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Abstract—The paper presents the results of many years of research on the compilation of a consolidated, refined, unified earthquake catalog for the western sector of the Russian Arctic for the entire instrumental observation period, in particular for the period from 1908 to 2020. The catalog includes data on recent seismicity in areas previously unavailable for detailed seismic monitoring. Based on the results of the study, we were able to more accurately determine the spatial distribution of seismicity in the region and compare the instrumental data with parameters of lineament-domain-focal (LDF) models of the General Seismic Zoning maps (GSZ, from Russian term abbreviated as OSR)—OSR-97 and OSR-2016. In the western sector of the Russian Arctic, the highest seismicity is observed in the continent-ocean transition zone, in the Belyi (Kvitøya) Island, Novaya Zemlya and Severnaya Zemlya archipelagos. The very shelf of the Barents and Kara Seas is characterized by rare and scattered seismicity. The configuration, the maximum possible magnitudes, and the depths of the seismogenic layers in the LDF models of OSR-97 and OSR-2016 maps are not always consistent with the instrumental data and need a correction. The consolidated refined earthquake catalog can be used as a basis for the further research aimed at seismic hazard assessment of the territory, construction of geodynamic models, and study of the stress-strain state of the Earth's crust. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of a study showing that anomalies in the seismic regime parameters before earthquakes of various magnitudes occur in stages. The occurrence in stages means the correlation between the times of formation and development of anomalies in various seismic regime parameters. Earthquakes in regions with two general types of tectonics are selected for analysis: in the subduction zone (Kamchatka and Japan) and in the rift zone (Iceland). The selection of regions is primarily based on the availability and quality of regional seismic catalogs. GR b-value and the composite parameter known as the RTL are used as the seismic regime parameters. The detection of spatiotemporal anomalies before the selected earthquakes is based on the known "precursory patterns" of the seismic regime parameters. Comparing the durations of the detected anomalies shows that the anomalies of b-value generally occur earlier than the RTL anomalies. Possible reasons why the anomalies occur in stages are suggested. In the vicinity of the studied earthquakes, a change in the seismogenic rupture concentration parameter within the corresponding seismic cycles is also estimated. Comparing the times at which the detected seismic regime anomalies occur with the values of the seismogenic rupture concentration parameter corresponding to these times shows that the formation of seismic regime anomalies occurs at a stage when the system of seismogenic ruptures accumulated during the seismic cycle has almost reached its critical value. [ABSTRACT FROM AUTHOR]

Abstract—The paper addresses the problems associated with the maximum earthquakes in a seismically active region. Pisarenko and Rodkin (2009; 2010; 2015) proposed an alternative to the ambiguously determined parameter of the maximum regional magnitude Mmax in the form of a clearly defined and statistically substantiated parameter of the maximum possible magnitude of an earthquake in a given region on a given future time interval T. In this work, we study the statistical characteristics of this parameter—quantiles with a given confidence level q. For the first time, the estimates for the bias, standard deviation, and root mean square deviation of these quantiles are conducted on a large set (1000) of independent samples (synthetic catalogs) with known distribution law. This allowed us to compare the true accuracy of the resulting estimates with that obtained in the case of using one catalog for which the distribution law is not known. The real efficiency of the quantile estimates is assessed from the examples with the exact known quantile values, and stability and robustness of these quantiles as an informative and important characteristic of seismic risk is demonstrated. The conducted comparisons make it possible to estimate the scatter of the quantiles in the region of large times T and with very high confidence levels q. The quantile estimates of the maximum possible events in a future time interval are substantially more robust at a stronger downward bend of the frequency–magnitude graph. A relationship is derived between the quantiles of a single earthquake and the quantiles of a maximum earthquake in the future time interval T. This relationship establishes the equivalence between the length of interval T and the level of significance (reliability) q, which in the case of heavy-tailed distributions should be taken into account in seismic risk assessment. The statistical analysis is carried out using two different methods of parameter estimation: by maximum likelihood estimation and by Bayesian approach. Both methods proved to be approximately equally efficient. Based on these methods, it is concluded that the estimate of the long-term seismic hazard for the regions with a distinctly pronounced downward bend of the frequency–magnitude graph is fairly stable and robust. [ABSTRACT FROM AUTHOR]

