Focal Mechanisms Research Articles

Estimating the slip rate in the North Tabriz Fault using focal mechanism data and GPS velocity field

Abstract This study delves into slip distribution on the North Tabriz Fault (NTF), a critical aspect of seismic hazard analysis due to its proximity to the Tabriz metropolis. The study operates within a uniform elastic half-space, maintaining constant values for fault geometry and regional rheological parameters throughout the research. To calculate strain boundary conditions, permanent and periodic global positioning system (GPS) data from the northwest region were utilized. The fault was constrained perpendicularly while allowing tangential movement, facilitating the determination of its annual slip rate using the boundary element method, with the Okada analytical model serving as the fundamental solution. The findings underscore the intricate relationship between the fault’s slip rate and boundary conditions, revealing a predominant right-lateral strike-slip motion. The study offers two slip rate assessments, obtained through earthquake focal mechanisms and GPS velocity data, yielding values of 5 and 5.5 mm / year {\rm{mm}}/{\rm{year}} , respectively. Importantly, the alignment of these calculated slip rates with paleo-seismological data underscores the credibility of the results generated via the boundary element method, distinguishing it as a reliable approach when compared to other numerical and analytical techniques. This research provides valuable insights into the behavior and slip dynamics of the NTF, which is pivotal for assessing seismic risks.

Identification of the mining accidents by a two-step clustering method for the mining-induced seismicity

Clustering methods aim to categorize data or samples into distinct groups based on their similarity. When applying clustering methods to earthquake events, it is crucial to establish a metric for quantifying the similarity between these events. Directly applying this clustering method to a catalog of mining-induced seismicity may lead to clustering earthquake events induced by different mining activities or accidents into the same group. To address this issue, a two-step clustering method has been proposed and applied for analyzing a catalog of mining-induced seismicity. The first step involves spatial distance-based clustering of seismic events, while the second step focuses on moment tensor analysis-based clustering of these events. The results obtained from the MT-based clustering method are visualized using Hudson Graphs, and box plots serve as an evaluation tool for assessing the quality of MT clustering. Most box plots demonstrate desirable quality in terms of MT cluster results, indicating successful outcomes. By the proposed two-step clustering method combined with actual mining activities, the potential accident locations and categories can be hypothesized while valuable recommendations provided for mining operations.

Brittle faulting and tectonic stress history on the western margin of the Congo Basin between Kinshasa and Brazzaville: Implications for the evolution of the Malebo Pool and the Congo River

The history of brittle faulting and associated paleostress states has been investigated in the rapids of the Congo River at the outlet of the Malebo Pool between Kinshasa (Democratic Republic of the Congo) and Brazzaville (Republic of the Congo). The aim of this study was to unravel the Meso-Cenozoic tectonic evolution of the western margin of Central Africa, as well as to investigate the dynamic evolution of the Pool and the capture of the Congo Basin drainage system by the Lower Congo River through the Central African Atlantic swell that formed between the Congo Basin and the Atlantic Ocean. We reviewed the geological evolution of the Pool area using recent data and new field observations to develop a consistent stratigraphic model for both sides of the Congo River. We collected a significant amount of data faults and fractures in the early Paleozoic Inkisi arkosic sandstones, identified four successive data subsets and determined their related paleostress tensors trough an iterative process utilizing relative chronological indications. All paleostress states exhibit a a strike-slip faulting regime, with varying orientation of horizontal principal compression. The timing of faulting was constrained by indirect observations based on the updated understanding of the Pool's evolution. The geodynamic interpretation of the brittle stages considered potential sources of compressional stress arising from plate boundaries and from the oceanic ridge push. A polyphase brittle tectonic history was identified, characterized by the gradual appearance of newly formed faults and reactivation of the existing ones, leading to the gradual saturation of the host rock with fractures. The most recent event let to a significant imprint on the current landscape and is believed to have facilitated the connection of the drainage system of the Congo Basin to the Atlantic coast in the Oligocene period. The current stress state, determined from earthquake focal mechanisms, aligns with the most recent paleostress state identified determined from fault-slip data, displaying similar stress axis orientations but with consistent with a transpressional stress regime instead of a strike-slip one.

