The 51.4-km-long Jiaocheng ground fissure, the longest documented in China, is situated on the western flank of the Taiyuan Basin within the Fenwei Graben System. It has inflicted severe damage on buildings along its path, leading to substantial economic losses. To investigate the cracking behavior and mechanisms of masonry walls under the dynamic effects of the longest ground fissure, this study integrated extensive field surveys, statistical analysis, and numerical simulations. Based on activity intensity and destructiveness, the fissure is subdivided into three sections from north to south: the Qingxu, Jiaocheng, and Wenshui sections. This north-south disparity is attributed to combined differential fault activity and varying intensities of anthropogenic groundwater extraction. Manifesting primarily as vertical offset, horizontal extension, and shear, the fissure has severely damaged masonry walls in 69 villages, leading to widespread structural failure and the complete resettlement of several villages. These wall failures can be categorized into three dominant patterns: vertical, diagonal, and combined cracks, influenced by both the dip angle and the displacement of the ground fissure movement. Mechanically, these cracks initiate at sites of high stress concentration and propagate orthogonally to the local stress trajectories. Overall, both the intensity and pattern of damage correlate strongly with proximity to the Jiaocheng Fault. This is evidenced by decreasing damage intensity with distance, dispersion of hazard sites, and a transition in dominant crack type from diagonal to vertical. The findings advance the understanding of fissure-structure interaction, offering a scientific basis for regional risk assessment and mitigation strategies.

Driven by environmental change and intensified human activities, the global occurrence of active ground fissures has increased, posing serious geohazards. Through comprehensive field investigations and the integration of various analytical techniques, we identified a typical reactivated ground fissure in the Taiyuan Basin, providing valuable insights for regional hazard assessment and for understanding similar basins globally. This approach enabled a systematic study of the fissure's reactivation mechanism and a detailed characterization of its reactivation process. The SBAS-InSAR technique was applied to obtain ground deformation data in the area containing the reactivated fissure, specifically analyzing the differences in subsidence rates and cumulative subsidence on either side of the fissure. Furthermore, the Peridynamic (PD) method was used to simulate fracture evolution under the specific hydro-geological conditions. A “repair bond” approach was introduced to model the initiation and propagation of the ground fissure, specifically simulating fracture formation under groundwater level fluctuations. The results indicate that the initial formation of the reactivated ground fissure is governed by basement tectonic dynamics, with its location and depth correlating closely with the underlying active faults. Following a period of dormancy, reactivation is mainly caused by asymmetric groundwater extraction across the fault boundaries. Theoretical analysis further reveals that the reactivation of ground fissures is governed by several key factors: basement compressive stress, the basement tectonic framework and fault activity, asymmetric variations in groundwater levels, and continuous groundwater extraction. This study deepens the understanding of the genetic mechanisms underlying reactivated ground fissures, analyzes the associated engineering hazards, and provides a scientific basis for risk assessment and mitigation strategies regarding the reactivation of dormant fissures under similar geological conditions.

The Fenwei Basin has developed more than 600 ground fissures of different scales, with the Ground Fissures on Marginal Mountainous Region (GFMMR) in the Basin cause the most severe damage. However, there is currently limited research on the common characteristics of GFMMR, and the formation mechanisms are not yet clear. This study utilizes geological surveys, trenching, drilling, geophysical exploration, interferometric synthetic aperture radar (InSAR), and numerical simulation, found that the GFMMR develop on the hanging wall of the marginal mountainous faults, with their strikes generally consistent with these faults, and the failure pattern of these ground fissures that near the mountain is primarily shear failure, gradually transitioning to tension failure at the distal end. Profile results show clear synsedimentary fault characteristics, and these ground fissures are connected to deep-seated faults. This study reveals that the formation mechanisms of the GFMMR in the Fenwei Basin involve two aspects: fault control and hydrodynamic triggering. The extensional stress in the NW–SE direction of the Basin, combined with the counterclockwise rotation of the Ordos block, leads to the extensional creep of the marginal mountainous faults, further controlling the exposure locations and activity intensity of the GFMMR. Human overpumping of groundwater induces uneven subsidence of the stratum, forming a series of subsidence funnels on the surface, which exacerbates the rupture and expansion of ground fissures while also accelerating their exposure through water erosion caused by rainfall. This study has essential reference value for disaster prevention and reduction of ground fissures in the Fenwei Basin.