Abstract—The paper addresses almost half a century's development of pattern recognition algorithms' application for solving the problem of determination of strong earthquake-prone areas. This approach was named Earthquake-Prone Areas (EPA). The pattern recognition algorithms applied for this purpose, the studied regions, and the methods for assessing the reliability of the obtained results including the theory of dynamic and limit recognition problems are considered. A recently developed alternative method for solving the problem by identifying the clusters of earthquake epicenters is also presented. This method is based on the approaches of the Discrete Mathematical Analysis (DMA) and implemented in the form of the algorithmic system named Formalized Clustering and Zoning (FCAZ). The comparison of the results obtained by the EPA approach and FCAZ system shows their good consistency which provides an additional argument in favor of their reliability. The possibilities for further development and joint application of the EPA approach and FCAZ system and creating, on this basis, an integrated method for systems analysis with the inclusion of artificial intelligence are outlined. In case of success, this method is expected to be used in seismic hazard assessment and planning of earthquake-resistant construction. [ABSTRACT FROM AUTHOR]

This paper presents the review of the experience in applying the approach based on the limiting distributions of the extreme value theory (the generalized Pareto distribution, GPS, and generalized extreme value distribution, GEV) for deriving the distributions of maximal magnitudes and related ground accelerations from the earthquakes on the future time intervals of a given duration. The results of analyzing the global and regional earthquake catalogs and the ground peak accelerations during the earthquakes are described. It is shown that the magnitude of the strongest possible earthquake M (and analogous characteristics for other types of data), which is often used in seismic risk assessment, is potentially unstable. We suggest a stable alternative for M in the form of quantiles Q(τ) of the maximal possible earthquake, which could occur during the future time interval of length τ. The quantity of the characteristic maximal event M, which has been introduced in our previous publications, is another helpful robust scalar parameter. All the cases of approximation of the tails of empirical distributions, which were studied in our works, turned out to be finite (bounded); however, the rightmost point of these distributions, M, is often poorly detectable and unstable. Therefore, the M parameter has a low practical value. [ABSTRACT FROM AUTHOR]

method is proposed for describing low-frequency microseismic noise from the network of broadband seismic stations in a large seismically active region of the Japan Islands. The median values of daily estimates from each station for seven parameters (three characteristics of the multifractal singularity spectra of the waveforms, their spectral exponents and the smoothness indices, the logarithmic variance and the linear predictability index) are used for the description. These parameters are determined for consecutive daily time intervals from the beginning of January 1997 through the end of February 2010. Since these parameters are taken as the median values of the estimates from each station, they are, actually, the integral statistics of the microseismic field. The present paper is the continuation of two previous works [Lyubushin, 2009; 2010], where the effects of synchronization in the low-frequency microseismic field on a large time scale were analyzed on the data from the F-net stations. In the present work, the number of different 'behavior modes' of the microseismic field are sought as the number of clusters in the optimal partition of the cloud of 7-dimensional vector parameters, estimated within a moving time window with a width of 2 years. A new characteristic of the geophysical field is introduced, namely, the notion of the cluster exponent, which is the power exponent in the dependence of the value of the compactness function of a cloud of vector parameters on the number of clusters in the optimal partition of this cloud. Previously, a relatively rapid increase was revealed in the level of synchronization of the microseismic field, which started in the middle of 2002 and lasted for approximately one year. The level of synchronization remains high up to now. During the past 4 years (taking into account the width (2 years) of the time window within which the estimates were made), the cluster exponent exhibits a long trend which is similar to the shorter trend before the Hokkaido event ( M = 8.3) that occurred on September 25, 2003. These facts, together with the pattern of variations in the coefficient of correlation between two multifractal parameters of the field, suggest a hypothesis of the enhancement of the seismic hazard in the region of the Islands of Japan from the second half of 2010. [ABSTRACT FROM AUTHOR]

Abstract—To obtain realistic and correct estimates of seismic effects in the Baikal Rift Zone (BRZ), a ground motion prediction equation has been developed based on the records of local earthquakes (magnitudes mb ~ 3.4–5.5, hypocentral distances R ~ 15–220 km) obtained by Ulan-Ude and Severomuisk seismic stations. At the first step, in our previous works, using stochastic simulation of the accelerograms of the recorded local earthquakes we estimated the regional parameters of radiation and propagation of seismic waves (stress drop in an earthquake source, quality function of the medium, geometrical spreading, wave attenuation at high frequencies, local site amplification, etc). These parameters were then used to generate a set of earthquake accelerograms over a wide range of magnitudes (Mw ~ 4.0–8.0) and distances (R ~ 1–200 km) on a rock site, and a ground motion prediction equation (GMPE) describing the dependence of peak ground accelerations (PGA) and peak ground velocities (PGV) on magnitude and distance are constructed. The obtained PGA estimates are compared with those estimated from GMPE recommended for BRZ by the international Global Earthquake Model (GEM) project. The scatter of the estimates obtained based on GEM GMPE indicates the relevance of developing the own GMPEs for Russian regions based on the records of local earthquakes. The GMPE derived in this work can be used for seismic hazard assessment in the BRZ eastern part and will be updated as new data are acquired. [ABSTRACT FROM AUTHOR]

