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The goal of this paper is to update the information of the Automated Information Management System of the EMERCOM of Russia Unified Emergency Prevention and Response System in order to increase the reliability of the results of seismic risk assessment and ensure the safety of the population in earthquake-prone areas of the Russian Federation. The study area is Stavropol krai, where, according to general seismic zoning (GSZ) and detailed seismic zoning (DSZ), possible earthquake source (PES) zones with Мmax = 5.0, 5.5, Мmax = 6, and Мmax = 7 have been identified. The relevance of this study follows from the activation of seismicity in recent years on the considered area according to the registration by the Geophysical Survey of the Russian Academy of Sciences (GS RAS), network of seismic events within a wide range of magnitudes with М ≥ 1. The scientific novelty is due to the fact that, for the first time in the study of a single region, the results of all stages of the study are presented. Estimates of seismic hazard and parameters of the seismic intensity attenuation equation are refined on the basis of the analysis of moderate events with magnitudes in the range of M = 3.3–4.5 from the beginning of the last century to the present; the seismic risk indicators and possible consequences of scenario events for the most hazardous possible source zones are computed. For the first time, we have conducted a joint analysis of all variables. Methods of computer simulation are used to assess the risk indicators, along with the Extremum GIS developed with the participation of the authors of this article. Estimates of possible damage due to scenario earthquakes with M = 6.0 and M = 5.0 for separate large cities of Stavropol krai are obtained. [ABSTRACT FROM AUTHOR]

This paper is the first in a series of studies generalizing the Map of Expected Earthquakes (MEE) medium-term earthquake forecast method and analyzing the prospects for its further improvement. Over the past 35 years, the MEE method has been used in seismically active regions around the world with different tectonic conditions and seismic regimes. The average prognostic efficiency of the algorithm was shown to be 2.5 times higher than for random guessing. The MEE can be further improved and upgraded. The new methods of data processing to be implemented into the upgraded MEE will significantly increase the amount of analyzed data, take into account the specific signs of the seismic process at different depths, use lineament–domain–focal (LDF) models of the structure of seismically active zones as stationary prognostic criteria, and build three-dimensional distributions of the probability of strong earthquakes. The improvement will involve an expansion of the list of used seismological precursors that have a physically justified link with the earthquake preparation process and the development of formalized techniques for identifying these precursors in the prognostic practice. [ABSTRACT FROM AUTHOR]

We consider some characteristics of seismicity in the region of Southwest Alaska. The aftershock zones of the Simeonof (July 22, 2020, Mw = 7.8) and Chignik (July 29, 2021, Mw = 8.2) earthquakes are identified. The characteristics of ring-shaped seismicity structures, which formed in a few decades prior to the Chignik earthquake, are described. The location and magnitude of a large event, which could be prepared to the east of the Simeonof earthquake rupture zone, was predicted in (Kopnichev and Sokolova, 2021a) based on the parameters of these structures. An estimate of the expected magnitude (Mw = 8.2 ± 0.2) was obtained using correlation dependences between the parameters of ring-shaped structures and the magnitudes of large and great earthquakes that occurred in the East Pacific region. This forecast, which was made on the basis of the data obtained prior to October 21, 2020, was presented in the mentioned paper, which was accepted for publication before July 29, 2021. We consider possible changes of the parameters of ring-shaped structures immediately prior to the Chignik earthquake and discuss geodynamic processes that can lead to the formation of ring-shaped structures. [ABSTRACT FROM AUTHOR]

A destructive earthquake, especially if it occurs in areas of high seismic risk, in the form of certain factors, has a significant impact on the environment, including biodiversity. These factors (earthquake effects) are determined by the strength of the earthquake (manifestations of intensity on the earth's surface), local conditions (geomorphological, geological structure, level of urbanization and seismic risk, etc.), disaster-zone recovery processes (fast and effective recovery, localization and prevention of secondary consequences, environmental protection, state opportunities and political decisions, etc.). It is clear that these three important basic conditions of effects are different in different seismic regions and countries, which means that the impact of an earthquake on the environment is different. To consider the features and factors of the impact of an earthquake on the environment, the 1988 Spitak earthquake—one of the most detailed and comprehensively studied earthquakes in the world—was taken as a test object. The main purpose of this article is to highlight in more detail and more fully the possible natural and human factors of the impact of a strong earthquake on the environment and predict the extent of these impacts. Thirty-six major earthquake factors affecting the environment have been identified, which are conditionally divided into three main groups according to the time of formation and genesis: (a) purely seismic, (b) secondary seismic, and (c) post seismic. The paper also attempts to assess possible changes in these factors depending on global warming and a decrease in precipitation. [ABSTRACT FROM AUTHOR]

This paper presents the results of studying the precursor cyclic stress-strain state of the lithosphere during the preparation of significant seismic events using the automated lineament analysis of multitemporal space images. The proposed method has been tested by the example of a number of strong and devastating earthquakes over the past decade in different parts of the world. The identified precursor cyclical dynamics of lineament systems has a period of 1 to 3 months and makes it possible to predict the time, place, and possible magnitude of earthquakes. [ABSTRACT FROM AUTHOR]