Towards atomistic modelling of solid Pb-O formation and dissolution in liquid lead coolant: Interatomic potential development

Microscopic description of solid Pb-O formation and dissolution in liquid lead coolant is important for the modelling of fast neutron reactors. For this purpose, in this work we develop interatomic potential models for lead melt with dissolved oxygen. Potentials fitting is based on ab initio density functional theory (DFT) calculations and quantum molecular dynamics. Two different potential models are trained on the DFT data using the force-matching method: a computationally cheap embedded atom method (EAM) potential and a computationally expensive machine-learned moment tensor potential (MTP) that allows reproducing DFT data very accurately. The potentials are further validated to reproduce the properties of lead melt and the coordination of oxygen atoms in molten lead. The diffusion coefficient for oxygen in molten lead is calculated and compared with the available experimental data. We analyse how these interatomic potential models describe the crystal structure of the solid lead oxide to consider PbO nucleation and dissolution in molten lead. We extensively discuss the arising problems with the description of long-range electrostatic interactions. The possibility of matching the experimental data on the oxygen solubility limit by tuning the EAM potential is shown.

Along-Strike Variation of Rupture Characteristics and Aftershock Patterns of the 2023 Mw 7.8 Türkiye Earthquake Controlled by Fault Structure

Abstract On 6 February 2023, an Mw 7.8 earthquake occurred along the East Anatolian fault zone (EAFZ) in southeastern Türkiye, representing the strongest earthquake in the region in nearly 80 yr. We investigate rupture characteristics and aftershock patterns of the earthquake through focal mechanism calculation, backprojection analysis, and finite-fault inversion. The results show bilateral rupture propagation of the mainshock with transient supershear speed in the southwest portion of the EAFZ, as well as shallower coseismic slip and abundant normal-faulting aftershocks in the same portion. We attribute these earthquake behaviors to the along-strike variation of fault structure of the EAFZ, which features a more complex fault geometry accompanied by numerous short normal faults in the southwest portion. These results shed light on fault segmentation, rupture speed variation, and slip partitioning along the EAFZ, advancing our understanding of fault structural control on earthquake behaviors in a complex multisegment fault system.

Detailed seismic structure beneath the earthquake zone of Yogyakarta 2006 (Mw ∼6.4), Indonesia, from local earthquake tomography

The earthquake, which occurred in Yogyakarta, Indonesia, on May 26, 2006, at 22:53:58 UTC with Mw ∼6.4, was one of the most destructive earthquakes in Indonesia. The earthquake caused thousands of fatalities, tens of thousands of injuries, and hundreds of thousands of house damages in the Yogyakarta area and its surroundings at a loss of billions of dollars. Previous studies from seismic tomography and satellite radar imaging hypothesized that the earthquake was caused by activating a so far unknown fault east of the Opak Fault. Although, in the beginning, the Opak fault was suspected to be the source of the Yogyakarta earthquake in 2006. This assumption was made because the damage was maximum in the Bantul area west of the Opak Fault. This study demonstrates that our seismic tomography achieved a higher resolution than the previous study and could resolve a failed complex fault system. We utilized more aftershocks (2170 events) and smaller grid sizes for seismic tomography inversion. Four focal mechanisms from aftershocks for Mw ≥ 4.5 were also conducted to support structure interpretation in the study area. Our results successfully delineate the Opak Fault and the second fault, namely the Ngalang Fault, parallel to the eastern part of the fault at a depth of 9 km. Two faults could be indicated by the velocity contrast of Vp, Vp/Vs ratio, and Vs from a horizontal section tomogram. Our focal mechanisms also support seismic tomography, revealing two fault planes in our study area. The results show that the two faults are connected by the Oyo Fault, which is ruptured in the opposite direction compared to the two faults.

Moment tensor potential for static and dynamic investigations of screw dislocations in bcc Nb

A new machine-learning interatomic potential, specifically a moment tensor potential (MTP), is developed for the study of screw-dislocation properties in body-centered-cubic (bcc) Nb in the thermally- and stress-assisted temperature regime. Importantly, configurations with straight screw dislocations and with kink pairs are included in the training set. The resulting MTP reproduces with near density-functional theory (DFT) accuracy a broad range of physical properties of bcc Nb, in particular, the Peierls barrier and the compact screw-dislocation core structure. Moreover, it accurately reproduces the energy of the easy core and the twinning-anti-twinning asymmetry of the critical resolved shear stress (CRSS). Thereby, the developed MTP enables large-scale molecular dynamics simulations with near DFT accuracy of properties such as for example the Peierls stress, the critical waiting time for the onset of screw dislocation movement, atomic trajectories of screw dislocation migration, as well as the temperature dependence of the CRSS. A critical assessment of previous results obtained with classical embedded atom method potentials thus becomes possible.

