地质力学学报

Research progress and prospects of deep stress measurement technology

SUN Dongsheng, LI Awei, YANG Yuehui, WU Bangchen, ZHANG Hao, SUN Weifeng, LI Ran

Objective With the implementation of the national strategy of seeking resources, safety, and space from deep Earth, the frequency and intensity of various engineering disasters caused by in-situ stress have also significantly increased. At the same time, in engineering fields such as underground gas storage and water diversion tunnels, using the minimum principal stress criterion to determine the upper limit operating pressure can to some extent improve the storage capacity of underground space or reduce tunnel support costs. Overall, the importance of in-situ stress in the process of advancing towards the deep Earth is becoming increasingly prominent. However, there are still bottlenecks in the demand oriented deep stress measurement technology, such as insufficient detection capability and low reliability of measurement results, which restrict the application of in-situ stress data in solving scientific problems such as tectonic activity, deep resource development, and space utilization. Methods On the basis of a brief review of the current development status of in-situ stress measurement technology, this article focuses on the progress and achievements of the team in theoretical research, technical development, and application practice of in-situ stress measurement in recent years. Results It points out the challenges faced by deep in-situ stress measurement in terms of theoretical methods and technical aspects, and proposes a research route and direction for deep borehole stress detection in conjunction with the current national science and technology major project "Key Technologies and Experiments for Deep Stress Detection". Conclusion The goal is to develop high, precise, and advanced in-situ stress measurement technology and equipment, construct an in-situ stress observation technology system covering the depth space of the hypocenter source. [ Significance ] Deep borehole in-situ stress detection technology holds significant potential for applications in geodynamics research, deep resource exploration, and disaster prediction and prevention.

Progress and perspectives in research on crustal stress and earthquakes

YANG Shuxin, YAO Rui, LI Yujiang, HUANG Luyuan, HU Xingping

Objective The crustal stress state is a key physical parameter for understanding lithospheric dynamics, elucidating earthquake preparation mechanisms, and assessing regional seismic hazards. It also provides essential data for the optimal design, safe construction, and operation of major underground energy and geotechnical engineering projects. Systematically reviewing the research context in this field and clarifying the current progress and challenges can provide guidance for future research. Methods Through a systematic review and synthesis, we summarize the technical methodologies and the evolution of development paradigms in three interconnected domains: acquisition of crustal stress data, analysis and modeling of stress fields, and stress processes associated with earthquakes. Results (1) Progress in stress information acquisition: Observation techniques have advanced from shallow to deep levels and from single-site measurements to network-based monitoring. Traditional methods have been continuously refined, while deep borehole in-situ techniques, such as elastic strain recovery (ASR) and differential strain curve analysis (DSCA), have extended observation depths beyond 5 km. The integration of multidisciplinary data has become a prominent trend. (2) Advances in stress field analysis and modeling: Methodologies have evolved from analytical and numerical approaches to an intelligent framework that integrates mechanisms, data, and knowledge. Numerical models have developed from two-dimensional elastic formulations to three-dimensional visco-elastoplastic representations, enabling the dynamic characterization of regional four-dimensional stress fields. (3) Developments in earthquake-related stress processes: In-situ stress measurements, Coulomb stress modeling, and combined physical–numerical experiments jointly reveal the cyclic pattern of “quiescence–accumulation–release–adjustment” during earthquake initiation, as well as stress triggering and shadow effects, and the physical mechanisms underlying fault instability nucleation. Conclusion Current research still faces challenges such as the scarcity of deep stress data, the complexity of integrating multi-source data, and the high uncertainty in determining the initial stress field. Future studies should focus on (1) developing intelligent, multi-method technologies for deep stress observation; (2) constructing machine learning–based inversion and four-dimensional dynamic stress field models constrained by physical principles; (3) advancing research on thermo–chemical–mechanical coupling rheology; and (4) promoting a new paradigm for seismic prediction that integrates stress mechanisms, big data, and expert knowledge. Thereby, future studies will provide a more robust scientific foundation for seismic risk assessment and disaster prevention and mitigation. [ Significance ] This review of advancements and prospects in crustal stress and earthquake research provides references and insights for the observation and analysis of seismic stress processes and for the research on seismic dynamic prediction methods.

How do borehole observations characterize crustal stress?

MA Xiaodong

Objective Knowing the in-situ stress state is of great importance for understanding a wide range of geomechanical processes in the Earth’s crust, and for addressing many practical problems in the subsurface. The in-situ stress characterization in boreholes through the classic hydraulic fracturing test and borehole failure observation has provided fundamental knowledge of the stress state in the brittle upper crust. Methods Compiling borehole observations and other stress indicators over much larger scales reveals coherent and consistent stress orientations and relative stress magnitudes over appreciable depths and between boreholes at the regional scale. Stress magnitudes determined using the hydraulic fracturing method and borehole failure observation are consistent with the classic Anderson and Coulomb faulting theories, as well as with the empirical Byerlee’s law. This is useful for constraining the in-situ stress state and quantifying fault stability. The general state of frictional equilibrium in the upper crust is present, although stress variations at local scales due to discontinuities, lithology contrasts, rock mass anisotropy and other factors are practically ubiquitous. Results To date, the hydraulic fracturing method and borehole failure observations—and their evolved variants—remain extremely useful. However, given the challenges ahead in subsurface exploration and engineering, it is imperative that we fundamentally revolutionize how we collect, interpret, and share the stress data with innovative developments in crustal stress characterization. Significance In this paper, we also present several ongoing projects that attempt to innovate stress observations at various scales. These attempts build upon the foundation laid by hydraulic fracturing tests and borehole failure observations. At the scale of individual boreholes, deep learning is being employed to automatically identify borehole stress indicators, such as fractures and breakouts, in image logs to increase the efficiency and robustness of stress interpretation. Processed image logs with various characteristics can further improve the applicability of deep learning models. At the scale of borehole arrays in subsurface engineering, the use of multiple boreholes and complementary approaches (hydraulic fracturing tests and borehole failure observations) enables stress characterization at finer spatial scales, which prompts the understanding of stress distribution and engineering practicality. At the scale of ultra-deep boreholes, the identification and classification of uncommon stress indicators, such as natural fractures, are utilized to invert the in-situ stress and crustal rock mass strength. The inversion confirms the frictional equilibrium hypothesis and offers an alternative approach for stress characterization. Conclusion These attempts underscore the importance of moving beyond the paradigm of borehole stress characterization and the interconnectedness between classic theories and novel developments.

