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The main disadvantages of selected elements of seismicity modeling for composing the General Seismic Zoning maps are considered in the framework of a probabilistic approach. We proposed a method that should provide more precise assessment of probable future seismicity after the improvements of the disadvantages. A stochastic seismicity model is suggested for the first time as a synthetic earthquake catalog, which is generated for an arbitrary conditional period and which reproduces the properties of the catalog of factual earthquakes including spatiotemporal grouping. The verification method of seismicity models is suggested to check the correspondence of the models to the primary data and the assessment of the predictive efficiency of the models and to compare various models based on these characteristics. [ABSTRACT FROM AUTHOR]

Abstract—This paper analyzes the use of the automated aftershock hazards assessment system (AFCAST) through the example of a series of aftershocks of the Mw 7.8 earthquake in Turkey of February 6, 2023 (the Pazarcik earthquake). The paper presents automated estimates of the aftershock activity area, the magnitude of the strongest aftershock, and the duration of the hazardous period, yielded using data on the main shock and on the first aftershocks. [ABSTRACT FROM AUTHOR]

For the first time, a numerical comparison of the General Seismic Zoning (GSZ) maps with the effect of earthquakes that actually occurred after the publication of the maps was carried out. The area of zones of expected intensity on the GSZ map is compared with the area of isoseists from actual earthquakes. It turned out that the isoseist area is on average by an order less than expected according to the GSZ. This paper describes possible reasons for such an overestimation and proposes ways to improve seismic hazard assessments. [ABSTRACT FROM AUTHOR]

A relative decrease in the fraction of large aftershocks in the first days after earthquakes in subduction zones is demonstrated, and a connection of this phenomenon with aseismic stress release is shown. [ABSTRACT FROM AUTHOR]

Mechanisms of stress transfer and probabilistic models have been widely investigated to explain earthquake clustering features. However, these approaches are still far from being able to link individual events and to determine the number of earthquakes caused by a single event. An alternative approach based on proximity functions allows us to generate hierarchical clustering trees and to identify pairs of nearest-neighbours between consecutive levels of hierarchy. Then, the productivity of an earthquake is the number of events of the next level to which it is linked. Using a relative magnitude threshold Δ M to account for scale invariance in the triggering process, we show that the Δ M -productivity attached to each event is a random variable that follows an exponential distribution. The exponential rate of this distribution does not depend on the magnitude of triggering events and systematically decreases with depth. These results could now be used to characterize active fault systems and improve epidemic models of seismicity. [ABSTRACT FROM AUTHOR]

The paper summarizes the results of the experiment on advance earthquake forecasting using the Reverse Tracing of Precursors (RTP) algorithm based on the phenomenon of the increase in seismicity correlation range before large earthquakes. During the test period from 2003 to 2019, 28 strong earthquakes occurred in five regions of the world, and 23 of these events fell within the regions and alarm intervals diagnosed by the algorithm. The probability of occasional success in the regions was at most 30% and averaged about 15%. These results confirm the efficiency of the RTP algorithm. The tests have also shown a high degree of nonrandom coincidence of the strong earthquakes and their preceding indicators in the form of the increase in the correlation range—the chains of the earthquakes. [ABSTRACT FROM AUTHOR]

Continuing the series of publications on aftershock hazard assessment, we consider the problem of estimating the time interval after a strong earthquake that is prone to aftershocks which may pose an independent hazard. The distribution model of this quantity, which depends on three parameters of the Omori–Utsu law, is constructed. With the appropriate averaged parameter estimates, the model fairly closely fits the real (empirical) distributions of this quantity on the global and regional scale. A key parameter in the model is the expected number of aftershocks of a given magnitude. This number broadly varies from earthquake-to-earthquake, which determines the wide confidence variant of the estimates based on the averaged parameters. Therefore, for forecasting the duration of the hazardous aftershock-prone period, we propose to use two variants of the estimates. The first variant is based only on the averaged parameter estimates for the region under study and on the value of the magnitude of the earthquake. This variant is applicable immediately after a strong earthquake. The second variant employs information about the aftershocks that occurred during the first few hours after an earthquake, which improves the forecast considerably. [ABSTRACT FROM AUTHOR]

This paper considers the global statistics of times of largest aftershocks relative to the times of the corresponding main shocks. A large data set was used to show that the time-dependent distribution of largest aftershocks obeys a power law distribution. This is analogous to the Omori law for the sequence of all aftershocks. It is also shown that the times of the second, etc., largest aftershocks obey the same distribution. Thereby, we have confirmed the hypothesis that the times and magnitudes in an aftershock sequence are independent and make a good case for the Reasenberg–Jones representation of the aftershock process as a superposition of the Omori–Utsu law and the Gutenberg–Richter relation. Events that are smaller than the largest in an aftershock sequence show no delay relative to the largest event; this rejects the idea of the aftershock process as a direct failure cascade involving gradual transitions from larger to lesser scales, which imposes certain restrictions on the widely popular stochastic models of aftershock generation as branching processes. The above result is important in practice for prediction of aftershock activity and for assessing the hazard of large aftershocks. [ABSTRACT FROM AUTHOR]

In seismology according to Båth’s well-known law, the magnitude of the strongest aftershock is on average by unity lower than the magnitude of the main shock. At the same time, most of the strongest aftershocks typically occur within a few hours after the main shock. From the practical standpoint, this activity is quite naturally perceived as a direct continuation of the main earthquake. The subsequent strong aftershocks occur against the rarer background shocks, are less expected, and therefore constitute a separate hazard. The average difference in magnitudes between the main shock and the strongest aftershock that occurs a certain time after the main shock gradually increases. In this work, we consider the problem of estimating the magnitudes of the strongest future aftershock at the successive instants of time after the main shock without taking into account the information about the aftershocks that have already occurred before a given time. For these estimates, we construct the theoretical distributions whose shape proves to be independent of time, whereas the time dependence of the shift in the magnitude proves to be known a priori. The predetermination of these dependences at the moment of the strong earthquake gives us grounds to characterize the constructed theoretical model as Båth’s dynamic law. [ABSTRACT FROM AUTHOR]

