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1
Wang, H. B., B. Zhou, S. R. Wu, J. S. Shi e B. Li. "Characteristic analysis of large-scale loess landslides: a case study in Baoji City of Loess Plateau of Northwest China". Natural Hazards and Earth System Sciences 11, n. 7 (5 luglio 2011): 1829–37. http://dx.doi.org/10.5194/nhess-11-1829-2011.
Testo completoAbstract (sommario):
Abstract. Landslides are one of the most common geologic hazards in the Loess Plateau of northwest China, especially with some of the highest landslide densities found in Shaanxi and adjacent provinces. Prior to assessing the landslide hazard, a detailed landslide inventory map is fundamental. This study documents the landslides on the northwest Loess Plateau with high accuracy using high-resolution Quickbird imagery for landslide inventory mapping in the Changshou valley of Baoji city. By far the majority of landslides are in loess, representing small-scale planar sliding. Most of the large-scale landslides involve loess and bedrock, and the failure planes occurred either along the contacts between fluvial deposits and Neogene argillites, or partially within the bedrock. In the sliding zones of a large scale landslide, linear striations and fractures of the soils were clearly developed, clay minerals were oriented in the same direction and microorganism growths were present. From the analysis of microstructure of sliding soils, it is concluded that the Zhuyuan landslide can be reactivated if either new or recurring water seepage is caused in the sliding surface. It can be concluded that most landslides are attributed to the undercutting of the slope associated with gullying, and numerous ancillary factors including bedrock-loess interface, slope steepness, vegetation cover and land utilization.
2
Glassmeyer, Michael P., e Abdul Shakoor. "Factors Contributing to Landslide Susceptibility of the Kope Formation, Cincinnati, Ohio". Environmental and Engineering Geoscience 27, n. 3 (11 marzo 2021): 307–18. http://dx.doi.org/10.2113/eeg-d-20-00077.
Testo completoAbstract (sommario):
ABSTRACT The objective of this study was to evaluate the factors that contribute to the high frequency of landslides in the Kope Formation and the overlying colluvial soil present in the Cincinnati area, southwestern Ohio. The Kope Formation consists of approximately 80 percent shale inter-bedded with 20 percent limestone. The colluvium that forms from the weathering of the shale bedrock consists of a low-plasticity clay. Based on field observations, LiDAR data, and information gathered from city and county agencies, we created a landslide inventory map for the Cincinnati area, identifying 842 landslides. From the inventory map, we selected 10 landslides that included seven rotational and three translational slides for detailed investigations. Representative samples were collected from the landslide sites for determining natural water content, Atterberg limits, grain size distribution, shear strength parameters, and slake durability index. For the translational landslides, strength parameters were determined along the contact between the bedrock and the overlying colluvium. The results of the study indicate that multiple factors contribute to landslide susceptibility of the Kope Formation and the overlying colluvium, including low shear strength of the colluvial soil, development of porewater pressure within the slope, human activity such as loading the top or cutting the toe of a slope, low to very low durability of the bedrock that allows rapid disintegration of the bedrock and accumulation of colluvial soil, undercutting of the slope toe by stream water, and steepness of the slopes.
3
Robertson, Jesse E., Karl E. Karlstrom, Matthew T. Heizler e Laura J. Crossey. "Realignments of the Colorado River by ∼2 m.y. of rotational bedrock landsliding: The Surprise Valley landslide complex, Grand Canyon, Arizona". Geosphere 17, n. 6 (1 ottobre 2021): 1715–44. http://dx.doi.org/10.1130/ges02280.1.
Testo completoAbstract (sommario):
Abstract The Surprise Valley landslide complex is the name used here for a group of prominent river-damming landslides in Grand Canyon (Arizona, USA) that has shifted the path of the Colorado River several times in the past 2 m.y. We document a sequence of eight landslides. Three are Toreva-block landslides containing back-rotated but only mildly disrupted bedrock stratigraphy. The largest of these landslides, Surprise Valley landslide, is hypothesized to have dammed the Colorado River, cut off a meander loop through Surprise Valley, and rerouted the river 2.5 km south to near its present course at the Granite Narrows. Another bedrock landslide, Poncho's runup, involved a mass detachment from the north side of the river that drove a kilometer-scale bedrock slab across the river and up the south canyon wall to a height of 823 m above the river. A lake behind this landslide is inferred from the presence of mainstem gravels atop the slide that represent the approximate spillway elevation. We postulate that this landslide lake facilitated the upriver 133 Mile slide detachment and Toreva block formation. The other five landslides are subsequent slides that consist of debris from the primary slides; these also partially blocked and diverted the Colorado River as well as the Deer Creek and Tapeats Creek tributaries into new bedrock gorges over the past 1 m.y. The sequence of landslides is reconstructed from inset relationships revealed by geologic mapping and restored cross-sections. Relative ages are estimated by measuring landslide base height above the modern river level in locations where landslides filled paleochannels of the Colorado River and its tributaries. We calculate an average bedrock incision rate of 138 m/m.y. as determined by a 0.674 ± 0.022 Ma detrital sanidine maximum depositional age of the paleoriver channel fill of the Piano slide, which has its base 70 m above the river level and ∼93 m above bedrock level beneath the modern river channel. This date is within error of, and significantly refines, the prior cosmogenic burial date of 0.88 ± 0.44 Ma on paleochannel cobbles. Assuming steady incision at 138 m/m.y., the age of Surprise Valley landslide is estimated to be ca. 2.1 Ma; Poncho's runup is estimated to be ca. 610 ka; and diversion of Deer Creek to form modern Deer Creek Falls is estimated to be ca. 400 ka. The age of the most recent slide, Backeddy slide, is estimated to be ca. 170 ka based on its near-river-level position. Our proposed triggering mechanism for Surprise Valley landslides involves groundwater saturation of a failure plane in the weak Bright Angel Formation resulting from large volumes of Grand Canyon north-rim groundwater recharge prior to establishment of the modern Deer, Thunder, and Tapeats springs. Poncho's and Piano landslides may have been triggered by shale saturation caused by 600–650 ka lava dams that formed 45 river miles (73 river km; river miles are measured along the Colorado River downstream from Lees Ferry, with 1 river mile = 1.62 river kms) downstream near Lava Falls. We cannot rule out effects from seismic triggering along the nearby Sinyala fault. Each of the inferred landslide dams was quickly overtopped (tens of years), filled with sediment (hundreds of years), and removed (thousands of years) by the Colorado River, as is also the potential fate of modern dams.
4
Adella Syavira, Y Yatini e Wrego Seno Giamboro. "Identification of landslide potential based on Ground Penetrating Radar (GPR) data in Prambanan District, Sleman, Yogyakarta". Global Journal of Engineering and Technology Advances 13, n. 2 (30 novembre 2022): 071–78. http://dx.doi.org/10.30574/gjeta.2022.13.2.0193.
Testo completoAbstract (sommario):
The application of the Ground Penetrating Radar (GPR) method which was carried out in the Prambanan District, Sleman, Special Region of Yogyakarta was to determine the geometry of the slip plane of potential landslides. This method can see the contrast between the slip plane of the landslide and the landslide material that is above the slip plane. Measurements were made on field "A" consisting of 6 tracks and field "B" consisting of 7 tracks. The cross section of the radargram shows a penetration depth of about 6 - 7 meters, divided into 3 layers, namely, the S1 layer (soil), the S2 layer (transition zone), and bedrock. The depth of the slip field for potential landslides produced at the boundary layers of S1 and S2 is about 1 – 1.5 meters and the depth of the boundary layers for s2 and bedrock is about 2 – 3 meters. The geometry distribution map of the slip plane shows the type of landslide in the form of a translational landslide.
5
Miles, D. W. R., e F. J. Swanson. "Vegetation composition on recent landslides in the Cascade Mountains of western Oregon". Canadian Journal of Forest Research 16, n. 4 (1 agosto 1986): 739–44. http://dx.doi.org/10.1139/x86-132.
Testo completoAbstract (sommario):
Shallow, rapid landslides are common events and significant causes of vegetation disturbance in the Pacific Northwest. Landslides remove surface soil and above- and below-ground biomass from steep slopes and deposit them downslope or in streams. Vegetation cover and frequency were sampled on 25 landslides aged 6–28 years in the Cascade Mountains of western Oregon. Landslides sampled were debris avalanches ranging in surface area from 36 to 1287 m2, in elevation from 460 to 1100 m, and in slope from 40 to 173%. The landslides originated in undisturbed forests, recently harvested tracts of timber, road cuts, and road fills. Substrates within landslide areas were separated into five types and the vegetation cover was estimated for each: bedrock, 19%; secondary erosion, 25%; primary scar, 51%; secondary deposition, 57%; primary deposition, 71%. Vegetation cover averaged 51% overall and cover ranged from 7 to 88% among landslide sites. No relation between landslide age and vegetation cover was established. Pseudotsugamenziesii (Mirb.) Franco was the most common tree species overall and dominated all substrates except bedrock, where no single tree species occurred on more than 20% of the plots. Rubusursinus Cham. & Schlecht. was the most common shrub species on all substrates. Anaphalismargaritacea (L.) B & H and Trientalislatifolia Hook, were the most common herb species on all substrates except bedrock, where annual Epilobium spp. were most common.