The morphostructures and paleoseismicity of the southern slope of the Kungei Ala-Too Range (Northern Tien Shan) have been studied. It has been found that the main seismogenic structures in the Late Pleistocene and Holocene were adyr (foothill) faults, that is, thrusts, strike-slips, and normal dips. With a general thrusting of block folds of the basement southwards (toward the Issyk-Kul Basin), there are also northward-moving underthrusts. The past seismic activity along the adyr faults is expressed by single seismogenic scarps, as well as by stair-like series of alluvial-proluvial and fluvioglacial surfaces, upthrown in the hanging walls of faults. In addition to the easily identifiable vertical component of slips along the faults, we have also identified significant horizontal slips, which often greatly exceed the vertical ones. In addition, a unique structure, that is, a neotectonic ramp graben bounded from the south and north by oppositely directed thrusts, was studied on the slope of the Kungei Range. The mentioned faults were also studied by trenching. It was found that in the middle–second half of the Holocene three strong morphogenetic seismic events occurred on the South Tegerek adyr fault and three strong earthquakes occurred on the North Tegerek adyr fault. The ages of four strong earthquakes were determined by the radiocarbon method. The maximum ages of the first three events are 3970–3755 BC, 220–405 AD, and 1380–1450 AD, while the minimum age of the last event is 1720–1815 AD. The magnitudes of historical and paleoearthquakes that occurred on the studied adyr faults range from M = 6.6–6.9 ± 0.5 (South Tegerek fault) to M = 6.8–7.4 ± 0.5 (Kultor adyr fault). Seismic events of similar magnitudes lead to deformations of the earth's surface and in building constructions, which can be estimated on a macroseismic scale at I ≥ IX. Our data obtained in this study can be used for a comparative analysis of similar post-platform orogens in Russia (e.g., Altay and Sayan mountains), as well as in compiling the new general seismic zoning map for the Kyrgyz Republic. [ABSTRACT FROM AUTHOR]

Data on the stress–strain state of the Earth's crust obtained by precision observations were studied using strain-gage analysis based on the geometric theory of deformation. Ground-based optical distance observations were made on one of the geodynamic polygons in Petropavlovsk-Kamchatsky to calculate the major axes of compression and tension. Out of ten baselines, four variants of the strain-gauge rosette were taken to calculate the invariant characteristics of deformation from measured displacements of the Earth's surface. The strain-gage analysis of the observation results made it possible to determine the main deformations and calculate the angle between the dominant loading axis and the shortening axis. Two sources of impact were proposed as factors that specify the dominant loading axis: magmatism (nearby active volcanoes) and the subduction zone (the impact of the subducting Pacific Plate). Since the region is seismically active, the analysis involved strong (M > 5.5) earthquakes to identify a possible relationship between earthquakes and deformation characteristics. [ABSTRACT FROM AUTHOR]

The region of Garhwal is one of the most seismically active areas in India. Many destructive earthquakes have occurred there in the past. The current seismic activity in Garhwal is also high. The region is characterized by a high population density; therefore, in choosing ways to develop it, protecting the population and reducing material damage from expected strong seismic events are of utmost urgency. The solution primarily requires using various antiseismic measures during construction, which are selected based on the characteristics of seismic treatments. The purpose of this research is to assess the seismic hazard and seismic treatments in some settlements of Garhwal. To solve this problem, data obtained in previous stages of studies in Western Himalaya are interpreted once again. In particular, the results of geological and geophysical and structural and geological studies have made it possible to reveal the main seismogenerating structures and determine their characteristics. The analysis of the data on strong ground motions in the epicenter areas of the Dharamsala (April 26, 1986, Mw = 5.5), Uttarkashi (October 20, 1991, Mw = 6.8), and Chamoli (March 28, 1999, Mw = 6.5) earthquakes and the study of the attenuation patterns of ground accelerations in the Garhwal region have enabled us to estimate the expected maximum magnitudes, focal depths, and source mechanisms of the earthquakes. A regional model of seismic source zones (SSZs) is proposed. Using the results of seismological and seismotectonic studies, the parameters of ground motions during the maximum credible earthquakes are estimated, such as peak ground accelerations, spectra and durations of vibrations, and the seismic-effect value in the seismic intensity scale points for some settlements in Garhwal. [ABSTRACT FROM AUTHOR]

Our archeoseismological investigations in the Episcopal basilica in Varna have revealed signs of seismic deformations in its walls: numerous shifts, tilts, and rotations of the wall parts around the vertical axis, as well as subvertical through-going joints cutting several stone blocks. A cluster of (at least) three seismic events occurred for a hundred years (from the early 5th to the early 6th centuries AD). Judging by kinematic indicators in the basilica structures built of high-quality stone blocks, the source of seismic motions was located north-northeast of the basilica. Strong seismic oscillations propagated apparently from the southwest. The seismic sources were along seismically active faults localized north and south of Varna. The local seismic intensity of seismic oscillations could reach Il ≤ 9 on MSK-64 scale. The intensity of the seismic oscillations increased due to unfavorable ground conditions at the location of the basilica. These data should be taken into account when assessing the seismic hazard assessment of Varna to build a new map of seismic zoning of northeastern Bulgaria. [ABSTRACT FROM AUTHOR]

