Desiccation micro-cracks in unsaturated soils play a crucial role in understanding their hydro-mechanical behavior, as well as the initiation and evolution of desiccation macro-cracks. Previous studies on soil desiccation micro-cracks have rarely considered the impacts of fine particle migration caused by wetting and drying (WD), despite its potentially significant role in reorganizing soil microfabric. In this study, environmental scanning electron microscope (ESEM) tests were carried out to investigate the fine particle migration in an intact loess during one WD cycle and its influences on desiccation micro-cracks. Results showed that fine particle migration driven by advancing and receding water meniscus results in clay matrix and connector assemblages in large-sized pores and between coarse particles, respectively. Furthermore, three types of desiccation micro-cracks in relation to fine particle migration were observed. Type-I and -II develop within the clay matrix and along its edge, respectively, while Type-III refers to the broken clay connector assemblages. Type-I and -III can be explained by the intrinsic heterogeneity of the clay matrix and the clay connector assemblage. In contrast, the interfacial heterogeneity between the clay matrix and coarse particles contributes to Type-II. The microscopic observations provide new insights into the formation of desiccation micro-cracks and their influences on the hydro-mechanical behavior of loess.

Loess-mudstone interfacial landslides represent a major geological hazard on China’s Loess Plateau. The existence of interfaces makes the properties of heterogeneous soil structures different from those of single homogeneous soil, and brings new disaster effects, most of which are related to water seepage. However, the microstructural controls on the stagnant water effect at the loess-mudstone interface remain insufficiently understood. To address this issue, loess-mudstone samples from Baota District, Yan'an City, China, were investigated using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and laser particle size analysis. The test results show that the loess-mudstone mainly undergoes a coupling effect of wetting collapse and swelling softening. Under water supply condition, the high initial water content of the mudstone limits its swelling capacity, resulting in an increase in microcracks at the interface during the seepage, weakening the stagnant water effect, promoting the connection with the top fractures, and ultimately triggering the loess-mudstone cut-through strata landslide. In contrast, extreme rainfall triggers a squeezing-pore clogging cycle, where the continuous swelling of the mudstone and the disintegration of aggregates block the pore throats, enhancing the stagnant water effect, and directly triggering sliding along the interface. These findings are helpful for further developing and improving the research on the mechanism of loess-mudstone landslides, and provide a scientific basis for the prevention and mitigation of such landslides.

Ground fissures in the Great Rift Valley pose significant risks to both linear infrastructure and community safety. As the most renowned intra-plate rift and the largest graben zone globally, the Great Rift Valley’s unique geological setting presents novel challenges for ground fissure research. In this study, we systematically investigate the spatiotemporal distribution, classification, and evolution of ground fissures in the central Kenyan Rift. Using an integrated approach combining field investigations, remote sensing interpretation, drone surveys, geophysical exploration and trenching, the main findings are as follows, (1) eighty-three ground fissures are primarily distributed in flat areas with sparse contour lines and gentle slopes, the frequency of these fissures has markedly increased since 1973; (2) ground fissures in the study area can be categorized into two types: nontectonic and tectonic; (3) the nontectonic fissures primarily arise from surface runoff, rutting, and drainage channels, and are all triggered by hydraulic erosion; (4) tectonic fissures developed on the hanging wall of normal faults indicate exposed secondary fault traces, while those within pyroclastic rock fracture zones stem from expansions of crustal magma chambers; (5) the ground fissures are characterized by their similarity, seasonality, variability, and repeatability, reflecting the interplay of climate change, tectonic activities, and human engineering endeavors. This comprehensive study not only enhances our grasp of ground fissure dynamics but also underscores the critical need for tailored mitigation strategies to safeguard infrastructure and human and livestock well-being in this geologically dynamic region.

