Global Centroid Moment Tensor Research Articles

ARCTIC

The article provides an overview and analysis of seismicity within the boundaries of the Arctic region for 2014, a description of seismic station networks and processing methods. The catalog of earthquakes in the Arctic region was compiled on the basis of catalogs of several organizations and seismological centers. In total, 452 earthquakes with ML≥1.5 are included in the earthquake catalog. Most of the earthquakes occurred in 2014, including all the strongest earthquakes, werelocated within the mid-ocean ridges of Mon, Knipovich and Gakkel. In the offshore territories, most of the earthquakes were confined to the Svalbard archipelago, in particular, to the seismically active zone in the Sturfjord strait. The renewal of instrumental seismological observations in 2011 (station ZFI) on Alexandra Land Island in the Franz Josef Land archipelago made it possible to record weak earthquakes in the north of the shelf of the Barents and Kara Seas. For seven earthquakes, the focal me-chanism parameters are presented according to Global CMT catalog.

GWFM: A Global Catalog of Moderate-Magnitude Earthquakes Studied Using Teleseismic Body Waves

AbstractWe present a compilation of 2131 high-fidelity mechanisms and centroid depths of moderate-magnitude earthquakes derived using synthetic body-waveform modeling (the Global Waveform-Modelled Earthquake Catalog v1.0—gWFM), which can be visualized and downloaded online (see Data and Resources). In this article, we describe the methods used to construct the gWFM and present a comparison between the earthquake depths and focal mechanisms in the gWFM with those derived by the International Seismological Centre, Global Centroid Moment Tensor (Global CMT) project, and the U.S. Geological Survey (USGS) W-phase, as well as 60 events studied using geodesy. We find that 20%–30% of the earthquakes in routine global catalogs have depths that differ by more than 10 km from those in the gWFM. Shallow-crustal earthquakes of Mw 5–6 are typically the worst located in depth by routine catalogs. Over 90% of the earthquakes in the gWFM are within ±15° in strike, ±5° in dip, and ±15° in rake of the Global CMT and USGS W-phase best double-couple moment tensor solutions. However, the mechanisms of shallow Mw 5–6 earthquakes in the routine catalogs can be inaccurate, due to the well-known insensitivity of long-period surface waves to the vertical dip-slip components of the moment tensor. The gWFM is an archive of well-constrained earthquake source parameters, though it will continue to update as new earthquake mechanisms and depths are published, thereby remaining an up-to-date research tool.

Regional Earthquake Magnitude Conversion Relations for the Himalayan Seismic Belt

AbstractWe present regional earthquake magnitude conversion relations among different magnitude scales (Mw, Ms, mb, ML, and MD) for the Himalayan seismic belt developed from data of local, regional, and international seismological agencies (International Seismological Centre [ISC], National Earthquake Information Centre [NEIC], Global Centroid Moment Tensor Solution [CMT], International Data Centre [IDC], China Earthquake Administration [BJI], and National Centre for Seismology [NDI]). The intra- (within the same magnitude scale) and inter- (with different magnitude scales) magnitude regression relations have been established using the general orthogonal regression and orthogonal distance regression techniques. Results show that the intra-magnitude relations for Mw, Ms, and mb reported by the Global CMT, ISC, and NEIC exhibit 1:1 relationships, whereas ML reported by the IDC, BJI, and NDI deviates from this relationship. The IDC underestimates Ms and mb compared with the ISC, NEIC, and Global CMT; this may be due to different measurement procedures adopted by the IDC agency. The inter-magnitude relations are established between Mw,Global CMT and Ms, mb, and ML reported by the ISC, NEIC, IDC, and NDI, and compared with the previously developed regional and global regression relations. The duration (MD) and local (ML) magnitudes reported by NDI exhibit a 1:1 relationship. The derived magnitude regression relations are expected to support the homogenization of the earthquake catalogs and to improve seismic hazard assessment in this region.

