiv2022

Phenomenology of earthquakes

Phenomenology is the unity of principles and methods of studying the essence of phenomena. This paper is a concise review of recent works in which the phenomenological ideas of physics are used to analyze earthquakes. An example of a phenomenological theory is thermodynamics. Maxwell's electrodynamics is also a perfect example of a phenomenological theory. The phenomenology of earthquakes has not yet reached such a level. So far, we have reached the status of prolegomena for the future phenomenology of earthquakes. The current state can be characterized as preliminary. Nevertheless, in this paper, using specific examples, it is shown that when searching for the foundations of a theory, when processing and analyzing specific manifestations of seismicity, it is useful to use phenomenological concepts of general physics. Keywords: geodynamics, Omori law, Batth law, master equation, deactivation factor, inverse problem, proper time, global seismicity, waiting time, triggers, triad of earthquakes, self-oscillations of the Earth.

physics.geo-ph↗

arXiv2022

About the waiting time for a strong earthquake

As an object of study, we chose the global activity of strong earthquakes (M > 7). The subject of the study is the waiting time for the next strong earthquake. The purpose of the study is to compare two distributions of waiting time, one of which is calculated when ordering events according to world time, and the second when ordering according to proper time. We have come up with unique underground clock to counting proper time. The average waiting time is 25 days in world time, and 10 ticks in proper time. We assert with a high degree of confidence that both distributions obey an exponential law. The coefficients of determination are 0.94 in the first case, and 0.98 in the second case. This is all the more surprising since our underground clock is a rather crude measuring instrument. We also consider general issues related to the chronologization of earthquakes. Keywords: proper time, deactivation factor, main shock, foreshocks and aftershocks, exponential and power distributions.

physics.geo-ph↗

arXiv2022

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.

physics.geo-ph↗

arXiv2022

On generalized models of earthquake evolution by the example of classical and mirror triads

The analysis of the classical and mirror triads of the sequence of earthquakes has been carried out in order to find the equations of evolution of foreshocks and aftershocks. The differential equation with cubic (quadratic) nonlinearity has been proposed to describe the activity of foreshocks (aftershocks). The solution of the governing equation for foreshocks indicates the explosive instability of rocks, leading to the main rupture and the main shock of the earthquake. It is suggested that explosive instability leads to a first-order phase transition, in which the main parameters of the earthquake source as a thermodynamic system change abruptly. A direction for further research has been outlined. Keywords: Omori law, evolution equation, earthquake triads, foreshocks, main shock, aftershocks , rise and fall in seismic activity.

physics.geo-ph↗

arXiv2022

Alfvén waves: To the 80th anniversary of discovery

The paper is dedicated to the anniversary of the discovery of Alfvén waves. The concept of Alfvén waves has played an outstanding role in the formation and development of cosmical electrodynamics. A distinctive feature of Alfvén waves is that at each point in space the group velocity vector and the external magnetic field vector are collinear to each other. As a result, Alfvén waves can carry momentum, energy, and information over long distances. We briefly describe two Alfvén resonators, one of which is formed in the ionosphere, and the second presumably exists in the Earth's radiation belt. The existence of an ionospheric resonator is justified theoretically and confirmed by numerous observations. The second resonator is located between reflection points located high above the Earth symmetrically with respect to the plane of the geomagnetic equator. Keywords: Alfvén velocity, dispersion law, group velocity, geometric optics, heavy ions.

physics.geo-ph↗

arXiv2022

Phenomenology of aftershocks: Once more on the Omori Law

Omori Law describes the evolution of the aftershocks of a strong earthquake. Established at the end of the century before last, it is characterized by the beauty of its form, quite definite clarity, as a result of which it still attracts considerable attention of the geophysical community. In recent years, we have accumulated considerable experience in studying the Omori law by theoretical and experimental methods. This paper summarizes the results of our study briefly. The main attention is focused on the phenomenological theory of aftershocks, the foundations of which were laid by Fusakichi Omori. Keywords: earthquake, source deactivation, logistic equation, nonlinear diffusion equation, Omori epoch, round-the-world echo, mirror triad.

