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This paper interprets the results from field monitoring which was carried out during vacuum-PVD improvement in a site located near an actively moving slope. Interestingly, the monitoring results showed, among other things, mitigation in the outward lateral movements during and after the preloading process indicating relative stability in the slope and the efficiency of vacuum to mitigate lateral movements during the preloading period. Analyses were made on other field parameters such as pore pressure and settlement, as well as back-calculation of flow parameters to be considered during vacuum preloading design, such as permeability ratio (kh/ks) and horizontal consolidation coefficient (Ch) due to vacuum-PVD, were carried out. Post improvement, appropriate geotechnical properties were obtained from laboratory tests of clay specimens from borehole samples and undrained shear strengths were measured from unconfined compression and field vane shear test. The obtained properties indicated improvement in soft soil properties with a reduction in water content and an increase in maximum past pressure, OCR and undrained shear strengths. The prediction made for final shear strength using past literature, where applied additional incremental stress was reduced with depth, matched well with the shear strengths recorded from field testing. [ABSTRACT FROM AUTHOR]

In Wenchuan, China, which was severely affected by an M8.1 earthquake in 2008, the geomorphic process has been driven by gravitational erosion brought on by post-shock rockfalls and landslides. However, a process-based delineation of the post-shock landscape modification using quantitative methods employing mathematical modeling and control experiments has not yet been successfully undertaken. This is due to the areas' substantial sediment yield and growing transportation capacity. This study looked into 31 minor watersheds along the Minjiang River's Wenchuan–Yingxiu stretch. Additionally, a digital gully model based on multi-source remote sensing, Geographic Information System (GIS), Differential Intereferometric Synthetic Aperture Radar (D-InSAR), and amplitude tracking technology was created for the quantitative estimation of post-shock gravity erosion and sediment yield by comparison of three-dimensional topographical alternation (before and after the shock). Following regression analysis, a useful model for sediment yield estimation was suggested. The following conclusions were reached: (1) There was a considerable favorable effect between an angle of 50 and 70 degrees, and various geomorphological parameters had scale effects. Gravitational sediment yield modulus displayed a positive power function relationship with relative relief and surface fragmentation, but there was no clear correlation between the modulus and slope, relative relief, or surface fragmentation at the watershed scale; (2) Both the budget for post-shock geo-materials and the production of sediment from gravity erosion showed an annual trend of decline; (3) A 10–20-year active period would be recognized by gravity erosion. [ABSTRACT FROM AUTHOR]

Landslides and their disastrous consequences on the environment and human life have emphasized the need for a better understanding of the dangers associated with slope movement. The objective of this research was to assess and utilize mapping methods for predicting the hazards of landslides and thus to limit the damage of these phenomena more effectively. In the current investigation, multi-hazard mapping was employed in evaluating the risk of slope movements for the municipality of Bensekrane in Tlemcen in Algeria. There has been no hazard assessment made for the study area although it has factors responsible for triggering landslides. The standard Farès method (arithmetic and probabilistic) was employed, and the results were compared with those obtained from the modified Farès technique (arithmetic and probabilistic), which was developed based on a synthesis or combination of previous approaches. In the modified Farès technique, dynamic factors were also included, such as seismic activity, vegetation cover and groundwater level, and, thus, it was considered more reliable. However, the choice of method depended mainly on the availability of data from the study area. The maps obtained showed that the study area is susceptible to slope movements and will be employed for land use planning. The maps obtained by the arithmetic modified Farès method were different from those obtained by the arithmetic Farès method. The former presented a large part of the surface (88%) with an average hazard, unlike the latter, which presented the largest surface (66%) and a low hazard. The maps generated by the probabilistic modified Farès method showed a surface with a high hazard, unlike that obtained by the probabilistic Farès method, where a high hazard did not exist. These differences between the maps were due to the addition of dynamic factors. It is better to choose the modified Farès method, which takes into account all the factors that exist in reality. In this study, enhanced spatial, natural hazard maps were created using the modified Farès method to better aid decision makers and builders in making correct choices for increased safety and town planning. It is crucial to be able to utilize reliable maps based on multi-hazard risk assessment for land development purposes to lessen the possibility of destructive landslides. The modified Farès method can be applied to any other comparable areas around the world. [ABSTRACT FROM AUTHOR]