Due to the significant decrease in strength of loess after encountering water, loess landslides induced by rainfall are very catastrophic and widely distributed in the Chinese Loess Plateau. On September 17, 2011, a catastrophic loess landslide induced by rainfall occurred in Baqiao district, Xi'an, Shaanxi Province, China, resulting in 32 casualties and bringing great fear to the local residents. This landslide event was characterized by three individual landslides. Field investigations, geological exploration and model experiments were conducted to reveal its initiation and movement mechanisms. The results show that 1) Multiple groups of fissures in the ring-cut adits were found at a location 3 m inward from the slope surface. The minimum opening width of these fissures is 0.5 cm, and the maximum is 4 cm. The fissures develop nearly vertically and have good extensibility and connectivity. 2) the whole process of rainfall-induced landslides can be divided into 3 stages: rainfall infiltration and weight increase; crack expansion and slope deformation; slope collapse and creep deformation. 3) The volumetric water content, pore water pressure and vertical stress variation of the soil in our model all increase first and then decrease. Specifically, these three parameters increase slowly during the pretest and stabilization periods and increase fast shortly before the landslide occurrence. The volumetric water content of the soil on the side containing joints increases faster, verifying that the joints act as preferential channels that accelerate rainwater infiltration. The results of the study provide an important scientific foundation for future research on rainfall-induced loess landslides and their deep-seated mechanisms, and fill the gaps in research related to large-scale physical modeling experiments.

Beijing is one of the Chinese cities currently affected by ground fissure, where we identified seven mapped ground fissure zones and conducted geological and geotechnical characterizations. Notably, stronger ground fissure activity exists in the Tongzhou and Gaoliying areas. These ground fissures are rapidly expanding, causing damage to roads, pipelines, and urban infrastructure. To ascertain their probable origin and physical properties, we conducted surveys, excavations, and drillings, and used various geophysical techniques. Our findings indicate that the ground fissures in Beijing typically trend northeast, with strike angles ranging from 30° to 50°, reach a maximum length of over 25 km, and affect an area up to 160 m wide. Most of the fissures were aligned with the underlying active faults, and as the depth increased, there was a corresponding vertical displacement. Surface displacement can range from slow gradual movements to rapid shifts, leading to abrupt ground failure and severe damage in nearby urban areas. Based on our analysis, we deduced that regional tectonic movement established the geological conditions necessary for the occurrence of ground fissure zones and that fault activities played a pivotal role in their formation. However, the primary cause of the escalating physical displacement is the progressive extraction of groundwater. In summary, the origin, overall features, and extent of the fissures in Beijing were comparable to those observed in other locations worldwide. Consequently, effective mitigation measures involve avoidance or implementation of suitable engineering designs.

Since the 1950’s， 212 earth fissures have been discovered in the Wei River Basin. During a field survey in 2016， an additional 48 earth fissures were discovered in Anren area， northeast of the Wei River Basin. The characteristics and formation mechanisms of these fissures were studied through field investigations， measurements， trench excavation， and drilling. On-site investigations indicated that these earth fissures were distributed along a fault-controlled geomorphic boundary. Fissures trended at 60°–80° NE and were divided into five groups. Trenches revealed multiple secondary fissures， exposing severe soil ruptures in the shallow earth surfaces. Drilling profiles revealed that earth fissures dislocated several strata， and resembled synsedimentary faults. Seismic reflection profiles revealed buried faults beneath the earth fissures. The Anren area fissures formed in the following three stages: regional extension that initially generated multiple buried faults; seismic activity rupturing multiple strata， resulting in multiple buried fractures; and finally， erosion processes that propagated the buried fractures to the surface， forming the current earth fissures.

The East African Rift System (EARS) hosts extensive unconsolidated volcanic sediments whose unique physicochemical characteristics interact with geological structure to drive erosion and geological hazard cascades. Focusing on the Central Kenyan Rift (CKR), this study integrates geotechnical testing, sediment property analysis, and geophysical imaging to decipher the mechanisms controlling erosion evolution and associated geological hazard chains. Key findings reveal: (1) Four characteristic erosional landforms (sinkholes, pipes, gullies, badlands) developed in CKR volcanic sediments; (2) Volcanic sediments exhibited high vulnerability indices with >40 % macroporosity (>32 mu m), bimodal grain size distributions, and alkaline profiles with surface Na+/metal enrichment. (3) Electrical resistivity tomography (ERT) delineated the erosion-piping networks, while Shallow seismic exploration (SSE) identified the strata dislocation patterns comprising stratal fracturing, normal faulting, reverse faulting, and uplifts. (4) Synergistic coupling between sediment properties and geological structure governs erosion and potential geological hazards. This integrated study advances understanding of erosion mechanisms of volcanic sediments in rift-related geological hazard cascades, providing critical insights for infrastructure resilience and land-use planning in active tectonic settings.

