Landslide Area Research Articles

Anthropogenic problems threatening major cities: Largest surface deformations observed in Hatay, Turkey based on SBAS-InSAR

The surface deformation caused by tectonic activities and anthropogenic factors poses a great threat to cities worldwide. The investigation and monitoring of these deformations are crucial in order to create risk analysis for the future. The problem in this case is to investigate the surface deformations and their negative effects caused by groundwater use and to identify possible landslide areas. In this study, the surface deformations in Hatay province were analyzed using SBAS-InSAR. The results from these analyses were evaluated by field observations. Sentinel-1 descending (183 datasets) and ascending (147 datasets) track geometries were selected to determine the surface deformation and its temporal evolution. Both east-west and vertical surface deformations were calculated, and the surface deformation profiles, surface 3D models and time series were created. These time series were associated with monthly precipitation data. The deformation area was interpreted with regard to available well-log data and geological setting of the study area. As a result of the study, a surface deformation resembling a bowl like structure was observed in the industrial zone located in the city center of Hatay-Güzelburç. The deformation rates are approximately 22.3 cm/year in the form of subsidence, 3.6 cm/year in the form of eastern movement and 10.1 cm/year in the form of western movement. The deformation of this bowl-like structure decelerated in the winter and accelerated in the summer due to excessive water use. The average monthly precipitation dataset supports these results. The stratigraphic data from water wells and the presence of limestone outside the eastern boundary of the deformation area show a thick clay layer in the eastern block of the bowl-shaped deformation structure. The difference between these two units, which causes a sharp anomaly at the eastern border of the deformation area, is interpreted as a probable normal fault. The second study area where surface deformations are observed is the landslide zone. The deformation was found to be 7.5 cm/year in a westward direction and 1.5 cm/year as subsidence.

Revealing the relation between spatial patterns of rainfall return levels and landslide density

Abstract. It is known that the spatial rainfall pattern can mark landslide distribution across the landscape during extreme triggering events. However, the current knowledge of rainfall controls on this distribution remains limited. Here, to reveal what rainfall characteristics control landslide spatial distribution, we explore the spatiotemporal pattern of a rainfall event that triggered over 7500 landslides (area ≈ 100–104 m2) at a regional scale with an area of ≈400 km2 in Japan. Using a 5 km resolution radar-driven and gauge-adjusted hourly precipitation dataset with 32 years of records, we compared rainfall return levels for various time ranges from 1 to 72 h and landslide density in each grid cell of the precipitation dataset (≈25 km2). The results show that, even if local slope distributions within the grid cells are comparable, the number of landslides in a ≈25 km2 grid cell was substantially high when rainfall return levels exceeded the 100-year return period in all examined timespans (i.e., 1–72 h). In contrast, when only specific-duration rainfall intensities (e.g., 6–48 h) exceeded the 100-year return level, the landslide density in corresponding grid cells tended to be low. Consequently, the landslide density increased with the increase in rainfall return levels of various timespans rather than a specific rainfall intensity, such as downpours for a few hours or long-term cumulative rainfall for several days. Moreover, with the increase in the landslide density, the number of relatively large landslides exceeding ≈400 m2 increased. Therefore, the spatial differences in rainfall return levels potentially constrain the density of total landsliding and relatively large landslides. In this sense, whether rainfall intensities reach high return levels rarely experienced in a wide timespan ranging from a few hours to several days is one of the key determinants of the spatial distribution of landslides and the extent of related hazards.

Analysis of Stress and Deformation Law of Tunnel Crossing Sliding Body Based on Pasternak Two Parameter Foundation Assumption

Because the landslide has an important influence on the internal force and deformation of the existing tunnel, and the research on the stress and deformation of the tunnel in the landslide area tends to field engineering monitoring, the corresponding theoretical analysis is relatively small, and there are some defects. First, Pasternak two parameter foundation model is introduced to establish the elastic foundation beam model of tunnel landslide interaction, which solves the soil discontinuity of Winkler foundation in the previous theory, and the transfer matrix method is used to derive the transfer matrix formula. Then, Matrix Laboratory (MATLAB) is used to compile the corresponding calculation program to analyze the distribution characteristics of internal force and deformation of the tunnel. Finally, the influence of relevant parameters such as the elastic coefficient of foundation inside and outside the landslide deformation area, the magnitude and distribution of landslide thrust, and the foundation shear stiffness inside and outside the landslide area are analyzed.