Disastrous landslides have become a focus of the world’s attention. Landslide susceptibility evaluation (LSE) can predict where landslides may occur and has caught the attention of scientists all over the world. This work establishes integrated criteria of potential landslide recognition and combines the historical landslides and newly-identified potential landslides to improve the accuracy, rationality, and practicability of a LSE map. Moreover, slope units can well reflect the topographic constraint to landslide occurrence and development, and Graph Convolutional Network (GCN) can well portray the topological and feature relation among various slope units. The combination of slope units and GCN is for the first time employed in LSE. This work focuses on Wanzhou District, a famous landslide-serious region in the Three Gorges reservoir area, and employs multisource data to conduct potential landslide recognition and LSE and to reveal the distribution characteristics of high landslide susceptibility. Some new viewpoints are suggested as follows. 1) The established criteria of potential landslide recognition consist of the characteristics of active deformation, stratum and lithology, tectonics, topography, micro-geomorphology, environment, meteorology, earthquakes, and human engineering activity. These criteria can well eliminate 4 types of false alarm regions and is successfully validated by field survey. 2) 34 potential landslides are newly discovered, and the movement of these potential landslides were controlled or induced by the combined action of soft-hard interbedding rock mass, steep topography, frequent tectonic movement, strong fluvial erosion, abundant precipitation, and intensive road and building construction. 3) The GCN algorithm reaches a relatively high accuracy (AUC: 0.941) and outperforms the other representative machine learning algorithms of Convolutional Neural Network (AUC: 0.926), Support Vector Machine (AUC: 0.835), and CART Tree (AUC: 0.762). 4) High landslide susceptibility is caused by the coupled action of weathered rock cavities, soft rock and swelling soil, strong river erosion, abundant rainfall, and intensive human engineering activity.

In Wenchuan, China, which was severely affected by an M8.1 earthquake in 2008, the geomorphic process has been driven by gravitational erosion brought on by post-shock rockfalls and landslides. However, a process-based delineation of the post-shock landscape modification using quantitative methods employing mathematical modeling and control experiments has not yet been successfully undertaken. This is due to the areas’ substantial sediment yield and growing transportation capacity. This study looked into 31 minor watersheds along the Minjiang River’s Wenchuan–Yingxiu stretch. Additionally, a digital gully model based on multi-source remote sensing, Geographic Information System (GIS), Differential Intereferometric Synthetic Aperture Radar (D-InSAR), and amplitude tracking technology was created for the quantitative estimation of post-shock gravity erosion and sediment yield by comparison of three-dimensional topographical alternation (before and after the shock). Following regression analysis, a useful model for sediment yield estimation was suggested. The following conclusions were reached: (1) There was a considerable favorable effect between an angle of 50 and 70 degrees, and various geomorphological parameters had scale effects. Gravitational sediment yield modulus displayed a positive power function relationship with relative relief and surface fragmentation, but there was no clear correlation between the modulus and slope, relative relief, or surface fragmentation at the watershed scale; (2) Both the budget for post-shock geo-materials and the production of sediment from gravity erosion showed an annual trend of decline; (3) A 10–20-year active period would be recognized by gravity erosion.

According to local villagers, the main Beiguo landslide on the Heyang Loess Tableland in China occurred several decades ago (the specific time is unknown). After the initial occurrence of the main landslide, there was no major activity for several decades until December 17–22, 2017 (2 months after the rainy season), when the main landslide was completely reactivated. One of the interesting findings of our field survey is that there are two erosion gullies and numerous loess caves (groups) developed at the top of the Beiguo landslide, which are generally considered to be the dominant channels by which rainwater or surface runoff enters the deep underground space. In order to better understand the process and triggering factors of the main landslide's reactivation, a multidisciplinary investigation including satellite remote sensing, interferometric synthetic aperture radar (InSAR), an unmanned aerial vehicle (UAV) survey, a terrestrial laser scanning (TLS) survey, an electrical resistivity tomography (ERT) survey, laboratory experiments, real-time monitoring using an inclinometer, and field investigations of the Beiguo landslide was conducted. We believe that the reactivation of the main Beiguo landslide may have been occurring for more than 10 years, or perhaps even longer. Since 2011, there have been several signs of local activity in the main landslide body, and the last accelerated stage of the entire deformation process occurred in 2017. The development and existence of loess caves directly destroyed the stability of the slope, and the rainfall and surface runoff quickly entered the interior of the main landslide. The influence of the loess caves on the landslide's reactivation was long-term and continuous. The results of this study suggest that the several days of abundant and continuous rainfall in the rainy season in 2017 were the last direct trigger of the final reactivation of the main landslide. The secondary landslide significantly changed the original slope, including the aspect of the slope profile's morphology, the slope gradient, relief, erosion, and accumulation, which accelerated the evolution of the tableland landform. This study enhances our understanding of the reactivation behavior of loess landslides, and also provides important support for the monitoring and prevention of reactivated landslides in the future. [ABSTRACT FROM AUTHOR]