Heavy metals (HMs) in soils constitutes a significant potential risk to both the local ecosystem and human health. This study selected Xi'an as a case study to systematically investigate HMs contamination, sources, and risks across various land use types within the urban-natural ecotone, and explored the influence of land use types on these factors. A total of 600 topsoil samples were collected for analysis from four primary land use types (cropland, grassland, shrubland, and forest) in the northern foothills of Qinling Mountains. Twelve heavy metal elements were assessed using ecological risk evaluation, geostatistics, positive matrix factorization (PMF), and health risk assessments (HRA). Results showed that most elements exhibited practically unpollution to moderate pollution, with Cd as the largest contaminant element. Pollution severity followed cropland > forest > grassland > shrubland. In contrast, the potential ecological risks were ordered as: shrubland > forest > grassland > cropland. The PMF model identified six major sources of heavy metals with reasonable predictive efficacy. However, their contributions differ significantly across various land use types. Probabilistic health risks fell within acceptable limits, though parent material posed the highest health risk. Multivariate statistical analyses revealed that land use types indirectly influenced HM accumulation by altering soil physicochemical properties. The findings highlight land use-driven spatial heterogeneity in HM distribution and emphasize natural geological processes as dominant risk contributors in urban-natural ecotone. The study provides critical insights for land use-specific HM pollution control strategies that balance urban development and ecosystem preservation.

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.

Due to cyclic freezing-thawing and drying-wetting, cracks are commonly encountered in loess regions and adversely affect the seepage and stability of slope engineering. However, the influences of freeze-thaw (FT) cycles on desiccation cracking of intact loess are rarely known. In this study, evaporation tests were performed on an intact loess with different water contents and subjected to various numbers of FT cycles. To interpret the desiccation cracking behavior, the microstructure of tested intact loess was determined by conducting the scanning electron microscope (SEM) tests. Results show that FT cycles further enhance the inherent loose structure of intact loess through pore expansion, pore connection and formation of continuous channel, and destroy the particle bonding contributed by fine particles and cementitious minerals. The intact loess subjected to 0 FT cycle predominately exhibit single cracks, while both single and Y-shaped cracks are observed in intact loess subjected to non-zero FT cycles. The difference in crack pattern is attributed to the enhanced loose structure owned by the latter, which forms a large number of structural defects. Furthermore, the crack ratio and the average width and total length of cracks increase with the increasing numbers of FT cycles. This can be attributed to the two effects induced by FT cycles, one is the degradation of tensile strength due to bonding breakage, and the other is the inhomogeneous shrinkage deformation due to the rapid evaporation of water in specimens with enhanced loose structure. Furthermore, the FT cycles cause more significant effects on the desiccation cracking of intact loess with higher water contents than those of intact loess with lower water contents, primarily due to the larger frost heaving forces induced in the former.

The South Jingyang Platform, China, is well-known for its continuous irrigation-induced loess landslides. Many scholars have discussed the loess landslides in this area, as the frequent occurrence of these landslides has led to a gradual reduction in the size of the platform. On the basis of these studies, this paper provides an updated summary of the distribution, evolution characteristics, and future trends of these landslides over the past 20 years. It was found that from 2003 to 2023, a total of 76 landslides occurred, mainly concentrated in three areas. In addition to forming retrogressive landslide groups, the large amount of landslide deposits at the substrate also transforms into loess mudflows, causing a disaster chain. The rapid rise of the groundwater level is the main key factor causing these flowslides, and the widely distributed joints, cracks, and caves in the slopes serve as preferential flow channels, actively contributing to the accelerated rise of the groundwater level. This further decreases the stability of the slopes and is also a significant factor promoting the occurrence of landslides. The occurrence of falls and slides is mainly due to the loosening of the slope caused by previous flowslides, which affects the soil structure and triggers the migration of the soil’s critical state. This explains why flowslides occur in the deep saturated zone, while slides and falls often occur in the shallow unsaturated zone in the study area. Since 2015, flowslides have decreased due to changes in irrigation practices and stabilized groundwater levels, confirming the close relationship between flowslide occurrence and groundwater level fluctuations.

Loess disaster chains on the Heifangtai Platform, China, cause frequent loess landslides and form landslide dams, thus obstructing rivers. In addition, the failure of landslide dams causes loess mudflows and other related disasters. In this study, the influences of different inflow rates on the failure process and triggering mechanisms of loess landslide dams were explored using five sets of model experiments. These experimental results revealed that the failure of loess landslide dams occurs through overtopping and piping failure, or overtopping failure. Overtopping and piping failure can be divided into infiltration, seepage channel development, break overflow, and rebalancing. When the inflow rate was < 1.0 L/s, the water had enough time to penetrate the dam, and the fine particles of loess were continuously transported to the backwater slope to form several complete seepage channels. The overlying soil in the channel then collapsed and slipped, which caused the dam failure. Overtopping failure can be divided into break initiation, acceleration, and rebalancing stages. When the inflow rate was > 1.0 L/s, the water could not penetrate the dam in time. Overtopping failure primarily involves horizontal and downward erosion of the breach. The inflow rate was positively correlated with soil transport, peak flow velocity, and peak bulk density based on the experimental data. The bulk density of the failure mudflow was categorized into slow increase, transition, and attenuation stages based on our experimental results. In addition, by analyzing the volume and stability of residual dams, the likelihood and damage degree of secondary hazards after the dam failure were initially explored. This study provides a scientific basis for relevant studies on loess landslide dam failure.