Insights into the statistical relationship between focal mechanisms and stress from synthetic experiments

LI Zhenyue, WAN Yongge

Objective The extent to which the spatial distribution patterns (particularly the clustering characteristics) of fault nodal planes or the P, B, and T axes of a set of focal mechanism data can provide information about background stress causing earthquakes has long been a controversial academic topic. Methods This study systematically investigates this issue through synthetic experiments designed on the basis of the stress–fault slip relationship, with stress parameters including the orientations of the three principal stresses and the stress shape ratio (R). Results The experimental results demonstrate that the spatial distribution patterns of both fault nodal planes and PBT axes are jointly controlled by the stress shape ratio and the fault failure conditions. In most cases, the two nodal planes exhibit widely scattered spatial distributions. Only when the shape ratio is close to 0.5 and the contact area between the Mohr-Coulomb failure envelope and Mohr’s circle is minimized do the distributions of both the actual and the auxiliary planes become relatively concentrated. Under these specific conditions, the fault nodal planes (their normals) gain statistical significance for estimating stress orientations. Identifying the actual fault plane among the two nodal planes in focal mechanisms would enhance the determination of principal stress directions. Notably, the spatial distribution of PBT axes effectively captures both the principal stress orientations and the shape ratio. Key findings include: (1) Due to the influence of fault failure conditions and the shape ratio, the P, B, and T axes may not cluster or disperse simultaneously. However, when clustering occurs, they converge near the

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axes, respectively. (2) A ring-shaped (toroidal) distribution of T axes indicates a high R-value. (3) P and T axes never exhibit fully random scattering; if such disorder is observed in real data, it suggests that the focal mechanisms may not share a common stress regime. Conclusion This study provides critical constraints for evaluating whether focal mechanism data used in stress inversion belong to a unified stress regime and for predicting stress parameters from the distribution of PBT axes. [ Significance ] These results offer significant implications for developing and applying stress inversion methodology using focal mechanisms.

Determination of hydraulic fracture closure pressure based on total system stiffness method: Case studies

YANG Yuehui, SUN Dongsheng, WU Bangchen, LI Awei, LI Ran, QIN Xianghui, SUN Weifeng, MENG Wen, CHEN Qunce

Objective Hydraulic fracturing is one of the most widely used and ISRM-recommended techniques for in-situ stress measurement in rock masses, where a key step is determining closure pressure from the pressure-decay curve as a proxy for the minimum horizontal principal stress. Conventional interpretation methods mainly rely on tangents or best-fit lines to analyze the pressure-decay rate, making the result highly sensitive to the selected time window and lacking clear physical representation of fracture closure, which introduces uncertainties in closure pressure and stress evaluation. Methods This study proposes a method based on the evolution of Total System Stiffness (TSS), in which the pressure-decay curve after shut-in is transformed into a TSS curve to better capture fracture-closure behavior, and the method is applied to hydraulic-fracturing datasets from different boreholes, lithologies and depths. Results The evolution of TSS after shut-in can be divided into three main stages whose features can be used to identify upper and lower bounds of closure pressure and to evaluate whether the pressure curve is suitable for in-situ stress interpretation; closure pressures obtained in this way show reduced sensitivity to the choice of time window compared with conventional approaches. Conclusion The TSS method provides clear physical meanings for the beginning and end of fracture closure and determines closure pressure directly from pressure data, without fitting or extrapolation. [ Significance ] The method offers a practical tool for improving closure-pressure interpretation and is expected to be widely applicable in hydraulic-fracturing-based in-situ stress analysis.

Cover Page

2025, 31(6).

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Contents

2025, 31(6): 1-2.

Abstract (25) HTML (11) PDF (465KB)(3)

2025, 31(6): 1109-1110. doi: 10.12090/jissn.1006-6616.20253102

Abstract (45) HTML (17) PDF (295KB)(19)

Research progress and prospects of deep stress measurement technology

SUN Dongsheng, LI Awei, YANG Yuehui, WU Bangchen, ZHANG Hao, SUN Weifeng, LI Ran

2025, 31(6): 1111-1126. doi: 10.12090/j.issn.1006-6616.2025089

Abstract (71) HTML (16) PDF (1565KB)(29)

Progress and perspectives in research on crustal stress and earthquakes

YANG Shuxin, YAO Rui, LI Yujiang, HUANG Luyuan, HU Xingping

2025, 31(6): 1127-1145. doi: 10.12090/j.issn.1006-6616.2025104

Abstract (169) HTML (30) PDF (4189KB)(57)

How do borehole observations characterize crustal stress?