Abstract—The significant deviation of the regime of the main earthquakes from the stationary Poisson process is shown for the regional catalog of shallow earthquakes in the Kamchatka region. The character of deviation was found to be similar for three different methods of aftershocks removal. The value of the deviations tends to grow as the averaging time increases. The work compares the trends in the characteristic spatiotemporal distance between earthquakes for artificial stationary sequences of independent events, real main events, and aftershock sequences. The parameters of the main event clusters are very different from those of the aftershock sequences, which apparently indicates a difference in how aftershock sequences and main event clusters physically emerge. It is found that the characteristic distance between consecutive earthquakes in groups of main events tends to grow as the intensity of the flow of events increases. Apparently, this trend is consistent with the fact that as the intensity of the flow of main events increases, the activity of larger seismogenic structures and the probability of larger earthquakes grow faster. The described significant non-stationarity of the flow of main events indicates a certain limitation of the generally accepted approach to seismic hazard assessment. [ABSTRACT FROM AUTHOR]

Abstract—The ruins of Odessos are located on the territory of Varna, Bulgaria. Archaeoseismological studies carried out at the archaeological sites of ancient Odessos revealed some significant damage and destruction in the ancient building constructions. These are numerous breaks, tilts, protrusions and turns of wall parts, longitudinal asymmetric deformation of the above-entrance arch, lateral in plan bending of the extended wall, outward knock-out of the stone blocks and intensive cracking. We attributed traces of subsequent shoddy repairs, which sometimes involved using single expensive stone blocks taken out of the ruins, as circumstantial evidence of strong earthquakes that had occurred here. Interestingly, medieval builders already knew about the possibility of strong earthquakes in the region and put wooden longitudinal beams in the walls to absorb vertical seismic vibrations. The degree of destruction and damage in medieval buildings built on loose fill soils increased due to subsidence. Archaeological research established 6 periods of construction in ancient Odessos: Using this periodization, we calculated the age of past seismic events: (1) around the 1st century A.D.—the destruction of the Late Hellenistic fortress wall; (2) the early 5th century—the early 6th century (a cluster of at least 3 strong earthquakes, judging also by deformations in the Bishop's Basilica of Odessos (Minchev et al., 2020)): dismantling of the fortress wall, discontinued use of both thermae. The gate of Odessos remains in operation after repairs. There is low quality construction of houses. Accumulation of tile debris; (3) the destruction of the Orthodox church in the 1444 earthquake. We were able to determine the average direction of the maximum aggregate seismic movements that destroyed the large and small thermae, as well as the excavated segment of the fortress wall and the Odessos gate complex. They propagated along the WNW-ESE axis, most likely from the Shabla-Kaliakra seismogenic zone. The deformations of the 13th-century Orthodox church were caused by seismic vibrations that propagated in the submeridional direction from one of the seismically active faults south or north of Varna, although they may have been affected by ground subsidence. Thus, as a result of the studies, we were able to detect traces of yet unknown strong earthquakes, to determine their age and direction to the ancient epicentral zones. The intensity of seismic vibrations during all these earthquakes was Il = VIII—IX MSK-64. The data obtained can be used to improve the seismic hazard assessment of Varna and NE Bulgaria. [ABSTRACT FROM AUTHOR]

Abstract—Deep earthquakes occur in subduction zones—they play a key role in the global tectonic model. There are only a few places on the Earth where deep-focus seismicity is observed on the continents in small localized areas at a considerable distance from the present-day subduction zones, in particular in the Vrancea region of the Carpathians. The strongest deep Vrancea earthquakes are felt at a distance of over 1000 km. They essentially define the seismic hazard for the East European platform, where either there are no local focal zones or these zones have small magnitudes. Therefore, studying deep Carpathian earthquakes is very important for adequate assessment of seismic hazard for the East European platform. We assume that although the strongest deep Carpathian earthquakes have been studied quite fully and thoroughly, not all existing information has been exhausted. The search for previously unknown primary sources may reveal new information about the macroseismic effect and, consequently, lead to more reliable and accurate earthquake parameter evaluations. This article examines the 1838 deep Carpathian earthquake using the original descriptions from primary sources. The earthquake magnitude has been determined by means of a new approach based on minimizing the discrepancies between the calculated and observed shaking intensities at all localities. It is shown that the magnitude of the 1838 earthquake is underestimated in the published catalogs by about 0.5 unit. We believe that the main reason is that the previously used macroseismic data in the far-field zone are not sufficiently complete. [ABSTRACT FROM AUTHOR]