Khlong Pa Bon Dam in Thailand underwent the greatest differential drawdown in impounded water in 2014. Unexpected deformation of the upstream slope of the dam was observed on June 27 in the year, after operation for 10 years. The drawdown was hypothesized as the possible cause of the slope deformation. The results from piezometers showed that the upstream slope remained partially undrained after sudden drawdowns. A rapid drawdown analysis confirmed that the movement did not occur due to the sudden drawdown of water in 2014. Back analysis revealed that the shear strength of the embankment slope was near its residual value at the time of failure, which was validated by the movement of inclinometers. Ring shear tests were used to determine the residual shear strength of the failure zone, and the results were validated by the finite element method in ABAQUS. Furthermore, the results of the numerical analysis demonstrated that strain softening was the major cause of the slope movement. [ABSTRACT FROM AUTHOR]

A 610-m-high portion of the South Wall of the Bingham Canyon open pit has experienced slow-moving slope deformations several times during spring melt until the movement was stabilized approximately 7 years ago. To develop and optimize life of mine slope designs, an understanding of the mechanism(s) and associated material strength parameters, was required. A back-analysis and calibration of the strength parameters for the salient rock mass and structural features was undertaken. The back-analysis consisted of understanding the conditions and trigger for the slope movement and adjusting strength parameters to match available monitoring data (time-domain reflectometer cables, inclinometers, interferometric radar data, etc.). The trigger for the movement was attributed to the spring high-perched water levels in the upper part of the wall. A FLAC3D model was built to back-analyze and capture the complex behavior of the slope during the high deformation period (August 2011). The back-analysis was consistent with the conceptual model and indicated that the slide was composed of mixed mechanisms, namely, a structurally controlled mechanism for the upper wall and a rock mass controlled mechanism for the lower wall (toe). The analysis supported by a converging FLAC3D model, were used to guide mining engineers in developing robust pit design in the South Wall. Today, the O-Slide instability is being fully managed by rigorous monitoring, implementation of a toe buttress, successful dewatering efforts, and unloading of the movement mass as another slice of mining advances down the South Wall. [ABSTRACT FROM AUTHOR]

Landslides are the most common natural hazard in British Columbia. The province has recorded the largest number of historical landslide fatalities in Canada, and damage to infrastructure comes at a great cost. In order to understand the potential impacts of landslides, radar remote sensing has become a cost-effective method for detecting downslope movements. This study investigates downslope movements in the Southern Interior of British Columbia, Canada, with Sentinel-1 and RADARSAT Constellation Mission (RCM) interferometric synthetic aperture radar (InSAR) data. The 2-dimensional time-series analysis with Sentinel-1 ascending and descending InSAR pairs from October 2017 to June 2021 observed distinct earthflow movements of up to ~15 cm/year in the east–west direction. The Grinder Creek, Red Mountain, Yalakom River, and Retaskit Creek earthflows previously documented are still active, with east–west movements of ~30 cm over the past four years. New RCM data acquired from June 2020 to September 2020 with a 4-day revisit capability were compared to 12-day Sentinel-1 InSAR pairs. The 4-day RCM InSAR pairs at higher spatial resolution showed better performance by detecting relatively small-sized slope movements within a few hundred meters, which were not clearly observed by Sentinel-1. The temporal variabilities observed from the RCM InSAR showed great potential for observing detailed slope movements within a narrower time window.

This paper assesses potential slope movement in a landslide area using a grouted cable of time domain reflectometry (TDR) technology compared with data from an inclinometer and bore logs. The paper quantifies the magnitude of a TDR coaxial cable by laboratory shear and extension tests. The maximum and average magnitudes of cable deformation by laboratory shear failure were 60 mm and 47 mm, respectively. Then, in the paper, the results of the laboratory testing were applied to a case study where there were two inclinometers and two TDR monitoring stations. Based on laboratory shear and extension testing, differences in TDR-reflected waveforms can be regarded as locations of cable deformations. Meanwhile, the magnitude of cable deformations can be measured by the regression equation of the relation between reflection coefficients and shear displacements. Finally, the working limit of the cable for potential slope movement can be determined at 210-mρ reflection coefficient in laboratory and field testing. When a grouted cable ruptured, the TDR technology can detect a reflection coefficient at 210 mρ corresponding to the potential shear displacement at approximately 47 mm, which means that a localized slope deformation significantly occurred at the location of the cable rupture. [ABSTRACT FROM AUTHOR]