6
Sanhueza-Pino, Katia, Oliver Korup, Ralf Hetzel, Henry Munack, Johannes T. Weidinger, Stuart Dunning, Cholponbek Ormukov e Peter W. Kubik. "Glacial advances constrained by 10Be exposure dating of bedrock landslides, Kyrgyz Tien Shan". Quaternary Research 76, n. 3 (novembre 2011): 295–304. http://dx.doi.org/10.1016/j.yqres.2011.06.013.
Testo completoAbstract (sommario):
AbstractNumerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains unresolved due to the lack of "absolute" age constraints. Here we present the first 10Be exposure ages for three prominent (> 107 m3) bedrock landslides that blocked major rivers and formed lakes, two of which subsequently breached, in the northern Kyrgyz Tien Shan. Three 10Be ages reveal that one landslide in the Alamyedin River occurred at 11–15 ka, which is consistent with two 14C ages of gastropod shells from reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in semi-arid continental interiors, with a 10Be age of 63–67 ka. The Ukok River landslide deposit(s) yielded variable 10Be ages, which may result from multiple landslides, and inheritance of 10Be. Two 10Be ages of 8.2 and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial erosion, hence their locations and 10Be ages mark maximum extents and minimum ages of glacial advances, respectively. Using toe-to-headwall altitude ratios of 0.4–0.5, we reconstruct minimum equilibrium-line altitudes that exceed previous estimates by as much as 400 m along the moister northern fringe of the Tien Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for glacial advances in landscapes where moraines and glacial deposits have low preservation potential.
7
Wang, Hao, Peng Wang, Hongyu Qin, Jianwei Yue e Jianwei Zhang. "Method to Control the Deformation of Anti-Slide Piles in Zhenzilin Landslide". Applied Sciences 10, n. 8 (19 aprile 2020): 2831. http://dx.doi.org/10.3390/app10082831.
Testo completoAbstract (sommario):
Anti-slide piles were used in the region of the Zhenzilin landslide in Sichuan, China. The horizontal displacement of these piles exceeds specifications. Deterioration in bedrock properties may cause deformation, thereby causing landslide destabilization. An approach was developed for the analysis of anti-slide pile in two bedrocks with different strengths below the slip surface. A relationship has been established between the modulus of subgrade reaction of the first weak bedrock and reasonable embedded length for landfill slopes with strata of various strengths. Furthermore, the influence of embedding length on deformation has been studied to determine the reasonable embedded length, which helps reduce deformation and ensure landslide stability. The results reveal that (1) at a constant embedded length, horizontal displacement increases with the thickness of the first soft bedrock, meanwhile the maximum shear force remains constant, and the bending moment first increases followed by subsequent decrease; (2) with an increase in the embedded length, horizontal displacement and the maximum shear force of the pile in the embedded bedrock decrease, whereas the bending moment increases; (3) the maximum internal forces and horizontal displacement increase with a decrease in the subgrade reaction modulus of the first weak rock; and (4) the reasonable embedded length of an anti-slide pile increases with a decrease in the subgrade reaction modulus of the first weak bedrock. The proposed approach can be employed to design anti-slide piles in similar landslide regions to control pile-head deformation.
8
Pan, Shangtao, Wei Gao e Ruilin Hu. "Physical Modeling for Large-Scale Landslide with Chair-Shaped Bedrock Surfaces under Precipitation and Reservoir Water Fluctuation Conditions". Water 14, n. 6 (21 marzo 2022): 984. http://dx.doi.org/10.3390/w14060984.
Testo completoAbstract (sommario):
The deformation and failure mechanisms of historical landslides, characterized with different types of bedrock surface shapes which are known to have been induced by rainfall and reservoir water fluctuations, is an important issue currently being addressed by many researchers. The Zhaoshuling Landslide of the Three Gorges Reservoir Region, which was characterized with a chair-shaped bedrock surface under rainfall and reservoir water fluctuation conditions, was selected as an example in this study’s physical modeling process. The results of different parameters, including the displacements, pore water pressure, and total soil pressure during the landslide event, revealed that the Zhaoshuling Landslide with a chair-shaped bedrock surface had been extremely sensitive to heavy rainfall coupled with the rapid lowering of the water levels. Then, based on the data analysis results of the monitoring of the rainfall and groundwater levels, as well as the reservoir water levels, a conceptual model was put forward to explain the failure mechanisms. It was believed that the chair-shaped bedrock at the toe of the slope had been subjected to a localized zone of high transient pore water pressure, which had significantly adverse effects on the mechanisms of the slope stability.
9
Regmi, Sanjeev, e Ranjan Kumar Dahal. "Slope stability issues of Bukula Landslide in Raghuganga Hydropower Project". Journal of Nepal Geological Society 65 (22 agosto 2023): 151–56. http://dx.doi.org/10.3126/jngs.v65i01.57774.
Testo completoAbstract (sommario):
Slope stability concerns hold global significance among researchers, professionals, and academicians. Despite various research studies, geological and geotechnical investigations on landslides, there is still a lack of proper and comprehensive landslide hazard study, accurate data acquisition, and effective monitoring mechanism in Nepal. The objective of this present study is to identify the type of failure, causes and effects of landslide and possible mitigation measures of Bukula Landslide located within Raghuganga Hydropower Project in Myagdi. This landslide is a large-scale landslide that spans over 500 meters with vertical relief exceeding 300 m. Based on visual inspection, wedge, toppling, and buckling failures prevail within the landslide. The bedrock is thinly foliated and moderately jointed, while 3 m long tension cracks are observed along the foot trail across the landslide area, indicating that the slope is unstable. Notably, buckling failures are common in highly jointed bedrock with low RQD. Likewise, sheared zones/weak zones were observed within the landslide area. The geological survey, kinematic analysis and numerical simulations of the hillslope revealed that Bukula landslide was triggered by sheared rock mass and river toe cutting. To mitigate the problems caused by the landslide, proper support structure installation and drainage system design are necessary.
10
Melchiorre, C., e A. Tryggvason. "Application of a fast and efficient algorithm to assess landslide prone areas in sensitive clays – toward landslide susceptibility assessment, Sweden". Natural Hazards and Earth System Sciences Discussions 2, n. 12 (19 dicembre 2014): 7773–806. http://dx.doi.org/10.5194/nhessd-2-7773-2014.
Testo completoAbstract (sommario):
Abstract. This work deals with susceptibility assessment in sensitive clays at national scale. The proposed methodology is based on a procedure which uses soil data and Digital Elevation Models to detect areas prone to landslides and has been applied in Sweden for several years. Specifically, we tested an algorithm which is able to detect soil and slope criteria guaranteeing a faster execution compared to other implementations and an efficient filtering procedure. The adopted computational solution allows using local information on depth to bedrock and several cross-sectional angle thresholds, and therefore opens up new possibilities to improve landslide susceptibility assessment. We tested the algorithm in the Göta River valley and evaluated the effect of filtering, depth to bedrock and cross-sectional angle thresholds on model performance. The thresholds were derived by analysing the relationship between landslide scarps and the Quick Clay Susceptibility Index (QCSI). The results gave us important insights on how to implement the filtering procedure, the use of depth to bedrock and the derived cross-sectional angle thresholds in landslide susceptibility assessment.
11
Wu, Hong Gang, Tao Yang, Xiao Yun Chen, Hui Min Ma, Hong Li Zhang e Jun De Zhang. "Damage Mechanism Research of Yushu Airport Road Landslide No.3 Base on Elastoplastic Damage Constitutive Model". Applied Mechanics and Materials 744-746 (marzo 2015): 464–69. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.464.
Testo completoAbstract (sommario):
Due to the earthquake of Yushu in April 14, 2010, Airport Road landslide No.3 deformed cracking, resulting in lower stability of slope, triggering landslides and other diseases. Selecting the section 2-2 (mileage K823 + 809) of Airport Road landslide No.3 as the calculation section, we use the ABAQUS finite element program to establish landslide numerical mode. The slip mass of landslide was simulated by the elastic-plastic damage constitutive model, and the bedrock was analyzed as Mohr - Coulomb constitutive model. Landslide No3 is analyzed for example, and showed that earthquake triggering mechanism elastplastic damage constitutive model can describe the landslide very well.
12
Shaller, Philip J., Macan Doroudian e Michael W. Hart. "The Eureka Valley Landslide: Evidence of a Dual Failure Mechanism for a Long-Runout Landslide". Lithosphere 2020, n. 1 (2 dicembre 2020): 1–26. http://dx.doi.org/10.2113/2020/8860819.