Loess, a typical unsaturated soil, is a Quaternary sedimentary deposit widely distributed across arid and semi-arid regions worldwide. In recent years, global climate change has led to significant temperature fluctuations in Northwest China, impacting loess properties and soil–water characteristic curves (SWCCs). This study investigated typical loess deposits in Mizhi County, Shaanxi Province, systematically analyzing their basic physical properties and microstructure. The SWCCs of the loess were measured at three temperature gradients (15 °C, 20 °C, and 25 °C) using the dynamic dew-point isotherm method to investigate the impact of temperature on SWCC hysteresis. The results showed that with increasing temperature, the SWCC exhibited increasing divergence. The magnitude of the water content change and the corresponding suction forces along the wetting and drying paths increased, leading to an enlargement of the hysteresis loop area. These findings indicate that temperature significantly affects the hysteresis behavior of loess, providing a certain basis and ideas for the study of the soil–water characteristic curves of unsaturated soils such as loess under the influence of temperature.

The Baota District of Yan’an City, located in the Loess Plateau, is an important patriotic education base in China. The region’s fragile geological environment and frequent geological disasters pose significant threats to the production and livelihood of residents. Establishing a landslide traces inventory can provide crucial assistance for studying regional land disaster distribution patterns and implementing disaster prevention and mitigation measures. However, the Baota District has not yet established a comprehensive and detailed landslide traces inventory, resulting in a lack of clear understanding and comprehensive knowledge regarding the threats and impacts of landslide disasters in the area. Therefore, this study employed high-resolution satellite images, applying a human–computer interactive visual interpretation method in conjunction with field survey verifications, to develop the most detailed and comprehensive landslide traces inventory for the Baota District to date. The results indicate that within the 3556 km2 area of the Baota District, there are 73,324 landslide traces, with an average landslide density of 20.62 km-2 and a total landslide area of 769.12 km2, accounting for 21.63% of the total land area. These landslides are relatively evenly distributed throughout the district, with a higher concentration in the east compared to the west. Most of the landslides are small in size. This study can support disaster prevention and mitigation efforts in the Baota District and serve as a reference for establishing landslide inventories in other regions of the Loess Plateau.

The development of earth fissures in a certain area often has certain genetic correlations, which is called ‘group-developing phenomenon’ of earth fissures. So far, 41 earth fissures have developed in the Beijing area in the North China Plain. Surveys and exploration studies have shown that these earth fissures have a good correspondence relationship with the activities of the adjacent control faults. Accordingly, they can be divided into 9 zones. The mechanical analysis of these fissures groups reveals that they are roughly formed through 3 models, namely, ‘contemporaneous model’ (dip-slipping movement), ‘secondary model’ (strike-slipping movement) and ‘companion model’ (basin extension movement). The characteristics of this type (fault-controlled) earth fissures in combination with their distribution regularities in the area can be used to indicate that the distribution of subsurface tectonic stress fields is as a whole an extension of the NW-SE-trending, which is not completely consistent with the near E-W-trending extension of deep material migration. These analyses show that under the background of extensional deformation of the basin, the subsurface stress field characteristics of superficial formations are more complex, which not only embodies the movement form (unity) of the deep structure in whole, but also partially reflects the adjustability of the regional tectonic stress field.

Since the mid to late 20th century, several regions in Northern China have had to contend with ground fissure disasters, with the FenWei basin and North China Plain being clear examples. The Jiaocheng ground fissure, which spans a total of 48 km in the FenWei basin, has caused severe damage to infrastructure along its path. In recent years, the local activity of the Jiaocheng ground fissure has worsened. Field investigations, mapping, trenching, geophysical surveys and other methods have been used to determine the origin mechanism and current activity characteristics of the Jiaocheng fissure. The Jiaocheng ground fissure has a general orientation stretching 48 km in the NE-NEE direction, inclining towards the SE. The Jiaocheng ground fissure involves horizontal tension and vertical dislocation, with segmented activity on the surface, with the most intense activity observed in the northern Qingxu section. In profile, it displays characteristics of synsedimentary faults and primary-secondary fissure combinations. The activity of the Jiaocheng fault underlies the occurrence of the Jiaocheng ground fissure. Over-extraction of groundwater has exacerbated the fissure activity. Recently, the Jiaocheng ground fissure has displayed localized intensification and the emergence of new fissures stretching towards the north. This has been linked to heightened tectonic activity in the northern region of the Taiyuan basin.