This paper reports a fiber-optic displacement sensor based on a Michelson interferometer using the spectral demodulation method. The displacement information is sensed through the length variation of the sensing fiber following the deformation of the measured object. By deploying the relaxed reference arm along the sensing arm, the optical path difference variation introduced by temperature can be eliminated. A spectral demodulation method is employed to obtain the displacement from the interference spectrum by using the fast Fourier transform and the Buneman frequency estimation. The experimental results show that the proposed displacement sensor has a high resolution of 90 nm over a long span of 15.7 m and a large displacement measurement range of 7.5 mm. The theoretical displacement measurement range of the proposed sensor can be up to 10 cm. The proposed displacement sensor will be very useful and promising in large-scale civil infrastructure monitoring applications. [ABSTRACT FROM AUTHOR]

Power consumption is one of the major issues associated with deploying a wireless sensor to monitor natural environments in the real world. It is not practical to frequently replace the battery of a sensor that is located in a remote mountainous area. While considering to save valuable energy, the sensor must be able to detect a particular event in a timely manner and report data. To satisfy these requirements, in this paper, we present a wireless sensor system, termed SMARTCONE, which is designed to monitor the slope movement and minimize the standby power consumption, while remaining active to detect events. Multiple SMARTCONEs need to synchronously change their operation modes to collect the physical parameters and transmit raw vibration data simultaneously. SMARTCONE is consuming a power of only 0.05 mA at 3.6 V in standby mode, which is significantly less than that consumed by the previous design. As far as we know, SMARTCONE is an unprecedented instrument for the monitoring of slope movement; no other instruments can achieve such a low-energy consumption while being triggered by external vibration and managed remotely. These complicated issues are considered while designing the SMARTCONE, whose performance is then evaluated. In order to prevent redundant effort and to reduce the entry-level knowledge required by the users who wish to design a system, and to promote the use of this design for monitoring natural environments, we would like to open source the design of SMARTCONE for the public. It can be modified for use in other applications to satisfy their requirements without the need to build from scratch. [ABSTRACT FROM AUTHOR]

Uprooting represents a key disturbance process in forests, forming pit-mound microtopography, which can then dramatically impact pedogenesis and the forest ecology. At our study sites in northern Michigan, where well-drained, sandy Spodosols dominate, pit-mound microtopography tends to persist for millennia. Because of its persistence, the influence of this type of microtopography is greater here than in most forests. In that respect, our sites represent an end member along a continuum of forest soil disturbance by uprooting. We studied post-uprooting pedogenesis (at 14 dated pit-mound pairs), mapped and characterized the pit-mound topography (over 2.8 ha), the soils below (within 317 soil profiles), and the trees above, to better understand the complex interactions among this type of disturbance regime and forest dynamics. We used a pair correlation function and chi-square test approach to study the relationships between treethrow features and the living trees at one of these sites. Soil variability as affected by microtopography, was studied using geostatistics. Pit-mound microtopography here covers 17% of the surface and are generally randomly distributed across the forest floor. Mounds are more prominent features of the forest floor than are pits. Pits infill with sediment and litter, obscuring them, whereas mounds persist for millennia in the sandy sediment because runoff is limited, and litter forms a protective armor. Treethrow features had volumes of roughly 214–225 m 3 /ha, and on average, each uprooting event translocated 0.6 m 3 of soil about 0.8 m laterally and 0.1–0.2 m vertically. Areas of the pit-mound features did not differ between slope aspects, supporting an idea that on the gentle slopes of the study sites, uprooting does little to affect the movement of sediment downslope. The exceptional longevity of the treethrow features is probably a factor in the statistical randomness with which treethrow features are distributed on the forest floor, as footprints of many uprooting events are interlaced across the forest floor. As reported elsewhere, soil development was accelerated in pits, leading to increasingly greater differences in soil development between pits and mounds, over time, and illustrating the concept of locally divergent pedogenesis. In older pits, the abnormally thick soil profiles extent so far below the depth of rooting that they are unlikely to be disturbed by future uprooting events. On the coarser spatial scale of the forest stand, uprooting decreased the ranges and increased the sills of spatial autocorrelation for O, E and Bhs horizon thicknesses. The effect of treethrow dynamics on soil characteristics was greatest and statistically most significant for E horizon thicknesses, where the range was decreased from 13 m to 10 m, whereas the maximal level of semivariance (sill) increased by 42%. All tree species preferred treethrow mounds to pits or undisturbed microsite for regeneration, especially Acer saccharum . [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Northern Apennines, landslides involving weak rocks such as clay shales are widespread and often cause damage to public infrastructure and private properties. These landslides, mostly classifiable as earthflows, generally exhibit continuous slow movements, with temporary increases of velocity controlled both by groundwater and rainfall regime. Although the relationship between precipitation, groundwater flow and displacement rate is evident, its quantitative description remains problematic. We use piezometric and slope movement continuous monitoring to investigate the groundwater flow system in the vicinity of the contact between clay shales and overlying more permeable units, where the village of Lizzano in Belvedere is located. Our aim is to describe the groundwater flow and its relation to slope deformation in order to simulate the effect of possible drainage measures both on piezometric levels and expected displacement rates. Timing and magnitude of piezometric responses at different depths are related to observed deformations and used to calibrate a transient 3D groundwater flow model. Groundwater modeling validates the conceptual hydrogeological scheme and allows simulation of the impact of surface and deep drainages on piezometric levels. Results indicate that horizontal drains are more effective than infiltration reduction measures, both in terms of drawdown and time effectiveness of action. Simulated hydraulic heads are then used to produce a probabilistic prediction of the expected displacement rates by means of an empirical method. In the case of Lizzano in Belvedere, according to our results, the lowering of hydraulic heads operated by horizontal drains can reduce the velocity of slope movements from centimeters per year to millimeters per year. [ABSTRACT FROM AUTHOR]