Which Global Moment Tensor Catalog Provides the Most Precise Non-Double-Couple Components?

Abstract The availability of digital seismic waveform data enabled compilation of seismic moment tensor catalogs that provide information about earthquake source processes beyond what could be derived from earlier methods that assume double-couple sources representing slip on planar faults. This additional versatility involves additional complexity. Moment tensors are determined by inversions minimizing the misfit between observed and synthetic waveforms, and depend on the specifics of the data inverted, the inversion algorithm, and the Earth structure assumed. Hence, substantial uncertainties arise in moment tensors and quantities derived from them, which can be assessed by comparing moment tensors from multiple global and regional catalogs using different data and inversion procedures. While the double-couple (DC) components of moment tensors are generally determined with greater certainty, non-double-couple (NDC) components for the same earthquake sometimes differ significantly between catalogs. This observation raises questions about the reliability of their determination and hence their geological significance. Using the correlation between NDC components in different catalogs, we quantify the reliability of NDC components in moment tensor catalogs through the determination of the effects of unmodeled and inaccurately modeled effects contained in them. We determine that the NDC components in the Global Centroid Moment Tensor catalog are, on average, more precise than in other catalogs, and thus studies on NDC components should be based on this catalog. Furthermore, their uncertainties are largely unrelated to uncertainties in the DC components. Therefore, the reliability of fault angles derived from a moment tensor is largely independent from the reliability of its NDC components.

The 2022 Goesan earthquake of the moment magnitude 3.8 along the buried fault in the central Korean Peninsula

AbstractOn October 28, 2022, a moment magnitude (Mw) 3.8 earthquake occurred in Goesan, South Korea, typically characterized as a stable continental region. Herein, we analyze 42 earthquakes, including the Mw 3.8 earthquake, the largest foreshock (Mw 3.3), which preceded the mainshock by 17 s, and the largest aftershock (Mw 2.9). The primary aim of this study is to identify interactions among the seismic events. To this end, we utilized the permanent seismic networks with the closest station at 8.3 km from the epicenter, and the temporary network deployed eight hours after the mainshock’s occurrence. Relocation results delineate that the mainshock occurred at the southeastern tip of the hypocenter distribution of three foreshocks, trending west-northwest–east-southeast. The aftershocks form an overall spatially diffused seismic pattern that propagates toward both ends of the inferred lineament in the downdip direction. The rupture directivity of the mainshock, along with waveform similarity across the mainshock and foreshocks, confirms the inferred geometry, corresponding well with the focal mechanisms of the mainshock and the largest foreshock. We demonstrate that the change in Coulomb failure stress (ΔCFS) by the largest foreshock was positive where the mainshock occurred and that the mainshock generated ΔCFS capable of triggering the propagation of the aftershocks.

Empirical analysis of unloading creep damage mechanism of salt rock at 110 °C

Underground energy storage in salt caverns involves operating in high-temperature conditions within deep strata, leading to unloading creep in the surrounding salt rock during cavity construction and natural gas extraction. Therefore, understanding the deformation and damage evolution of salt rock in such conditions is vital for ensuring safe construction and prolonged operation of deep salt cavern gas storage. The present study involves graded unloading creep tests and synchronous acoustic emission tests on the salt rock at 110 °C. The moment tensor inversion theory is employed to analyze focal mechanisms and microscopic crack propagation modes based on the test results. The findings reveal that under constant deviatoric stress, decreasing confining pressure exponentially increases the duration of the deceleration creep stage in salt rock. The creep increment and axial steady-state creep rate exhibited a U-shape trend. Instantaneous strain during stress change mainly involves elastic-plastic strain, where the instantaneous strain decreases first and then increases, exhibiting hardening characteristics in the middle process. The evolution of microcracks in salt rock can be categorized into three stages: compaction stage, stable propagation stage, and accelerated propagation stage. The acoustic emission energy, b-value, and fractal dimension of each stage are different. In unloading creep tests, the peak frequency in acoustic emission signal presents zonal distribution in low-frequency and high-frequency regions. It is found that as the confining pressure decreases, the peak frequency of acoustic emission signal and the proportion of high-frequency signal decrease, and the b-value and fractal dimension exhibit an upward-fluctuation-downward trend. The rupture slip angle of the acoustic emission source can effectively characterize the creep slip behavior in salt rock crystals. The slip gradually shifts from vertical to horizontal, while the strike angle and dip angle of rupture orientation are minimally affected by unloading. The obtained results can provide a reference for the safe construction and the design of the operation pressure for ultra-deep salt cavern gas storage.