MA Xiaodong

2025, 31(6): 1146-1158. doi: 10.12090/j.issn.1006-6616.2025153

Abstract (108) HTML (20) PDF (1817KB)(38)

Insights into the statistical relationship between focal mechanisms and stress from synthetic experiments

LI Zhenyue, WAN Yongge

2025, 31(6): 1159-1167. doi: 10.12090/j.issn.1006-6616.2025082

Abstract (121) HTML (36) PDF (17540KB)(27)

Determination of hydraulic fracture closure pressure based on total system stiffness method: Case studies

YANG Yuehui, SUN Dongsheng, WU Bangchen, LI Awei, LI Ran, QIN Xianghui, SUN Weifeng, MENG Wen, CHEN Qunce

2025, 31(6): 1168-1176. doi: 10.12090/j.issn.1006-6616.2025099

Abstract (58) HTML (12) PDF (1902KB)(33)

Tectonic stress field and crustal strength of the central-southern Tanlu Fault Zone

MENG Wen, CHEN Qunce, GUO Xiangyun, HUANG Xin

2025, 31(6): 1177-1187. doi: 10.12090/j.issn.1006-6616.2025107

Abstract (107) HTML (23) PDF (2328KB)(30)

Major advances and prospects in in-situ stress measurement and estimation methods over the past 10 years (2014–2025）

WANG Chenghu, LI Wei

2025, 31(6): 1188-1209. doi: 10.12090/j.issn.1006-6616.2025080

Abstract (144) HTML (31) PDF (2357KB)(44)

Research and development of a volumetric mining-induced stress monitoring sensor and its application

LI Guanghan, SUN Dongsheng, HAN Jun, GUO Baolong, MA Shuangwen, ZHU Zhijie

2025, 31(6): 1210-1221. doi: 10.12090/j.issn.1006-6616.2025078

Abstract (220) HTML (52) PDF (1882KB)(30)

In-situ stress characteristics in the project area of a large hydropower station on the northern margin of the eastern Himalayan syntaxis

WANG Bin, DONG Zhihong, LIU Yuankun, FU Ping, HAN Xiaoyu, AI Kai, ZHOU Chunhua, ZHANG Xinhui, LUO Sheng, YANG Yuehui

2025, 31(6): 1222-1237. doi: 10.12090/j.issn.1006-6616.2025101

Abstract (86) HTML (24) PDF (2892KB)(29)

Research on the application of the Quantum-behaved Particle Swarm Optimization algorithm in the inverse estimation of in-situ stress based on fault-slip fractures

ZHOU Weiwei, FENG Yongcun, LI Xiaorong, LIU Jie, SU Feiyu, HU Han

2025, 31(6): 1238-1254. doi: 10.12090/j.issn.1006-6616.2025095

Abstract (71) HTML (14) PDF (3371KB)(16)

Comparative study of excavation schemes for underground plant caverns based on in-situ stress field inversion

ZHAO Chunlei, ZHANG Yanxin, LI Zishuo, WANG Qiang

2025, 31(6): 1255-1267. doi: 10.12090/j.issn.1006-6616.2025081

Abstract (82) HTML (21) PDF (3138KB)(20)

Fine geomechanics modeling and in-situ stress simulation around the well

XIONG Chenhao, LIU Xiaojing, ZHOU Jianghui, CHEN Qi

2025, 31(6): 1268-1281. doi: 10.12090/j.issn.1006-6616.2025097

Abstract (46) HTML (10) PDF (6679KB)(10)

A method for determining characteristic pressure parameters during hydraulic fracturing based on linearized fitting

XIAO Haifan, WU Ningyu, GAO Guiyun, LIU Jikun, YANG Xinshuai, HUANG Xiaopan

2025, 31(6): 1282-1295. doi: 10.12090/j.issn.1006-6616.2025091

Abstract (110) HTML (26) PDF (1311KB)(26)

Mechanical properties of Carboniferous volcanic rock reservoirs and correction of dynamic and static parameters

LYU Bei, CHENG Leiming, ZHANG Yufei, LUO Yao, LI Mengjie, FU Junwang, LI Jinquan, LI Shiyuan

2025, 31(6): 1296-1309. doi: 10.12090/j.issn.1006-6616.2025102

Abstract (55) HTML (17) PDF (3814KB)(12)

Numerical simulation of deformation and stress processes in fault–bend folding: Quantitative constraints based on elastoplastic parameter control

MA Jia, WANG Xiaochen, HE Dengfa, ZHANG Weikang, LU Guo, HUANG Hanyu, LIU Chiyue

2025, 31(6): 1310-1329. doi: 10.12090/j.issn.1006-6616.2025093

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2025, 31(6): 1330-1333. doi: 10.12090/j.issn.1006-6616.2025159

Abstract (49) HTML (14) PDF (811KB)(10)

2025, 31(6): 1334-1334. doi: 10.12090/jissn.1006-6616.20253103

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Contents of Vol. 31

2025, (6): 1-4.

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Inside Front Cover

Key Topic Selection Guide for Journal of Geomechanics in 2026

2025, 31(6).

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Inside Back Cover

Subscription Notice for 2026

2025, 31(6).

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ZHU Shu, ZHANG Quan, WANG Yanbing, LI Jin, LI Renjie, HUANG Yong, LI Benliang, LIU Fucai, YAN Yuping

doi: 10.12090/j.issn.1006-6616.2025170

[Abstract](40) [PDF 2408KB](12)