physics.geo-ph↗

arXiv2021

Mirror triad of tectonic earthquakes

It is natural to call the trinity of foreshocks, main shock and aftershocks a classical triad. The magnitude of the main shock is always greater than the maximum magnitudes of foreshocks and aftershocks. In the classical triad, the number of foreshocks is less than the number of aftershocks. In many cases, foreshocks are completely absent even before very strong earthquakes. In this work, we found a rare but extremely interesting species of triad (we called it the mirror triad), in which the number of foreshocks is greater than the number of aftershocks at the interval of 24 h before and 24 h after the main shock. Quite often, aftershocks are absent in mirror triads at all. In this paper, we described the properties of mirror triads and made an attempt to understand their origin. A schematic classification of tectonic triads is proposed. Keywords: foreshock, main shock, aftershock, Gutenberg-Richter law, Bath law, Omori law, solitary earthquake.

physics.geo-ph↗

arXiv2021

Dependence of the source deactivation factor on the earthquake magnitude

Three fundamental laws of the physics of earthquakes, bearing the names of their discoverers Omori, Gutenberg, Richter and Bath, are widely used in original, review, monographic, and encyclopedic literature. In this paper, we have tried to look at laws from an unusual point of view. The idea behind our approach is as follows. Each of the three laws was established in the course of work on solving a specific research problem, and the result was expressed in a specific mathematical form. We asked ourselves whether it is possible to modify the statement of the problem, and/or modify the form of expression of the law in order to see new facets of a well-known scientific statement? The result was successful in relation to Omori's law, according to which the frequency of aftershocks hyperbolically decreases over time. The modified formulation of the problem was to find a differential equation describing the time evolution of aftershocks. We found a simple differential model, within the framework of which the concept of deactivation of the earthquake source is introduced. The question of dependence of the deactivation factor on the magnitude of main shock is analyzed theoretically and experimentally. A monotonic decrease in the deactivation factor with an increase in the magnitude of the main shock has been reliably established. Other possible applications of the proposed methodological technique are considered. In particular, it is indicated how to overcome the contradiction between the Omori law and the law of energy conservation. Keywords: Omori law, Gutenberg-Richter law, Bath law, main shock, aftershock, deactivation factor, Omori epoch, differential equation of evolution.

physics.geo-ph↗

arXiv2021

Equation of the Aftershocks and its Phase Portrait

Recently, simple differential models of aftershocks have attracted increased attention of researchers at the Institute of Physics of the Earth, Russian Academy of Sciences for their remarkable properties. The shortened Bernoulli equation allows us to introduce the concept of the source deactivation factor and phenomenologically describe the nonstationarity of the geological environment in the earthquake source, "cooling down" after the main shock. The Verhulst logistic equation makes it possible to take into account the transition of the aftershock flow to the background seismicity mode. The Kolmogorov-Petrovsky-Piskunov nonlinear diffusion equation is convenient for modeling the spatio-temporal evolution of aftershocks. This paper focuses on the phase portrait of a dynamical system that simulates the evolution of aftershocks. The phase portrait allows us to understand why the Omori hyperbolic law is most clearly manifested after strong earthquakes. It is noted that the Omori epoch, during which the deactivation coefficient is constant, does not immediately end with a transition to the background mode. In the experience after the end of the Omori epoch, the deactivation coefficient changes over time in a rather complex way, and can even becomes negative. The theory predicts that if negative values of the coefficient are held long enough, then a geotectonic explosion occurs, vaguely resembling the main shock of earthquake. The paper discusses possible directions for the further development of the theory. Keywords: earthquake, aftershock, deactivation factor, Omori epoch, logistic equation, explosive instability, Bath law.

physics.geo-ph↗

arXiv2021

Discrete Spectrum of ULF Oscillations of the Ionosphere

This work relates to the field of ultra-low-frequency (ULF) spectroscopy of near-Earth plasma. Our attention is focused on the Alfvén ionospheric resonator (IAR), the spectrum of which is a series of discrete lines. The aim of the study is to experimentally verify a well-defined theoretical prediction. Within the framework of an idealized resonator model, a hypothesis about the relationship between the frequencies of spectral lines has been formulated. To test the hypothesis, observations of ULF oscillations at the mid-latitude Mondy observatory were used. The result of the analysis confirmed the hypothesis that odd harmonics of the IAR discrete spectrum are observed on the Earth's surface. Key words: electromagnetic oscillations, Alfvén waves, ionospheric Alfvén resonator, ultra-low-frequency spectroscopy.