The Homogenized Instrumental Seismic Catalog (HORUS) of Italy from 1960 to Present

AbstractWe implemented an automatic procedure to update in near-real time (daily to hourly) a homogeneous catalog of Italian instrumental seismicity to be used for forecasting experiments and other statistical analyses. The magnitudes of all events are homogeneously revalued to be consistent with Mw standard estimates made by the Global Centroid Moment Tensor project. For the time interval from 1960 to 15 April 2005, catalogs and online resources available for the Italian area were merged and all magnitudes were homogenized to Mw according to empirical relationships computed using the chi-square regression method, which properly consider the uncertainties of both variables. From 16 April 2005 to the present, an automatic procedure periodically downloads the data of the online bulletin of the Istituto Nazionale di Geofisica e Vulcanologia and of online moment tensor catalogs from respective websites, merges the different sources, and applies traditional magnitude conversions to Mw. The final catalog is provided on a website for public dissemination.

Source Process for Two Enigmatic Repeating Vertical‐T CLVD Tsunami Earthquakes in the Kermadec Ridge

AbstractTwo repeating compensated linear vector dipole (CLVD) earthquakes occurred in 2009 and 2017 on the Kermadec Ridge near the Curtis submarine volcano. The tsunami and seismic waveforms of both events are almost identical. Simulated tsunami and seismic waveforms are compared with observations of the 2017 event to estimate the location and geometry of the source. A CLVD source model at 8–14 km depth is consistent with the global CMT solution but generates no tsunami. The tsunami waveforms can be well reproduced if the source model is about 1.5 km deep. However, a seismic source at this depth is not consistent with the observed seismic waves. This suggests that two sources were involved with different depths. The main, shallow, tsunami source could be due to hydrofracturing of heated water in a shallow sediment layer triggered by a deeper earthquake.

GCAPjoint, A Software Package for Full Moment Tensor Inversion of Moderately Strong Earthquakes with Local and Teleseismic Waveforms

AbstractEarthquake moment tensors and focal depths are crucial to assessing seismic hazards and studying active tectonic and volcanic processes. Although less powerful than strong earthquakes (M 7+), moderately strong earthquakes (M 5–6.5) occur more frequently and extensively, which can cause severe damages in populated areas. The inversion of moment tensors is usually affected by insufficient local waveform data (epicentral distance <5°) in sparse seismic networks. It would be necessary to combine local and teleseismic data (epicentral distance 30°–90°) for a joint inversion. In this study, we present the generalized cut-and-paste joint (gCAPjoint) algorithm to jointly invert full moment tensor and centroid depth with local and teleseismic broadband waveforms. To demonstrate the effectiveness and explore the limitations of this algorithm, we perform case studies on three earthquakes with different tectonic settings and source properties. Comparison of our results with global centroid moment tensor and other catalog solutions illustrates that both non-double-couple compositions of the focal mechanisms and centroid depths can be reliably recovered for very shallow (<10 km) earthquakes and intermediate-depth events with this software package.

Tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its adjacent areas*

To investigate the tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its surrounding areas, we selected over 1,500 focal mechanism solutions of inland earthquakes (epicenter locates at least 100 km to the coastlines) from Global Centroid Moment Tensor (GCMT) project and analyzed the p-values of tidal normal and shear stress as well as tidal Coulomb failure stress. For Coulomb failure stress calculation, we used Coulomb 3.40 software. We find that: (1) p-values of tidal stress change suggests a high tidal correlation of earthquake imitations with tidal normal stress change; (2) when tidal normal stress reached the local maximum values of compression and when tidal shear stress were closed to the positive peaks, earthquakes generated more frequently; (3) particular seismogenic environments such as strong continental plate interactions and the existence of fluids or rheologic substance possibly raise the tidal correlations and (4) higher sensitivity of earthquake initiation to earth tide presents along with higher seismicity, suggesting the rate of rain energy accumulation somehow has a dominating effect on the tidal correlation of earthquake initiation.

Seismicity on Conjugate Faults in Ölfus, South Iceland: Case Study of the 1998 Hjalli‐Ölfus Earthquake