Abstract:
The Jiali Fault on the southeastern margin of the Tibetan Plateau is a key boundary structure for the southeastward extrusion of plateau material. Its geometric distribution and activity are crucial for understanding the tectonic evolution of the plateau and assessing regional engineering risks. However, the precise spatial location and Holocene activity of its southeastern segment (Guxiang to Gongrigabu section) have long been controversial due to rugged terrain and thick vegetation cover. Targeting this key contentious segment, this study integrated multiple methods, including high-resolution remote sensing interpretation, field geological and geomorphological surveys, drilling and trenching exposure, and magnetotelluric sounding, to systematically investigate the fault's spatial distribution, structural characteristics, and activity. The results indicate that the southern branch of the Jiali Fault Zone continuously extends along a line from south of Guxiang, through Gionala, Jinzhunongba, to Langqiunongba. Tectonic geomorphic evidence such as fault troughs, sag ponds, pressure ridges, bedrock fault mirrors, and horizontal slickensides were identified via remote sensing and field investigations. Magnetotelluric data revealed clear low-resistivity fracture zones, and drilling core samples exposed significant fault-related rocks. This evidence collectively confirms the existence and distribution of the fault within this segment. Combined with regional paleoseismic studies, it is concluded that this segment has the potential for Holocene activity. The research further systematically analyzed the deep engineering effects potentially triggered by fault activity, including surrounding rock deterioration, cosismic offset, high in-situ stress, seismic motion amplification, water inrush and mud gushing, geothermal anomalies, and secondary disasters at tunnel portals. The research results not only provide key geological constraints for improving the tectonic model of the southeastern Tibetan Plateau but also offer indispensable scientific basis for the planning, seismic design, and risk prevention and control of major projects (such as the Sichuan-Tibet Railway) traversing the fault zone.

The Stress Effect of the 2025 Dingri M6.8 Earthquake on the Surrounding Area

chenchen zhang, YongGe WAN, ZhaoXuan GUAN, jiebin zhao, RunYan WANG, MingYue ZHOU

doi: 10.12090/j.issn.1006-6616.2025072

[Abstract](37) [PDF 5156KB](6)

Abstract:
In order to study the stress effect of the 2025 Dingri, Tibet M6.8 earthquake on the surrounding area, the multi-source focal mechanism solution data were collected in this study, and the central focal mechanism solution parameters were determined as follows: nodal plane I strike 184.37°, dip 47.67°, slip -78.10°; nodal plane II strikes 346.99°, dip 43.66°, slip -102.76°, which is diagnosed as a normal fault earthquake. By analyzing the relative shear stress and normal stress on the fault plane projected by the regional tectonic stress field, it is confirmed that the earthquake is the energy release under the action of regional tectonic stress, and it is preliminarily inferred that the node plane I is the seismic fault plane, and the Dengmecuo fault may be a seismogenic fault. Based on the elastic half-space model and the seismic rupture model, the characteristics of the displacement field and strain field induced by the earthquake are obtained: the horizontal displacement field presents the phenomenon of material gushing out from the east and west sides of the epicenter and a small amount of inflow from the north side. The vertical displacement field is characterized by subsidence in the north of the epicenter and uplift in the northeast. The distribution of volumetric strain and areal strain showed significant regularity. In addition, the estimated Coulomb failure stress increases on the southern segment of the Shenza-Dingjie Fault and the eastern segment of the Lazi-Qiongdoujiang Fault exceeds the triggering threshold of 0.01MPa, which warranting close attention to seismic activity on these faults. The Dengmecuo Fault exhibits the largest stress unloading, further validating its role as the seismogenic fault. The findings in this study provide a critical references for regional seismic hazard assessment.

Wu Chengjie^1,2，Zeng Huaien^1,2,3，Chen Jun⁴，FengYu⁵ , Li xi^2,3，WeiPengcheng^2,3,Yan Baorui^1,2

chengjie wu, HuaiEn CENG, jun chen, Yu FENG, xi li, pengcheng wei, baorui yan

doi: 10.12090/j.issn.1006-6616.2025077

[Abstract](106) [PDF 1363KB](2)

Abstract:
Accurate prediction of landslide displacement is a crucial component of landslide early warning systems. This paper proposes a landslide displacement prediction model based on Gaussian Process Regression (GPR) combined with diverse time-series feature engineering, achieving high-precision displacement prediction and uncertainty quantification. TAKING THE BAZIMEN LANDSLIDE AS AN EXAMPLE, During the feature engineering phase, displacement lag features, rolling mean of rainfall, rolling variance of reservoir water level, and displacement change rate are constructed. Additionally, temporal decomposition features including monthly and quarterly components are extracted. SUBSEQUENTLY, EMPLOY THREE-FOLD TIME SERIES CROSS-VALIDATION, ALONG WITH A GRID SEARCH SCHEME, TO OPTIMIZE HYPERPARAMETERS IN CONJUNCTION WITH THE TIME SERIES CROSS-VALIDATION STRATEGY, THEREBY MITIGATING THE RISK OF OVERFITTING IN THE SMALL-SAMPLE SCENARIO. The results demonstrate that after incorporating multi-source temporal features, the prediction coefficients of determination (R²) for monitoring points ZG110 and ZG111 at the Bazimen Landslide significantly increase to above 0.99. Metrics such as MAE, RMSE, and MAPE are substantially reduced, indicating a significant improvement in prediction accuracy. This study integrates probabilistic modeling with feature interpretability analysis. The proposed method achieves high-precision landslide displacement prediction in small-sample environments while simultaneously quantifying prediction uncertainty. It provides effective decision support for landslide risk early warning and engineering safety assessment.