Spatiotemporal variations in the Gutenberg–Richter (GR) b-value and in the minimum magnitude of a predicted earthquake (MPE) are studied in detail depending on the depth and lateral position of the selected sample of earthquakes in the Garm region, Tajikistan. The time variations in b-value estimated from the data on the earthquakes in the different depth intervals indicate that most of the "strong" events with M ≥ MPE were preceded by the significant time anomalies localized in the vicinity of the source depths of these earthquakes. The maximum amplitudes of these anomalies gravitate to the vicinity of the hypocenters of the strong earthquakes and decay with distance from the hypocenter. The observed time anomalies in the b-value, which have a shape of a positive bay, are not accidental, which is demonstrated by their sufficient statistical representativeness (18 events). It is concluded that based on the used approach it will be possible to estimate the source depth of a future strong earthquake. The estimate of earthquake prediction quality based on 38 "strong" earthquakes with M ≥ MPE that occurred in seven local regions during a 23-year observation period shows that in 84% of cases, the emergence of b-value anomalies is accompanied by the successful forecasts. At the same time, the overall probability estimate of a medium-term forecast of the "strong" earthquakes with false alarms and missed events taken into account is 71%. Meanwhile, the forecasting quality of the strong earthquakes substantially increases if the b-value time variations are monitored separately in the different depth intervals of the Earth's crust. It is shown that the parameter of the minimum MPE estimated from the rightmost part of the linear segment of GR relationship is a characteristic of the structural blocks of the Earth's crust and varies both across the area and along the depth. It is hypothesized that the front of the deformation waves emerging on certain time intervals in a number of the local regions of the sample has probably been detected. The supposed deformation waves propagate with the velocities of 40–50 km/yr with their front moving NE to SE.The results of the study can be used for medium-term forecasting of the earthquakes with M ≥ MPE, for estimating the depth of the expected earthquake, and for overall seismic hazard assessment in the seismically active regions. [ABSTRACT FROM AUTHOR]

A new composite model is suggested for the frequency–magnitude relation of the earthquakes. The new model statistically reasonably describes the distribution in the range of weak and moderate events (the Gutenberg–Richter law) and in the range of strongest events (generalized Pareto law—one of the limiting laws in the extreme value theory). By the example of Japan and Kuriles, based on the GCMT catalog, it is shown that the model fairly adequately describes the seismicity in the circles containing at least 80 main shocks in the range of the reliably detected events m ≥ 5.3. The restriction on the number of the events imposes a statistical limitation on the resolution of the proposed model. In the case of the studied regions, this limitation allows reliable estimation of seismicity parameters for the areas with a radius of 300 km on a 2° × 2° grid. The use of this model in our previously designed statistical method for seismic risk assessment (Pisarenko and Rodkin, 2007; 2010; 2013) provides a theoretical basis for developing this technique towards more robust results and a better spatial resolution approaching the scale of the general seismic zoning maps. [ABSTRACT FROM AUTHOR]

The distribution of the number of seismic events by magnitudes—the Gutenberg–Richter frequency–magnitude relation—is of paramount importance for seismic hazard assessment of a territory. The generalization of the Gutenberg–Richter relation—the Unified Scaling Law for Earthquakes (USLE) proposed in 1988 makes it possible to take into account the pattern of epicentral distribution of seismic events when changing the spatial scale of the analysis. This is extremely important for adequate downscaling of the frequency of occurrence into a smaller area within the territory under study (e.g., in the megalopolis). In 2002, Per Buck suggested a dual formulation of USLE where, instead of the number of earthquakes over a certain period of time, the reciprocal of their frequency of occurrence—the time between seismic events—is used. The same year, the Institute of Earthquake Prediction Theory and Mathematical Geophysics of the Russian Academy of Sciences developed a modified algorithm for robust estimation of USLE parameters referred to as Scaling Coefficients Estimation (SCE) for producing seismic hazard maps of territories prone to seismic effects. This brief review is focused on the use of the USLE approach to the assessment of seismic hazard and associated risk. [ABSTRACT FROM AUTHOR]