Highly reliable and large-scale simulations of promising argyrodite solid-state electrolytes using a machine-learned moment tensor potential

The high ionic conductivity of argyrodite makes it an attractive candidate for solid-state electrolytes (SSEs) in all-solid-state Li-ion batteries (ASSBs). Although great effort has been devoted to using ab initio molecular dynamics (AIMD) to evaluate ionic conductivity and elucidate the Li-ion diffusion mechanism of argyrodite-based SSEs, limitations in system size, simulation temperatures, and time associated with AIMD make accurate predictions and analysis of Li-ion diffusion challenging. Here, we present a reliable, large-scale computational approach to realistic simulation of SSEs in the bulk and at the grain boundary (GB) based on moment tensor potentials (MTPs) trained at the van der Waals optB88 level of theory. MTPs enable sufficiently large-scale and long-time simulations that reflect all possible configurational disorder of experimental crystal structures and provide accurate ionic conductivities that are close to values measured experimentally in halogenated Li-argyrodite (Li6PS5X [X = Cl, Br, I]). Our simulations show that the vibrational motion of a PS4 polyhedron has a positive effect on ionic conductivity. We also developed an accurate MTP using an active-learning approach to exploring Li-ion diffusion at the GB in polycrystalline SSEs. Simulations of the molecular dynamics of large ∑5100021 (>10,000-atom) GB models reveal that Li-ion accumulation around the GB region retards ionic conductivity and extends into an interior region approximately 20 Å from the GB interface. This work provides a practical approach to realistic large-scale and interfacial GB simulations that are otherwise inaccessible through ab initio calculations by developing accurate machine-learned MTPs.

Stress Patterns and Crustal Anisotropy in the Eastern Alps: Insights From Seismological and Geological Observations

AbstractIn the Eastern Alps, the indentation of the Adriatic promontory since the Cenozoic affected the kinematics of separate crustal domains bounded by faults that accommodate lateral extrusion processes and differential shortening. Deciphering the pattern of crustal stresses in the orogen interior is challenging, due to the lack of in situ stress measurements at crustal depths. We define stress regimes and the orientations of the most‐compressive horizontal stress (SHmax) by integrating published results with new data, including stress analysis from fault plane solutions, estimation of crustal anisotropy through the shear wave splitting analysis, paleostress determination from fault slip data, and computation of cumulative seismic displacements. The retrieved regional SHmax are generally consistent with N‐S convergence. In the northern part of the study area, current stress orientations are almost parallel to paleo‐SHmax, suggesting a rather uniform compressional regime since the late Cenozoic. Conversely, sharp deflections and divergence with paleo‐SHmax appear at the western border of the Adriatic promontory across major transpressive and extensional shear zones and in the Southalpine domain, indicating a change in tectonically induced second‐order stresses. A current strike‐slip regime with subordinate orogen‐parallel seismic displacements affects a belt to north of the Periadriatic Lineament and NE‐extension characterizes the Ortles‐Engandine region. Seismic anisotropy locally exhibits fault‐parallel fast axes (Brenner‐Giudicarie fault‐systems, Dinaric and Southalpine thrusts), whereas stress‐induced anisotropy parallel to SHmax characterizes the southern part of the orogen. Cumulative seismic displacements are small compared to geodetic ones, and unravel partitioning of deformation into second‐order transpressive and extensional belts in response to indentation.

High‐ and Low‐Frequency Waveform Analysis the Marsquake of Sol 1222: Focal Mechanism, Centroid Moment Tensor Inversion and Source Time Function

AbstractThe seismometer onboard InSight NASA Mars mission discovered a seismically active planet. We focused on the strongest event named S1222a (4 May 2022, Mw ∼ 4.7), which was recorded by the Very Broad Band sensors and associated channel ELYSE and is located 37.2° away from InSight. We use two different methods based on a point source approach for an elastic, horizontally layered medium to retrieve source parameters of S1222a. In the first case, the seismic moment tensor inversion of high‐frequency seismogram data is calculated using a matrix method for the direct waves. The process includes the generation of records in displacement using the frequency‐wavenumber integration technique. A method of inversion of the moment tensor of direct P‐ and S‐waves, less sensitive to path effects than reflected and transformed waves, is presented, which significantly increases the accuracy and reliability of the method. In the second case, tensors were calculated using common low‐frequency full‐waveform inversion and the tests to verify the plausibility of this solution obtained from the single station calculation were performed and the uncertainty estimations for inversions can be useful in future research.