Study on disaster-prone geological structure and instability mode of typical goaf landslide in Southwest mountainous area

HaoXiang ZHANG, SaiNan ZHU, LeiHua YAO, Feng GAO, LiMei ZHANG, Long YANG, WeiJia TAN, XuSheng DAI, Yu GAO

doi: 10.12090/j.issn.1006-6616.2025047

[Abstract](94) [PDF 2775KB](11)

Abstract:
Abstract: [Objective] Landslides occur frequently in the goaf areas of the mountainous regions in southwest China. The purpose of this study is to explore the commonalities and differences among such landslides, so as to formulate scientific disaster prevention and mitigation countermeasures. [Methods] This article takes the Jiguanling landslide in the limestone area, the Zhaojiagou landslide in the clastic rock area and the Shanyang landslide in the metamorphic rock area as the research objects for a comparative study. It adopts methods such as data collection and analysis, on-site investigation, multi-phase remote sensing interpretation, physical and mechanical tests of rock and soil masses and numerical simulation to analyze the similarities and differences in the disaster-prone geological structure and instability mechanism of the research objects.[Results] The research results show that when the slope has features such as steep terrain, good open-air conditions and binary structure, landslide disasters are prone to occur. The numerical simulation results indicate that under the goaf condition, the displacement of each landslide increases, the maximum shear strain increment is concentrated in the potential sliding surface and the roof area of the goaf, and the overall stability of each landslide decreases. [Conclusion] The limestone mountainous area is characterized by thick layers of hard rock interbedded with thin layers of soft rock, presenting high-intensity rock mass characteristics. The Jiguanling landslide belongs to the toppling - sliding failure mode type. The clastic rock mountainous area is affected by the interbedded structure of thin-layer fragmented soft and hard rocks, and the overall strength of the rock mass is weakened. The Zhaojiagou landslide belongs to the type of creep - tensile fracture failure mode. The metamorphic rock mountainous area presents a structure of hard rock at the top and soft rock at the bottom, with significant differences in strength. The Shanyang landslide belongs to the type of slipping-collapse failure mode. [Significance] This article provides an important scientific basis for the early identification and disaster formation pattern research of landslides in goaf areas.

Tectonic stress field characteristics in Wushi , Xinjiang and the stress impact of the Wushi M7.1 earthquake

ZeYao SONG, YongGe WAN, PeiYuan GU, MingYue ZHOU

doi: 10.12090/j.issn.1006-6616.2025085

[Abstract](144) [PDF 2767KB](20)

Abstract:
[Objective] The Wushi region in Xinjiang is located at the intersection of multiple tectonic units, making it a key area for stress concentration and release. Although previous studies have revealed some characteristics of the tectonic stress field in this region, there is still a lack of in-depth and systematic analysis regarding the potential impact of the 23 January 2024 Wushi M 7.1 earthquake on the regional stress field. Therefore, adopt more systematic focal mechanism data to conduct a detailed analysis of the regional tectonic stress field characteristics and to explore the influence of the Wushi M 7.1 earthquake on the regional stress field. The aim is to provide more comprehensive scientific references for understanding the regional seismogenic environment and predicting future seismic activity.[Methods] Using the damped stress tensor inversion method and incorporating data from multiple institutions, we analyzed the stress field in different subregions of the study area and compared the changes in the tectonic stress field before and after the earthquake.[Results] The results of the stress field inversion show that, except for the area near the Jiashi seismic group, the R value is greater than 0.5, and the azimuth of the maximum principal compressive stress in the Wushi region gradually rotates from approximately NNW in the south to near N—S in the north, the azimuth is from 168.75° to 183.45°, and plunge angle is from 6.85° to 19.58°, it is in a compressive stress state. The Jiashi seismic area cluster shows a strike-slip feature of NNE—SSW compression and NWW—SEE extension.The northern area of the Jiashi seismic shows a thrust stress state, while the southern area presents a strike-slip stress state. By comparing and analyzing the regional stress field changes before and after the Wushi earthquake, it is found that the optimal principal compressive stress direction before the earthquake was N—S direction, and deviated by 12.53° in azimuth after the earthquake, with a spatial rotation angle of 15.06°. This indicates that this earthquake had a relatively small impact on the stress field of this area, which meaning that the stress field did not undergo significant changes after the earthquake, and still remains in the compressive stress system. [Conclusion] The tectonic stress field in the Wushi region is subject to N—S compression from the collision of the Indian plate with the Eurasian plate on the western margin of the Tibetan Plateau to form a strong near-north-south horizontal compression, and the stress from the plate collision is transmitted to the northeast to the Tian Shan orogenic belt, which leads to the shortening of the crust and retrograde thrusting between the Tarim Basin and the Tian Shan. The Wushi M 7.1 earthquake had a relatively minor impact on the regional stress field. The stress system of the entire area is still controlled by deep tectonic activities. The overall stress field is consistent, but the seismic cluster in northern Jiashi is located at the junction of the northern margin of the Tarim Plate and the Tianshan Mountains, presenting a thrust stress mechanism. This area is the plate tectonic transition boundary between the Tarim Basin and the Tianshan orogenic belt.[Significance] By analyzing the characteristics of the tectonic stress field in the Wushi region of Xinjiang and the impact of the Wushi M 7.1 earthquake on the regional stress field, the characteristics of the stress field and the effect of earthquakes on the regional stress field. This contributes to a deeper understanding of the tectonic relationship between the Tianshan orogenic belt and the Tarim Basin. In addition, the northern part of the Jiashi seismic exhibits a thrust stress mechanism, which is inferred to represent a tectonic transition boundary between the Tarim Basin and the Tianshan orogenic belt. This finding holds significant implications for regional tectonic segmentation and seismic hazard assessment.