黄土滑坡和降雨关系尤为密切.为深入研究降雨入渗对滑坡的促发作用,在对陕西西安地区"9·17"灞桥滑坡现场勘察的基础上,利用数值模拟方法系统研究了黄土边坡在降雨入渗条件下土体相关物理力学指标的变化响应特征及时空分布规律;从滑动面安全系数变化的角度分析了边坡的失稳过程,并揭示了该类滑坡的启动机制.结果表明:①降雨入渗首先引起坡面土体的基质吸力逐渐降低,而且不同分布位置的降幅不同;②滑坡启动前,坡体的高体积含水量范围随降雨明显扩大,且体积含水量表现出从古土壤层向邻近黄土层递减的规律;③边坡的水平方向位移自坡面中部向坡体的上下部呈放射状递减特征,垂直方向位移由上至下逐渐减小,而临界滑动面的安全系数也随降雨入渗过程逐步递减;④节理处土体的孔隙水压力和体积含水量的变化响应时间及幅度都早于且强于坡体其他区域,坡体内最大剪应变的区域分布与坡面基本平行,模拟结果与原型滑坡一致;⑤基于黄土独特的水敏性、地质构造和人类工程活动等诱因的影响,加上节理裂隙为水的入渗和运移提供了优势通道,降雨加速了黄土潜蚀和坡体结构破坏过程,改变了边坡内部应力场、位移场和水文地质条件,进而促发了滑坡.

The Fenwei Basin, which has 612 developed ground fissures, is the most concentrated and severe area in China and even the world for ground fissure hazards. The Jiaocheng ground fissure in the Taiyuan Basin is known for being the longest length and causing the most damage and impact in China. To discover the origin of the Jiaocheng ground fissure, surveying, trenching, and geophysical exploration were used to study its geological basis, developmental characteristics, and genetic processes. With a total length of 46 km and an impact bandwidth of 80–120 m, it is one of the longest ground fissures found in the world. The fissure is located on the hanging wall of the Jiaocheng fault, and the NE strike is quite consistent with this fault. Houses, roads, fields, and other structures have all been damaged to varying degrees by the fissure. The most common movements are vertical slip, horizontal tension, and right-lateral slide. According to trenching and shallow seismic profiling, this fissure has synsedimentary features. The Jiaocheng ground fissure was formed due to the interaction of several forces. First, the Jiaocheng fault shifted because of regional extension, creating a rupture system in the surface strata. Pumping activity contributed to the formation of the current ground fissure. This research has significant implications for understanding fissure mechanics and preventing and mitigating ground fissures.

The active characteristics and genetic mechanism of coupled ground fissures mainly induced by fault activities and pumping are studied, and the Songzhuang Town in Tongzhou District of Beijing is taken as the research archetype. The damage of surface planes and stratigraphic profiles caused by ground fissure activities are clarified through field investigation, and the variation characteristics of the displacement field and stress field of the strata caused by different dislocation amounts and groundwater level drop are revealed. The response processes of the model stratum under the two conditions of fault misalignment and groundwater extraction are simulated and studied respectively by using the finite difference method. Finally, the relationship between this type of ground fissure and the main inducing factors is discussed. The results show that（1） the ground fissure is characterized by three-dimensional activities, which causes the vertical tension of the shallow stratum and wall to be 0.3-1.2 cm,and the vertical dislocation of the deep stratum gradually increases with the burial depth.（2） Stress changes caused by fracture activities are concentrated in the ground fissure development area and lead to significant vertical displacements in the hanging wall, the stratum located in the ground fissure area has large shear and traction deformation, and the vertical displacement difference between the two sides is the largest. The gradual increase of fault dislocations causes the hidden fractures to extend upward, and cause secondary cracks on the shallow surface of the hanging wall, resulting in the overall distribution of ground fissures with a certain width.（3） The vertical extension and horizontal expansion of ground fissures are aggravated by the lowering of groundwater levels, and the surface on both sides of the crack produces continuous settlement response, making the center of the subsidence funnel become a concentrated development area of ground fissures, with the maximum settlement of 10.2 cm in the model stratum at the fissure in its central area, and the settlement range of about 38 m in the hanging wall and about 16 m in the foot wall.（4） This type of ground fissures is obviously controlled by faults, but the increased activity in this period is mainly due to groundwater over-exploitation. This work will be of great theoretical and practical significance to understand ground fissure mechanism, establish quantitative relationship between formation and fault with groundwater, and prevent and reduce disasters.

