Frequent seismic activity in the Yigong region of Tibet poses a serious threat to slope stability. This study investigates the Yigong rock mass using field surveys and discrete element numerical simulations to systematically reveal the critical role of repeated seismic loading in triggering the massive 2000 Yigong landslide. The results demonstrate a three-stage progressive failure mode under seismic conditions: the initial damage phase is characterized by the expansion and connection of rear-edge fractures; the stable deformation phase features accelerated development of secondary joint networks; and the final instability phase involves overall structural collapse accompanied by significant block rotation and ejection. Frequent earthquakes lead to rock mass fragmentation and strength degradation, which are identified as key factors in inducing this extremely large landslide. The findings clarify the mechanical mechanisms of progressive failure in rock slopes within high-intensity seismic zones, providing important theoretical and practical support for early identification and risk management of geological hazards in southeastern Tibet.

The southeastern Tibetan Plateau, located within the highly active Eastern Himalayan Syntaxis, experiences frequent strong earthquakes that induce significant rock mass fracturing and slope weakening. However, assessing the seismic dynamic response of slopes in this region remains challenging due to complex topography and a scarcity of in situ monitoring data. To address this, seismic stations were deployed at two high mountain slopes—Zelongnong (ZLN) and Badengze (BDZ)—to record signals from the 4.6-magnitude Medog earthquake. Combined with FLAC3D numerical simulations, this study systematically analyzes the dynamic response characteristics and failure mechanisms of these slopes under strong seismic shaking. The results demonstrate that the predominant frequency of the ZLN slope (1.63–4.89 Hz) is higher than that of BDZ (0.72–2.92 Hz), indicating a more complex internal geological structure at ZLN. Both sites exhibit significantly stronger horizontal than vertical dynamic responses. Numerical simulations reveal that under strong seismic loading, the ZLN slope fails primarily through a “tension–shear slip” mode, while the BDZ slope undergoes typical “spalling–sliding” failure. These distinct failure behaviors are attributed to differences in geological structure, topographic features, and elevation effects. This study provides new observational evidence and theoretical insights into the seismic dynamic response and disaster mechanisms of high mountain slopes in alpine gorge regions.

The “horizontal well with staged multi-cluster fracturing” technology currently serves as the primary development approach for CBM resources in Zhengzhuang Block. However，how to set fracturing parameters under different geological conditions to achieve the best development effect is still unclear. The study conducts a comprehensive analysis of key hydraulic fracturing parameters, including rock mechanics and crustal stress, within the No.3 coal seam of Zhengzhuang Block. On the basis of previous research, a hierarchical analysis method was used to construct a coal rock fracturability evaluation system that includes three factors: brittleness index, horizontal stress difference coefficient, and natural fracture development coefficient, achieving hierarchical zoning of fracturability in the Zhengzhuang block. Using the integrated numerical simulation method of geological engineering, the fracture stage spacing and cluster spacing of horizontal wells in each region were optimized based on the characteristics of fracturability zoning. Ultimately, a segmented cluster selection fracturing parameter optimization method suitable for medium and shallow high-rank CBM horizontal wells was established.Key findings indicate: For Class I zones, recommended stage spacing is 55–65 m with cluster spacing of 20–30 m；Class II zones perform optimally with 50–60 m stage spacing and 15–25 m cluster spacing；Class III zones present high fracture development risks, making them unsuitable for horizontal well development. This achievement has been promoted and applied in 5 newly put into operation hydraulic horizontal wells in the northern ZS58 well area, with a daily gas production increased from the previous 7000m3/d to 15000m3/d, achieving significant results. At the same time, it provides theoretical basis and technical support for the efficient development of medium shallow high-rank CBM horizontal wells.