Experimental Investigation and Energy Evolution of Brittle Limestone Subjected to Multistage Cyclic Loading

Abstract In earthquake engineering, dynamic response of rock is a hot topic for investigating rock mechanism characteristics. In this article, limestone collected from the Hongshiyan landslide area induced by the 2014 “8.03” Ludian earthquake in southwest China is used to conduct multi-stage cyclic loading tests. The test results show that as confining pressure, loading frequency, and stress amplitude increase, the dynamic elastic modulus increases gradually. Damping parameters are dependent on confining pressure and can be divided into two evolution modes. Three stages can be obtained based on the residual strain curve, including stable, slow increase, and rapid increase, which correspond to the rock failure process. In addition, energy evolution characteristics are analyzed to express the influence of loading strategies. Dissipated energy gradually accumulates linearly, but stress amplitude and cyclic number promote it.

Identifying the Groundwater Sources of Huangtupo Landslide in the Three Gorges Reservoir Area of China

Groundwater plays a crucial role in triggering and reactivating deep-seated landslides. However, classical hydrogeological investigations have limitations in their applicability to deep-seated landslides due to anisotropic and heterogeneous media. The Huangtupo landslide in the Three Gorges Reservoir area has garnered significant attention due to its high hazard potential. Of particular interest is the NO.1 Riverside Sliding Mass (HTP-1), which has shown notable deformation and has become the primary focus of landslide research. The study aims to investigate the sources of water in the HTP-1 landslide through hydrochemical analysis. This was achieved by monitoring the major ion content in the groundwater within the landslide for one year. Furthermore, stable isotope investigations were conducted on the groundwater in and around the landslide area, and an analysis of the mineral composition of the landslide soil was also performed. The results indicate that the groundwater in the landslide area (LGW) is a mixture of karst groundwater (KGW) from the adjacent upslope and local precipitation (LP). The karst groundwater is a major contributor to the recharge of the landslide groundwater system, causing a high component of groundwater that can easily exceed the critical level that causes landside failure during heavy rainfall events. Furthermore, prior to the relocation of residents from the Huangtupo landslide, the landslide groundwater was also impacted by human sewage, which not only affected the chemical composition of groundwater, but also had potential implications for slope stability. These findings provide a more scientific basis for the design and implementation of interception and drainage measures for the Huangtupo landslide and other large-scale landslides with similar geological conditions in the Three Gorges Reservoir area.

Identification of Slip Area in Makale Selatan District Using the Geoelectric Method

Landslides are most common in steep areas with heavy rainfall. Aside from rainfall, there are numerous other factors that contribute to landslides. The presence of slip fields in the subsurface layer is one of the primary causative factors. South Makale is one of the sub-districts in Tana Toraja Regency that is located in the mountains, where landslides frequently occur, claiming lives. The purpose of this study was to determine the slip area of potential landslides in three sub-districts, which are Sandabilik, Tiromanda, and Randan batu villages. The geoelectric method with the Wenner-Sclumberger configuration type was used. The measurement data is in the form of rock resistivity values, which are then interpreted based on the rock layer type. The findings revealed that the Sandabilik and Randan Batu villages were landslide risk areas. Sandabilik Village has a slip area in the form of lava rock at a depth of 6.5 - 19.8 meters on line 1 and 1.5 - 16 meters on line 2. Rocks of the same type can also be found in Randan Batu Village, a landslide point with depths ranging from 2 to 16 meters on line 1 and 5 to 20 meters on line 2.

