Earth's Lithosphere Research Articles

Deformation and fracture of lithosphere-inspired polymeric multi-layer composites

Inspired by the diversity of structures and patterns inherent in the earth's lithosphere, this study endeavors to enhance the interplay between stiffness and toughness through the introduction of a new class of polymeric multi-layer composite materials termed by the authors as "lithomers". Structured single-edge notched bending specimens were fabricated using a combination of additive manufacturing and casting, employing two different methacrylate-thiol resins. The outer layers exhibit a stiff and brittle characteristic, while the layer in between is compliant in nature. Three types of lithomers with wave-like structures and one with a rectilinear structure were investigated regarding their stiffness and toughness in a 3-point bending setup. The results were compared with those of a pure stiff matrix material. The findings revealed that fracture toughness increased regardless of the interlayer's shape compared to the pure matrix material. Correspondingly, this enhancement in fracture toughness correlated with a reduction in stiffness. The most balanced results in terms of stiffness and fracture toughness were achieved, with the lithomer having a wave-like structure in its initial stage. It exhibited a roughly 27 times improvement in fracture toughness with a moderate decrease in stiffness of approx. 1/5 compared to the pure matrix material.

Deciphering the biodegradation of thiamethoxam by Phanerochaete chrysosporium with natural siderite: Synergistic mechanisms, transcriptomics characterization, and molecular simulation

Fungi play vital roles in the fate of organic pollutants, particularly when interacting with minerals in aquatic and soil environments. Mechanisms by which fungi may mitigate pollutions in fungus-mineral interactions are still unclear. Inspired by biogeochemical cycling, we constructed a range of co-culture systems to investigate synergistic effects of the white-rot fungus Phanerochaete chrysosporium and the iron-bearing mineral siderite on thiamethoxam (THX) transformation, a common neonicotinoid pesticide. Co-culturing with siderite significantly enhanced THX transformation during the initial 10 days with a dose effect, achieving 86 % removal within 25 days. Fungi could affect siderite’s dissolution, transformation, and precipitation through their biological activities. These interactions triggered physiological adaptation and resilience in fungi. Siderite could enhance the activity of fungal ligninolytic enzymes and cytochrome P450, facilitating biotransformation. Genes expression related to growth, energy metabolism, and oxidative stress response upregulated, enhancing fungal resilience to THX. The primary THX degradation pathways included nitro-reduction, C-N cleavage, and de-chlorination. Molecular dynamics simulations provided insights into catalytic mechanisms of enzyme-THX interactions. Together, siderite could act as natural enhancers that endowed fungi to resist physical and chemical stresses in environments, providing insights into contaminants attenuation, fungal biomineralization, and the coevolution of the Earth's lithosphere and biosphere.

Geochemistry and Mineralogy of Phlogopite and Its Implications for Serpentinization of Jian Forsterite Jade in Southern Jilin Province, China

Mica is a kind of important rock-forming mineral in the lithosphere of Earth, which can be a superior tool used to trace the origin and late evolution of rock. The Jian forsterite jade (a kind of geological skarn) is an emerging kind of gemstone in China with a beautiful color and luster, discovered in Ji’an County, Jilin Province, Northeast China. It is mainly composed of rare Mg-rich forsterite (Mg# (Mg/(Mg + Fe2+) up to 99), serpentine and brucite. The source of hydrothermal fluid triggering the late metamorphism (the serpentinization of forsterite) of forsterite jade deposits remains unclear. We report a series of phlogopites with a regular range of mineral compositions in the forsterite jade deposit. Micrographs show that the phlogopites are associated with forsterite and coexist with serpentine in forsterite jade, tourmaline and tremolite in the contact zone, and plagioclase in pegmatite, and the related replacement of phlogopite seems to have not occurred. The phlogopites that occurred as single grains or veinlets in forsterite jade named type I are characterized by high XMg, ranging from ~0.98 to ~0.95, and the phlogopites that occurred in the contact zone of forsterite jade and pegmatite named type II are rich in Fe, with a range of XMg from ~0.82 to ~0.66. Additionally, the type II phlogopites are also rich in Ti, Mn, Cl, Li, Rb, Zn, V, Co, Nb and Ta but poor in Na, Sr and F compared to the type I phlogopite. Petrological and mineralogical characteristics and geochemical compositions suggest that the phlogopites are crystallized from the corresponding fluid component by hydrothermal metasomatism. The abundant Mg of the fluid phase is produced during the serpentinization of forsterite, triggered by pegmatitic hydrothermal fluid, and other main materials like K, Al, Si and H2O are provided by the intrusive pegmatite. With the occurrence of and regular compositional variation in phlogopites in the forsterite jade deposit, we suppose that the hydrothermal fluid triggering the serpentinization of the Jian forsterite jade is produced by the intrusive pegmatite.