Testo completoAbstract (sommario):
Abstract Long-runout landslides are well-known and notorious geologic hazards in many mountainous parts of the world. Commonly encompassing enormous volumes of debris, these rapid mass movements place populations at risk through both direct impacts and indirect hazards, such as downstream flooding. Despite their evident risks, the mechanics of these large-scale landslides remain both enigmatic and controversial. In this work, we illuminate the inner workings of one exceptionally well-exposed and well-preserved long-runout landslide of late Pleistocene age located in Eureka Valley, east-central California, Death Valley National Park. The landslide originated in the detachment of more than 5 million m3 of Cambrian bedrock from a rugged northwest-facing outcrop in the northern Last Chance Range. Its relatively compact scale, well-preserved morphology, varied lithologic composition, and strategic dissection by erosional processes render it an exceptional laboratory for the study of the long-runout phenomenon in a dry environment. The landslide in Eureka Valley resembles, in miniature, morphologically similar “Blackhawk-like” landslides on Earth, Mars, and minor planet Ceres, including the well-known but much larger Blackhawk landslide of southern California. Like these other landslides, the landslide in Eureka Valley consists of a lobate, distally raised main lobe bounded by raised lateral levees. Like other terrestrial examples, it is principally composed of pervasively fractured, clast-supported breccia. Based on the geologic characteristics of the landslide and its inferred kinematics, a two-part emplacement mechanism is advanced: (1) a clast-breakage mechanism (cataclasis) active in the bedrock canyon areas and (2) sliding on a substrate of saturated sediments encountered and liquefied by the main lobe of the landslide as it exited the main source canyon. Mechanisms previously hypothesized to explain the high-speed runout and morphology of the landslide and its Blackhawk-like analogs are demonstrably inconsistent with the geology, geomorphology, and mineralogy of the subject deposit and its depositional environment.
13
Marc, Odin, Jens M. Turowski e Patrick Meunier. "Controls on the grain size distribution of landslides in Taiwan: the influence of drop height, scar depth and bedrock strength". Earth Surface Dynamics 9, n. 4 (17 agosto 2021): 995–1011. http://dx.doi.org/10.5194/esurf-9-995-2021.
Testo completoAbstract (sommario):
Abstract. The size of grains delivered to rivers by hillslope processes is thought to be a key factor controlling sediment transport, long-term erosion and the information recorded in sedimentary archives. Recently, models have been developed to estimate the grain size distribution produced in soil, but these models may not apply to active orogens where high erosion rates on hillslopes are driven by landsliding. To date, relatively few studies have focused on landslide grain size distributions. Here, we present grain size distributions (GSDs) obtained by grid-by-number sampling on 17 recent landslide deposits in Taiwan, and we compare these GSDs to the geometrical and physical properties of the landslides, such as their width, area, rock type, drop height and estimated scar depth. All slides occurred in slightly metamorphosed sedimentary units, except two, which occurred in younger unmetamorphosed shales, with a rock strength that is expected to be 3–10 times weaker than their metamorphosed counterparts. For 11 landslides, we did not observe substantial spatial variations in the GSD over the deposit. However, four landslides displayed a strong grain size segregation on their deposit, with the overall GSD of the downslope toe sectors being 3–10 times coarser than apex sectors. In three cases, we could also measure the GSD inside incised sectors of the landslides deposits, which presented percentiles that were 3–10 times finer than the surface of the deposit. Both observations could be due to either kinetic sieving or deposit reworking after the landslide failure, but we cannot explain why only some deposits had strong segregation. Averaging this spatial variability, we found the median grain size of the deposits to be strongly negatively correlated with drop height, scar width and depth. However, previous work suggests that regolith particles and bedrock blocks should coarsen with increasing depth, which is the inverse of our observations. Accounting for a model of regolith coarsening with depth, we found that the ratio of the estimated original bedrock block size to the deposit median grain size (D50) of the deposit was proportional to the potential energy of the landslide normalized to its bedrock strength. Thus, the studied landslides agree well with a published, simple fragmentation model, even if that model was calibrated on rock avalanches with larger volume and stronger bedrock than those featured in our dataset. Therefore, this scaling may serve for future modeling of grain size transfer from hillslopes to rivers, with the aim to better understanding landslide sediment evacuation and coupling to river erosional dynamics.
14
Sauer, E. Karl, e E. A. Christiansen. "The Denholm landslide, Saskatchewan, Canada, an update". Canadian Geotechnical Journal 24, n. 1 (1 febbraio 1987): 163–68. http://dx.doi.org/10.1139/t87-017.
Testo completoAbstract (sommario):
The lower block of the Denholm landslide has moved 370 m over alluvium deposited by the North Saskatchewan spillway and river during the last 11 500 years at an average rate of 32 mm/year. These values must be considered minimal because erosion of the toe of the landslide is required for the formation of retrogressive landslides. The shear strength for the bedrock clay (shale) of the Lea Park Formation was back calculated to be [Formula: see text] assuming zero cohesion. Key words: retrogressive landslide, clay shale, residual strength, movement rates, geological age, inclinometer.
15
DE, Sunil Kumar. "Landslides and human interference in Darjiling Himalayas, India". Revista de Geomorfologie 19, n. 1 (10 dicembre 2017): 44–57. http://dx.doi.org/10.21094/rg.2017.014.
Testo completoAbstract (sommario):
Landslides are among the nature's primarily ways of adjustment to slope stability. In Darjiling Himalayas the process has been intensified by human interference mainly through rapid deforestation, incorrect construction procedure and unplanned tapping of natural resources. The present paper aims at investigating the occurrence of landslides mainly due to human intervention. For analyzing the acuteness of the problem, important events of landslides over time, landslide susceptibility map using traditional check-list and investigation of the nature of human intervention for landslide occurrences have been carried out. From the study it is found that extreme rainfall events of consecutive days accumulating an amount of 1000 to 1200 mm, coupled with deep weathering in susceptible structure could trigger to 5 to 10 m-thick landslides. Being saturated with percolating rainwater, such slopes even with a rainfall 50 of mm/h would cause disastrous landsllides. Common occurrence of landslides is found along the springs, where thick debris is removed along the slope, ontop of the bedrock.. Generally deforested urbanized tracts, illegal coal mining sites, tea gardens, artillery roads connecting hills with the plains are the most susceptible areas to sliding.
16
Postoev, G. P. "Mechanism specifics of the landslide-hazardous massif limit state formation and landslide block displacement". Геоэкология. Инженерная геология. Гидрогеология. Геокриология, n. 2 (18 maggio 2019): 13–20. http://dx.doi.org/10.31857/s0869-78092019213-20.
Testo completoAbstract (sommario):
In the landslide cycle of deep block movement development, the landslide process starts with the separation of the new landslide block from the bedrock massif, and it ends with the block displacement until the steady landslide head is formed in the hotbed (on the landslide slope). The initial stressed state in the bedrock massif with horizontal earth surface (before the landslide block forms) is controlled by the Mohr-Coulomb criterion. The landslide hotbed forming as well as the sliding basis appearing cause the change in the initial stress state and the formation of horizontally oriented dissipative blocks-structures. The principal stresses are concentrated on the boundary surfaces of these structures (which are of a circular cylindrical shape). The limit state forms along these boundary surfaces of the appropriate block in the local massif zone on the contact with the landslide hotbed. The displacement occurs along the same surfaces, provided the equilibrium is disturbed. In forming the limit state of the head scarp massif, the adjacent part of the landslide massif (within the boundaries of the earlier separated landslide block) acts as an additional load (creates an active vertical pressure from the landslide mass weight) to the horizon of the landslide basis. The bedrock massif interacts with the slope at the stage of preparing block displacement. The block limit state is achieved in case the head scarp height reaches its critical value (the slope edge is higher than the landslide head). Under the soil masses weight in the new landslide block, separated from the bedrock massif, as it subsides, the soil crushes in a lower part of the block, which has lost its balance, in the slide basis zone. The paper considers the conditions of the new landslide block formation, the beginning of block displacement process, the mechanism of interaction between blocks, the bedrock massif and the landslide body, which consists of earlier displaced landslide blocks. The paper also provides the rationale for the soil strength changes in the process of displacement and its significance in the landslide cycle completing, with comparing the results of theoretical and experimental studies.
17
Sun, Zhijie, Xuanyu Yang, Shuai Lu, Yang Chen e Pengfei Li. "Influence of a Landslide on a Tunnel in Loess-Bedrock Ground". Applied Sciences 12, n. 13 (3 luglio 2022): 6750. http://dx.doi.org/10.3390/app12136750.
Testo completoAbstract (sommario):
By combining model testing and numerical simulation, this paper focuses on the influence of landslides on tunnels in loess-bedrock strata by using the perfect landslide–tunnel system (LTS). A mechanical test and simulation (MTS) system was used to provide thrust for loading and unloading the trailing edge of the slope. A Particle Image Velocimetry (PIV) and 32 cluster strain gauges were adopted to monitor the deformation of the tunnel structure and landslide soil, and the sliding surface, respectively. By means of a numerical simulation, the deformation characteristics of a tunnel crossing loess-bedrock strata are comprehensively described. The influence of a cyclic load on the mechanical behavior and displacement of the tunnel and sliding surface is discussed in detail. The experimental results show that the thrust required for the first landslide is the largest, during multiple loading and unloading. With the increase in loading and unloading time, the sliding thrust gradually decreases and eventually remains stable. The landslide presents a progressive failure mode. There is a stress concentration in the upper part of the tunnel, which causes the secondary sliding phenomenon. The deformation of the sliding surface mainly occurs in the upper soil of the tunnel. The deformation direction of the tunnel is consistent with the sliding direction, and the deformation of the sliding surface mainly occurs in the soil above the tunnel. When disturbed by an external force, the tunnel deforms downward, and, when unloaded, the tunnel has a small rebound deformation. However, with the increase in loading–unloading times, the rebound deformation of the tunnel gradually decreases, and the permanent deformation gradually accumulates until the tunnel fails. The research results can provide reference for the construction and protection of tunnel engineering in loess regions, and have reference value for the control of tunnels crossing landslides.