Landslide Soil Failure Parameters Characterization Using Geoelectrical Resistivity Methods in Uruagu, Nnewi, Anambra State, Nigeria

Electrical Resistivity Imaging (ERI) and Vertical Electrical Sounding (VES) were deployed over the Uruagu landslide area. The main purpose of the study was to characterize the landslide failure parameters in to identify the soil failure mechanisms. Ten profiles of 2D ERI measuring 200 m each, and thirty VES, with three VES along each profile, were executed. Nine of the ten profiles were executed within the landslide site while one profile was executed in a residential street as a control profile. Four soil samples were also taken for physical and geotechnical laboratory index analysis. The PASI resistivity meter was used for the geoelectrical resistivity measurements. The Wenner-Schlumberger array was deployed for the ERI with a minimum electrode spacing of 10 m. The Schlumberger array was deployed for the VES with a maximum current spacing of 130 m. ERI resistivity data analysis involved inversion using the RES2DINV software package involving mean model residual and construction of iso-apparent resistivity contour maps. VES resistivity data analysis involved calculated parameters from plotted field data on a log-log graph then used as initial models in an iterative forward modeling WinResist software package. The results of the ERI and VES for the control profile reveal that the subsurface strata are originally composed of silty clay of resistivity values (16.7 – 60.9) Ωm, clayey silty sand having resistivity values (116 – 800) Ωm and sandstone layer with resistivity values (>814 Ωm). The ERI and VES results for the devastated landslide site reveal counteraction material of resistivity values (>814 Ωm), colluvia and regoliths (116 - 300 Ωm), and variably wet weathered sandstones of resistivity values (<60.9 Ωm). The laboratory results revealed the landslide site is majorly composed of silty sandy clay, silty clay, sandy silty clay, and sandstones as the pre-landslide existing lithologies. The natural water content ranges from 10.6% to 14.0%. The liquid limit ranges from 44.0% to 46.0%, the plastic limit ranges from 15.0% to 17.0%, and the plasticity index from 28.0% to 29.1%. The geophysical and laboratory results revealed consistency in the lithological units in agreement with the characteristic geology of the study area. The landslide site has high gully slope gradients and collects a large volume of floods during the intense rainy season. These soils, during the intense rainfall, imbibe more water, following their high plasticity slide along the sandstone to activate the soil failure.

A Comparative Analysis for Defining the Sliding Surface and Internal Structure in an Active Landslide Using the HVSR Passive Geophysical Technique in Pujilí (Cotopaxi), Ecuador

Geophysical techniques were employed to analyze one of the landslides that affected the main access road to Pujilí (Ecuador). A passive seismic technique was utilized to test a total of 70 horizontal to vertical spectral ratio (HVSR) points, complemented by an active seismic-refraction profile and a multichannel analysis of surface waves (MASW) survey. The results from the active geophysical surveys facilitated the determination of the shear-wave-velocity value for the surface materials that were in motion. However, the HVSR provided the fundamental frequency fo and amplification Ao values of the ground. The Nakamura (1989) relationship was applied to obtain the thickness of the sediments over a compact material from the fundamental frequency of the terrain in a two-layer model. Additionally, constrained models of the shear-wave velocity (Vs) distribution in the landslide area, obtained from the active seismic surveys, were used to invert the ellipticity curves. The results from this inversion were compared with those obtained by applying the Nakamura equation. The landslide-rupture surface was delineated for each type of analysis, which verified the correlation and minimal differences between the results of the three proposed studies, thus validating the procedure. The directivity of the microtremor HVSR signals was also analyzed, demonstrating a relationship with the internal structure of the sliding material. Furthermore, the ability to slide concerning the Kg parameter (vulnerability index, Nakamura, 1989) was studied. The usefulness of the directivity analysis in defining the internal structures in landslide materials and in determining the areas with the most significant instability was demonstrated. Overall, the HVSR is considered valuable when conducting early landslide studies and is helpful in determining the rupture plane while remaining a simple, fast, and economical technique.

Enhance the Accuracy of Landslide Detection in UAV Images Using an Improved Mask R-CNN Model: A Case Study of Sanming, China.

Extracting high-accuracy landslide areas using deep learning methods from high spatial resolution remote sensing images is a hot topic in current research. However, the existing deep learning algorithms are affected by background noise and landslide scale effects during the extraction process, leading to poor feature extraction effects. To address this issue, this paper proposes an improved mask regions-based convolutional neural network (Mask R-CNN) model to identify the landslide distribution in unmanned aerial vehicles (UAV) images. The improvement of the model mainly includes three aspects: (1) an attention mechanism of the convolutional block attention module (CBAM) is added to the backbone residual neural network (ResNet). (2) A bottom-up channel is added to the feature pyramidal network (FPN) module. (3) The region proposal network (RPN) is replaced by guided anchoring (GA-RPN). Sanming City, China was selected as the study area for the experiments. The experimental results show that the improved model has a recall of 91.4% and an accuracy of 92.6%, which is 12.9% and 10.9% higher than the original Mask R-CNN model, respectively, indicating that the improved model is more effective in landslide extraction.