In high-mountain and steep-gorge regions, traditional hydrological methods often underestimate the peak discharge of dam-break debris flows because they simplify the chain-like transformation from landslide blockage to rapid breaching. This study focuses on the Yizhong River in Deqin, Yunnan, a typical landslide-blockage-dam-break disaster chain developed in a confined V-shaped gully. By integrating a gradual-breaching calculation model with Massflow dynamic simulations, the full process was quantified under extreme rainfall scenarios with 1

Rock avalanches commonly erode and entrain loose substrate, significantly amplifying the hazard magnitude and expanding the inundation area. However, effectively simulating the runout processes while simultaneously accounting for the roles of erosion and entrainment remains a challenge. In this study, we present large-scale physical experiments on flow–substrate interaction, using a self-developed experimental apparatus. Emphasis is particularly placed on the deformation and mobilization behavior of the substrate under intensive erosive loading, which provides critical implications in developing a new erosion model. This model highlights two mechanisms. First, we incorporate the contribution of the normal stress exerted by the flow or adjacent substrate columns, which can be interpreted as a slope-parallel pressure gradient-induced longitudinal thrust acting on the substrate element. Second, the distinction between supply-unlimited and supply-limited conditions is made by identifying whether the erosion failure is distributed throughout the substrate body or localized along its base. This erosion model is then embedded into a multi-phase mass flow simulation framework, resulting in a novel approach capable of simulating the runout processes of real-world rock avalanches while explicitly accounting for the critical effects of erosion and entrainment. Finally, the proposed modeling is applied to simulate the Baige and Sedongpu rock avalanches, yielding results that closely match real observations. Further analysis reveals that erosion model-controlled entrainment spatial pattern and intensity modify the flow geometry and the rheological properties, thereby profoundly affecting flow dynamics. Our model provides a closer approximation to both experimental and field observations, particularly in capturing the dominant occurrence of substrate entrainment near the flow front.

The desert-loess transition zone, located at the interface of climate and geomorphology, is one of the most severely eroded regions on the Loess Plateau in China. Soil detachment rate (Dr), which indicates the initial stage of soil erosion, is directly influenced by vegetation restoration that alters soil properties through root traits. However, the synergistic effects of roots and soil on regulating Dr under vegetation patterns in this zone still lacks quantitative analysis. In this study, soil detachment of vegetation restoration types, including grassland, shrubland, forestland, and cropland (as a control) was clarified by flume experiments under five flow discharge rates. The results indicated that, compared with cropland, vegetation restoration significantly enhanced soil resistance to detachment, following the order: grassland > shrubland > forestland. The mean Dr of cropland was 6.15 times that of grassland. Among the hydrodynamic parameters, shear stress (τ) was the best predictor of Dr. Soil organic matter (SOM), root length density (RLD), and root mass density (RMD) were identified as key resistance factors. Their synergistic mechanisms involved RLD providing spatial network entanglement and RMD promoting biomass-driven soil aggregation, both functioning together with SOM to consolidate soil structure. When the performances of traditional nonlinear and machine learning algorithms were compared, the random forest (RF) model achieved superior predictive accuracy for Dr (NSE > 0.93).This study elucidates the synergistic mechanisms by which root–soil systems regulate Dr and provides a highly accurate RF predictive model, offering a scientific basis for vegetation restoration and the selection of soil-consolidating plants in the desert–loess transition zone.

Avalanches are complex natural hazards whose dynamics and destructive capacity vary widely with snowpack properties, terrain, and climate. This study investigates the formation characteristics, mechanisms, and dynamic responses of different avalanche types in the northern Himalayas of Tibet. Field observations, including video monitoring and snow property measurements, were conducted to characterize avalanche development and obtain key physical parameters. Based on measured snow density and cohesion, numerical simulations using the Rapid Mass Movement Simulation (RAMMS) model were performed to compare the dynamic characteristics of powder, flow, and slab avalanches. The effects of erosion entrainment and terrain conditions on avalanche dynamics and impact pressure were further evaluated. Results indicate that powder avalanches are characterized by high mobility, short movement duration, and relatively low impact pressure due to weak basal interaction and limited erosion capacity. Slab avalanches exhibit stronger destructive potential, with higher impact pressure and more pronounced erosion-induced volume amplification resulting from their dense structure. Flow avalanches show intermediate dynamic characteristics between powder and slab avalanches. The simulations further reveal that accounting for erosion processes alters avalanche motion and affects predicted velocity and impact pressure. Moreover, terrain characteristics strongly regulate avalanche impact pressure, with steep, concave, and smooth terrains promoting higher impact forces, whereas gentle, convex, and rough terrains reduce impact intensity. This study improves understanding of the dynamic mechanisms and destructive effects across avalanche types. It provides a scientific basis for avalanche risk assessment and the optimization of mitigation strategies in the northern Himalayas region of Tibet.