A new version of the Barrier algorithm is proposed for recognition of strong-earthquake prone regions based on training over a single reliable training class. The modification of the algorithm consists in creating blocks that reveal the geological–geophysical features (attributes) characteristic of the recognized highly seismic objects and provide their quantitative estimates. The recognition of the areas prone to earthquakes with M ≥ 6.0 is carried out for the Altai–Sayan–Baikal region. The results of the recognition are used for assessing the effect of the remote earthquakes that occurred in the Altai–Sayan orogenic region on the stability of structural-tectonic crustal blocks in the contact zone of the West Siberian platform and the Siberian plate. [ABSTRACT FROM AUTHOR]

The results of modeling the stress-strain state for the epicentral zone of the earthquake that occurred on December 26, 2003 in the southeast of Iran in the city of Bam, Kerman province, before and after the rupture are presented. It is shown that the source of the earthquake is located in the zone of high stresses, whereas the emerged rupture traces this zone on the surface and corresponds to its length. The aftershocks are localized in the area of the maximal stress drop after the formation of the rupture. The drop in the stress stimulates the release of the accumulated tectonic stresses during the subsequent aftershock process. The obtained results can be useful for the deterministic approach to seismic hazard assessment and forecasting, as well as for setting up the geophysical observations intended for forecasting the strong crustal earthquakes in the continental regions. [ABSTRACT FROM AUTHOR]

The hypocenters of the earthquakes recorded in the north of the Russian Plate from 1982 to 2013 are relocated. The relocation of the hypocenters is based on the common velocity section, common methodology, and the entire set of the initial data and bulletins available from the Russian and foreign seismic stations. The efficiency of the algorithm for calculating the hypocentral parameters and the velocity section is demonstrated by the example of two nonmilitary nuclear explosions in July 18, 1985 and September 6, 1988 in the northern part of the European Russia. For the first time, two earthquakes of July 19, 1982 and October 7, 2012, which have not been previously reported in the catalogs for the north of the Russian plate, are included in the seismic catalog. [ABSTRACT FROM AUTHOR]

The technology which is being developed based on the seismic entropy method for monitoring and forecasting the earthquakes in the territory of Russia is described. This technology relies on seismostatistics and makes it possible to automate the monitoring system and to efficiently tap the networks of ground-based and ground-and-satellite-based observations of operative precursors. The main seismic systems responsible for the preparation of the strong earthquakes with magnitudes М ≥ 5.5 are described. The track and energy diagrams constructed for each seismic system provide the means for monitoring the preparation and forecasting the strong earthquakes in the real-time mode. Forty-four seismic systems controlling almost all seismically hazardous regions in Russia were identified and tested in real time during the period from 2010 to 2015. The guidelines for the practical application of the results of monitoring and forecasting are developed. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard analysis has become a standard procedure preceding the antiseismic construction. An important component of the relevant calculations is the allowance for the uncertainty in the strong motion parameters (e.g., peak ground acceleration (PGA)). In the present-day approaches of probabilistic analysis, this uncertainty is modeled by a random variable (a residual) which has a lognormal distribution. With this model, the extrapolation into the area of long return periods yields nonzero probabilities of unrealistically high PGA. In the present work, the distribution of the logarithmic PGA residuals is modeled by different parametric distributions. From the set of these distributions, the one which provides the closest approximation of the empirical data is selected by the statistical criteria. The analysis shows that the generalized extreme value distribution (GEVD) most accurately reproduces the residuals of the logarithmic PGA, and the tail of the distribution is approximated by the generalized Pareto distribution (GPD). [ABSTRACT FROM AUTHOR]