Modeling the area of co-seismic landslides via data-driven models: The Kaikōura example

The last three decades have witnessed substantial developments in data-driven models for landslide prediction. However, this improvement has been mostly devoted to models that estimate locations where landslides may occur, i.e., landslide susceptibility. Although susceptibility is crucial when assessing landslide hazard, another equally important piece of information is the potential landslide area once landslides initiate on a given slope.This manuscript addresses this gap in the literature by using a Generalized Additive Model whose target variable is the topographically-corrected landslide areal extent at the slope unit level. In our case, the underlying assumption is that the variability of landslide areas across the geographic space follows a Log-Normal probability distribution. We test this framework on co-seismic landslides triggered by the Kaikōura earthquake (7.8 Mw on November 13th 2016). The model performance was evaluated using random and spatial cross-validation. Additionally, we simulated the expected landslide area over slopes in the entire study area, including those that did not experience slope failures in the past.The performance scores revealed a moderate to strong correlation between the observed and predicted landslide areas. Moreover, the simulations show coherent patterns, suggesting that it is worth extending the landslide area prediction further. We share data and codes in a GitHub repository https://github.com/mmorenoz/GAM_LandslideSize to promote the repeatability and reproducibility of this research.

Assessment of urban landslide groundwater characteristics and origin using artificial tracers, hydro-chemical and stable isotope approaches

In the framework of landslides, the hydrogeological features play an essential role in slope stability, governing water movement and thus resulting in modification of the effective stress in the soil. In this framework, the hydrogeological conceptualization of landslide areas and the identification of groundwater origin are key points to developing risk mitigation measures. In fact, groundwater recharge cannot always be attributed to local precipitation alone. Mixing processes between water derived from local infiltration and deep water upflow along tectonic lineaments or anthropogenic water can affect the groundwater balance on a local scale. This study aims to define the potential groundwater origin of one of the highest risk urban landslides in central Italy and to define a hydrogeological conceptual model by exploiting its existing drainage system network. This research is based on a multiple-techniques approach based on hydrological water balance, artificial tracer tests during recharge period, seasonal monitoring of the water stable-isotope content, hydro-chemical survey during low-flow periods, and analysis of the piezometric level fluctuation. All these analyses are coupled with a detailed reconstruction of the geology of the area depicted from boreholes and drill holes. Two groundwater bodies have been evidenced from the study. The shallower one is located in the landslide unstable zone and is hydraulically connected to a deeper groundwater body hosted in the underlying bedrock. Results highlighted that the local rainfall regime could not fully explain the hydro-chemical facies. Local water contributions to the landslide area coming from leakage of the urban sewerage system have been evidenced, excluding deep groundwater upflow from the fault system.

Elucidating the role of soil hydraulic properties on aspect-dependent landslide initiation

Abstract. Aspect-dependent landslide initiation is an interesting finding, and previous studies have attributed this to the mechanical effects of plant roots. In the present study, an overwhelming landslide probability on a south-facing slope over a north-facing slope was found in a localized area with only granite underneath and high cover of Larix kaempferi. These observations cannot be attributed to plant roots but may result from factors related to hillslope hydrology. Differential weathering associated with hillslope hydrology behaviors such as rainfall water storage and leakage, pore water pressure, particle component, and hillslope stability fluctuation were used to examine these observations. Remote sensing interpretation using the high-resolution GeoEye-1 image, digitalized topography, and field investigations showed that landslides on south-facing slopes have a higher probability, larger basal area, and shallower depth than those on a north-facing slope. The lower limits of the upslope-contributing area and slope gradient condition for south-facing landslides were less than those for north-facing landslides. The higher basal areas of south-facing landslides than those of the north-facing landslides may be attributed to the high peak values and slow dissipation of pore water pressure. The absorbed and drained water flow in a given time interval, together with the calculated water storage and leakage measured during the rainy season, demonstrate that the soil mass above the failure zone for south-facing slope is more prone to pore water pressure, which results in slope failures. In comparison, the two stability fluctuation results from the finite and infinite models further verified that landslides on south-facing slopes may fail under conditions of prolonged antecedent precipitation and intensive rainfall. Meanwhile, those on north-facing slopes may fail only in response to intensive rainfall. The results of this study will deepen our knowledge of aspect-dependent landslide initiation from both classical mechanics and the state of stress.