A billion-year shift in the formation of Earth’s largest ore deposits

Banded iron formations (BIFs) archive the relationship between Earth's lithosphere, hydrosphere, and atmosphere through time. However, constraints on the origin of Earth's largest ore deposits, hosted by BIFs, are limited by the absence of direct geochronology. Without this temporal context, genetic models cannot be correlated with tectono-thermal and atmospheric drivers responsible for BIF upgrading through time. Utilizing in situ iron oxide U-Pb geochronology, we provide a direct timeline of events tracing development of all the giant BIF-hosted hematite deposits of the Hamersley Province (Pilbara Craton, Western Australia). Direct dating demonstrates that the major iron ore deposits in the region formed during 1.4 to 1.1 Ga. This is one billion to hundreds of millions of years later than previous age constraints based upon 1) the presence of hematite ore clasts in conglomerate beds deposited before ~1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at ~2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a ~2.2 to 2.0 Ga event, reflecting widespread, but now largely eroded iron mineralization occurring when the Pilbara and Kaapvaal cratons were proximal. No existing phosphate mineral dates overlap with obtained hematite dates and therefore cannot be related to hematite crystallization and ore formation. New geochronology conclusively links all major preserved hematite deposits to a far younger (1.4 to 1.1 Ga) formation period, correlated with the amalgamation of Australia following breakup of the Columbia supercontinent.

Association between Ultradian Rhythms of Body Temperature in Small Mammals and Earth's Crust Stress.

Association was assessed between the data harvested by a long-baseline laser interference deformograph and the dynamics of body temperature (BT) in hamsters deprived of natural daily light-darkness changes. The power spectral data revealed the positive correlation between simultaneous time series of hamster BT and the Earth's crust deformation (ECD). The superposed epoch analysis established an association between abrupt upstrokes of hamster BT and ECD increments. Thus, the direct relationships between BT dynamics (reflecting predominance of sympathetic part of autonomic nervous system) and ECD (according to long-baseline laser interference deformography) were established. The study observed synchronization of the free-running circadian rhythm of hamster BT with the tidal stress in Earth's lithosphere. Further studies are needed to find the physical factor underlying the revealed relationships.

A Continental Model of Curie Point Depth for China and Surroundings Based on Equivalent Source Method

AbstractThe Curie Point Depth (CPD) marks a significant temperature boundary (∼580°C) within the Earth's lithosphere. However, there has been ongoing debate regarding its spatial distribution. In this research, we utilized the Equivalent Source Method (ESM) based on Gauss‐Legendre integration and data obtained from the EMM2017 model, along with a five‐layer susceptibility model, to generate a 0.5° × 0.5° grid of continental CPD distribution for China and surroundings. The average CPD in the study area is 30.4 km, which is slightly shallower than the average depth of global continental Moho (∼33 km). Notably, stable and cold cratonic basins, such as the Tarim Basin and the Sichuan Basin, exhibit deep CPD of ∼45 km. In contrast, the North China Craton, which has experienced significant tectono‐thermal activity since the Late Mesozoic, shows moderate CPD of ∼30 km and a gradual uplift from west to east. The Tuva‐Mongol orocline within the Central Asian Orogenic Belt, the Deccan Volcanic Province in the Indian subcontinent and the Eastern Yangtze Craton have shallow CPD of ∼20 km. We estimate the surface heat flow by CPD, and the result is consistent with measurements within a RMSE of 18.1 mW/m2. When comparing the CPD with Moho, we find that the CPD may lie below Moho in stable and cold cratonic areas. In comparison to two recent global CPD models, our regional model demonstrates better alignment with tectonic features.

Geoscience for energy transition

We are living in the midst of a great technological revolution in history—the energy transition from today's fossil fuel‐dominated civilization to low‐carbon economies and industries. Geoscientists will significantly contribute to energy science, policy and technologies by advancing our knowledge base of the complex interacting processes and substances in Earth's lithosphere, oceans and atmosphere. Mapping the flow of energy in various forms and intensities in Earth systems, exploration of energy resources and minerals and evaluating the environmental impacts of energy technologies from upstream to downstream will be increasingly embedded in geoscience education, research and workforce development. This article outlines major pathways of how geoscience will contribute to various components of the energy transition.