On July 4, 2023, a high-elevation rock avalanche-debris flow occurred in Yitougou, Changtan Town, Wanzhou District, Chongqing, threatening the lives of 408 residents. To enhance the understanding of the dynamic mechanisms governing such high-altitude rock avalanches, this study conducted a numerical simulation of the event using the smoothed particle hydrodynamics (SPH) method integrated with a modified Johnson-Cook (MJC) constitutive model within the self-developed LPF3D simulation platform. The simulation results indicate that the motion process of the avalanche-debris flow can be divided into four distinct stages: (1) weakening of the slope due to external disturbances; (2) frontal traction and initial acceleration; (3) middle-rear compression and fragmentation; and (4) energy dissipation and final deposition. Furthermore, the study reveals that the shear-induced fragmentation of the rock mass and its subsequent transformation into a debris flow are key mechanisms driving the high-speed and long-runout movement. This research not only deepens the theoretical insights into the dynamics of high-elevation rock avalanches but also provides quantitative support for hazard assessment and spatial prediction of similar events in mountainous regions.

The Sedongpu Gully in the Eastern Himalaya has experienced a sharp increase in rock–ice avalanches in recent years. Here we examine how climatic and seismic forcings jointly precondition slope disruption and trigger multi-stage hazard cascades by integrating multi-source remote sensing observations and numerical simulations. We identify at least 24 hazard-cascade events in the Sedongpu gully between November 1961 and October 2023, with a cumulative slope-material loss exceeding 700 ± 22 million m³ that repeatedly dammed the Yarlung Zangbo River. Our findings suggest that sustained glacier and snow retreat and climatic warming act as long-term destabilizing processes that progressively modify slope boundary conditions, while strong seismic shaking provides an additional disturbance to these preconditioned slopes. Furthermore, deformation analysis and numerical simulation suggest that future potential rock–ice avalanches could still generate large volumes of debris to block the river. This research establishes an integrated framework for investigating and assessing multi-stage cascading hazards in tectonically active and climate-warming mountain regions. Remote sensing data and numerical simulations suggest earthquake-induced rock-ice avalanches in the Sedongpu gully lead to cascading hazards in areas that have been destabilized by the long-term action of climatic warming and retreating glaciers

Flow regime transitions from rock-ice avalanches to debris flows remain insufficiently quantified, particularly in terms of the relative influence of internal meltwater production versus external water entrainment. On 17 October 2018, a large rock-ice avalanche-debris flow occurred in the Sedongpu gully, Southeastern Tibet, traveling over 10 km and impounding the Yarlung Tsangpo River to form a landslide-dammed lake. Here we reconstruct the evolution of this catastrophic event using field investigations and a state-of-the-art multiphase thermomechanical model, and assess how ice/snow melt and substrate entrainment influence the flow regime transition. Our results suggest that the highly saturated entrained moraine fosters the swift transition from rock-ice avalanche to water-rich debris flow, increasing its mobility and destructive potential. Water influx from the saturated substrate, which resulted from glacial meltwater and precipitation, was a more dominant driver of the flow regime transition than internal ice melt, with notable ice fragments remaining within the final deposits. Climate-driven variations in substrate moisture and composition govern the flow regime as a rock-ice granular avalanche or debris flow, highlighting the influence of seasonal and climatic changes on shaping flow behavior and ultimate runout. Recognizing this external control is crucial for anticipating rock-ice flow behaviors in future warming scenarios.