Analysis of structural surface stability in the Panlong lead-zinc mine and engineering implications

HUANG XiaoPan, WANG ChengHu, YANG ChengWei, LIU JiKun, XIAO HaiFan

doi: 10.12090/j.issn.1006-6616.2025083

[Abstract](142) [PDF 2246KB](17)

Abstract:
[Objective] The Panlong lead-zinc deposit, an important polymetallic deposit in the central Guangxi region. The increasing depth brings challenges related to high in-situ stress and structurally complex rock masses. Instabilities along structural planes have become a major geotechnical hazard. However, current understanding of the interplay between fracture geometries and stress fields remains limited. This study aims to evaluate the stability of structural surfaces at depth and their implications for safe mine development. [Methods] High-resolution data on fracture orientation and spacing were obtained through ultrasonic borehole television imaging in boreholes SK1 and SK2. Hydraulic fracturing tests were used to determine the magnitude and orientation of in-situ stresses. Stress tensor transformation and the Coulomb friction criterion were applied to estimate shear and normal stresses on structural planes and assess their slip tendency under current stress conditions. [Results] The rock mass in the Panlong mine contains steeply dipping structural planes predominantly oriented NW–NNW and NE–NEE. Cluster analysis revealed three dominant fracture sets, reflecting tectonic control from nearby faults. Furthermore, in-situ stress measurements between 500～850 m depth show S_H = 28.29～44.69 MPa, S_h = 19.46～27.09 MPa, and S_v = 14.50～22.68 MPa. The lateral stress coefficients k_H and k_h average 2.07 and 1.28, respectively, indicating a horizontal compressive regime with S_H oriented NW–NNW. Analysis of borehole breakouts and drilling-induced fractures supports the NW–NNW orientation of maximum horizontal stress. Subsequently, a total of 2,948 structural planes were analyzed. Slip tendency evaluation based on slip tendency (T_s = 0.2～0.4) shows that fractures with T_s > 0.20 are primarily distributed at depths less than 550 m. Steeper fracture planes (40°～75°) exhibit a high slip potential, indicating a higher likelihood of shear slip. NW–NNW-oriented planes exhibit both high density and high slip potential, especially when fracture aperture exceeds 10 mm. [Conclusion] It is found that the structural planes in the Panlong mine are characterized by steep dips and strong orientation clustering, primarily NW–NNW and NE–NEE, reflecting significant tectonic control. The in-situ stress regime is governed by horizontal compression, which favors the activation of reverse faults. This aligns with observed fracture development and supports the role of tectonic faults in stress field evolution. NW–NNW-oriented fractures, particularly those with low slip tendency and wide apertures, pose the highest risk for shear reactivation under current conditions and require targeted monitoring and support. Furthermore, structural planes in shallow zones (<550 m) present higher slip potential than deeper zones, emphasizing the need for depth-specific design strategies. [Significance] The findings provide a detailed understanding of structural plane behavior under deep mining conditions and provides scientific support for roadway layout optimization, support system design, and hazard mitigation.

Tectonic evolution of the Sumatran Fault: synthesis and perspective

GUO Lin, CHU Yang, LIN Wei, LEI YiYang, LIU TanJie, GUO YiLin, MENG LingTong

doi: 10.12090/j.issn.1006-6616.2025067

[Abstract](231) [PDF 3242KB](27)

Abstract:
Abstract: [Objective]Oblique convergence between the Indo-Australian Plate and the Eurasian Plate produced a ~1,900-km-long dextral strike-slip fault—the Sumatran Fault—within the overriding plate. While previous studies have extensively examined its geometry, kinematics, and seismicity, the tectonic evolution of the fault remains poorly constrained. [Methods] This study integrates multidisciplinary evidence from structural geology, geomorphology, seismicity analysis, geodesy (GPS), low-temperature thermochronology (apatite/zircon (U-Th)/He dating), and volcanic distribution mapping. We systematically synthesize data on fault segmentation, slip rates, cumulative displacement, magmatic-tectonic relationships, and regional geodynamic models to evaluate the fault’s spatiotemporal evolution. [Results] The Sumatran Fault is a highly segmented dextral strike-slip system, currently can be divided into 19 segments by geometric complexities and seismic activities. Slip rates along the fault are relatively uniform from south to north, with an average rate around ~15 mm/yr, and a total cumulative displacement estimated at approximately 20–25 km. Regionally, the distribution of active arc magmatism closely aligns with the trace of the fault, indicating a dynamic interaction between faulting and magmatism: while magma-induced crustal weakening facilitates fault development, extensional zones associated with normal faulting in turn influence the volcanic activity. Despite its tectonic significance, low-temperature thermochronological studies on the Sumatran Fault remain limited. Existing thermochronological data reveal a period of rapid uplift at ~2 Ma, likely driven by dip-slip motion along the fault. [Conclusion] A three-stage model is proposed. From an earlier period up to 2 Ma, oblique convergence accommodated primarily by the forearc faults (e.g., Mentawai Fault) and shear zones. Around 2 Ma, the Sumatran Fault initiated, coevally with the Mentawai Fault, manifesting strain localization in the overriding plate. At present, the Sumatran Fault accommodates the majority of the strain, while strike-slip motion on the Mentawai Fault has significantly diminished. The uplift phase correlates with the initial timing of the Sumatran Fault inferred from present-day slip rates and cumulative offsets, suggesting that the current throughgoing structure of the fault and the modern tectonic framework were established at the same time. [Significance] To better understand the dynamics of large strike-slip faults at obliquely convergent margins, comprehensive geochronological and structural investigations—particularly focused on fault segmentation and deformation timing—are essential. It helps to provide a paradigm for understanding strain partitioning and the genesis of trench-parallel strike-slip faults at oblique convergent margins globally, with implications for seismic hazard assessment and plate boundary reorganization.