This paper shows that the number of aftershocks with a relative magnitude does not depend on the magnitude of the main shock, and, in global and regional consideration, it is characterized by an exponential distribution that is similar to the Gutenberg-Richter repeatability law. This type of distribution makes it possible to give a simple and adequate interpretation of Bath’s law. [ABSTRACT FROM AUTHOR]

Develops a model of irregular temporal change in seismic activity using data on acoustic emission in the process of metallic-specimen destruction. Variations of tectonic stress; Reduction in the plastically deformed volume and localization of the destruction; Relation between the development of the unstable brittle crack to a short-term lull.

Abstract—The spatial distribution of the triggered seismic events in mining conditions in the tectonically loaded rock masses is studied using the example of seismicity in the Khibiny Mountains. It is shown that the distribution of distances from the triggering to triggered events, on average, obeys the power-law with a parameter independent of the magnitude of the triggering event. The model of the maximum distances from a triggering event's hypocenter to the triggered shocks expected with a given probability is derived. It is shown that the model is consistent with the real data. Based on the error diagram analysis, the guidelines are proposed for the practical use of the model. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of forecasting the magnitude of the strongest aftershock starting from a certain instant of time in the future. This problem is topical since the strong aftershocks that occur later against a background of less frequently repeating shocks are less expected and thus pose an independent hazard. At the same time, the magnitudes of the strongest aftershocks decrease with time after the main shock. The purpose of accurately forecasting them is to minimize the underestimation or overestimation of the magnitude of future risks. In this study, the aftershock process is represented by the superposition of the Gutenberg–Richter and Omori–Utsu laws whose parameters are estimated by the Bayess method using the data on the aftershocks that have already occurred up to a given time point and the a priori information about the probable values of the parameters. This significantly improves the forecast compared to the estimates that are based on the magnitude of the main shock alone. The quality of forecasting is estimated relative to Båth's dynamic law with the use of two independent criteria. The first criterion is based on the similarity estimates, and the second, on the error diagram. [ABSTRACT FROM AUTHOR]

The geometry of supposed coupling zones in the Kamchatka subduction zone is determined by the earthquake size distribution based on ealier revealed relationship between its shape and rate of inelastic deformations. In the areas of higher aseismic slip, a break of linearity in earthquake size distribution is observed owing to the deficit of large earthquakes. Zones of higher coupling between the oceanic and continental plates are characterized by an excess of large earthquakes and an inverse bend in the earthquake size distribution. The mapping results of the bend value agree with the coupling zones distinguished from satellite geodetic data and inversion of marigrams. [ABSTRACT FROM AUTHOR]

The issue of whether tidal forces really affect seismicity has been raised many times in the literature. Nevertheless, even though there seems to be a kind of consensus that such effects do exist, no quantitative estimates are available to relate tide parameters to changes in the level of seismic activity. Such estimation for aftershocks of large earthquakes near Kamchatka is the goal of the present study. We consider the influence on seismicity due to ocean tides only, because their effects are stronger than those of solid earth tides. Accordingly, we only consider earthquakes that occurred in the ocean. One important feature that distinguishes the present study from most other such research consists in the fact that we study the height of ocean tides and its derivative rather than tidal phases as the decisive factors. We considered 16 aftershock sequences of earthquakes near Kamchatka with magnitudes of 6 or greater. We also examined shallow background earthquakes along the coast of Kamchatka. Our basic model of aftershock rate was the Omori–Utsu law. The background seismicity distribution was assumed to be uniform over time. In both of these cases we used the actual distributions in space. The heights of sea tides were estimated using the FES 2004 model (Lyard et al., 2006). The variation in activity from what the basic model assumes in relation to tidal wave height and its time derivative was estimated by the method of differential probability gain. The main practical result of this study consists in estimates of averaged differential probability gain functions for aftershock rate with respect to both of the considered factors. These estimates can be used for earthquake hazard assessment from aftershocks with ocean tides incorporated. The results of our analysis show a persistent tendency of aftershock rate increasing during periods when the ocean tide decreased at a high rate. For the background events, we found a typical tendency of events rate increasing when the ocean tide decreased with high tidal amplitudes. The difference in the main factors that affect aftershocks and background seismicity suggest the inference that the effects of tides on aftershocks are more likely to be direct dynamic initiation of events during high strain rates, while the effects on the background events were static in character. [ABSTRACT FROM AUTHOR]

The paper addresses the study of the ability of mining-induced earthquakes to generate successive shocks. Based on the example of the Khibiny natural–technogenic system, it is shown that the number of the initiated shocks (the productivity) has the exponential distribution with the form independent on the magnitude and depth of the events. This result is consistent with the similar productivity law previously established for the tectonic earthquakes on the global and regional levels, expanding the validity of this law to the lower energy scales of seismic events ~104 J (M ≥ 0). [ABSTRACT FROM AUTHOR]

A new approach is proposed for determining earthquake hypocenters aimed at a more comprehensive characterization of its uncertainty and ambiguity. Application of the new approach to study the seismic focal subduction zones and volcanic seismicity is discussed by the example of the data of the Kamchatka Branch of the Geophysical Survey of the Russian Academy of Sciences. [ABSTRACT FROM AUTHOR]