Against the backdrop of global warming, frequent seismic activity, and ongoing hydropower development in the southeastern Tibetan Plateau, the blockage and breach hazards of large-scale successive landslide dams (LSLDs) along the Yarlung Zangbo River pose significant threats to infrastructure and regional safety. Exemplified by the Sedongpu (SDP) landslide dam, this study investigates the historical evolution, damming structures, and breaching hydraulics of typical LSLDs that are characterized by ultra-long river-alignment lengths and recurrent deposition. By integrating multi-temporal remote sensing imagery, high-precision digital elevation models (DEMs), and extensive field investigations, we reveal that the SDP has experienced over 15 distinct damming events since 2001, with newly deposited volumes reaching up to 14.41 × 10⁶ m³ annually. The dam deposits comprise heterogeneous sediments with distinct water contents, forming complex accumulation architectures. We propose three successive river-blocking patterns—mixed deposition (MDP), superimposed deposition (CDP), and embedded deposition (EDP)—which illustrate how volume cumulative effects exacerbate blockage hazards. By 2025, the partially breached SDP dam extended approximately 4.3 km along the river, maintaining a reservoir capacity of 2.28 × 10⁸ m³. The breach channel exhibits distinct three-dimensional morphodynamics, characterized by an irregular sinuous planform and spatiotemporal oscillations. Two partial breach discharge modes are identified: channelized erosive flow and debris flow, which hydrodynamic characteristics and the movement mechanisms of dam materials differ significantly. These findings provide a critical geological and technical framework for assessing cascading hazards induced by LSLDs, offering essential support for hazard mitigation in the Yarlung Zangbo River basin.

The net primary productivity （NPP） of vegetation in the Qinghai section of the Yellow River Basin （YRB） showed significant spatial and temporal heterogeneity driven by climate. Based on the yearly MODIS-NPP data and month-by-month temperature， precipitation， and solar radiation data from 2001 to 2022， the temporal and spatial characteristics of vegetation NPP and its response to climatic factors in the Qinghai section of the Yellow River Basin were investigated by using the Theil-Sen slope estimation， the MK trend test， the biased correlation， and complex correlation analyses. The results showed that： ① Vegetation NPP in the study area showed a fluctuating upward trend at a rate of 2.01 g·（m2·a）-1 from 2001 to 2022. The annual average vegetation NPP was closely related to the vegetation type and showed strong vertical zonation. It was obviously driven by precipitation from 2001 to 2010， and it was driven by temperature from 2011 to 2022. ② The response of vegetation NPP to climate was more pronounced in river valleys and basins than in mountains in static terms， with a nonlinear increase （decrease） in vegetation NPP within the thresholds of temperature （-2-8.5℃）， precipitation （300-550 mm）， and solar radiation （3 350-3 700 MJ·m-2）， In dynamic terms， with different types of vegetation responding to climatic conditions with different relationships and degrees， except for alpine vegetation and thickets， vegetation in the watershed responded better to precipitation than to air temperature and radiation. Air temperature and precipitation were the main driving factors for changes in vegetation NPP in the watershed. The response mechanisms of different geomorphic zones to climate were very different， with the overall zoning pattern of "four screens， three zones， and one highland." The results of this study provide a reference basis for understanding the ecological and environmental change mechanisms in the upper Yellow River Basin.

Erosion and entrainment of substrate are pivotal in amplifying the scale of granular flows and altering their dynamic behaviors. However, the mechanisms behind erosion and entrainment remain poorly understood, with numerous conflicting interpretations. Here, a series of experiments were conducted using a large-scale apparatus, where a dry granular mass descended through a steep rigid channel, subsequently eroded and entrained substrates with varying conditions laid on a gentle plane, and finally deposited on a horizontal platform. Substrate deformation responses under erosive loading, post-entrainment runout, and deposit characteristics were captured by multi-point, multi-source monitoring devices. Two long-standing issues are emphasized: the mechanisms governing substrate erosion and entrainment, and the effects of substrate entrainment on granular-flow dynamics. The experiments reveal that substrate erosion and entrainment involve multiple dynamic processes that are spatially dependent across different erodible areas. In the proximal area, impact-induced ploughing dominates the interaction process and induces substantial energy dissipation. In the middle area, eroded substrate grains are readily entrained into the granular flow, forming a coupled basal deformation layer that enhances granular-flow runout. In contrast, entrainment in the distal area is strongly suppressed, thereafter inducing upward shear localization and intensified collisional dissipation. Furthermore, fine substrate enrichment at the granular-flow base after entrainment forms a low-friction shear-deformation layer capable of lubricating granular flow. These results indicate that the energy feedback associated with substrate erosion and entrainment is fundamentally controlled by spatially specific erosion–entrainment mechanisms and their associated rheological transitions. Our experiments provide important insights for explicitly modelling and further understanding erosive rock avalanches.