AbstractThe Ölfus seismic belt lies at the western end of the ~E‐W sinistral transform shear zone in South Iceland, called the South Iceland Seismic Zone (SISZ), where most seismicity and surface faulting show ~N‐S dextral slip. Unlike the rest of SISZ, seismicity in west Ölfus is predominantly along the ~ENE‐WSW direction. Throughout recorded history, Ölfus has shown an interactive behavior with the Hengill volcanic system that lies northwest of the zone. For instance, the 13 November 1998 Mw 5.1 earthquake in the Hjalli area (west Ölfus) and its ~ENE trending aftershock sequence were likely triggered by the 4 June 1998 Mw 5.4 Hengill earthquake sequence. These events point to an interplay between conjugate ~N‐S and ~ENE‐WSW faults in the region. Relative relocations of earthquakes in Hjalli‐Ölfus from July 1991 to December 1999 (Icelandic Meteorological Office, 2017) are chiefly limited to 4‐ to 8‐km depth along the ~ENE direction with a few distributed on smaller ~N‐S faults. The foreshocks of the November 1998 earthquake occurred on a ~N‐S fault until a day prior to the mainshock when they shifted to the ~ENE direction. The subsequent aftershocks are also mainly restricted to the ~ENE direction. We find that the Mw 5.1 (Global Centroid Moment Tensor moment = 5.43 × 1016 N‐m) Hjalli‐Ölfus earthquake ruptured a near‐vertical ~ENE fault area of 24–40 km2 with left‐lateral average slip of 5–8 cm. Multiple relocations of the mainshock using various constraints indicate that the event likely occurred close to the junction of the conjugate ~ENE‐WSW and ~N‐S faults.

Empirical relations for conversion of surface- and body-wave magnitudes to moment magnitudes in China’s seas and adjacent areas

An earthquake catalog based on a unified magnitude scale is an important prerequisite for analyses of seismic activities and seismic hazards. To unify the magnitude scales of earthquakes in China’s seas and neighboring regions, we developed conversion relationships between surface- and body-wave magnitudes and the global centroid moment tensor (GCMT) and National Research Institute for Earth Science and Disaster Resilience (NIED) moment magnitudes for shallow and intermediate- and deep-focus earthquakes in China’s seas and adjacent areas. We employed data collected by the Chinese Earthquake Network Center, GCMT, and NIED for earthquakes of magnitude 4.5 and higher in China’s seas and neighboring regions from 1976 to 2018. We used the linear least squares regression method and the orthogonal regression method to fit the seismic data under different magnitude ranges and different focal depth ranges. The results provided empirical formulas to unify magnitude scales for the earthquakes in China’s seas and neighboring regions and also provided an important basis for seismic catalog integrity analyses and seismic activity studies for this area. The results are significant for seismic hazard analyses, seismic zoning, and mid- and long-term forecast analyses of seismic activities in the area.

Mapping of active major faults in the Mamasa and surrounding areas using satellite gravity data and topographic features

The mapping of active faults in Indonesia, especially in areas near the city center is very important to determine the building code. Mamasa Regency, West Sulawesi is one of the areas that have active faults, has not been mapped well in the 2017 seismic hazard book, which is a guidebook in creating building codes in Indonesia. A total of 762 earthquakes occurred in this area from November to December 2018. This study aims to map active faults associated with the source of these earthquakes. TOPEX satellite gravity data were processed to obtain the Complete Bouguer Anomaly. The residual and regional gravity values were separated using a Gaussian filter to identify the lineation of the fault and the existing fracture zone. The multiscale second vertical derivative was also implemented to identify and characterize the fault. Topographic contour mapping was carried out to confirm the presence of fault on the surface as well as to observe the direction of fault movement. We used seven focal mechanism data from Global CMT to support the interpretation result of gravity and topographic data. The result, the main fault is a sinistral strike-slip fault with N164E strike orientation. This strike-slip fault has two sides. The movement of the strike-slip fault on these two sides causes a pull-apart which results in normal faults in the pull zone between the two faults.

Estimated Seismic Source Parameters for 2019 Magnitude 7.6 Papua New Guinea Earthquake

On 14 May 2019, a major (Mw 7.6) earthquake struck eastern Papua New Guinea, causing a tsunami warning that was later canceled. The last major rupture in the region was a 2000 Mw 8.0 event, which resulted in massive horizontal land movements of up to several meters and a series of aftershocks with primarily thrust mechanisms, and caused a damaging tsunami. Seismic methods for characterizing the source process were applied. Vertical components of the long-period P-waves from 35 stations of the Global Seismic Network with even azimuthal coverage were adopted in the inversions. First, the focal mechanism solution was retrieved after the earthquake. From the inverted results as well as aftershock distribution, the causative fault of the great PNG earthquake was confirmed to be a fault of strike = 316°, dip = 84°, and rake = 0°, indicating that the earthquake was a left-lateral strike-slip event. Then, to clearly understand the spatiotemporal evolutionary process of the source rupture of the earthquake, far-field body wave data were collected, and the source rupture process of this earthquake was studied using the finite fault inversion method. A finite-fault model was estabished with length and width of 152 and 32 km, respectively, and we set the initial seismic source parameters referring to the center of the focal mechanism solution. This was estimated by the focal mechanism solutions of defferent studies referring to different focal mechanism solutions. We found that the focal mechanism solution determined by Global Centroid Moment Tensor Catalog was not appropriate. Inversion results indicated that the seismic moment was 3.63 × 1020 Nm (Mw 7.6), and the source duration was ~ 40 s. The rupture propagated mainly toward the northwest in an asymmetrical bilateral mode, with a maximum slip of ~ 13.2 m, and a large-scale slip patch strongly ruptured to the surface. The study of Coulomb stress changes suggested that the PNG earthquake may trigger a thrust-type rupture in the New Britain Trench, which has the potential to trigger a tsunami.