physics.geo-ph↗

arXiv2021

Dynamic and stochastic models of the evolution of aftershocks

This paper is devoted to the theory of aftershocks. The history of discovery of the Omori law is briefly described, the initial formulation of the law is given in the form of an algebraic formula describing the decrease in the frequency of aftershocks over time. An important generalization of the Oiori formula which is widely used in modern seismology is presented. The generalized law is also expressed by an algebraic formula, but it contains an additional parameter, which makes it possible to more flexibly approximate the observational data. The alternative approach to the theoretical description of aftershocks is to use the differential evolution models. To simulate the averaged dynamics of aftershocks, it is proposed the Verhulst differential equation, also known as the logistic equation. It is shown that the decrease in the frequency of aftershocks with time at the first stage of evolution occurs according to the Omori hyperbola, i.e. in accordance with the original wording of the law. The paper also proposes a stochastic generalization of the equation for the evolution of aftershocks. A random function of time is added to the right-hand side of the logistic equation to simulate noise that affects a dynamic system. As a result, a stochastic Langevin equation was obtained, which can be used to simulate fluctuations in the frequency of aftershocks.

physics.geo-ph↗

arXiv2021

A Paradox of Whistling Atmospherics

Analyzing paradoxes is interesting and instructive. Sometimes the analysis leads to non-trivial results. This methodological note sets out a paradox arising in the theory of propagation of electromagnetic waves in moving plasmas. The paradox is interesting in itself, and, generally speaking, it should be taken into account when analyzing geoelectromagnetic waves. The paradox is as follows: contrary to expectations, the group velocity of the waves is the same in the comoving and laboratory frames of reference. The condition for the appearance of the paradox is the quadratic dependence of the frequency on the wave number. A paradoxical property manifests itself in the theory of the propagation of radio waves (in particular, whistling atmospherics), Langmuir waves and Alfvén waves. From a cognitive point of view, it is interesting that the paradox can be traced in relation to de Broglie waves. An explanation of the paradox is proposed. Keywords: group velocity, moving plasma, Doppler Effect, dispersion, longitudinal waves, transverse waves.

physics.geo-ph↗

arXiv2020

The Phenomenology of Aftershocks

The presented paper is devoted to the search for mathematical basis for describing the aftershock evolution of strong earthquakes. We consider the experimental facts and heuristic arguments that allow to make a choice and to focus on the nonlinear diffusion equation as the master equation. Analysis of the master equation indicates that, apparently, the selected mathematical basis makes it possible to simulate two important properties of the aftershock evolution known from the experiment. We are talking about the Omori law and the slow propagation of aftershocks from the epicenter of the main shock. Keywords: earthquakes, propagation of aftershocks, Omori law, deactivation coefficient, nonlinear diffusion, master equation, inverse problem

physics.geo-ph↗

arXiv2019

Unimodal part of the magnitude-frequency distribution of earthquakes according to the USGS catalog

In this paper, we used the Global Catalog of the National Earthquake Information Center US Geological Survey (NEIC USGS) for analysis of the magnitude-frequency distribution of earthquakes. We selected the unimodal part of the distribution and proposed an empirical formula that approximates this part in a wide range of magnitudes. The formula may be useful in studying the problems seismology, in which the expected effect is manifested in relatively weak earthquakes. The paper will be sent to the journal Geodynamics and Tectonophysics (ISSN 2078-502X). Keywords: planetary seismicity, Gutenberg-Richter law, unimodal distribution, statistical sum, entropy, spheroidal oscillations

physics.geo-ph↗

arXiv2019

Global Magnitude of the Earthquakes

The idea of the global daily magnitude (GDM, unit designation is Mg) of earthquakes is introduced. The formula is given for calculating Mg from earthquake strength data, characterized by the classic magnitude M on the Richter scale. An example of the calculation of Mg is given. It is noted that the Mg index may be useful in studying a number of seismological problems.

physics.geo-ph↗

arXiv2019

The search for empirical formulae for the aftershocks descriptions of a strong earthquake

The paper is based on the report read by the author on October 24, 2018 at the meeting of the Scientific Council of the Institute of Earth Physics of the Russian Academy of Sciences. The report was dedicated to the 150th anniversary of the outstanding Japanese seismologist Fusakichi Omori. As is known, Omori established the first empirical law of the earthquakes physics, bearing his name. The Omori law states that the frequency of aftershocks on average decreases hyperbolically over the time. Three versions of Omori law are described briefly. The recent version allows to poses the inverse problem of the earthquake source, that cools down after the main shock. Keywords: earthquake source, aftershocks equation, deactivation coefficient, inverse problem

physics.geo-ph↗