ABSTRACT Differential SAR Interferometry (DInSAR) is a technique that can be used to detect and characterize slope movements. It is investigated here as a tool for establishing a detailed overview of complex slope movements at a regional scale in an Alpine context. This paper gives specific recommendations to use and to understand DInSAR signals in mountainous areas located above the tree line, excluding glaciated areas. It proposes a systematic procedure based on accurate interpretations of interferometric signals from a large DInSAR dataset to locate and estimate the displacement rate of moving zones. The methodology was successfully applied in the Western Swiss Alps, where about 1500 moving objects were detected above the tree line using a large dataset of ERS and JERS interferograms dating from the 1990s. The DInSAR-detected movements had a displacement rate ranging from a few centimeters to several meters per year and were attributed to various types of mass wasting phenomena (rock glaciers, landslides, etc.). This kind of inventory derived from DInSAR can be used as a preliminary tool for natural hazard management and process understanding in mountain areas. As automatic data archiving and systematic acquisition of SAR data are ensured worldwide for most SAR sensors, a similar methodology can basically be applied in many other parts of the globe - also by using data from current SAR sensors - as long as a high resolution DEM is available. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Based on the results of similar material simulation, the laws of slope movement due to mining under a gully were analyzed. Selected a slope rock as objective, the mechanisms of slope movement influence upon underground mining were proposed, and respective structural models were built by means of numerical modeling and physical simulation. It holds the point that the influence of slope movement on underground mining could be controlled to some extent by appropriate measures. The results indicate that, for gully-ward mining, which mines toward a gully, the slope rock slides horizontally and rotates in layers; for gully-away mining, which mines away from the gully, the slope rock rotates in a reversed polygon. The slope movement associated with mining under a gully is attributed to pre-existing free faces in the ground gully and underground mining-induced free faces. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Dereköy landslide threatening the town of Dereköy, Konya, Turkey is investigated in order to assess and manage the associated risk. Dereköy town, located 12 km west of Konya city center, which is the second largest city in central Anatolia, has been extending due to the demand for new settlement places in Konya for the last decade. As most of the town is situated on the slopes of Meram river valley, on which the slope movements are observed, the risk of landslide has been increasing due to these new settlements. In this study, the landslide risk in Dereköy is assessed by following the so-called decision analytical procedure. The risk is defined by multiplication of hazard and consequences of the hazard. The hazard, which is the probability of slope failure, is computed by using the first-order second-moment (FOSM) method. The possible consequences of a landslide in Dereköy are analyzed and their costs are assessed relative to each other. A decision tree for choosing among the possible alternatives for reducing the risk is constructed in order to manage the risk. [ABSTRACT FROM AUTHOR]