Crustal Structure of Andaman Islands using Joint Inversion of Receiver Functions and Surface Wave Dispersion Measurements

We investigate the crustal structure of Andaman Islands, central part of Burma-Sunda-Java subduction complex, through joint inver- sion of receiver functions and surface wave dispersion measurements. For this study, we used teleseismic earthquakes recorded over 13 temporary broadband seismographs operated in two different phases: pre and post 2004 Sumatra earthquake. Beneath the Andaman fore- arc region, the crustal thickness varies between ~24 and 28 km. The uppermost crust consists of ~4 to 7 km thick soft accretionary sed- iments. Average Vp/Vs ratio, between ~1.79 and 1.83, suggests accretionary hydrated oceanic crust with different level of saturation. Combining derived crustal structure with global seismicity and CMT fault plane solutions indicate a complex convergence along the arc, with transitional (continental-oceanic) type in the north to oceanic type in the south Andaman.

The current state of crustal stresses in the Caucasus according to the unified catalogue of earthquake focal mechanisms

The current state of crustal stresses in the Caucasus and adjacent territories has been reconstructed. Stress inversion was performed by the cataclastic analysis of earthquake focal mechanisms considered as seismological strain indicators. The data were taken from the unified catalogue of focal mechanisms of the Northern Eurasia, which was consolidated by the Laboratory of Tectonophysics of IPE RAS in the early 1990s. It contains the information from many seismological data sources of various authors who worked both in the USSR and abroad. Seismological data for the last years after the collapse of the USSR were taken from Global CMT catalogue. The study area has been quite densely covered by reconstructions of the principal stress axes. At the same time, the area of stress averaging has been considerably reduced by the iterative use of a window for stress averaging, which was gradually expanded for zones with reduced densities of earthquake epicenters. The revealed regularities of the current stress field based on the unified catalogue of focal mechanisms collected by different authors correlate with the reconstructions performed according to the Global CMT catalogue. The cataclastic analysis of displacements along fractures allowed estimating the stress magnitudes, and the crust of the study area was zoned with respect to the intensity of normalized values of the lowest and highest stresses of horizontal compression, as well as to the normalized values of shear stresses acting on the crustal basement. In all cases, the values were normalized to the rock strength. The stress parameters are presented in “Tectonic Stresses of Eurasia”. This new Internet resource created by the Laboratory of Tectonophysics on the IPE RAS website shows the stress data in different scales and levels of details.

A Multi-fault Model Estimation from Tsunami Data: An Application to the 2018 M7.9 Kodiak Earthquake

In this study, we developed a new search algorithm to find a multi-fault model of a complex earthquake using tsunami data, and applied it to the January 23, 2018 M7.9 Kodiak earthquake. Our method includes a Green’s function based time reverse imaging (GFTRI) approach to invert for sea surface displacement using tsunami waveforms, followed by inversion of the sea surface displacement for the earthquake slip distribution. The global CMT focal mechanism for this event indicates that faulting occurred on a steeply dipping fault striking either N–S (right lateral) or E–W (left lateral), while subsequent work reveals a more complex pattern of strike-slip faulting. We carried out a number of source inversions using different combinations of faults to find the model based on an extremum for residual errors. Our results suggest that the rupture occurred on at least three faults oriented in approximately N–S and E–W directions. We further explored the fault-geometry parameters by perturbing them within a range suggested by previous work. We found that the sea surface displacement model is best fit by our preferred three fault-model with the set of parameters (strike, dip, rake): ($$165^{\circ }$$, $$60^{\circ }$$, $$154^{\circ }$$) and ($$265^{\circ }$$, $$60^{\circ }$$, $$10^{\circ }$$) for N–S and E–W directions, respectively.