18
Postoev, German P., Andrey I. Kazeev e Marat M. Kuchukov. "BEHAVIOR OF SOILS AND DISSIPATIVE GEOLOGICAL STRUCTURES DURING THE FORMATION OF A LANDSLIDE BLOCK". Gruntovedenie 2, n. 19 (2022): 58–64. http://dx.doi.org/10.53278/2306-9139-2022-2-19-58-64.
Testo completoAbstract (sommario):
The peculiarities of soil state and strength and its role as a “weak” layer in the groundmass are often represented as the main factor that determines the occurrence of a landslide or its activation. These concepts are usually extended both to shallow shear landslides and liquefaction-flow types, as well as to deep block landslides, such as compression-extrusion type, with the release of so-called “the main deformable horizon” of soils in the latter. The formation of a new landslide block is accompanied by the occurrence of destructive displacements in the landslide cirque, involving in displacements of the whole slope. Such events are common in urbanized areas, on slopes with the development of deep compression-extrusion landslides. This article discusses the mechanism of formation of a landslide block and the geological features of transformation of the stress-strain state of the ground mass. New data on the behavior of soils at various stages of dissipation are presented, including the case when the dissipative geological structure is separated from the bedrock in the form of a landslide block.
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Campforts, Benjamin, Charles M. Shobe, Philippe Steer, Matthias Vanmaercke, Dimitri Lague e Jean Braun. "HyLands 1.0: a hybrid landscape evolution model to simulate the impact of landslides and landslide-derived sediment on landscape evolution". Geoscientific Model Development 13, n. 9 (31 agosto 2020): 3863–86. http://dx.doi.org/10.5194/gmd-13-3863-2020.
Testo completoAbstract (sommario):
Abstract. Landslides are the main source of sediment in most mountain ranges. Rivers then act as conveyor belts, evacuating landslide-derived sediment. Sediment dynamics are known to influence landscape evolution through interactions among landslide sediment delivery, fluvial transport and river incision into bedrock. Sediment delivery and its interaction with river incision therefore control the pace of landscape evolution and mediate relationships among tectonics, climate and erosion. Numerical landscape evolution models (LEMs) are well suited to study the interactions among these surface processes. They enable evaluation of a range of hypotheses at varying temporal and spatial scales. While many models have been used to study the dynamic interplay between tectonics, erosion and climate, the role of interactions between landslide-derived sediment and river incision has received much less attention. Here, we present HyLands, a hybrid landscape evolution model integrated within the TopoToolbox Landscape Evolution Model (TTLEM) framework. The hybrid nature of the model lies in its capacity to simulate both erosion and deposition at any place in the landscape due to fluvial bedrock incision, sediment transport, and rapid, stochastic mass wasting through landsliding. Fluvial sediment transport and bedrock incision are calculated using the recently developed Stream Power with Alluvium Conservation and Entrainment (SPACE) model. Therefore, rivers can dynamically transition from detachment-limited to transport-limited and from bedrock to bedrock–alluvial to fully alluviated states. Erosion and sediment production by landsliding are calculated using a Mohr–Coulomb stability analysis, while landslide-derived sediment is routed and deposited using a multiple-flow-direction, nonlinear deposition method. We describe and evaluate the HyLands 1.0 model using analytical solutions and observations. We first illustrate the functionality of HyLands to capture river dynamics ranging from detachment-limited to transport-limited conditions. Second, we apply the model to a portion of the Namche Barwa massif in eastern Tibet and compare simulated and observed landslide magnitude–frequency and area–volume scaling relationships. Finally, we illustrate the relevance of explicitly simulating landsliding and sediment dynamics over longer timescales for landscape evolution in general and river dynamics in particular. With HyLands we provide a new tool to understand both the long- and short-term coupling between stochastic hillslope processes, river incision and source-to-sink sediment dynamics.
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Calista, Monia, Enrico Miccadei, Tommaso Piacentini e Nicola Sciarra. "Morphostructural, Meteorological and Seismic Factors Controlling Landslides in Weak Rocks: The Case Studies of Castelnuovo and Ponzano (North East Abruzzo, Central Italy)". Geosciences 9, n. 3 (9 marzo 2019): 122. http://dx.doi.org/10.3390/geosciences9030122.
Testo completoAbstract (sommario):
We investigated the role of the morphostructural setting and seismic and meteorological factors in the development of landslides in the piedmont of the Abruzzo Apennines. In February 2017, following a heavy snow precipitation event and a moderate seismic sequence (at the end of the Central Italy 2016–2017 seismic crisis), several landslides affected the NE-Abruzzo chain and piedmont area. This work is focused on the Ponzano landslide (Civitella del Tronto, Teramo) and the Castelnuovo landslide (Campli, Teramo) in the NE Abruzzo hilly piedmont. These landslides consist of: (1) a large translational slide-complex landslide, affecting the Miocene–Pliocene sandstone clay bedrock sequence of the piedmont hilly sector; and (2) a complex (topple/fall-slide) landslide, which occurred along a high and steep scarp on conglomerate rocks pertaining to terraced alluvial fan deposits of the Pleistocene superficial deposits. Both of the landslides are typical of the Abruzzo hilly piedmont and both of them largely affected houses and villages located on top of the scarp or within the slope. The landslides were studied by means of field geological and geomorphological mapping, borehole investigations, geostructural analysis and photogeological analysis. For the Ponzano landslide, a detail pre-post-landslide air photo interpretation allowed for defining the deformation pattern occurred on the slope. For the Castelnuovo landslide, the triggering factors and the stability of the slope were evaluated with FLAC3D numerical modelling, in pre- and post-landslide conditions. Through this integrated analysis, the triggering factors, the landslide mechanism and the stability conditions of the landslides and the characterization of two main types of landslides affecting the piedmont hilly area of the Abruzzo region were investigated.
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Huntley, David, Jessica Holmes, Peter Bobrowsky, Jonathan Chambers, Philip Meldrum, Paul Wilkinson, Shane Donohue et al. "Hydrogeological and geophysical properties of the very-slow-moving Ripley Landslide, Thompson River valley, British Columbia". Canadian Journal of Earth Sciences 57, n. 12 (dicembre 2020): 1371–91. http://dx.doi.org/10.1139/cjes-2019-0187.
Testo completoAbstract (sommario):
Landslides along a 10 km reach of Thompson River south of Ashcroft, British Columbia, have repeatedly damaged vital railway infrastructure, while also placing public safety, the environment, natural resources, and cultural heritage features at risk. Government agencies, universities, and the railway industry are focusing research efforts on a representative test site — the very-slow-moving Ripley Landslide — to manage better the geohazard risk in this corridor. We characterize the landslide’s form and function through hydrogeological and geophysical mapping. Field mapping and exploratory drilling distinguish 10 hydrogeological units in surficial deposits and fractured bedrock. Electrical resistivity tomography, frequency domain electromagnetic conductivity measurements, ground-penetrating radar, seismic pressure wave refraction, and multispectral analysis of shear waves; in conjunction with downhole measurement of natural gamma radiation, induction conductivity, and magnetic susceptibility provide a detailed, static picture of soil moisture and groundwater conditions within the hydrogeological units. Differences in electrical resistivity of the units reflect a combination of hydrogeological characteristics and climatic factors, namely temperature and precipitation. Resistive earth materials include dry glaciofluvial outwash and nonfractured bedrock; whereas glaciolacustrine clay and silt, water-bearing fractured bedrock, and periodically saturated subglacial till and outwash are conductive. Dynamic, continuous real-time monitoring of electrical resistivity, now underway, will help characterize water-flow paths, and possible relationships to independently monitor pore pressures and slope creep. These new hydrogeological and geophysical data sets enhance understanding of the composition and internal structure of this landslide and provide important context to interpret multiyear slope stability monitoring ongoing in the valley.
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Zhu, Bao Long, e Xi Yong Wu. "An Analysis of Rainfall-Induced Landslide in Colluvial and Eluvial Soils Overlying Xigeda Strata, Southwestern Sichuan, China". Advanced Materials Research 250-253 (maggio 2011): 2682–88. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2682.
Testo completoAbstract (sommario):
In late-July, 2005, a series of thunderstorms dropped 10 cm of rain in a 72-h period over southwestern Sichuan province. The storms also triggered more than 17 shallow landslides along the Lama Stream, about 2.5km from Jiuxiang Town, in Hanyuan County. Almost all of the landslides were translational, occurring along the contact between colluvial and eluvial soils and the underlying bedrock (claystones, mudstones, siltstones). 1# landslide was selected in the affected area for a detailed study of the shallow landslides. The record was made of the stratigraphy, slope geometry, landslide dimensions, hydrologic conditions, and contributing factors. Both colluvial soils and underlying bedrock were sampled for laboratory investigations, which included determination of natural water content, specific gravity, natural density, Atterberg limits, coefficient of consolidation, permeability, and shear-strength parameters. Data from laboratory tests were used to perform stability analyses by the infinite-slope analysis method, with respect to varying slope angles, strength parameters, and thicknesses of saturated colluvial and eluvial soils. The results of the study indicate that the shallow landslides of Xigeda strata occurred when the colluvial soils reached 90% to 100% saturation, depending upon the slope angles. It provides a basis for taking reasonable reinforcement measures for the landslides.