Testing the P/S Amplitude Seismic Source Discriminant at Local Distances Using Seismic Events Within and Surrounding the Kloof Gold Mine, South Africa, and the Kiruna Iron Ore Mine, Northern Sweden

ABSTRACT We investigate the utility of the P/S amplitude discriminant for small seismic events recorded at local distances on surface seismic networks using (1) mining-related events from within the Kloof gold mine in South Africa; and (2) mining-related events and earthquakes within and adjacent to the Kiruna iron ore mine in northern Sweden. For the Kloof mine, seventy-five source mechanisms characterized by moment tensor solutions obtained using high-frequency in-mine seismic data are used to evaluate three mine-related source types, isotropic (crush), compensated linear vector dipole (crush-slip), and double-couple (DC; pure slip). For the Kiruna mine region, 270 events are used to evaluate earthquake sources, chemical explosions, and mine-related seismic events (primarily isotropic). For the Kloof mine events, we find that average P/S amplitude ratios measured in the 2–6 Hz frequency band discriminate between isotropic and DC events, and if only pure-slip events with a DC component of >60% are considered, the effective frequency band can be extended from 2 to 8 Hz. For the Kiruna region events, P/S amplitude ratios effectively discriminate earthquakes from chemical explosions in the 4–6 Hz and 10–28 Hz frequency bands. Our findings further show that average P/S amplitude ratios for mine-related events and earthquakes separate at frequencies of 10 Hz and higher. A comparison of amplitude ratios for crush and pure-slip events located within a depth range of 1 km in the Kloof mine, and a comparison of amplitude ratios of shallow (<10 km depth) and deep-focus (>20 km depth) earthquakes in the Kiruna region, indicate that the P/S amplitude discriminant is not influenced significantly by source depth. These findings thus suggest that the P/S amplitude discriminant, originally developed for larger events recorded at regional and teleseismic distances, can be extended to smaller events recorded at local distances.

Кинематика разрывных нарушений Сахалина по геологическим и сейсмологическим данным

The paper presents a tectonic map of Sakhalin Island showing digitized faults derived from 1:1,000,000 scale tectonic maps and identified by geological surveys (detailed on 1:200,000 and 1:50,000 scale maps). The structural geological data on the kinematics of faults have been compared with seismological data on the earthquake focal mechanisms. A reasonable correspondence of these data has been obtained. The predominant kinematic type of faults is thrust/throw in the southern and northern parts of Sakhalin Island. In the central part of Sakhalin, a mixing of fault kinematic types is observed, mainly thrust faults with rare normal and strike-slip faults. Two uninformative zones have been identified with virtually no data on both structural geology and seismology. The earthquake focal mechanisms with a strike-slip component are dominant at their boundaries.

A weak subducting slab at intermediate depths below northeast Japan.

Knowledge of the state of stress in subducting slabs is essential for understanding their mechanical behavior and the physical processes that generate earthquakes. Here, we develop a framework which uses a high-resolution focal mechanism catalog to determine the change in the position of the neutral plane before and after the M9 Tohoku-oki earthquake to determine that the deviatoric stress within the slab at intermediate depths must be very low (∼1 MPa). We show that by combining the static stress calculated from coseismic slip distributions with the stress orientations before and after the mainshock, we can determine the full deviatoric stress tensor within the subducting slab at intermediate depths. These results preclude earthquake source mechanisms that require large background driving stresses, favoring a mechanically weak subducting slab, thus providing quantitative constraints on the physical processes that generate intermediate-depth earthquakes.

Seismic hazard identification around Surabaya City, East Java, Indonesia: a preliminary result based on the June 2023 Mojokerto earthquake

An earthquake was felt in the Mojokerto area, East Java (Indonesia) with a magnitude of M 4.4. This area has a low seismicity level according to the latest earthquake catalog. In this paper, we conduct a study to determine the direction of fault movement in the area, using data from BMKG seismic sensors with a distance of less than 250 km. The moment tensor inversion results show that the Strike/Dip/Rake values at each nodal plane are 257/88/4 and 167/86/175. To determine the direction of fault movement, we prefer a strike of 167 degrees for this earthquake, following the direction of deformation around the area from the northeast of Java Island. From the results of the moment tensor solution and the history of seismicity that has occurred in the area around Surabaya, it can be shown that the city of Surabaya is a city that is close to seismic activity, although it tends to have small activity, this needs to be considered considering that Surabaya is one of the cities with the highest population density in Indonesia. Further research needs to be done related to disaster vulnerability around the city of Surabaya. From the results of the source mechanism and seismicity in the Surabaya area it can be concluded that the Surabaya area has a disaster risk, there needs to be further research that discusses the local footprint effects of soil in the area in the Surabaya area. This research is needed for further discussion of the possibility of disasters in the Surabaya area.