Thermal Stability of F‐Rich Phlogopite and K‐Richterite During Partial Melting of Metasomatized Mantle Peridotite With Implications for Deep Earth Volatile Cycles

AbstractPhlogopite and K‐richterite constitute important carrier phases for H and F in Earth's lithosphere and mantle. The relative importance depends on their stabilities at high pressure and temperature, which in turn depends on bulk composition. Most previous experimental studies focused on the thermal stability of phlogopite and K‐richterite were conducted using simplified chemical compositions. Here, partial melting experiments on metasomatized and carbonated, OH ± F‐bearing near‐natural peridotite were performed at high pressures (2 and 5 GPa) and temperatures (1,100–1,350°C) to assess the thermal stability of F‐free versus F‐bearing phlogopite and K‐richterite. Experimental results demonstrate that the thermal stability of F‐bearing phlogopite is increased by >55°C/wt.% F, relative to F‐free phlogopite, whereas K‐richterite is absent in all experiments with significant degrees of melting (>2%). The thermal stability of phlogopite containing several wt.% F exceeds continental and oceanic geotherms within the upper 150 km. Fluorine‐rich phlogopite would therefore be stable in virtually all of the continental lithosphere, only to be decomposed during large, regional melting events such as continental break‐up, thereby acting as a major long‐term sink for F and/or H. This could even be the case for the oceanic asthenosphere, depending on the oceanic geotherm of the area of interest.

Characterizing the Complexity of Subduction Zone Flow With an Ensemble of Multiscale Global Convection Models

AbstractSubduction zones are fundamental features of Earth's mantle convection and plate tectonics, but mantle flow and pressure around slabs are poorly understood because of the lack of direct observational constraints on subsurface flow. To characterize the linkages between slabs and mantle flow, we integrate high‐resolution representations of Earth's lithosphere and slabs into a suite of global mantle convection models to produce physically plausible present‐day flow fields for Earth's mantle. We find that subduction zones containing wide, thick, and long slabs dominate regional mantle flow in the neighboring regions and this flow conforms to patterns predicted by simpler regional subduction models. These subduction zones, such as Kuril‐Japan‐Izu‐Bonin‐Mariana, feature prismatic poloidal flow coupled to the downgoing slab that rotates toward toroidal slab‐parallel flow near the slab edge. However, other subduction zones, such as Sumatra, deviate from this pattern because of the competing influence of other slabs or longer‐wavelength mantle flow, showing that upper mantle flow can link separate subduction zones and how flow at subduction zones is influenced by broader scale mantle flow. We find that the non‐linear dislocation creep reduces the coupling between slab motion and asthenospheric flow and increases the occurrence of non‐ideal flow, in line with inferences derived from seismological constraints on mantle anisotropy.

Influence of high‐strain deformation on major element mobility in garnet: Nanoscale evidence from atom probe tomography

AbstractGarnet is a common rock‐forming mineral that occurs in a variety of rock types and over a wide range of pressure (P)–temperature (T) conditions in the Earth's lithosphere. Because garnet is considered a high‐strength mineral stable across an extensive range of conditions (1–25 GPa, <300–2000°C), it is generally accepted that garnets can retain their microstructures and chemical composition during deformation and metamorphism. Therefore, garnet is commonly used as a geothermobarometer and geochronometer to provide P–T and timing constraints on tectonic events. Herein, we study garnet from an eclogite facies mylonite (central Australia) to investigate the mechanisms of element mobility during high‐strain deformation under relatively dry, lower crustal conditions. Electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) reveal evidence of crystal plasticity associated with brittle deformation in the form of heterogeneous misorientation patterns and low‐angle grain boundaries developed over length scales of 20–50 μm in the rims of garnet porphyroclasts. Atom probe tomography (APT) analysis of a low‐angle grain boundary within a highly strained portion of a clast shows Ca enrichment and Mg depletion along dislocations, whereas APT data along the rim of a mostly undeformed clast reveal a homogeneous distribution of garnet major components in the specimen matrix with the exception of Ca, Fe and Mg enrichment within a healed microfracture. The above‐mentioned results suggest that under relatively dry conditions, crystal plasticity enhances bulk element mobility via pipe diffusion, highlighting the importance of deformation‐induced microstructures on element mobility, with important implications for the robust and reliable use of garnet as a petrological tool.