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Pushpakumara, T. D. C., e P. P. G. P. Madushanka. "Analysis and Prediction of Landslide using Drone Image and GIS Techniques- Case Study Aranayaka Area". International Journal of Advanced Remote Sensing and GIS 9, n. 1 (24 dicembre 2020): 3466–72. http://dx.doi.org/10.23953/cloud.ijarsg.497.
Testo completoAbstract (sommario):
Occurrence of Landslides has become a major impact considering the damage a landslide can do in a quick time. Among the natural hazards the country is exposed up to now, severe landslides are the upcoming major issue since it can affect to the lives of people too. In this case study from Aranayaka area, a method is developed to analyses and identify landslide prone areas. The methodology of the research includes collecting terrain data, building a model using geographic information system (GIS), satellite image processing, preparation of a landslide susceptibility potential map and giving recommendations on the landslide hazards. Among the factors that influence a landslide such as drainage, bedrock condition, slope angle range, land forms and etc. (published by National Building Research Organization), the foremost controllable and mostly varying factor. In this research, landslide prone areas are identified using the land use data. Identification of landslide hazards plays an important role in disaster management and risk controlling since a severe landslide can affect several aspects such as human lives, agricultural aspects, economic activities and transportation. This paper includes the background of the entire research that has developed up to current situation. This method can be used around the world as well as in the country.
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Marc, Odin, Robert Behling, Christoff Andermann, Jens M. Turowski, Luc Illien, Sigrid Roessner e Niels Hovius. "Long-term erosion of the Nepal Himalayas by bedrock landsliding: the role of monsoons, earthquakes and giant landslides". Earth Surface Dynamics 7, n. 1 (25 gennaio 2019): 107–28. http://dx.doi.org/10.5194/esurf-7-107-2019.
Testo completoAbstract (sommario):
Abstract. In active mountain belts with steep terrain, bedrock landsliding is a major erosional agent. In the Himalayas, landsliding is driven by annual hydro-meteorological forcing due to the summer monsoon and by rarer, exceptional events, such as earthquakes. Independent methods yield erosion rate estimates that appear to increase with sampling time, suggesting that rare, high-magnitude erosion events dominate the erosional budget. Nevertheless, until now, neither the contribution of monsoon and earthquakes to landslide erosion nor the proportion of erosion due to rare, giant landslides have been quantified in the Himalayas. We address these challenges by combining and analysing earthquake- and monsoon-induced landslide inventories across different timescales. With time series of 5 m satellite images over four main valleys in central Nepal, we comprehensively mapped landslides caused by the monsoon from 2010 to 2018. We found no clear correlation between monsoon properties and landsliding and a similar mean landsliding rate for all valleys, except in 2015, where the valleys affected by the earthquake featured ∼5–8 times more landsliding than the pre-earthquake mean rate. The long-term size–frequency distribution of monsoon-induced landsliding (MIL) was derived from these inventories and from an inventory of landslides larger than ∼0.1 km2 that occurred between 1972 and 2014. Using a published landslide inventory for the Gorkha 2015 earthquake, we derive the size–frequency distribution for earthquake-induced landsliding (EQIL). These two distributions are dominated by infrequent, large and giant landslides but under-predict an estimated Holocene frequency of giant landslides (> 1 km3) which we derived from a literature compilation. This discrepancy can be resolved when modelling the effect of a full distribution of earthquakes of variable magnitude and when considering that a shallower earthquake may cause larger landslides. In this case, EQIL and MIL contribute about equally to a total long-term erosion of ∼2±0.75 mm yr−1 in agreement with most thermo-chronological data. Independently of the specific total and relative erosion rates, the heavy-tailed size–frequency distribution from MIL and EQIL and the very large maximal landslide size in the Himalayas indicate that mean landslide erosion rates increase with sampling time, as has been observed for independent erosion estimates. Further, we find that the sampling timescale required to adequately capture the frequency of the largest landslides, which is necessary for deriving long-term mean erosion rates, is often much longer than the averaging time of cosmogenic 10Be methods. This observation presents a strong caveat when interpreting spatial or temporal variability in erosion rates from this method. Thus, in areas where a very large, rare landslide contributes heavily to long-term erosion (as the Himalayas), we recommend 10Be sample in catchments with source areas > 10 000 km2 to reduce the method mean bias to below ∼20 % of the long-term erosion.
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Hadi, Arif Ismul, Kirbani S. Brotopuspito, Subagyo Pramumijoyo e Hary C. Hardiyatmo. "Determination of Weathered Layer Thickness Around the Landslide Zone using the Seismic Refraction Method". IOP Conference Series: Earth and Environmental Science 830, n. 1 (1 settembre 2021): 012022. http://dx.doi.org/10.1088/1755-1315/830/1/012022.
Testo completoAbstract (sommario):
Abstract The thickness of the weathered layer in the landslide zone can be determined by the seismic refraction method. This study aims to determine the thickness of the weathered layer based on the primary wave velocity (P-wave or Vp ). Data acquisition is taken around the landslide zone, namely above the landslide, parallel to the landslide, and perpendicular to the landslide. The data were collected using a digital seismograph 16S24. Furthermore, the data obtained in the field is processed to obtain a 2-D model. The results showed that the thickness of the weathered layer above the landslide was 2.15 m - 4.59 m with a Vp value equal to 185 m / s. For the thickness of the weathered layer parallel to landslides is 0.80 m - 4.11 m with a Vp value equal to 300 m / s and the thickness of the weathered layer perpendicular to landslides is 0.01 m - 2.35 m with a Vp value equal to 300 m / s. Meanwhile, the bedrock layer under the weathered layer has Vp of between 517 m / s to 1065 m / s in the form of sub-consolidated clay to very dense clay lithology.
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Hadi, Arif Ismul, Kirbani S. Brotopuspito, Subagyo Pramumijoyo e Hary C. Hardiyatmo. "Determination of Weathered Layer Thickness Around the Landslide Zone using the Seismic Refraction Method". IOP Conference Series: Earth and Environmental Science 830, n. 1 (1 settembre 2021): 012022. http://dx.doi.org/10.1088/1755-1315/830/1/012022.
Testo completoAbstract (sommario):
Abstract The thickness of the weathered layer in the landslide zone can be determined by the seismic refraction method. This study aims to determine the thickness of the weathered layer based on the primary wave velocity (P-wave or Vp ). Data acquisition is taken around the landslide zone, namely above the landslide, parallel to the landslide, and perpendicular to the landslide. The data were collected using a digital seismograph 16S24. Furthermore, the data obtained in the field is processed to obtain a 2-D model. The results showed that the thickness of the weathered layer above the landslide was 2.15 m - 4.59 m with a Vp value equal to 185 m / s. For the thickness of the weathered layer parallel to landslides is 0.80 m - 4.11 m with a Vp value equal to 300 m / s and the thickness of the weathered layer perpendicular to landslides is 0.01 m - 2.35 m with a Vp value equal to 300 m / s. Meanwhile, the bedrock layer under the weathered layer has Vp of between 517 m / s to 1065 m / s in the form of sub-consolidated clay to very dense clay lithology.
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Togubu, Jamalun, Firman Firman, Anas Abdul Latif, Amrih Halil e Samsulbahri M. Madjid. "KAJIAN POTENSI LONGSOR LERENG GALIAN CURAM DI KELURAHAN KALUMATA KOTA TERNATE MENGGUNAKAN GEOLISTRIK". Journal of Science and Engineering 5, n. 2 (20 ottobre 2022): 121. http://dx.doi.org/10.33387/josae.v5i2.5240.
Testo completoAbstract (sommario):
The study of the potential for landslides on steep excavation slopes in Kalumata Village, Ternate City using geoelectricity is important to do. The location of the sirtu mining excavation which tends to be steep and close to residential areas is urgent to know the type of lithology so as to facilitate recommendations for handling to be carried out. The purpose of this study was to determine the lithological composition of the material from tracks 1, 2, and 3 along the steep excavation slope using the geoelectric resistivity Sclumberger configuration method. In addition, knowing the potential for landslides that will occur if there is no handling of steep slopes. This research is a quantitative type of field research. The research location is in the formation of lahar deposits (Gtla) and pyroclastic debris (pr) deposits. Trajectory 1 dominant lithology is 17.52 m of sand, andesite rock as an interlude and on the bedrock it is characterized by large resistivity (3241 m) while the top layer is clay type overburden. The 2 lithological paths consist of overburden, sand (7.82 m), silt (10.5 m), and andesite bedrock (resistivity 2811 m). The lithology of track 3 consists of overburden, andesite, sand (16.9 m), and andesite bedrock (4575 m). Lithology that tends to landslide in the field is overburden filled with sedimentary material in the form of clay, silt, and sandy silt (resistivity 1.5-114 m). Sand lithology with a resistivity of 479-855 m is very susceptible to landslides. Another factor causing landslides is the slope of the excavation which tends to be steep (> 60o). Keywords: Kalumata Village, Sclumberger configuration, lithology, landslide, sand
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Tohari, A., D. D. Wardhana, S. Feranie e G. A. Salsabila. "Identification of sliding surface using electrical-resistivity tomography for landslide mitigation: A case study of the Cibitung Landslide". IOP Conference Series: Earth and Environmental Science 1314, n. 1 (1 marzo 2024): 012030. http://dx.doi.org/10.1088/1755-1315/1314/1/012030.