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.

Loess-red silty clay interface landslides are one of the most widely distributed types of loess landslide disasters in China. In this study, field investigations, numerical simulation, model tests, and microscopic tests were conducted to reveal the failure mechanism of the loess-red silty clay interface landslide that occurred on the Heifangtai Platform on 1 April 2023. The findings revealed that the landslide, which was characterised by high speed and long distance, exhibited remarkable features. It lasted 39 s, during which the maximum sliding velocity reached 14.2 m/s. The maximum thickness of the deposits resulting from the landslide was 6.94 m, and the sliding distance exceeded 250 m. A large number of cracks were distributed around the edge slope of the landslide; these served as primary pathways for infiltration. Furthermore, the difference in permeability between the loess and red silty clay led to the accumulation of water at the bottom of the loess. This increased the water content of the loess and decreased the soil strength, thereby initiating the landslide. During the seepage process, water infiltration carries many fine particles in loess, accumulating at the interface between the loess and red silty clay, causing blockages. This accelerates the gathering of water flow at the interface, contributing to decreased soil strength. In additon, the pores in the loess undergo significant changes, with large pores in the soil decreasing and small pores increasing, forming a flocculent structure. These findings provide scientific evidence for the failure mechanism of loess interface landslides.

The Dongzhi tableland suffers from land degradation due to severe gully erosion. To determine the relationship between the gullies development and the evolutionary of geohazards chains in the gullies, a small watershed of the Dongzhi tableland was chosen as the study area. Subsequently, the morphometric characteristics and development process of loess gullies were systematically examined through statistical methods, including field investigations, unmanned aerial vehicle (UAV) photogrammetry, and geographic information system (GIS) spatial analysis. Results revealed that (1) The study area comprised 914 small incised gullies (SIGs), 57 incised gullies (IGs), and 5 dry gullies (DGs) based on the length, width, and depth of loess gullies. (2) SIGs were clustered and distributed at the bottom of the loess gully or on the edge of the loess tableland, and the SIG length exhibited a good power exponential relation with elevation difference, average gradient, area, and perimeter. (3) Based on the type of gully head and the degree of surface complexity, the SIGs were further divided into 27 profile types. And the most and least common profile combinations in the upper-middle-lower profiles were flat-flat-flat in 160 locations and concave-flat-stepped in one location. The corresponding results revealed loess collapse as the most dominant form of disaster during the evolution of SIGs. (4) Overall, SIG evolution was divided into four stages: initial, development, expansion, and stabilization stages. These stages mainly evolved in the form of geohazard chains and caused development of the SIGs. The results of this study will provide a scientific basis for the selection of preventive and control measures to manage gully erosion of the Dongzhi tableland.

A total of 24 hydropower stations are planned for construction in the upper Yellow River, from the Longyangxia to the Qingtongxia section, with completion anticipated by 2050. These stations represent the densest and highest-capacity reservoirs in China and play a crucial role in the ecological preservation and water resource management of the Yellow River Basin. To assess the ecological impacts of reservoirs on the surrounding environment, we analyzed vegetation dynamics in 10 reservoir areas between 2000 and 2020 using the normalized difference vegetation index (NDVI), examined the relationship between vegetation and climatic elements using biased correlation, and quantified the impacts of climatic factors and reservoir construction on the riparian vegetation using a generalized linear model (GLM) and path analysis. The findings indicated that the rate of vegetation growth declined after reservoir construction, and the overall trend indicated greening. Climate change impacts on riparian vegetation showed significant spatial heterogeneity, and the GLM analysis identified reservoir construction as the primary contributor to riparian vegetation dynamics, with a contribution rate of >50%. Temperature and soil moisture were the main climatic factors influencing vegetation growth in the reservoir area, with a 10–20% contribution rate. Path analysis further verified that reservoir construction directly enhanced riparian vegetation growth (with an impact coefficient of 0.514) and indirectly affected vegetation by altering the microclimate. This study emphasizes the importance of reservoir construction in assessing the relationship between riparian vegetation and climatic factors and provides insights for improved ecological conservation and water resource management strategies.