Analysis on the three-dimensional in-situ stress state and underground cavern stability of a pumped storage hydropower project area in Xinjiang Uygur Autonomous Region

xiaofei zhang, JiMing WANG, Peng ZHANG, ZhengZheng LI, changhu li, JiangQuan OUYANG

doi: 10.12090/j.issn.1006-6616.2025076

[Abstract](154) [PDF 1517KB](18)

Abstract:
[Objective] In order to investigate the characteristics of the in-situ stress field and the stability of surrounding rock in underground caverns of a large-scale, deeply buried pumped storage power station on the southern margin of the Tianshan Orogenic Belt in Xinjiang, and to ensure the geological safety of the underground powerhouse and water diversion tunnels. [Methods] This study conducted the following work: First, two sets of three-dimensional hydraulic fracturing stress measurements were carried out in the underground powerhouse to obtain fundamental data on the in-situ stress field. Subsequently, a 3D geological model of the project area was established, and the 3D in-situ stress field was inverted using finite element numerical simulation. Finally, based on the distribution characteristics of the 3D stress field, the stability of the underground caverns was evaluated from two aspects: the rationality of the cavern axis layout and the risk of rockburst in the surrounding rock of the underground powerhouse and water diversion tunnels. [Results] The results indicate: (1)The 3D in-situ stress measurements in the underground powerhouse reveal that the maximum principal stress (σ1) ranges from 16.19 to 16.23 MPa, oriented N43.98°E–N54.44°E with a dip angle of -4.81° to 6.93°; the intermediate principal stress (σ2) ranges from 9.82 to 12.23 MPa, oriented approximately SE with a dip angle of -18.89° to -14.52°; and the minimum principal stress (σ3) ranges from 6.90 to 10.41 MPa, exhibiting a near-vertical orientation. (2)The 3D stress field inversion shows that the maximum principal stress (σ1) in the underground powerhouse ranges from 16.54 to 17.21 MPa, with an azimuth of N47.88°E–N56.32°E, while along the axis of the water diversion tunnel, σ1 ranges from 14.86 to 24.32 MPa. [Conclusion] The angles between the axes of the underground powerhouse and water diversion tunnels and the measured maximum horizontal principal stress (S_H) deviate by ≤10°from the optimal angle (62.84°) for an SHV-type stress field, which is favorable for cavern stability. Based on multiple criteria, including the rock strength-stress ratio method and Tao Zhenyu’s criterion, the surrounding rock of the underground powerhouse and water diversion tunnels is generally classified as having a slight rockburst risk. [Significance] The findings provide a scientific basis for the design and construction of the underground powerhouse and water diversion tunnels of this pumped storage power station, while also supplementing the lack of 3D in-situ stress measurement data on the southern margin of the Tianshan Orogenic Belt in Xinjiang.

NUMERICAL SIMULATION OF THE INFLUENCE OF NORMAL STRESS ON STRIKE-SLIP FAULT SUB-INSTABILITY COORDINATION

DAI ShuHong, SUN ZhaoYang

doi: 10.12090/j.issn.1006-6616.2025022

[Abstract](203) [PDF 0KB](0)

Abstract:
[Objective] In order to reveal the synergy law of strike-slip faults under different normal stresses, this study systematically investigates the instability process of strike-slip faults through numerical simulation methods. [Methods] By using the numerical simulation method, based on the FLAC3D software and the frictional-hardening and frictional-softening model, a numerical model of strip-slip fault (elastic modulus 22.3 GPa, Poisson's ratio 0.25) is established. Six normal stress schemes (0.1~3.5 MPa) are set, and the loading rate is 0.5 mm/min for all. By comparing and analyzing the spatiotemporal evolution characteristics of the shear strain field of strike-slip faults under different normal stress conditions, the influence of normal stress on the evolution of the shear strain field and fault displacement is discussed. Based on the changes of the shear strain field and fault displacement, the degree of synergy is quantitatively determined. [Results] Under the same conditions, the normal strain perpendicular to the fault direction shows a decreasing trend with the increase of time steps; while the shear strain parallel to the fault direction has similar evolution patterns at different monitoring points but with different mean values. The mean value of shear strain at monitoring point 1 is negative, that at monitoring point 11 is positive, and the mean values at monitoring points 2 to 10 tend to zero, the monitoring points refer to the locations where data changes are obtained. In the sub-unstable stage, when the fault stress accumulates to the critical point, the shear strain in the weak areas within the system increases significantly first. The range of the concentrated shear strain area gradually expands and connects, eventually forming a continuous shear strain connected area. Normal stress is positively correlated with both coseismic displacement and shear strain, and the change in shear strain energy density is also positively correlated with stress. Normal stress has an important influence on the displacement in the sub-unstable stage. With the increase of normal stress, the synergy coefficient gradually decreases and the degree of synergy increases. In the sub-unstable stage, the synergy coefficient shows a significant downward trend. [Conclusion] Normal stress significantly affects the degree of coordination in the sub-instability stage of strike-slip faults by regulating the spatial distribution and release process of shear strain energy. The increase in normal stress leads to an increase in co-seismic displacement, an accumulation and enhancement of shear strain energy, and effectively improves the degree of fault coordination. The synergy coefficient can be used as a key indicator to quantify the degree of synergy before fault instability and has application value in identifying the sub-instability state of faults. [Significance] This study clarifies the positive correlation between normal stress and the degree of coordination of strike-slip faults, providing an important scientific basis for earthquake prediction and disaster prevention and mitigation.

Geochemical characteristics of late Paleozoic-Early Mesozoic volcanic rocks in Heiyingshan, Beishan orogenic belt: indication of Paleo-Asian ocean from subduction to collision

DING YiWen, SHAO ZhaoGang, CHEN YanFei, CHEN XuanHua, LI Bing, YU Wei, XU DaXing, HAN LeLe

doi: 10.12090/j.issn.1006-6616.2025017

[Abstract](207) [PDF 3841KB](10)