Testo completoAbstract (sommario):
Abstract Landslide mitigation efforts require a knowledge of the geometry and depth of the sliding surface present in a landslide body. Electrical resistivity tomography is the most common geophysical method used in landslide investigation. This paper presents the results of a series of electrical resistivity tomography surveys performed using a dipole-dipole array configuration to identify the sliding surfaces within a landslide body located in the Cibitung landslide area. The ERT images parallel the landslide body suggest that the sliding surface located below the crown is characterized by a bedrock layer with very low resistivity values. This bedrock layer continues down-slope at a maximum depth of 9 m below the ground surface. In contrast, the landslide body is characterized by a higher resistivity value. Based on the interpretation of the ERT images, the landslide involved a non-circular deep sliding surface. The results of this study have been used, in combination with the geotechnical drilling data, to construct the landslide cross-section necessary to analyze landslide stability and subsequently to recommend a landslide stabilization measure.
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Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee e K. Freeborough. "Controls on the magnitude-frequency scaling of an inventory of secular landslides". Earth Surface Dynamics 1, n. 1 (11 dicembre 2013): 67–78. http://dx.doi.org/10.5194/esurf-1-67-2013.
Testo completoAbstract (sommario):
Abstract. Linking landslide size and frequency is important at both human and geological timescales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. The statistical behaviour of the magnitude-frequency of landslide inventories is usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behaviour is often characterised by a power-law relationship with a small landslide rollover. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behaviour and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite geological time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power-law relationship, well approximated by either an inverse gamma or double Pareto model. The scaling exponent for the power-law scaling of medium to large landslides is α = −1.71 ± 0.02. The small-event rollover occurs at a significantly higher magnitude (1.0–7.0 × 10−3 km2) than observed in single-event landslide records (~ 4 × 10−3 km2). We interpret this as evidence of landscape annealing, from which we infer that the SLI underestimates the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions. There are several possible reasons for this, including an incomplete data set, an incomplete landscape (i.e. relatively steep slopes are under-represented), and/or temporal transience in landslide activity during emergence from the last glacial maximum toward a generally more stable late-Holocene state. The proposed process of landscape annealing and the possibility of a transient hillslope response have the consequence that it is not possible to use the statistical properties of the current SLI database to rigorously constrain probabilities of future landslides in the UK.
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Hugenholtz, Chris H., e Denis Lacelle. "Geomorphic Controls on Landslide Activity in Champlain Sea Clays along Green’s Creek, Eastern Ontario, Canada". Géographie physique et Quaternaire 58, n. 1 (26 giugno 2006): 9–23. http://dx.doi.org/10.7202/013108ar.
Testo completoAbstract (sommario):
AbstractLandslides in Champlain Sea clays have played an important role in shaping Eastern Ontario’s landscape. Despite extensive research, there is a limited understanding of the relations between landslide activity, climatic controls, and the geomorphic evolution of river valleys in Champlain Sea clay deposits. With these issues in mind, a study was undertaken to determine the controls on the spatio-temporal distribution of contemporary landslide activity in valley slopes composed of Champlain Sea clay. The study area was the Green’s Creek valley located in the east end of Ottawa, Ontario. Observations and measurements indicate that landslide activity is closely related to valley development. An inventory of landslide activity from 73 years of aerial photographs revealed that landslides occurred preferentially in slopes located on the outside of meander bends, and that they often recurred in the same slope after a period of ripening. The largest and highest density of landslides occurred along a major tributary valley where geomorphic features such as knickpoints, V-shaped valley profiles and bedrock depth-to-slope height ratios reflect an unstable phase of valley development. A small number of landslides incurred successive failures along the slopes of the backscarp for several years-to-decades after the initial failure. Correlation analysis showed that the temporal distribution of landslide activity has fluctuated in response to decadal-scale changes in the amount of precipitation.
31
Dyachenko, V. V., V. A. Turkin, A. E. Vorobev, V. V. Kukartsev e Ya A. Tynchenko. "Mechanisms of high hazard landslide formation (rapid and slow)". Mining Industry Journal (Gornay Promishlennost), n. 4/2024 (23 agosto 2024): 96–100. http://dx.doi.org/10.30686/1609-9192-2024-4-96-100.
Testo completoAbstract (sommario):
The article discusses the results of studying the mechanism of formation and movement of rapid and slow clay landslides characterized by increased danger and catastrophic consequences for the technosphere. The consequences of landslides that occurred in various physical and geographical zones with different mineralogical and petrographic composition of rocks are considered. The analysis of the landslide formation features takes into account the slope gradients, actual elevations and local differences in elevation, changes in slope gradients, terrain roughness and direction of slopes, catchment areas, proximity of water bodies, tectonics, as well as the composition of soils and rocks. Three mechanisms that cause the movement of the landslide geomaterials are explained: the impact of gravity forces, fluidization and lubrication of the landslide bed in the direction of movement. It has been established that the gravity forces alone do not enable the rapid displacement of significant masses of geomaterials over long distances. An important factor is the reduced friction at the landslide bed due to lubrication, which is formed as a result of rainfall infiltration or geochemical transformation of a thin layer of bedrock in the course of the landslide geomaterial displacement. Landslides of the discussed genesis can pose a great hazard to various mine workings, open pits, in fact to any form of activity and facilities of the mining industry.
32
Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee e K. Freeborough. "Controls on the magnitude-frequency scaling of an inventory of secular landslides". Earth Surface Dynamics Discussions 1, n. 1 (1 luglio 2013): 113–39. http://dx.doi.org/10.5194/esurfd-1-113-2013.
Testo completoAbstract (sommario):
Abstract. Linking landslide size and frequency is important at both human and geological time-scales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. Landslide inventories are usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behavior is typically characterized by an inflected power-law relationship. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behavior and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power law relationship, well approximated by an inverse Gamma or double Pareto model. The scaling exponent for the power-law relationship is α = −1.76. The small-event rollover occurs at a significantly higher magnitude than observed in single-event landslide records, which we interpret as evidence of “landscape annealing” at these relatively short length-scales, noting the corollary that a secular dataset will tend to underestimate the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions, which we interpret as a non-linear or transient landscape response as the UK emerged from the last glacial maximum and through relatively volatile conditions toward a generally more stable late Holocene climate.
33
ur Rehman, Qasim, Waqas Ahmed, Muhammad Waseem, Sarfraz Khan, Asam Farid e Syed Husnain Ali Shah. "GEOPHYSICAL INVESTIGATIONS OF A POTENTIAL LANDSLIDE AREA IN MAYOON, HUNZA DISTRICT, GILGIT-BALTISTAN, PAKISTAN". Rudarsko-geološko-naftni zbornik 36, n. 3 (2021): 127–41. http://dx.doi.org/10.17794/rgn.2021.3.9.
Testo completoAbstract (sommario):
The Mayoon landslide in the Hunza District is a slowly developed, non-catastrophic landslide that has gained its importance in the last few years after its rapid activation and fast slip rate. The area is characterized by high earthquake hazards (zone 3 with a peak ground acceleration value of 2.4–3.2 m/s2) by the Building Code of Pakistan due to frequent earth quakes. The past high earthquake activity in the area has displaced the foliated rocks towards the south and is responsible for opening the bedrock joints. The head and body of the landslide are covered by unconsolidated material and have fractures of varying lengths and widths. The non-invasive geophysical techniques, including Ground Penetrating Radar (GPR) and Electrical Resistivity Soundings (ERS), are deployed to evaluate the Mayoon landslide subsurface. The subsurface is interpreted into a two-layer model. Bright reflectors and highly variable resistivity characterize the top layer (Layer-1). This layer is associated with a loose, highly heterogeneous, fragmented material deposited under glacial settings over the existing bedrock. Hyperbolic reflections and intermediate resistivity characterize the bottom layer (Layer-2). This layer is associated with foliated metamorphic bedrock. The hyperbolic reflections show faults/fractures within the bedrock. The extension of these fractures/faults with depth is uncertain due to decay in the GPR signal with depth. The intermediate resistivity shows the bedrock is weathered and foliated. Reflections within Layer-1 have disrupted directly above the fractures/faults suggesting a possible movement. A bright reflection between the two layers highlights the presence of the debonded surface. Loose material within Layer-1 coupled with debonding possesses a significant hazard to generate a landslide under unfavourable conditions, such as an intense rainstorm or earthquake activity.
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Clifton, A. Wayne, Richard T. Yoshida e Roy W. Chursinoff. "Regina Beach — a town on a landslide". Canadian Geotechnical Journal 23, n. 1 (1 febbraio 1986): 60–68. http://dx.doi.org/10.1139/t86-007.