New Updated Classification of Shallow Earthquakes Based on Faulting Style

Earthquakes occur on faults and create new faults. They also occur on normal, reverse and strike-slip faults. The aim of this work is to suggest a new unified classification of Shallow depth earthquakes based on the faulting styles, and to characterize each class. The characterization criteria include the maximum magnitude, focal depth, b-constant value, return period and relations between magnitude, focal depth and dip of fault plane. Global Centroid Moment Tensor (GCMT) catalog is the source of the used data. This catalog covers the period from Jan.1976 to Dec. 2017. We selected only the shallow (depth less than 70kms) pure, normal, strike-slip and reverse earthquakes (magnitude ≥ 5) and excluded the oblique earthquakes. The majority of normal and strike-slip earthquakes occurred in the upper crust, while the reverse earthquakes occurred throughout the thickness of the crust. The main trend for the derived b-values for the three classes was: b normal fault>bstrike-slip fault>breverse fault. The mean return period for the normal earthquake was longer than that of the strike-slip earthquakes, while the reverse earthquakes had the shortest period. The obtained results report the relationship between the magnitude and focal depth of the normal earthquakes. A negative significant correlation between the magnitude and dip class for the normal and reverse earthquakes is reported. Negative and positive correlation relations between the focal depth and dip class were recorded for normal and reverse earthquakes, respectively. The suggested classification of earthquakes provides significant information to understand seismicity, seismtectonics, and seismic hazard analysis.

Spatial variation in the present-day stress field and tectonic regime of Northeast Tibet from moment tensor solutions of local earthquake data

SUMMARYFocal mechanism solutions and their predicted stress pattern can be used to investigate tectonic deformation in seismically active zones and contribute to understanding and constraining the kinematic patterns of the outward growth and uplift of the Tibetan Plateau. Herein, we determined the focal mechanisms of 398 earthquakes in Northeast Tibet recorded by the China National Seismic Network (CNSN) by using the cut-and-paste method. The results show that the earthquakes predominately exhibited thrust and strike-slip faulting mechanisms with very few normal events. We then combined the derived focal mechanisms with global centroid moment tensor (GCMT) catalogue solutions and previously published solutions to predict the regional distribution of the stress field through a damped linear inversion. The inversion results show that most of region is dominated by a thrust faulting regime. From the southern East Kunlun fault in the west to the northern Qilian Mountains along the Altyn Tagh fault (ATF), the maximum compression axis rotates slightly clockwise; farther to the south of the Haiyuan fault in the east, there is an evident clockwise rotation of the maximum compression axis, especially at the eastern end of the Haiyuan fault. In the Qilian Mountains, the axis of the compressive stress orientation approximately trends NE–SW, which does not markedly differ from the direction of India–Eurasia convergence, emphasizing the importance of the compressive stress in reflecting the remote effects of this continental collision. The overall spatial pattern of the principal stress axes is closely consistent with the GPS-derived horizontal surface velocity. A comparison of the stress and strain rate fields demonstrated that the orientations of the crustal stress axes and the surface strain axes were almost identical, which indicates that a diffuse model is more suitable for describing the tectonic characteristics of Northeast Tibet. Additionally, the compressive stress orientation rotated to ENE–WSW in the northern Qilian Mountains along the ATF and to ENE–WSW or E–W along the eastern part of the Haiyuan fault and its adjacent area to the south, highlighting the occurrence of strain partitioning along large left-lateral strike-slip faults or the lateral variation of crustal strength across these faults. Combining geodetic, geological and seismological results, we suggest that a hybrid model incorporating both the diffuse model associated with shortening and thickening of the upper crust and the asthenospheric flow model accounting for the low-velocity zone in the middle-lower crust may reflect the primary mode of crustal deformation in Northeast Tibet.