Landslide detection in Kinnaur Valley, NW India using PS-InSAR technique

ABSTRACT Remote sensing techniques, such as Interferometric Synthetic Aperture Radar (InSAR), have the potential to document and monitor surface deformation up to a millimetre scale especially in areas where ground monitoring is not feasible. The InSAR technique has been used to isolate and map some current and potential landslide areas in Kinnaur region of the Satluj Valley in Himachal Pradesh. The fragile ecosystem of Kinnaur has been challenged by the shifting climatic pattern and immense anthropogenic pressure associated with burgeoning hydroelectric projects, leading to destructive landslides of epic proportions. Three recent landslides that occurred at Ribba and Pangi villages of the Satluj River Valley and the Batseri landslide in the Sangla Valley were studied and potential landslide areas along the Satluj Valley were mapped with Sentinel-1 multi-baseline interferograms using data acquired between 2016 and 2021. The analysis suggests significant changes in velocities (±11 mm/y) where the subsidence rate ranges from −6 to −11 mm/y with a cumulative displacement of ±45 mm/y. Our study highlights the potential locations for future landslides and provides an early warning landslide map to support future disaster prevention in highly deformed regions.

Integrating the SLIDE model within CAESAR-Lisflood: Modeling the ‘rainfall-landslide-flash flood’ disaster chain mechanism under landscape evolution in a mountainous area

The interaction mechanism between the dynamically changing environment and the subsequent natural hazards in the years following an earthquake has been studied based on a multi-temporal remote sensing dataset and continually measured data. However, how to quantitatively model this interaction mechanism has not been fully addressed. In this study, we first modeled the interaction mechanism between the ‘rainfall-landslide-flash flood’ disaster chain and the dynamically changing environment in mountainous areas by incorporating the SLope-Infiltration-Distributed Equilibrium (SLIDE) model within the landscape evolution model (CAESAR-Lisflood) and then applied the integrated CAESAR-Lisflood model in a Wenchuan earthquake-stricken area. The results demonstrated that the landslide susceptibility under extreme rainfall can be predicted effectively based on the integrated CAESAR-Lisflood model and that new/enlarged landslides occur more easily in mountain valleys, near the valley outlet, and in the main steep gullies. Most of the high landslide susceptibility areas are not located in coseismic landslide areas with high vegetation recovery. The landslide legacy effects had a significant influence on the landscape erosion and deposition processes and a great effect on the spatial distribution pattern of the material redistribution in the basin, which in turn affected the subsequent disaster occurrence. The integrated CAESAR-Lisflood model compensates for the effect of the “rainfall-landslide-flash flood” disaster chain on the process of erosion and deposition, improves the model’s applicability in earthquake-stricken areas, and provides scientific information for regional disaster management and reduction.

The longest tree-ring based chronology of mass movements in Central Europe and their meteorological triggers

Knowledge of meteorological triggers of mass movements is crucial for determining the degree of hazards, but also for predicting their occurrence. Dendrogeomorphic methods (tree-ring based) have repeatedly provided data on historical landslide activity as a basis for detailed trigger analysis. However, the construction of long dendrogeomorphic chronologies encounters limits in the sensitivity of growth disturbances in trees as well as their age dependence. Moreover, accurate meteorological instrumental data usually do not cover the entire length of long tree-ring based chronologies of landslide movements. To resolve these uncertainties, this study has compiled the longest tree-ring-based chronology of mass movements in Central Europe for Mt. Kněhyně in Outer Western Carpathians, spanning more than a quarter of a millennium and based on 228 tree-ring series of disturbed individuals of Norway spruce (Picea abies (L.) Karst.). The resulting chronology is a combination of two sub-chronologies that we constructed from different tree growth disturbances (reaction wood and tree-ring eccentricity), combining the advantages of both approaches. To identify potential meteorological triggers, we combined instrumental data from the nearest meteorological station together with reconstructed data from the wider landslide study area and documentary records. This gave us a uniquely long overlap of the two datasets across the full length of the mass movement chronology, allowing for more robust results compared to significantly shorter overlays. The studied mass movements followed up to three years of above-mean precipitation and were immediately triggered by short (several days) precipitation extremes. Snowmelt lasting several days to weeks in selected cases further modified this pattern.