Testo completoAbstract (sommario):
The town of Regina Beach is constructed on landslides along the Last Mountain Lake valley, a glacial meltwater channel in south-central Saskatchewan, Canada. The landslides are retrogressive in nature and are seated in bentonitic clay shale of the Bearpaw Formation. A study was conducted at Regina Beach to determine the sensitivity of the slopes to changes in slope geometry as a result of regrading, or groundwater changes. Back-calculated shear strength was compared with values from the laboratory and from other landslides in Cretaceous bedrock shales. Modest changes in grading of the toe areas would result in significant reductions in the local stability and future movements of upslope portions of the landslide. Development should minimize the amount of grading. Increased slope movement due to breaks in watermains was observed and measured. This correlated well with analysis. Development in landslide areas must assume that differential vertical and horizontal movements will occur. Proper site reconnaissance should identify optimum locations for buildings and services such that the risk of rupture or damage is minimized. Key words: landslide, retrogressive, back analysis, residual shear strength, Bearpaw Formation, inclinometer, slope movement.
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Blodgett, Troy A., e Bryan L. Isacks. "Landslide Erosion Rate in the Eastern Cordillera of Northern Bolivia". Earth Interactions 11, n. 19 (1 dicembre 2007): 1–30. http://dx.doi.org/10.1175/2007ei222.1.
Testo completoAbstract (sommario):
Abstract The northeastern edge of the Bolivian Eastern Cordillera is an example of a tectonically active plateau margin where orographically enhanced precipitation facilitates very high rates of erosion. The topography of the steepest part of the margin exhibits the classic signature of high erosion rates consisting of high-relief V-shaped valleys where landsliding is the dominant process of hillslope erosion and bedrock rivers are incising into the landscape. The authors mapped landslide scars on multitemporal aerial photographs to estimate hillslope erosion rates. Field surveys of landslide scars are used to calibrate a landslide volume versus area relationship. The mapped area of landsliding, in combination with an estimate of the time for landslide scars to revegetate, leads to an erosion rate estimate. The estimated revegetation time, 10–35 yr, is based on analysis of multitemporal aerial photographs and tree rings. About 4%–6% of two watersheds in the region considered were affected by landslides over the last 10–35 yr. This result implies an erosion rate of 9 ± 5 mm yr−1 assuming that 90% of a single landslide reaches the river on average. Classified Landsat Thematic Mapper images show that landslides are occurring at approximately the same rate all across an approximately 40-km-wide swath within the high-relief zones of the cordillera.
36
Qin, Yi, Jin Bing Wei, Hong Chun Zheng e Yu Long Cui. "Cause and Stability Analysis of Daomakan Lanslide in Xiangjiaba Reservoir". Applied Mechanics and Materials 204-208 (ottobre 2012): 581–85. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.581.
Testo completoAbstract (sommario):
Daomakan slope, a typical ancient slope by Jingsha River, locates in Xiangjiaba Reservoir. With the rising of water level of Xiangjiaba Reservoir, Daomakan slope might pose threaten to the reservoir. Based on the detailed field investigation, the author firstly proves that Daomakan slope is an ancient landslide by the following evidences: a 1.5 meters cracked layer was found at the front of the landslide and a very deep shearing scratch appeared on the bedrock surface. Meanwhile ,the evidences above can be used to speculate that the strong earthquake is the main cause in triggering the landslide. According to the triggering and sliding process, stability analysis is conducted from an engineering geological perspective. The method adopted in this paper is suitable for field investigation, and provides a certain reference value on the ancient seismic landslides stability analysis in Xiangjiaba Reservoir area.
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Li, Gen K., e Seulgi Moon. "Topographic stress control on bedrock landslide size". Nature Geoscience 14, n. 5 (29 aprile 2021): 307–13. http://dx.doi.org/10.1038/s41561-021-00739-8.
Testo completo
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Kvashuk, S. V., A. I. Bogdanov e V. S. Trapeznikov. "Dynamics of landslide processes within the Borisov Plateau of the East Manchurian Highlands". IOP Conference Series: Earth and Environmental Science 1154, n. 1 (1 marzo 2023): 012040. http://dx.doi.org/10.1088/1755-1315/1154/1/012040.
Testo completoAbstract (sommario):
Abstract The activation of unfavorable exogenous processes within the Borisov Plateau of the East Manchurian Highlands (landslides, which are the leading ones in the area, karst processes, ravine formations, etc.) is determined by the specific geological structure of the territory, in which eluvial-deluvial formations of the Quaternary age participate in the upper part of the section. They intensively change their physical and mechanical properties when moistened in a typical coastal climate, which causes unfavorable processes and phenomena that lead to deformations of artificial structures and subgrade. The currently used standard and innovative anti-landslide protection structures do not give a positive effect due to the deep bedrock. Recommendations are given for the development of anti-landslide measures.
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Iqbal, Javed, Xinbin Tu e Wei Gao. "The Impact of Reservoir Fluctuations on Reactivated Large Landslides: A Case Study". Geofluids 2019 (15 aprile 2019): 1–16. http://dx.doi.org/10.1155/2019/2374236.
Testo completoAbstract (sommario):
Filling of Xiangjiaba Reservoir Lake in the Southwest China triggered and reactivated numerous landslides due to water fluctuation. In order to understand the relationship between reservoirs and slope instability, a typical reservoir landslide (Dasha landslide) at the right bank of Jinsha River was selected as a case study for in-depth investigations. The detailed field investigations were carried out to identify the landslide with respect to its surroundings and to find out the slip surface. Boreholes were drilled to find out the subsurface lithology and the depth of failure of Dasha landslide. The in situ geotechnical tests were performed, and the soil samples from exposed slip surface were retrieved for geotechnical laboratory analysis. Finally, stability analysis was done using the 3D strength reduction method under different conditions of reservoir water level fluctuations and rainfall conditions. The in-depth investigations show that the Dasha landslide is a bedding rockslide which was once activated in 1986. The topography of Dasha landslide is relatively flat, while the back scarp and local terrain is relatively steep. The total volume of landslides is about 580×104 m3 with an average thickness of 20 m. Bedrock in the landslide area is composed of Suining Formation of the Jurassic age. The main rock type is silty mudstone with sandstone, and the bedding orientation is 300~310° ∠ 7~22°. The factor of safety (FOS) of Dasha landslide obtained by 3D strength reduction cannot meet the minimum safety requirement under the working condition of reservoir level fluctuation as designed, with effect of rainfall and rapid drawdown.
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Chen, Sheng-Chuan, Chia-Chi Chang, Hsun-Chuan Chan, Long-Ming Huang e Li-Ling Lin. "Modeling Typhoon Event-Induced Landslides Using GIS-Based Logistic Regression: A Case Study of Alishan Forestry Railway, Taiwan". Mathematical Problems in Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/728304.
Testo completoAbstract (sommario):
This study develops a model for evaluating the hazard level of landslides at Alishan Forestry Railway, Taiwan, by using logistic regression with the assistance of a geographical information system (GIS). A typhoon event-induced landslide inventory, independent variables, and a triggering factor were used to build the model. The environmental factors such as bedrock lithology from the geology database; topographic aspect, terrain roughness, profile curvature, and distance to river, from the topographic database; and the vegetation index value from SPOT 4 satellite images were used as variables that influence landslide occurrence. The area under curve (AUC) of a receiver operator characteristic (ROC) curve was used to validate the model. Effects of parameters on landslide occurrence were assessed from the corresponding coefficient that appears in the logistic regression function. Thereafter, the model was applied to predict the probability of landslides for rainfall data of different return periods. Using a predicted map of probability, the study area was classified into four ranks of landslide susceptibility: low, medium, high, and very high. As a result, most high susceptibility areas are located on the western portion of the study area. Several train stations and railways are located on sites with a high susceptibility ranking.
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Xiao, Zhuan Wen, e Lei Huang. "Analysis and Treatment of Landslide at the Tunnel Portal in Nanjing Road". Applied Mechanics and Materials 353-356 (agosto 2013): 686–91. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.686.
Testo completoAbstract (sommario):
The landslide at the tunnel portal in Nanjing Road is mainly determined by a weak intercalated layer between the completely weathered bedrock and the strongly weathered bedrock. The weak intercalated layer has low permeability and weak shear strength, and its interface dip outside of the slope. As the consequence, landslide is likely to happen again due to a rainstorm or other inducement. In order to prevent a second landslide, a comprehensive treatment scheme is presented, which implements anti-slide piles as the major treatment and several auxiliary treatments including filling and compacting the cracks, cutting-off and draining water, locally bolt-shotcrete support, and repairing the existing retaining wall and the lattic frame beams. After applying this scheme, the slope stability meets the design requirements.
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Wooten, Richard M., Corey M. Scheip, Jesse S. Hill, Thomas J. Douglas, David M. Korte, Bart L. Cattanach, G. Nicholas Bozdog e Sierra J. Isard. "Responses to Landslides and Landslide Mapping on the Blue Ridge Escarpment, Polk County, North Carolina, USA". Environmental and Engineering Geoscience 28, n. 1 (20 gennaio 2022): 25–54. http://dx.doi.org/10.2113/eeg-d-21-00022.