On the distribution of tangential mass forces in the Earth's lithosphere

The study aims to determine and interpret the distribution of the global tangential mass force (TMF) vector field by azimuthal orientation and intensity. Using cluster and correlation analysis, we compared the direction of the TMF vector field with the direction of movement of permanent GNSS stations and the direction of movement of the GSRM model continental velocities from the Global Strain Rate Map Project. Methodology. The author continues their study of additional planetary stresses in the lithosphere caused by distributed mass forces. The forces in question may be linked to the repositioning of the Earth's lithosphere, which can create stresses aimed at aligning the distribution of lithospheric masses with the geoid's figure. This repositioning happens through the mechanism of gravitational forces and the principle of minimum potential energy. The presence of a deviation of the plum line from the normal to the surface of the solid Earth determines the appearance of TMF acting in the upper shell of the Earth. It is proposed to calculate the amplitudes and directions of the vectors of such TMF based on data regarding the difference in the parameters of two global ellipsoids that approximate the physical surface of the lithosphere and the geoid. Originality. For the modern era, the value of the angle of rotation between the smallest axis of the ellipsoid approximating the surface of the lithosphere and the axis of rotation of the Earth is 2.6°. The distribution of the TMF vector field is consistent with the contours of the continents, i.e., the arrows of the vectors indicate the directions of lateral movement of tectonic plates and the movement of continents during the Earth's evolution. As a result of the change in the orientation of the ellipsoid describing the lithosphere, an updated field of potential horizontal forces is formed, which, by the conservation of the momentum of motion, move lithospheric masses and generate stresses and deformations in the lithospheric shell. Since the TMF has different directions and intensities, a cluster analysis of the TMF distribution was performed. It revealed certain regularities in the distribution of these parameters. We also compared the directions of the TMF vector field with the directions of movement of permanent GNSS stations and the directions of movement of model velocities of the continents of the GSRM (digital model of the tensor field of the global velocity gradient). Scientific novelty. The study detailed the peculiarities of the connection between the directions of the TMF vector field, the directions of movement of permanent GNSS stations, and the ones of the model velocities of the GSRM continents. Studies of the TMF, which arise as a result of the reorientation of the thin solid shell of our planet, have shown that a deformation field of shear is formed on its surface. In our opinion, this is one of the likely factors of the process that triggers global movements of lithospheric blocks. As a result, the shape of the lithosphere is transformed, which is characterized by a change in the size of the axes of the ellipsoids describing the surface of the lithosphere and their orientation. Practical significance. The research results make it possible to more reliably interpret the peculiarities of the TMF distribution. These forces can trigger mechanisms for discharging accumulated stresses, which is important for studying seismicity.

Simulation of propagation of video pulse signals of GPR in the Earth's lithosphere

Представлены результаты моделирования прохождения негармонических сигналов от расположенной на поверхности Земли антенны через верхний слой литосферы и отражения этих сигналов от различных неоднородностей в литосфере в случае, когда на антенну подается видеоимпульсный сигнал специальной формы. Используемая в работе модель основана на явной схеме численного интегрирования уравнений Максвелла. В этой схеме электрическое и магнитное поля вычисляются в одни и те же моменты времени в одинаковых узлах пространственной сетки, а также используется расщепление по пространственным направлениям и физическим процессам. В работе изучается, какую информацию о характере неоднородности литосферы можно извлечь из формы отраженного сигнала. Также исследуется влияние параметров видеоимпульсного сигнала на амплитуду и форму отраженных от типичных неоднородностей литосферы сигналов. Показано, что некоторые типы неоднородностей можно определить по форме отраженного сигнала.

Decoding the nanoscale porosity in serpentinites from multidimensional electron microscopy and discrete element modelling

Serpentinites, widespread in Earth's lithosphere, exhibit inherent nanoporosity that may significantly impact their geochemical behaviour. This study provides a comprehensive investigation into the characteristics, scale dependence, and potential implications of nanoporosity in lizardite-dominated serpentinites. Through a combination of multidimensional imaging techniques and molecular-dynamics-based discrete element modelling, we reveal that serpentinites function as nanoporous media with pore sizes predominantly less than 100 nm. Crystallographic relationships between olivine, serpentine, and nanoporosity are explored, indicating a lack of significant correlations. Instead, stochastic growth and random packing of serpentine grains within mesh cores may result in interconnected porosity. The analysis of pore morphology suggests that the irregular pore shapes align with the crystal form of serpentine minerals. Furthermore, the nanoporosity within brucite-rich layers at the serpentine-olivine interface is attributed to delamination along weak van der Waals planes, while pore formation within larger brucite domains likely results from low-temperature alteration processes. The fractal nature of the pore size distribution and the potential interconnectivity of porosity across different scales further support the presence of a pervasive nanoporous network within serpentinites. Confinement within these nanopores may introduce unique emergent properties, potentially influencing fluid transport, mineral solubility, and chemical reactions. As such, these processes may have profound implications for the geochemical evolution of serpentinites.