Ultrahigh-resolution shear-wave reflection imaging of vertical-component data in a quick-clay prone to landslide area in southwest Sweden

We have investigated the potential of ultrahigh-resolution seismic reflection imaging of vertical-component data to identify hazardous conditions in a quick-clay landslide area in southwest Sweden. A high-fold survey with a fine shot and receiver spacing has been acquired using a 5 kg sledgehammer, vertical hit, with the objective of producing a high-quality unaliased shear-wave reflection section retrieved from vertical-component data. On the receiver side, 1C wireless recorders are deployed in a fixed geometry juxtaposed to a landstreamer of 3C-microelectro mechanical system (MEMS)-based units, which recorded in a roll strategy to cover most of the profile length. Particle motion analysis of main reflections has been conducted on the 3C MEMS sensors, given their side-by-side location with the wireless recorders, to inspect the wave polarization. Distinct shear-wave reflections in an extremely slow shear velocity medium (70–100 m/s) imply a vertical super resolution of 1–2 m down to a bedrock level of 40 m deep. Interestingly and as shown in earlier studies, quick clays appear to overlie the coarse-grained horizons justifying why their high-resolution imaging can be significant for quick-clay landslide studies and a better understanding of potential risks. Two shallow reflections are delineated through a combination of first-break traveltime tomography for P and S waves and reflection seismic processing for P- and S-reflections of the vertical-component data. After seismic imaging and borehole data correlation, the shallowest reflection is interpreted to be from coarse-grained materials interbedded within normally consolidated clays and the deepest one from an undulating bedrock. Interpretations of the S-S processing outcomes indicate that the coarse-grained layers are not homogeneous because of the generation of strong shear-wave diffractions, suggesting the presence of either large boulders or patchy sandy-silty conditions.

Compilation of Parameter Control for Mapping the Potential Landslide Areas

Batu Tourism City is located in a mountainous area, so based on information from the BNPB, it has quite a large potential for landslides. Landslide hazards can frequently disrupt public traffic due to road cuts. Landslide mapping digitally will contribute to handling and mitigation activities since the database can be updated in real time to anticipate landslide hazards. This study aims to map landslide-prone areas located in the Payung zone, Songgokerto Village, and Batu City. Landslide areas can be determined by mapping analysis using GIS software. GIS can determine the classification level for a landslide susceptible area. Some input data that will influence landslides, such as rainfall, wind, earthquakes, etc., was collected as the control parameters. All parts of the study area could be classified as areas with minor, medium, and major potential for landslides. Primary data are collected from geo-surveying (aerial images) using drone devices for interpretation of landslide susceptibility areas, geophysical to identify the type of soil or rock layers that completed their behavior, and slip planes as well using geo-electric, geotechnical engineering to predict slope stability with the correlation from cone penetration test (CPT) data, and geo-hydraulic to observe the rainfall and the catchment area model using the available secondary data. Geometrically, measurement data found that the average slope angle at the upper and lower of the East Java Province highway is around 40–50o. Studies from geophysical data identified that the hilly terrain in the object study area has been dominated by the weathered rock layer. Geotechnical data obtained shows the soil layers at the slope location will be stable with the water content under 35% during the dry season and may become unstable with the water content reaching over 50% due to the increase in saturation during the rainy season. The landslide that occurred was more caused by seepage behavior from surface water flow towards the sloping plane, and then the safety factor during the rainy season reached the critical values at SF = 0.58. During the dry season, the unsaturated process due to the temperature change generates a safety factor (SF) of more than 1.2. The compilation data produced maps of susceptible landslides and surface flow distribution. Doi: 10.28991/CEJ-2023-09-04-016 Full Text: PDF