According to the current maps of general seismic zoning of the Republic of Kazakhstan (2006), the territory of the Semipalatinsk Test Site (STS) is considered an aseismic region. However, recent investigations and an analysis of archived data have shown that the Test Site territory and its vicinity have experienced and still experience tectonic and induced earthquakes. The maximum magnitude of recorded earthquakes is 5–5.9. An analysis of global seismological bulletins and data on historical seismicity from literature sources is performed to solve the problem of seismicity in the STS region. Historic analog seismograms of earthquakes have been collected since 1925; the earthquake parameters are estimated more precisely. Modern instrumental seismic data of the Kazakhstan monitoring network since 1994 are processed, as is the data of temporary networks of seismic stations operating on the territory of the test site in 2005–2010 in the region of the Sary-Uzen, Balapan, and Degelen test sites. These works resulted in the creation of a common earthquake catalogue for the STS territory and its vicinity from 1783 up to the present. Macroseismic data of the felt earthquakes have been collected; strong motion records have been analyzed. Deep faults dividing Earth's crust blocks have been marked out. Tectonic elements are located by decoding the Landsat space images and using materials of geologic and topographic surveys. The calculations show that the STS territory can experience events with intensity 6 based on the MSK-64 scale. [ABSTRACT FROM AUTHOR]

Abstract: The results of an analysis of the properties of low-frequency seismic noise in the Japanese Islands from early 1997 to March 2018 are presented. The time interval under consideration includes one of the largest seismic disasters of recent times, the Tohoku earthquake of March 11, 2011. The presence of a dense network of seismic observations provides a unique opportunity to investigate how the preparation of a strong earthquake is reflected in changes in the properties of seismic noise in time and space. An analysis of the clustering of the daily multifractal and entropic properties of seismic noise in a 1-year moving time window averaged over all stations of the network made it possible to find a 2.5-year periodicity established since the beginning of 2003. This periodicity correlates with the occurrence of strong earthquakes in Japan. Studying features of the spatial distribution of seismic-noise properties allows us to put forward a hypothesis about the increased danger of the next megaearthquake in Japan in the area of the contact between the northern boundary of the Philippine Sea plate and Honshu Island, in the Nankai deepwater trough area, not far from Tokyo. In the Japanese Islands, in addition to the network of seismic observations, there is a dense network of fixed GPS points for which observations are available from the beginning of March 2015 with a time step of 5 min. The availability of such measurements makes it possible to complement the analysis of seismic-noise properties and to calculate the degree of correlation of GPS data at any point from measurements at neighboring stations. An analysis and processing of measurement results show that the most intense spot of increased correlation of the Earth's surface tremor, measured using GPS, is located in the Nankai Trough, with the center at the point of 34° N and 138° E. [ABSTRACT FROM AUTHOR]

Abstract: On May 12, 2008, a catastrophic earthquake with magnitude MS = 8.0 occurred in Wenchuan County, Sichuan, China. Its epicenter was located in the Longmen Shan mobile tectonic belt and its hypocentral depth was 14 km. The mainshock produced the system of primary seismodislocations (ruptures) on the surface: Beichuan-Yingxiu Fault of more than 240 km long, Guanxian-Anxian Fault of about 70 km long, and Xiaoyudong Fault of 7 km long. The maximum measured vertical and dextral displacements along the faults were up to 10 m and 4.8 m, respectively. The rupturing and manifold landslides, rockfalls, and rock avalanches that followed caused significant destructions in a number of localities, damaged roads, and led to massive human deaths. Data collected on the distribution of primary and secondary effects of earthquakes has helped outline zones with shaking intensities of IX, X, and XI. Notably, the seismic intensity of surface shaking was anomalously low even close to the fault system. We have conducted a comprehensive seismotectonic study of the epicentral zone of the Wenchuan earthquake. When assessing the shaking intensities, we apply the Earthquake Environmental Effects (EEE) scale developed in the framework of INQUA project (2004-2016). A comparison shows that the isoseismals identified from macroseismic data on damages in buildings and structures coincide with the locations of zones with various seismic effects on the EEE scale. [ABSTRACT FROM AUTHOR]

Any natural phenomenon (process) occurs, develops, and dies away within a specific environment. Therefore, a study of its development patterns and forecast of its occurrence or extinction requires thorough knowledge of the host environment. In view of this, we have considered some characteristic features of the structure and functioning of the global endo-drainage system (GEDS) as a geological medium where all the seismic zones are concentrated and most of the major earthquakes in the world occur. We have described the basic principles of regional hydrogeodeformatics, which gives a methodology for the strain-field monitoring of extensive geological objects aimed at the short-term prediction of strong and devastating earthquakes. Based on data from long-term monitoring over the evolution of the earth's hydrogeodeformation (HGD) field, we show some examples of possible earthquake predictions. [ABSTRACT FROM AUTHOR]