Tectonic stress around the South Caspian basin deduced from earthquake focal mechanisms

ABSTRACT In this paper, we study the tectonic stress around the South Caspian Basin (SCB), which includes the Kopeh Dagh, Alborz, Talesh, eastern Greater Caucasus mountain belts, the Apsheron sill, and the Balkhan-Ashkabad fault zone. We apply the stress inversion to focal mechanisms of 410 mainshocks that have occurred over the last 69 years. These mechanisms indicate that the surrounding fault zones of the SCB exhibit diverse types of faulting, ranging from thrust to strike-slip, normal, and their combinations. The results of the stress inversion align with the kinematics of the major fault zones bounding the SCB and emphasize the spatial heterogeneity of the stress field in this region. The region is predominantly under compression, but transpressive and strike-slip regimes are also present. This highlights the role of obliquely oriented basement faults with respect to the maximum horizontal compressive stress (S Hmax ) in accommodating deformation through convergent zones. The orientation of the S Hmax is in the NE to NNE direction in the Kopeh Dagh, Alborz, Talesh, and Ashkabad-Balkhan fault zones, being rotated to NNE-N in the Greater Caucasus. The orientation of the S Hmax relative to the convergence direction of the Arabian and Eurasian plates indicates that the Arabian-Eurasian oblique convergence-derived tectonic stress is the primary contributor to the total stress and deformation in this region.

TRP channels: a provocative rationalization for local Ca2+ control in arterial tone development.

Arterial networks are controlled by the consolidated output of stimuli that set "how much" (magnitude) and "where" (distribution) blood flow is delivered. While notable changes in magnitude are tied to network wide responses, altered distribution often arises from focal changes in tone, whose mechanistic foundation remains unclear. We propose herein a framework of focal vasomotor contractility being controlled by pharmacomechanical coupling and the generation of Ca2+ waves via the sarcoplasmic reticulum. We argue the latter is sustained by receptor operated, transient receptor potential (TRP) channels through direct extracellular Ca2+ influx or indirect Na+ influx, reversing the Na+/Ca2+ exchanger. We view this focal regulatory mechanism as complementary, but not redundant with, electromechanical coupling in the precision tuning of blood flow delivery.

Spatio-temporal characteristics of seismic strain anomalies reveal seismic risk zones along the Longmenshan fault zone and adjacent areas

Introduction: Identifying and quantifying earthquake precursors, and analyzing their physical mechanisms, continues to be a challenge for earthquake forecasting. In this study, orthogonal functions were developed to effectively identify precursor anomalies, thereby improving the forecasting of strong earthquakes.Methods: To study the spatio-temporal contour anomalies in seismic strain fields, we assessed them for seismic activity variables and natural orthogonal function expansion, in six strong earthquakes near the Longmenshan Fault Zone, China, that have occurred since 2008.Results: We observed that, prior to these earthquakes, the temporal factor (the time variation characteristics of the strain field) displayed anomalies with high/low values exceeding the mean square error within a stable context. The anomalies exhibited multi-component characteristics and were primarily concentrated in the first four-strain fields. Short-term and impending-earthquake anomalies were observed in the temporal factor before the 2008 Wenchuan (M8.0) and 2013 Lushan (M7.0) earthquakes, while medium-term and long-term anomalies appeared before the other four strong earthquakes, without notable short-term anomalies. The temporal evolution of strain field contour anomalies, and the strain contours positive and negative intersection, showed that central areas surrounded by multiple strain field contour anomalies were potential locations for strong earthquakes. This suggests a potential approach for earthquake location forecasting. Since 2009, there have been five strong earthquakes, each affected to varying degrees by anomalous strain fields from the 2008 Wenchuan (M8.0) earthquake.Conclusion: The results of this study corroborate the findings of the focal mechanism’s node shear stress, indicating significant physical implications of the anomalies and the reliability of these conclusion.