IntroductionIn mining areas of the mountainous regions of Southwestern China, the overlying strata above goafs are mostly thick bedrock with well-developed structural planes. With large-scale exploitation of mineral resources, extensive water- conducting fractured zones (WCFZs) may develop in the overlying strata, frequently inducing water inrush and high-position collapse-sliding hazards. Rapidly estimating the height of the WCFZ (HWCFZ) is therefore critical for the prevention of water hazards and collapse-sliding disasters.MethodsIn this study, mining- induced structural overburden was taken as the research object. Based on the instability criterion of the three-hinged arch structure, the influences of mining thickness, strata thickness, joint spacing, broken expansion coefficient, and damage factor on the HWCFZ were analyzed. A simplified fitted prediction model constrained by the three-hinged arch mechanism was established. Using the calculation results of the three-hinged arch mechanical discrimination model as benchmark values, fitting error analysis was conducted through 27 orthogonal tests, and the prediction model was applied to engineering cases in typical mining areas.ResultsThe results show that, within the parameter ranges considered in this study, the HWCFZ is approximately linearly and positively correlated with mining thickness, and negatively correlated with strata thickness, joint spacing, and broken expansion coefficient in an inverse-function form, characterized by a rapid decrease at the early stage and subsequent stabilization. In the high-damage range, the HWCFZ shows an accelerated nonlinear increase with increasing damage factor. The sensitivity ranking of the factors affecting the HWCFZ is mining thickness, strata thickness, broken expansion coefficient, joint spacing, and damage factor. The simplified fitted prediction model has a mean absolute error of 3.26 m and a coefficient of determination R2 of 0.96, indicating that the model exhibits good internal consistency with the theoretical three-hinged-arch discrimination model.DiscussionWhen applied to the Faer Coal Mine in Shuicheng, Guizhou, and the Zengziyan Bauxite Mine in Nanchuan, Chongqing, the calculated results are close to those obtained from theoretical formulas, numerical simulations, and centrifuge model tests. The results provide a reference for calculating the HWCFZ induced by ore-seam mining under similar geological conditions.

The types, propagation, and scales of catastrophic geohazard were closely associated with geomorphic units. This paper systematically analyzed the characteristics of catastrophic geohazard in the orogenic belts of the Qinghai-Tibet Plateau, Periphery of the Qinghai-Tibet Plateau, and the Yangtze Platform, which also revealed the impact of gully curvature on debris avalanche movement, combined with topographic and geomorphic analyses, statistical movement parameters, and physical model experiments. The research findings indicated that the geohazard types in the orogenic belts of the Qinghai-Tibet Plateau were predominantly rockslides, rock-ice avalanches, and ice avalanches, disaster volumes exceeding 10 million m3 and movement distances exceeding 5 km. Additionally, geohazards in this region often occur with temperature changes, tectonic patterns, and extreme heavy rainfall. Geohazards were primarily characterized by rockfall and rockslides in the Yangtze Platform, with the deposits volume ranging between 5 × 105 and 1 × 106 m3 and movement distances below 2 km. The sliding bodies in this area were generally influenced by factors such as structural planes, tectonic forms, and topographic conditions, exhibiting five types structures. For various curved movement paths, there has been some decrease in velocity with long movement distance and high length-to-width ratio of the deposits as the curvature of the path increased. Compared to straight movement paths, curved paths enhance the lateral momentum transfer of debris particles while weakening the longitudinal momentum effect. This study between the geohazard chains and gully topography may be considered in hazard assessment and dynamics of high mountains.