The Yellow River (YR), China’s second-largest river, is rich in water resources, particularly in its upper reaches, which are characterized by mountainous canyons and considerable hydropower potential. Since the 1950s, 24 reservoirs have been constructed along a 918 km stretch of the upper Yellow River (UYR), creating the highest concentration of cascade reservoirs. This development has had significant ecological impacts on the surrounding environment. This study examines the relationship between reservoir attributes and climate factors to evaluate the environmental effects of reservoirs in the UYR. (1) Following reservoir construction, the average annual temperature and precipitation increased by 3–10%, though seasonal and spatial distributions varied. Temperature increases were most pronounced in winter, while precipitation decreased in some regions during spring and summer, although the overall trend remained positive. (2) The ecosystem experienced significant post-construction changes, including reductions in arable land, grassland, and unused land, while water bodies, construction land, and forests expanded. Consequently, the ecosystem within the reservoir area now accounts for 5.2–12.5% of the total area of the region. (3) Temperature and precipitation were closely linked to reservoir attributes, with storage volume (CAP) and long-term average flow (DIS) significantly affecting precipitation, while surface area (AREA) and normal storage level (FSL) had a greater influence on temperature. In conclusion, the dual impacts of reservoir construction on local climate and land use highlight the complex environmental mechanisms involved, providing valuable insights for future reservoir development and ecological protection in the Yellow River Basin and similar regions.

The compression curve of loess is crucial for the serviceability design of transportation lines across the Chinese Loess Plateau (CLP). Loess in the CLP exhibits a zonal particle size distribution from northwest to southeast (i.e., sandy, silty, and clayey loess zones), due to its aeolian deposition. So far, there is a lack of a unified understanding and calculation method for the compression curve of loess across the CLP that takes into account particle size distribution and sample preparation method. This shortcoming limits the efficient design of transportation lines across the CLP. In this study, a series of water content controlled 1D compression tests were conducted with sandy, silty, and clayey loess in both intact and remolded states across the CLP. Results show that the yield stress of intact loess increases with clay content at low water contents (i.e. <20 %). This is because clay particles in the intact loess form bridges between silt particles, enhancing its skeleton stability. The compression index of intact loess is higher than that of remolded loess at high water contents (i.e. >20 %), with this trend more pronounced at higher clay contents due to enhanced clay bridging structure. Based on 59 compression tests from this study and the literature, a unified calculation method for the compression curve of loess with different particle size distributions and sample preparation methods was developed through the concept of void index and capillary bonding function. Three empirical equations relating the parameters to macro-micro properties of loess were proposed. Comparisons between measured and calculated results show that the errors in void ratios are less than +/- 10 %, while the accuracy of collapsibility exceeds 80 %.

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 meso-interfaces are geologically structural surfaces visible to the naked eye (i.e., 0.1 mm to 1 m), mainly including meso-cracks and meso-pores. They disrupt the integrity of loess mass and significantly influence the failure of loess slope. However, the current understandings of the genesis, characteristic, and disaster effects of loess meso-interface are incomplete, particular in a field scale. To address this gap, an extensive field geological investigation was carried out to study the loess meso-interfaces on the Chinese Loess Plateau. Results show that the genesis of loess meso-interfaces includes geo-stress, gravity, biological activity, water, and weathering. The meso-interfaces primarily distribute within the 3.0 m depth of shallow layer on loess slopes. The single mesocracks are typically shaped as saw-tooth, needle tip, ring, and hook, while the patterns of arborescent morphology, stepped arrangement, feather-like pattern, irregular polygon, cross-cutting arrangement, and parallel lineation are exhibited by the multiple meso-cracks. The dominate width of loess meso-cracks ranges from 0.1 mm to 1 mm, and their angles mainly ranges from 60 degrees to 120 degrees, with a peak intensity around 90 degrees. The threedimensional morphologies of meso-pores are shaped as ellipsoid, flatten sphere, tube, and pore network connected by tube-like pores. The more irregular the meso-pores, the larger their volume, but the fewer their number. The loess meso-interfaces promote geological disasters in shallow layer on slopes by separating, loosening and providing seepage channels. The development of loess meso-interface is characterized by a successive initiation process, accompanied by the transformation of disaster effects. In addition, the location of loess mesointerface contributes to the different evolution modes of slope disaster.