The Yangjiazhuang-Maguduo ground fissure, which is in front of the Luoyun Mountain on the western margin of the Linfen Basin, is a typical ground fissure that developed in the transition zone between the basin and mountain. In this paper, the developmental characteristics and mechanisms of the ground fissure in the transition zone between the basin and mountain under the action of fault activity and pumping were studied and analyzed through ground investigation, engineering geological mapping, trenching and geophysical exploration. The investigation and research confirmed that the strike of the ground fissure is parallel to the Luoyun Mountain piedmont fault and the ground surface has both horizontal extension and vertical offset. Trench result shows that the plane of the superficial part of the ground fissure is rough, which is typical tensile failure; the plane of the ground fissure under the bottom of the trench is smooth and mainly displaying shear deformation, and meanwhile the vertical offset of the stratum increases with depth showing synsedimentary structural characteristics. Shallow geophysical results reveal that the ground fissure is a manifestation of the Luoyun Mountain piedmont fault. Research suggests that deep tectonic activity caused pre-existing faults in the Luoyun Mountain piedmont to be in a continuous tensile shear state, which enhanced their activity and caused the pre-existing faults to extend to the surface, forming the ground fissure in the hanging wall of the fault. Continuous groundwater overexploitation led to the consolidation and settlement of the hanging wall of the Luoyun Mountain piedmont fault, which increased the differential settlement on both sides of the Luoyun Mountain piedmont fault, thus intensifying the movement speed of the Yangjiazhuang-Maguduo ground fissure and forming the present ground fissure. The development characteristics and formation mechanism of the Yangjiazhuang-Maguduo ground fissure provide not only an important reference for studying ground fissures in basin-mountain transition zones, but also guidance for the prevention and mitigation of such geological disasters.

The Weihe Basin is part of the regionally extensive Fenwei Graben System, which is a major tectonic block impacted by active tectonics and human activities. There are 200 tectonic ground fissures in the Weihe Basin, some of which have resulted in loss of life and severe damage to infrastructure. The development characteristics and dynamic mechanisms of these fissures were investigated by surveying, mapping, and geological drilling. The fissures are distributed along the boundary faults between fault blocks with prominent regional, zoning, and directional characteristics. On the profiles of fissures, the tectonic ground fissures are connected with underlying faults and possess the characteristics of synsedimentary faults. The deeper the stratum is, the greater the fault displacement of the stratum is, and the greater the thickness of the strata on the hanging walls is than that on the heading walls. These fissures are driven by dynamic tectonic processes, including uplift of the upper mantle and extension of the crust, differential movement of the fault blocks, and fault activity. The extension and opening of fissures are accelerated by hydrodynamic progresses, including pumping and raining. This paper describes a study of the mechanisms of the fissures and provides guidance for prevention of disasters and reduction of disaster severity in this area.

Earth fissure is one of main geological hazards in China. By 2015, 5002 earth fissures were discovered in more than 1, 500 localities across 22 provinces. These earth fissures caused huge economic loss. Based on a series of geological investigations including in surveying, mapping, trenching, drilling and monitoring, the spatial distribution and development rules of the earth fissures are summarized, and the movement characteristic of the earth fissures are revealed. The results show that the earth fissures mainly distribute in North China and South China, especially in the Fenwei Basin, Hebei Plain and Yangtze River Delta. The giant earth fissures, longer than 1 km, mainly distribute in the Fenwei Basin and Hebei Plain. These earth fissures exhibit the following five regular patterns: clustering along fault zones, distributing along geomorphic boundaries, appearing on the edge of subsidence areas, dispersing in loess collapsible area, and centralizing in larger and medium cities. The movement characteristics of the earth fissures can be divided into four types: tension type, tension-shear type, shear-tension type and shear type.

The shear behavior of loess is closely related to its microstructural variation. Their relationship is of great significance to better understand the loess landslide mechanism. Consolidated-undrained triaxial tests were performed on natural loess from Yan' an, China, with various initial water contents under different confining pressures to investigate the shear behavior. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests were conducted on the specimens before and after the triaxial tests to study the variations in microstructure and pore characteristics and their relationship with the shear behavior. The triaxial tests revealed three different failure modes (shearing, homogeneous and plastic failure) and the corresponding stress-strain response of specimens depending on confining pressure level and initial water content. The cohesion decreases exponentially with increasing initial water content whereas the internal friction angle decreases slightly. This effect is closely related to the weakening effect of water on the inter-particle cementation and water-air interface in loess. The macroscopic shear behavior of loess is essentially the result of the continuous adjustment and change in its microstructure system under loading and wetting. This variation process is related to the confining pressure, initial water content and failure mode of the specimen. This condition is manifested by the softening, dispersion, disintegration and reassembly of cementations, particle movement and rearrangement, the reduction and mutual transformation of the inter-aggregate pore populations larger than 0.05 mu m in diameter (macmpores and abundant mesopores decrease, small pores increase), and the generation and development of cracks under certain conditions.