High-position and long-runout landslides constitute a category of highly destructive geological hazards, the kinematic mechanisms of which are fundamentally governed by dynamic fragmentation processes controlled by rock mass structural planes. Traditional continuous or discontinuous numerical methods often face limitations in characterizing the complete evolution from initial failure to full granular flow transformation, particularly in realistically reflecting the controlling effects of structural planes on energy dissipation and kinematic behaviors. To address this, based on the landslide post-failure (LPF3D) platform, this study integrates the Holmquist-Johnson-Cook (HJC) elastoplastic damage constitutive model with field-acquired structural plane data to propose a coupled numerical model capable of simulating the progressive failure, dynamic fragmentation, and multi-state flow of rock masses. Taking the January 2024 Liangshui Village high-position rock avalanche in Zhenxiong, Yunnan, as a case study, the effects of structural plane spacing, initial damage degree, initial grain size, and discontinuity orientation on kinematic processes and deposition morphology were systematically analyzed. The simulation results indicate that dense structural planes or high initial damage significantly promote rock mass fragmentation, facilitating the formation of a low-friction fluidized lubricating layer, thereby enhancing the runout distance. Conversely, larger grain sizes or better rock integrity inhibit long-runout motion by dissipating more energy through block fragmentation and interlocking mechanisms. The fragmentation-flow coupling mechanism introduced in this study effectively enhances the fidelity and prediction accuracy of simulations for high-position and long-runout landslides, providing a new methodological approach for the risk assessment of such hazards.

The formation and subsequent failure of a landslide dam represent a major cascading hazard for areas along rivers. Due to the continuous and complex multiphase dynamic processes involving sliding, damming, backwatering, and breaching, a numerical simulation for the assessment of landslide dam cascading hazard (LDCH) tends to be challenging. In this paper, we present a new methodology in which the depth-averaged two-phase model named D-Claw is enhanced and later applied to seamlessly simulate all the stages of the LDCH. The key innovation lies in the establishment of river boundary conditions to simulate the water inflow, storage, and outflow processes. This solves the problem of water inflow into the dammed lake, thus bringing the capability of simulating the backwatering and connecting the subsequent capability of simulating the hydraulic breach, which previous modeling approaches failed to include in this particular framework. By modeling the evolution of the solid and fluid volume fractions, both the landslide and water body are conceptualized as special cases of these volume fractions. Thus, the model enables an efficient simulation of the LDCH as a unified single-layer continuum system, characterized by dynamically evolving solid-grain concentrations. To test the new methodology, the enhanced D-Claw model was applied to investigate the cascading hazard event of the Shaziba Landslide that occurred on July 21, 2020, China. The new function enhanced the simulation of the breach process caused by backwater inundation and erosion, revealing key characteristics such as irregular oscillation of the breach channel, preferential scouring on the opposite bank, and transmission of high-concentration solid flow. These characteristics were highly consistent with the actual evolution process of the 2020 Shaziba Landslide. The enhanced D-Claw model provides a more realistic simulation of landslide environments and actual backwater-dam breach processes, offering an efficient numerical tool for the comprehensive risk assessment and prevention research of LDCH.

Extreme weather-induced wind and solar electricity droughts (WSEDs) can seriously disrupt the electricity balance in power systems with high shares of variable renewable energy (VRE). However, limited long-term VRE output data have prevented systematic investigation of WSED characteristics and quantitative identification of their meteorological drivers, particularly in countries such as China and India, where VRE deployment has only recently accelerated. Therefore, this study collected VRE output records from 2016 to 2024 for the Yunnan provincial power grid, one of China’s earliest large-scale VRE deployment regions. Based on a novel mathematical formulation of WSEDs, we established China’s first provincial-level WSED dataset. Analysis revealed that wind and solar electricity droughts occurred approximately nine and six times per year, respectively. During the study period, most identified events lasted 2–4 days, while compound droughts remained considerably rarer, occurring about twice annually. Wind electricity droughts were primarily triggered by wind speed deficits exceeding 55.5% below monthly averages or smaller deficits accompanied by temperature declines. Solar electricity droughts required radiation drops exceeding 65.2% below normal or milder deficits accompanied by temperature reductions of 15.9%, with precipitation further lowering triggering thresholds. The results provide new support for Yunnan Power Grid in China to defend against WSEDs.