For the Himalayas and neighboring regions, the maps of seismic hazard and seismic risk are constructed with the use of the estimates for the parameters of the unified scaling law for earthquakes (USLE), in which the Gutenberg-Richter law for magnitude distribution of seismic events within a given area is applied in the modified version with allowance for linear dimensions of the area, namely, log N( M, L) = A + B (5 − M) + C log L, where N( M, L) is the expected annual number of the earthquakes with magnitude M in the area with linear dimension L. The spatial variations in the parameters A, B, and C for the Himalayas and adjacent regions are studied on two time intervals from 1965 to 2011 and from 1980 to 2011. The difference in A, B, and C between these two time intervals indicates that seismic activity experiences significant variations on a scale of a few decades. With a global consideration of the seismic belts of the Earth overall, the estimates of coefficient A, which determines the logarithm of the annual average frequency of the earthquakes with a magnitude of 5.0 and higher in the zone with a linear dimension of 1 degree of the Earth's meridian, differ by a factor of 30 and more and mainly fall in the interval from −1.1 to 0.5. The values of coefficient B, which describes the balance between the number of earthquakes with different magnitudes, gravitate to 0.9 and range from less than 0.6 to 1.1 and higher. The values of coefficient C, which estimates the fractal dimension of the local distribution of epicenters, vary from 0.5 to 1.4 and higher. In the Himalayas and neighboring regions, the USLE coefficients mainly fall in the intervals of −1.1 to 0.3 for A, 0.8 to 1.3 for B, and 1.0 to 1.4 for C. The calculations of the local value of the expected peak ground acceleration (PGA) from the maximal expected magnitude provided the necessary basis for mapping the seismic hazards in the studied region. When doing this, we used the local estimates of the magnitudes which, according to USLE, corresponded to the probability of exceedance 1% and 10% during 50 years or, if the reliable estimate is absent, the maximal magnitudes reported during the instrumental period. As a result, the seismic hazard maps for the Himalayas and the adjacent regions in terms of standard seismic zoning were constructed. Based on these calculations, in order to exemplify the method, we present a series of seismic risk maps taking into account the population density prone to seismic hazard and the dependence of the risk on the vulnerability as a function of population density. [ABSTRACT FROM AUTHOR]

The combined geological, geomorphologic, and geophysical study has significantly ascertained the spatial location of main seismogenerating structures in the region of Sochi. The research, which is aimed at identifying and thoroughly exploring all active faults in this area, was conducted in 2007-2009 in the territory between Adler and Krasnaya Polyana. It is found that the Monastyrskii and Krasnopolyanskii faults are the most important structures for seismic hazard assessment. Dramatic deformations of young deposits and prominent landforms are revealed, and seismogravitational features associated with these units are identified. [ABSTRACT FROM AUTHOR]

The main objective of the present study is to evaluate seismic attenuation relationships for the Campanian area (southern Italy) using the felt intensity report data obtained from comprehensive historical databases (DOM 4.1). We focused our attention on the Campania region because it is characterized by a high seismic hazard and risk, particularly in the Naples area and its suburbs. In order to derive an attenuation relationship for the area, we fitted the observed data by using several functions. We found that a linear plus logarithmic model gives the best fits for the data in the Campanian region. Most of the attenuation relationships proposed up to now for the Italian Peninsula have an isotropic behavior and do not always properly describe the macroseismic attenuation. Therefore, in order to check the possible dependence of the attenuation on the azimuth of the seismic rays, we divided our data set in octants and performed for each of them the same analysis we carried out for the whole data set. The obtained results differ from octant to octant and the differences, besides being associated with the source effects, could be interpreted as probably due to the existence of lateral variations in the lithological and physical features of the crust at different depths, which could affect the patterns of attenuation. [ABSTRACT FROM AUTHOR]

The structure of low-frequency seismic noise in the range of periods from 2 min to 500 min is studied from the data of continuous seismic monitoring at 77 seismic stations of the F-net broadband network in Japan from the beginning of 1997 to May 15, 2012. A new statistical characteristic of seismic noise is suggested, namely, the minimal normalized entropy En of the distribution of squared orthogonal wavelet coefficients. This parameter of seismic noise is analyzed in conjunction with the multifractal statistics-the support width of the singularity spectrum, Δα, and the generalized Hurst exponent, α*, which were extensively used by the author in the previous works for analyzing the low-frequency seismic noise. The method for constructing the maps of spatial distribution of Δα, α*, En, and their aggregated normalized value over the time windows with a given length is proposed. The maps are constructed by averaging the succession of the elementary charts, each of which corresponds to a day of observations. It is shown that, for the islands of Japan, the reduction in Δα and α* and the increase in En outline the area of the forthcoming mega earthquake of March 11, 2011, with M = 9 (Tohoku earthquake). According to the analysis of about a year's worth of data after this event, the region south of Tokyo (Nankai trough) is still dominated by decreased Δα and α* and increased En. This gives grounds to hypothesize that this region remains at a high level of seismic threat since the accumulated stresses were incompletely released by the Tohoku earthquake. Drawing an analogy to the behavior of the coefficient of correlation between Δα and α*, we may suppose that there is an increased probability of a strong earthquake occurring in the second half of 2013 or the first half of 2014. Constructing the averaged maps of the distributions of seismic noise parameters and their aggregated value in a moving time window is suggested as a new method for dynamical assessment of seismic hazards. [ABSTRACT FROM AUTHOR]