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.

Loess–mudstone interface landslides (LMILs) are among the most frequent loess landslides in China, caused by contrasting permeability and mechanical properties between loess and mudstone. In August 2020, a large LMIL occurred in Yan’an, exhibiting creeping deformation for nearly two years, severely impacting nearby infrastructure and necessitating costly remediation. This study investigates the landslide’s evolution, material properties, triggering factors, and formation mechanisms through field surveys, boreholes, UAV photogrammetry, deformation monitoring, triaxial tests, SEM scanning, and GeoStudio simulation. Results show that the landslide underwent three distinct sliding phases, triggered by combined effects of artificial excavation, rainfall, and reservoir water level rise. The landslide measured approximately 340 m wide, 230 m long, 5–49 m thick, with a total volume of 2.65 × 10⁶ m³. Deformation exhibited clear zoning (tensile–shear–extrusion), with decreasing displacement and crack density from rear to front. Loess and mudstone strength declined significantly with increased water content, as infiltrating water dissolved soluble salts and cementing agents, reducing cohesion and internal friction. SEM analysis revealed increased pore development and microstructural damage, altering stress–strain behavior. Under high water content, mudstone showed a marked drop in elastic modulus, increased Poisson’s ratio, and transitioned from brittle to ductile failure, softening the interface and promoting instability. The formation of a softened zone at the loess–mudstone interface, due to differential permeability and hydrological disturbance, was key to development of the sliding surface and ultimate failure. These findings highlight the critical role of hydro-mechanical coupling in LMIL evolution and provide insights for early warning and mitigation.

Landslides occurring at the interface of strata are among the most common forms of loess landslides in China. Statistics indicate that significant loess-red silty clay interface landslides induced by irrigation in the Heifangtai Platform than loess-paleosol interface landslides in the South Jingyang Platform. To uncover the permeability characteristics, structural failure patterns, and triggering processes of two typical strata structures. This study employs Nuclear Magnetic Resonance (NMR) and Scanning Electron Microscopy (SEM) techniques to investigate the permeability and structural failure of two soil combination types: loess-red silty clay and loess-paleosol. The results revealed a positive correlation between the stagnant water effect and flow rate, but a negative correlation with the initial water content. Notably, these two typical strata exhibited distinct differences in the stagnant water effect. In loess-red silty clay, continuous filling of mesopores and macropores by fine clay particles, while at the same time the agglomerates disintegration at the interface, thereby enhancing the stagnant water effect. In contrast, loess-paleosol exhibited good connectivity between the mosaic pores at the interface. This facilitated the formation of several elongated microcracks, which acted as dominant channels for infiltration and weakened the stagnant water effect. However, the macroscopic triggering mechanism for loess landslides in both loess-red silty clay and loess-paleosol combination strata remains similar. Irrigation water stagnates within the relatively impermeable layers, saturating and structurally damaging the bottom of loess layer, ultimately inducing landslides. These findings provide a scientific basis for the future study of loess landslide hazards in different strata structures, which is of great significance.

The East African rift system (EARS) is the most famous continental rift valley on earth, and its ground fissure disasters have been receiving increasing attention. Kenya is located in the middle of the EARS, and its widespread ground fissures have damaged infrastructure, threatened community safety, and restricted urban and rural planning. In the study area, field mapping revealed 85 ground fissures of different scales. The morphology of ground fissures comprises mainly linear, broken lines and arcs, and their lengths range from tens of meters to several kilometers. Ground fissures can extend in all directions, with the dominant strikes being NE, NW, and NNW. Ground fissures are dominated by horizontal tension, and there are no offsets on the two opposite walls. The morphology of ground fissures on the profile is mainly linear and trumpet-like, ranging from young to old fissures. Field investigations, geophysical exploration, and geotechnical testing indicated that ground fissures in the Kenyan Rift are controlled by tectonic activity, stratigraphic lithology, and erosion. The origin and formation of ground fissures can be divided into three stages: Stage I, where tectonic activity forms rock fractures in the crust that are prototypes of ground fissures; Stage II involving formation of rainfall-controlled ceiling collapses and underground voids; and Stage III, involving expansion and connection of ceiling collapses and underground voids, and formation of ground fissures. The study of ground fissures in the Kenyan Rift fills the gaps in ground fissure research and supports local community development and safety.