Episodic evolution of a protracted convergent margin revealed by detrital zircon geochronology in the Greater Caucasus

AbstractConvergent margins play a fundamental role in the construction and modification of Earth's lithosphere and are characterized by poorly understood episodic processes that occur during the progression from subduction to terminal collision. On the northern margin of the active Arabia‐Eurasia collision zone, the Greater Caucasus Mountains provide an opportunity to study a protracted convergent margin that spanned most of the Phanerozoic and culminated in Cenozoic continental collision. However, the main episodes of lithosphere formation and deformation along this margin remain enigmatic. Here, we use detrital zircon U–Pb geochronology from Paleozoic and Mesozoic (meta)sedimentary rocks in the Greater Caucasus, along with select zircon U–Pb and Hf isotopic data from coeval igneous rocks, to link key magmatic and depositional episodes along the Caucasus convergent margin. Devonian to Early Carboniferous rocks were deposited prior to Late Carboniferous accretion of the Greater Caucasus crystalline core onto the Laurussian margin. Permian to Triassic rocks document a period of northward subduction and forearc deposition south of a continental margin volcanic arc in the Northern Caucasus and Scythian Platform. Jurassic rocks record the opening of the Caucasus Basin as a back‐arc rift during southward migration of the arc front into the Lesser Caucasus. Cretaceous rocks have few Jurassic‐Cretaceous zircons, indicating a period of relative magmatic quiescence and minimal exhumation within this basin. Late Cenozoic closure of the Caucasus Basin juxtaposed the Lesser Caucasus arc to the south against the crystalline core of the Greater Caucasus to the north and led to the formation of a hypothesized terminal suture. We expect this suture to be within ~20 km of the southern range front of the Greater Caucasus because all analysed rocks to the north exhibit a provenance affinity with the crystalline core of the Greater Caucasus.

Numerical exploration of factors that control stress amplification in Earth's lithosphere

SUMMARY The mechanical heterogeneity of Earth's lithosphere leads to significant amplification of stresses across spatial scales ranging from mineral grains to tectonic plates. These stress amplifications play a key role in mechanical and chemical processes within the rock that affect bulk rock strength. Identifying the most effective causes of stress amplification is critical for understanding processes such as strain localization and fluid transport at scales ranging from microshear zones to tectonic plate boundaries. However, studies quantifying and predicting stress heterogeneities and amplifications are limited. We used numerical modelling of two-phase isotropic viscous systems to explore the factors influencing and controlling stress amplification and the potential magnitude of stress amplification in viscous regimes. We found the most geologically relevant amplification factors to be weak-phase spacing, rheological contrast and loading type. Our results indicate that stress amplification can reach a factor of ∼9 under specific conditions, but most of our experiments suggest amplifications at or below a factor of 2. Pressure differences across the model domains generally do not exceed ∼55 MPa, but some are as high as ∼110 MPa. The stress and pressure amplifications resulting from our analyses are large enough to drive a variety of geologically important processes such as failure and strain localization, as well as transient permeability and fluid migration.