Abstract:
[Objective] Regarding the tectonic evolution of the Paleo-Asian Ocean in the northern part of the Beishan orogenic belt, it is generally believed that the Carboniferous-Permian is in the stage of ocean-continent evolution. However, there is much controversy among scholars about the closure time of the Paleo-Asian Ocean. The Heiyingshan area is located in the northern margin of the Beishan orogenic belt and is a key area for studying the evolution of the Paleo-Asian Ocean in the Beishan orogenic belt. The geochemical characteristics of tuff in this area are analyzed in order to reveal its tectonic evolution background and further constrain the evolution process of the Paleo-Asian Ocean in the northern Beishan orogenic belt. [Methods] The Late Carboniferous and Late Triassic volcanic tuffs exposed in Heiyingshan area were analyzed by means of petrological and geochemical methods. Through the determination of major, trace and rare earth elements, the geochemical characteristics of the volcanic tuffs were obtained. Combined with the published regional volcanic rock age and geochemical data, the petrogenesis and tectonic setting of volcanic tuff are discussed. [Results] The results show that the Late Carboniferous volcanic tuff belongs to the peraluminous calc-alkaline series, which is enriched in large ion lithophile elements (LILE) Rb, Ba, Th and U, and depleted in high field strength elements Nb, Ta, Zr, Hf and Ti. The total rare earth element ΣREE is 74.64×10^-6~142.45×10^-6, and the light and heavy rare earth fractionation is obvious (LREE/HREE=5.14~7.49, (La/Yb)_N=4.58~6.36). The chondrite-normalized rare earth distribution pattern is right-leaning, with weak negative Eu anomaly (δEu=0.35~0.66). It shows the characteristics of I-type granite. The Late Triassic volcanic tuff belongs to the peraluminous high-K calc-alkaline series, rich in silicon and alkali, poor in aluminum and magnesium, with strong negative Eu anomaly (δEu=0.02~0.22). The chondrite-normalized rare earth distribution pattern is slightly right-leaning ‘seagull type’, enriched in large ion lithophile elements such as Rb, Th and U, depleted in incompatible elements such as Ba, Nb, Zr and Ti, depleted in high field strength elements Hf and Zr, and has the characteristics of S-type granite. The Th content of the Late Carboniferous and Late Triassic rock samples in the Heiyingshan area is 7.66~32.2μg/g, with an average of 19.24μg/g, which is much higher than the average mantle abundance and closer to the crust. The Nb/Ta values of the rock samples are 8.01~12.78, with an average value of 10.36, which is much lower than the average value of 60 in the mantle and closer to the average value of 11 in the crust. In addition, the Ba/La ratios of the Late Carboniferous volcanic rocks range from 19.19 to 24.09, with an average of 21.64, slightly higher than the continental crust average of 15.63. [Conclusion] The results show that the Late Carboniferous and Late Triassic volcanic tuffs in the Heiyingshan area were formed in the subduction and collision background of the Paleo-Asian Ocean, respectively, indicating that the tectonic environment changed from the Late Carboniferous to the Late Triassic in the Hongshishan-Heiyingshan area. The volcanic magma in this area is mainly derived from partial melting of the crust, and the Late Carboniferous volcanic rocks may be mixed with a small amount of mantle-derived materials. [Significance] The geochemical characteristics of the Late Carboniferous and Late Triassic volcanic tuffs in the Heiyingshan area provide petrological evidence for the subduction-collision process of the Paleo-Asian Ocean in the Beishan orogenic belt. The results limit the time limit of the tectonic environment transformation in the Hongshishan-Heiyingshan area in the northern Beishan, which is of great significance for understanding the final closure process of the Paleo-Asian Ocean.

Composition, tectonic framework, and evolution of the Luxi Orogenic Belt in the North China Craton

DongMing WANG, JianMin HU, YuanFang ZHAO, JiYuan YAN, WangBin GONG, ZhiGang ZHANG

doi: 10.12090/j.issn.1006-6616.2025033

[Abstract](186) [PDF 5011KB](22)

Abstract:
[Objective] The growth and evolution of the early Earth’s crust is one of the hot topics in Precambrian research. The accretion and evolution of Earth’s early crust represent one of the central scientific questions in Early Precambrian research. As one of the oldest cratons in the world, the North China Craton (NCC) has undergone a complex cratonization process accompanied by crustal growth and reformation. [Methods] Petrological, geochemical, chronological, and deformation studies are summarized to reveal the tectonic evolution of the Luxi granite-greenstone belt in the eastern NCC. [Results] There exists a series of evidence indicating late Neoarchean crustal growth, including the continental arc and arc magmatic rocks represented by the Feicheng‒Tengzhou magmatic arc and the late Neoarchean volcanic rocks, the post-collisional crustal-derived magmatism represented by the Lushan‒Yishui magmatic belt, the sedimentation of back-arc basin defined by the late Neoarchean metamorphic sedimentary rocks, and the strike-slip shear deformation caused by the oblique convergence of plates. The >2.60 Ga tonalite, trondhjemite, granodiorite (TTG suite) and supracrustal rock belt exposed in the central part of the Luxi area represents an ancient microcontinent with apparent affinity to the Jiaoliao Block. [Conclusions] Therefore, the Luxi granite-greenstone belt is an accretionary orogenic belt located on the western margin of the Jiaoliao Block, namely the Luxi Orogenic Belt. The high-angle oblique arc-continent collision and the underplating of large amounts of mantle-derived magmas represent two crustal growth modes in the horizontal and vertical directions, respectively. This orogenic belt has undergone multi-stage evolution, including formation of initial oceanic crust, subduction, and intracontinental extension from the Neoarchean to the end of the Paleoproterozoic. [Significance] In the late Neoarchean, extensive crustal growth occurred around the Jiaoliao Block in the eastern NCC, which was controlled by the early plate tectonic regime characterized by hot subduction.

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Supervisor： China Geological Survey

Sponsor： Institute of Geomechanics, Chinese Academy of Geological Sciences; Geological Society of China (GSC)

Editor-in-Chief： DENG Jun

ISSN 1006-6616

CN 11-3672/P

Post Issue Number 82-124

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