Using Seismic Source Parameters to Model Frequency-Dependent Surface-Wave Radiation Patterns

AbstractThe excitation of surface waves depends on the frequency-dependent eigenfunctions of the Earth, which are determined numerically. As a consequence, radiation patterns of Rayleigh and Love waves cannot be calculated analytically and vary with source depth and with frequency. Owing to the importance of surface-wave amplitudes for inversions of source processes as well as studies of the elastic and anelastic structure of the Earth, assessing surface-wave radiation patterns for different source mechanisms is desirable. A data product developed in collaboration with the Incorporated Research Institutions for Seismology (IRIS) Consortium provides visualizations of the radiation patterns for Rayleigh and Love waves for all possible source mechanisms. Radiation patterns for known earthquakes are based on the moment tensors reported by the Global Centroid Moment Tensor project. These source mechanisms can be modified or moment tensor components can be chosen by the user to assess their effect on Rayleigh- and Love-wave radiation patterns.

Ground motion prediction equation for West Sumatra due to distant shallow crustal, interface, andiIntraslab warthquakes

Ground motion prediction equation (GMPE) is an important component for seismic hazard study to minimize the casualty from an earthquake, especially in the building collapse. This study presents ground motion prediction equation for West Sumatra due to distant shallow crustal, interface, and intraslab earthquakes. The data sets consist of 375 strong motion data that are recorded by Meteorological, Climatological, and Geophysical Agency’s (BMKG) accelerograph sensors that located in West Sumatra, earthquake parameter data are from BMKG’s earthquakes catalog with the range moment magnitude of 4.0-6.4 and recorded at sites with hypocentral distance of 17 – 1000 km, focal mechanism data are from Global Centroid Moment Tensor (GCMT), and use site classification to enhance the quality of the results. This study shows good results with the standard deviation of residual value of 0.23 for shallow crustal, 0.29 for interface, and 0.49 for intraslab earthquakes.

A Model for Visual Assessment of Fault Plane Solutions and Active Tectonics Analysis Using the Global Centroid Moment Tensor Catalog

In this study, individual fault plane solutions are developed using various methods to improve the understanding of active tectonics on a regional scale. The comparative analysis of a focal mechanism solution (FMS) has not elicited the attention of researchers. Therefore, this study aims (1) to visually analyze the fault plane solution for 20 local faults that are responsible for all the earthquakes that occurred using visualization techniques such as: fault parameters, the linked Bingham method, the ad hoc pressure (P) axis and tension (T) axis method, and the moment tensor method; (2) to identify the best method for FMS; and (3) to understand the active tectonics of a fault population. A comparative analysis of the models is systematically documented to improve the understanding of the methods. An analysis of the overall fault mechanism is conducted for the analytic determination of fault movement using fault population data from the Global Centroid Moment Tensor catalog. The approach used in this work is a newly designed method for analyzing the reliability of various techniques for fault mechanism and overall fault movement research. Findings show that for the fault mechanism analysis, the P and T axes method and the moment tensor method are better than the fault plane solution from the fault parameters and the linked Bingham method based on the input parameters, output information, model outfit, and accuracy. The moment tensor method is one of the best approaches for analyzing fault mechanism because the errors in the nine components used as input data for the modeling are negligible. Meanwhile, the P and T axes method is one of the best techniques for the overall analysis of fault movement. P and T dihedral analysis using Kamb contouring is modeled. It indicates that the overall mechanisms of compression and dilation are features at the NW–SE and E–W directions, respectively. This comprehensive and consistent analysis of the fault mechanism provides an overview of the seismotectonic settings in Sabah, Malaysia.

Modern state of crustal stresses of the Apennine Peninsula and adjacent territories (Central Mediterranean region)

This paper discusses models showing the formation of the Central Mediterranean region and the geodynamic setting of the Apennine Peninsula. Cataclastic analysis is used for a repeated reconstruction of the Central Mediterranean region. The catalogue of earthquake focal mechanisms includes 662 events (3.6≤Mb≤6.5) recorded in the study area from 1977 to 2015 (Global CMT, http://www.globalcmt.org; RCMT, http://rcmt2.bo.ingv.it/index.html; Italian CMT dataset, http://rcmt2.bo.ingv.it/Italydataset.html). The reconstruction yielded the directions of principal stresses (including algebraically maximum and minimum ones), locations of domains differing in geodynamic regime, Lode – Nadai coefficients, and orientation of tangential shear stresses acting from the mantle to the crust. By comparing our results to the published data obtained by M.‐L. Zoback’s method, we have identified differences in the orientations of maximum horizontal compression axes at points where the stress ellipsoid takes on its critical values. It is revealed that the strongest earthquakes (M>6) were generated in the areas characterized by the minimum and average relative stress magnitudes.