A MATLAB based backpropagation neural network (BPNN) model has been developed. Two major geo-engineering applications, namely, earth slope movement and ground movement around tunnels, are identified. Data obtained from case studies are used to train and test the developed model and the ground movement is predicted with the help of input variables that have direct physical significance. A new approach is adopted by introducing an infiltration coefficient in the network architecture apart from antecedent rainfall, slope profile, groundwater level and strength parameters to predict the slope movement. The input variables for settlement around underground excavations are taken from literature. The neural network models demonstrate a promising result predicting fairly successfully the ground behavior in both cases. If input variables influencing output goals are clearly identified and if a decent number of quality data are available, backpropagation neural network can be successfully applied as mapping and prediction tools in geotechnical investigations. [ABSTRACT FROM AUTHOR]

In the Ecuadorian Andes, episodic slope movements comprising shallow rotational and translational slides and rapid flows of debris and soil material are common. Consequently, not only considerable financial costs are experienced, but also major ecological and environmental problems arise in a larger geographical area. Sediment production by slope movement on hillslopes directly affects sediment transport and deposition in downstream rivers and dams and morphological changes in the stream channels. In developing countries world-wide, slope movement hazards are growing: increasing population pressure and economic development force more people to move to potentially hazardous areas, which are less suitable for agriculture and rangelands.This paper describes the methods used to determine the controlling factors of slope failure and to build upon the results of the statistical analysis a process-based slope stability model, which includes a dynamic soil wetness index using a simple subsurface flow model. The model provides a time-varying estimate of slope movement susceptibility, by linking land-use data with spatially varying hydrologic (soil conductivity, evapotranspiration, soil wetness) and soil strength properties. The slope stability model was applied to a high Andean watershed (Gordeleg Catchment, 250 ha, southern Ecuadorian Andes) and was validated by calculating the association coefficients between the slope movement susceptibility map of 2000 and the spatial pattern of active slope movements, as measured in the field with GPS. The proposed methodology allows assessment of the effects of past and future land-use change on slope stability. A realistic deforestation scenario was presented: past land-use change includes a gradual fragmentation and clear cut of the secondary forests, as observed over the last four decades (1963–2000), future land-use change is simulated based on a binary logistic deforestation model, whereby it was assumed that future land-use change would continue at the same rate and style as over the last 37 years (1963–2000). [Copyright &y& Elsevier]

Landslides are the most common natural hazard in British Columbia. The province has recorded the largest number of historical landslide fatalities in Canada, and damage to infrastructure comes at a great cost. In order to understand the potential impacts of landslides, radar remote sensing has become a cost-effective method for detecting downslope movements. This study investigates downslope movements in the Southern Interior of British Columbia, Canada, with Sentinel-1 and RADARSAT Constellation Mission (RCM) interferometric synthetic aperture radar (InSAR) data. The 2-dimensional time-series analysis with Sentinel-1 ascending and descending InSAR pairs from October 2017 to June 2021 observed distinct earthflow movements of up to ~15 cm/year in the east–west direction. The Grinder Creek, Red Mountain, Yalakom River, and Retaskit Creek earthflows previously documented are still active, with east–west movements of ~30 cm over the past four years. New RCM data acquired from June 2020 to September 2020 with a 4-day revisit capability were compared to 12-day Sentinel-1 InSAR pairs. The 4-day RCM InSAR pairs at higher spatial resolution showed better performance by detecting relatively small-sized slope movements within a few hundred meters, which were not clearly observed by Sentinel-1. The temporal variabilities observed from the RCM InSAR showed great potential for observing detailed slope movements within a narrower time window. [ABSTRACT FROM AUTHOR]

In September 1979, rain-induced complex landslides occurred in two separate localities along the slopes of the Akovolwo Mountains near Jato-Aka in the Kwande Local Government area of Benue State, Nigeria. The two movements developed on bedrock slopes covered by a veneer of colluvium and (or) residuum no more than 1.5 to 2m deep. Each started as a slump and graduated into a debris flow. The slump, extending downhill a short distance away from the head scarp, had been reconstituted into a debris flow as the initial movement (sliding movement) of the soil mass caused remoulding of the saturated moving mass into viscous debris-laden mud. The resulting mass moved partly along a pre-existing mountain stream channel and partly along a fresh channel it cleared in the savanna forest. At the break of slope, the mass of boulders was dumped and a trail of smaller fragments littered the channels towards the Katsina-Ala River. [ABSTRACT FROM AUTHOR]