Freely accessible inventory and spatial distribution of large-scale landslides in Xianyang City, Shaanxi Province, China

In this study, we used high-resolution optical satellite images on the Google Earth platform to map large-scale landslides in Xianyang City, Shaanxi Province, China. After mapping, a comprehensive and detailed large-scale landslide inventory that contains 2924 large-scale landslides was obtained. We analyzed the spatial distribution of landslides with seven influencing factors, including elevation, slope angle, aspect, curvature, lithology, distance to a river, and distance to the fault. Landslide Number, Landslide Area, Landslide Number Density (LND), and Landslide Area Percentage (LAP) were selected as indexes for the spatial distribution analysis. The results show that the number and area of landslides in the elevation range of 1000–1200 ​m is the highest. The highest number of landslides was observed in the slope angle of 25°–30°. North-facing slopes are prone to sliding. The area and number of landslides are the largest when the slope curvature ranges from −1.28 to 0. The LND and LAP reach their maxima when the slope curvature is less than −2.56. Areas covered by the Tertiary stratum with weakened fine-grained sandstone and siltstone show the highest LND and LAP values. Regarding distance to a river, the LAP peaks in the range of 300–600 ​m, whereas the LND peaks in an area larger than 2100 ​m. The values of LND and LNP rise as the distance from the faults increases, except for the locations 30 ​km away from active faults. This phenomenon is because active faults in this area pass through the plain areas, while landslides mostly occur in mountainous areas. The cataloging of landslide development in Xianyang City provides a significant scientific foundation for future research on landslides. In addition, the spatial distribution results are useful for landslide hazard prevention decisions and provide valuable references in this area.

Insights into landslide development and susceptibility in extremely complex alpine geoenvironments along the western Sichuan–Tibet Engineering Corridor, China

The Sichuan–Tibet Engineering Corridor (STEC), which provides the key function of transportation between the plain and plateau regions, is subjected to widely distributed landslides in the southeastern margins of the Tibetan Plateau. This study investigated the landslides in terms of geomorphological and geological analyses and susceptibility assessment along the western STEC between Changdu and Nyingchi Cities, which is characterized by extremely complex geoenvironments across three major river catchments. The results suggested the spatial feature that the landslides preferentially occurred in river valley regions with high elevation and distinctive local relief. Soft rock types of shale, siltstone, schist and gneiss controlled most landslide areas, while faults and rivers strongly dominated landslide formation. Landslide susceptibility results performed by the support vector machine (SVM), k-nearest neighbor (KNN), and multilayer perception (MLP) models were highly dependent on various sample sets, revealing different hazard-formation backgrounds among the Lancang, Nu, and Yarlung Tsangpo (YLTP) river catchments. A comparative analysis demonstrated the most robust model, the SVM, indicating that lithology, elevation, local relief, slope, and distance to faults were the most significant factors causing landslides. In summary, the investigations signified that the development of landslides along the STEC was macroscopically controlled by regional and vertical zonation of the tectonic geomorphology driven by regional uplift, and was locally dominated by lithology and suture zones. Eventually, further surface erosion and earthquakes dynamically offered inducements for landslide initiation. This study strengthens the understanding of landslide development and susceptibility in response to landscape evolution in southeastern Tibet, and provides a conceptual model for disaster prevention and mitigation in similar high-relief plateau margin regions.

Anthropogenic factors as determinants of deformation and damage of a bridge structure founded on clayed ground – a case study

Bridges are often built in complex geological-engineering conditions, on difficult soils, landslide areas or within the range of negative mining influences. These objects are classified as geotechnical category II or III and a ground investigation documentation or geotechnical design should be carried out for them. The correct investigation of the soil, design, and execution in accordance with technical knowledge, the art of construction and the Building Code are a guarantee of the safety of the facility. However, very often it is the complexity of the geological structure, concentrated vertical and horizontal loads transferred by the supports to the soil that make it necessary to use deep foundations, special methods of soil reinforcement and imposing a special technological regime during the execution of construction works. The paper pays attention to anthropogenic and natural factors, as well as those that are the consequence of inappropriate human actions at the design or execution stage. Particular attention is paid to errors in the soil analysis and execution of construction works. An example of such errors analysis is presented in relation to the implementation of a bridge structure.