Fluids in the Earth's lithosphere: From petrology to geodynamics

Fluids in the Earth's lithosphere: From petrology to geodynamics

IMPACT OF HIGH RADIO FREQUENCY SATELLITE OSCILLATIONS ON INITIATING EARTHQUAKES

Advanced satellite technology is worse than all the disasters on Earth due to the lack of dynamic security. The study of earthquakes is the most innovative research of all man-made disasters - no doubt, but there are new horizons of wonder for the thoughtful. Earthquakes are increasing unexpectedly in different countries of the world. People of most countries are worried about sudden earthquakes, but no one is able to reveal the main secret of these earthquakes. Many are blaming nature for this earthquake. Through this survey the exact origin of the matter has been presented to the whole world with proper evidence. Research shows that climate criminals are misusing advanced satellite technology to cause these earthquakes. According to research, misuse of advanced satellite technology causes artificial earthquakes at specific GPS locations on Earth, resulting in severe damage to humans, animals, plants and other objects. The intensity of these earthquakes is so intense that everyone is surprised. Studies have shown that the misuse of satellite technology has caused massive damage in man-made technological earthquake at a particular tectonic plate and other disasters. Due to these sudden earthquake, human suffering increases, standing institutions are demolished, road communication systems are ruptured, crop lands and residential areas are destroyed, individuals lose their lives. The study revealed that artificial earthquakes are caused by sudden radio-waves and strong oscillations of variable magnitude anywhere on earth. The study also showed the climate criminals use various fake messages and wireless tracking to influence policy-makers, the public and the media, as can be doubted in this study, All citizens and administrations should be aware and vigilant to prevent the rise of earthquake terror. The research shows that using advanced satellite technology, earthquakes can be created in time on any tectonic plate on the Earth. Moreover, the question remains that when technology was not invented, but earthquakes occurred - which were natural. Humans now generate artificial oscillations at specific GPS locations through earthquake simulation coding by multiplying the magnetosphere of previous natural earthquakes. The study shows that the EMMAST (Earthquake Mitigation and Management through Advanced Satellite Technology) model will make disaster mitigation systems safer and more efficient, saving millions of lives. The study on earthquakes is unique with world- class scientific research, which will open many research gateways for future generations.

Constraints from the Ntaba Mhlope Syncline and the Mkomozane Homocline, Moodies Group (3.22 Ga), Eswatini, on the deformation of the southern margin of the Barberton greenstone belt

The Barberton Greenstone Belt (BGB) has been classically thought to be a first-order synclinal structure, therefore constraining vertically-dominated models of early Earth lithosphere (de-)formation. Geological mapping, strain analysis, U-Pb zircon age dating, and Raman spectroscopy of carbonaceous matter (RSCM) of the Ntaba Mhlope Syncline (NMS) and the Mkomozane Homocline (MH) close to the southeastern linear margin of the BGB in Eswatini assess this interpretation by constraining the type and timing of the dominant late-phase deformation in this region. Geologic mapping shows that the NMS is a steeply doubly plunging, highly strained syncline composed of basal Moodies conglomerates overlain by sandstones and subordinate shales and siltstones. Deformation of conglomerate clasts is markedly constrictional and of uniform orientation throughout the syncline, suggesting that regional deformation occurred in zones of ductile strain. RSCM indicates maximum peak paleotemperatures of ca. 500 °C, somewhat elevated compared to temperatures measured throughout the BGB. Shortening may have occurred contemporaneously with lower crustal extension.

Spatiotemporal analysis of the distribution of earthquake chains 
 in the Baikal rift system with the purpose of revealing migrating seismicity

The study of the phenomenon of migrating seismicity in the epicentral fields of various seismically active regions of the Earth is the subject of many works. Chains of "migrations" of earthquakes are identified using various methods and are often explained by the passage of deformation waves in the Earth's lithosphere. This paper presents the results of studying the spatiotemporal distribution of quasi-linear chains of earthquakes in the Baikal region using statistical approaches and a large amount of initial data on earthquakes of representative energy classes. It is shown that the chains are formed mainly within the Baikal Rift System (BRS) and are confined to zones of seismotectonic destruction of the lithosphere. When studying the lengths of earthquake chains, five maxima of the distribution of chains were revealed, three of which correspond to possible geological and geophysical processes in the BRS lithosphere.

ON PROPER TIME OF THE SOURCE OF A STRONG EARTHQUAKE

The physics of earthquakes was contriubuted to by the concept of proper time of the source of a strong earthquake, which is different from universal (calendar) time. The earlier idea of proper time was implicit and has been considered only in relation to the physics of aftershocks. The present paper extends the applicability of the concept of proper time, proposes a possible way of its measuring, and provides an example to illustrate the procedure for sequential ordering of earthquakes by proper time. The object of this study is a global activity of strong (M≥7) earthquakes. We consider the sequence of earthquakes as a Poisson-type random process. Comparatively weak earthquakes are used as the "underground clock", the tick of which marks the proper time. The Poisson distribution is compared with the distributions for two sequences of strong earthquakes. One of the sequences is ordered by universal time, and another - by proper time. The studies indicate the distribution of events ordered by proper time is closer to the Poisson distribution than that of events ordered by universal time. We attribute this to the non-stationarity of the geological medium, which is an immanent property of the Earth's lithosphere.