Testo completoAbstract (sommario):
ABSTRACT Landslides occur in Polk County, North Carolina, primarily along the Columbus Promontory of Blue Ridge Escarpment (BRE), which has 400 m of topographic relief and slopes typically >20°. Bedrock is characterized as late Proterozoic to early Paleozoic metamorphic rocks within Paleozoic thrust sheets. On May 18, 2018, ∼200 mm of rainfall over a 3- to 4-hour period triggered numerous debris flows and slides along the BRE, causing one fatality and severe damage to homes and roads. The State Emergency Operations Center tasked the North Carolina Geological Survey to assess slope stability ahead of search and rescue operations and assess damage along the North Pacolet River valley. The loss of life and destruction from the 2018 storm and ongoing threats to infrastructure prompted us to map landslides throughout Polk County in 2019–2021 to fully document the 2018 landslides and place them in the context of past and ongoing landsliding. We mapped 920 varied types of landslides and attribute 241 to the 2018 storm, making it one of the largest events in North Carolina since 2004 with respect to landslide numbers and spatial frequency. The highest concentrations of landslide features in Polk County are along the slopes of the BRE, especially the Pacolet River and Green River valleys. These rivers exploit post-orogenic brittle fractures to form linear reentrants where the May 2018 and other landslides are concentrated. This article describes our landslide response and mapping efforts and relates our findings to the geomorphic and geologic framework and to past landslide events in the region.
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Yamagishi, Hiromitsu, Yoji Ito e Makoto Kawamura. "Characteristics of deep-seated landslides of Hokkaido; analyses of a database of landslides of Hokkaido, Japan". Environmental and Engineering Geoscience 8, n. 1 (1 febbraio 2002): 35–46. http://dx.doi.org/10.2113/gseegeosci.8.1.35.
Testo completoAbstract (sommario):
Abstract More than 12,800 deep-seated landslides of Hokkaido were inventoried by photointerpretation, and plotted in topographic maps (Yamagishi,1993). They were later published in a database of land-slides (Yamagishi et al.,1997), which is composed of localities (latitude and longitude), scales (length, width and area), elevation, directions, and geologic lithofacies of the main scarp and underlying bedrock. Several parameters of the landslides from the database, such as frequency histograms, scale, elevation, direction and lithofacies were analyzed. As a result, landslide distribution maps from many points of view were obtained, as well as many graphs by numerical analyses.
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Liu, Fan, Yahong Deng, Tianyu Zhang, Faqiao Qian, Nan Yang, Hongquan Teng, Wei Shi e Xue Han. "Landslide Distribution and Development Characteristics in the Beiluo River Basin". Land 13, n. 7 (10 luglio 2024): 1038. http://dx.doi.org/10.3390/land13071038.
Testo completoAbstract (sommario):
The Beiluo River Basin, situated in the central region of the Loess Plateau, frequently experiences landslide geological disasters, posing a severe threat to local lives and property. Thus, establishing a detailed database of historical landslides and analyzing and revealing their development characteristics are of paramount importance for providing a foundation for geological hazard risk assessment. First, in this study, landslides in the Beiluo River Basin are interpreted using Google Earth and ZY-3 high-resolution satellite imagery. Combined with a historical landslide inventory and field investigations, a landslide database for the Beiluo River Basin is compiled, containing a total of 1781 landslides. Based on this, the geometric and spatial characteristics of the landslides are analyzed, and the relationships between the different types of landslides and landslide scale, stream order, and geomorphological types are further explored. The results show that 50.05% of the landslides have a slope aspect between 225° and 360°, 68.78% have a slope gradient of 16–25°, and 38.97% are primarily linear in profile morphology. Areas with a high landslide density within a 10 km radius are mainly concentrated in the loess ridge and hillock landform region between Wuqi and Zhidan Counties and in the loess tableland region between Fu and Luochuan Counties, with a significant clustering effect observed in the Fu County area. Loess–bedrock interface landslides are relatively numerous in the northern loess ridge and hillock landform region due to riverbed incision and the smaller thickness of loess in this area. Intra-loess landslides are primarily found in the southern loess tableland region due to headward erosion and the greater thickness of loess in this area. Loess–clay interface landslides, influenced by riverbed incision and the limited exposure of red clay, are mainly distributed in the northern part of the southern loess tableland region and on both sides of the Beiluo River Valley in Ganquan County. These results will aid in further understanding the development and spatial distribution of landslides in the Beiluo River Basin and provide crucial support for subsequent landslide susceptibility mapping and geological hazard assessment in the region.
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Bell, R., J. E. Kruse, A. Garcia, T. Glade e A. Hördt. "Subsurface investigations of landslides using geophysical methods : geoelectrical applications in the Swabian Alb (Germany)". Geographica Helvetica 61, n. 3 (30 settembre 2006): 201–8. http://dx.doi.org/10.5194/gh-61-201-2006.
Testo completoAbstract (sommario):
Abstract. Landslides occur frequently all over the world, causing at times considerable economic damage, injuries and even death. In order to improve hazard assessment, common landslide types of a given region need to be investigated in detail. While traditional techniques of subsurface investigation are expensive and only provide point information, geophysical methods are suitable tools for gathering 2D and 3D information on the subsurface quickly, reliably and cost-effectively. In this study, the suitability and limitations of 2D resistivity for the determination of landslide extent, structure and soil moisture conditions are presented. For this purpose, two identical profiles were taken during a two-month period. Significant differences in electrical resistivity (>1000 Ωm) due to varying soil moisture conditions were observed. Using various inversion parameters, it was possible to model two distinct subsurface images. Regrettably, the sliding plane could not be detected reliably, possibly due to the homogeniety of the landslide material and underlying bedrock.
46
Pánek, Tomáš, Veronika Smolková, Jan Hradecký, Jan Sedláček, Valentina Zernitskaya, Jaroslav Kadlec, Anna Pazdur e Tomáš Řehánek. "Late-Holocene evolution of a floodplain impounded by the Smrdutá landslide, Carpathian Mountains (Czech Republic)". Holocene 23, n. 2 (29 agosto 2012): 218–29. http://dx.doi.org/10.1177/0959683612455539.
Testo completoAbstract (sommario):
Landslides affecting narrow mountainous valleys might significantly determine sedimentation dynamics of floodplains. We present here a detailed study of the sedimentary archive within a landslide-controlled impounded floodplain (Smrdutá site, Czech Flysch Carpathians) using geochronological (14C and 137Cs), sedimentological and pollen evidence. A sedimentary sequence deposited above the landslide dam points to three highly discontinuous and instantaneous depositional events dated to 4.6 and 2.0 cal. ka BP, whereas the last cycle started approximately in the 17–18th centuries and has continued to recent times. Such sedimentary pulses characterized by the duration of several decades to a few centuries originated as a consequence of the blockage and/or reduction of the valley floor width by successive long-runout landslides from a slope formed by tectonically and lithologically anisotropic flysch bedrock. Stages of mass movement activity revealed by the Smrdutá landslide correlate well with major humid late-Holocene oscillations suggesting its high sensitivity to century-scale climatic deteriorations. The character of lithological units forming individual sedimentary pulses, erosional hiatuses and sedimentary traces caused by the July 1997 extreme flood indicate a decisive role of large flood events during accretion and erosion of the floodplain-impounded section.
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Salas-Romero, Silvia, Alireza Malehmir, Ian Snowball e Benoît Dessirier. "Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling". Solid Earth 10, n. 5 (11 ottobre 2019): 1685–705. http://dx.doi.org/10.5194/se-10-1685-2019.
Testo completoAbstract (sommario):
Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.
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Eckel, B. F., E. Karl Sauer e E. A. Christiansen. "The Petrofka landslide, Saskatchewan". Canadian Geotechnical Journal 24, n. 1 (1 febbraio 1987): 81–99. http://dx.doi.org/10.1139/t87-008.
Testo completoAbstract (sommario):
Both abutments and all piers of the Petrofka bridge are on a landslide. The bridge has performed satisfactorily for 23 years, indicating the factor of safety of the Petrofka landslide is greater than unity. This stability is abnormal because landslide slopes on bedrock clays (shale) in this region are notoriously unstable. A dormant landslide is difficult to analyze because the input parameters must represent a condition of limiting equilibrium.The Petrofka landslide is 70 m high, 880 m long, 3000 m wide, and up to 100 m thick. The shear zone is in highly plastic, montmorillonitic clays in an unnamed formation of probable Tertiary age. The Upper Cretaceous Lea Park, Judith River, and Bearpaw formations and the unnamed formation underly the landslide and are restricted to a collapse structure resulting from dissolution of Devonian evaporites.A retrogressive mechanism developed as valley downcutting progressed. The pore-water pressures could be estimated from the hydraulic head in the artesian aquifer of the Judith River Formation. The hydraulic head was maintained at critical as the valley deepened until the Judith River Formation was eroded downstream. The landslide was active for only a few hundred years, between 11 500 and 11 000 years ago.The back-calculated effective angle of friction for the bedrock clay (shale) was estimated at between 5.6° and 6.5°, assuming c′ = 0, resulting in a present-day factor of safety between 1.2 and 1.3. Key words: back analysis, dormant landslide, collapse structure, artesian pressure, historical simulation, residual shear strength.
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Biagini, Luiz, Renato Macciotta, Chris Gräpel, Kristen Tappenden e Roger Skirrow. "Characteristics, Kinematics and Contributing Factors of Compound and Translational Landslides in the Interior Plains of Canada". Geosciences 12, n. 8 (25 luglio 2022): 289. http://dx.doi.org/10.3390/geosciences12080289.
Testo completoAbstract (sommario):
Understanding landslide kinematics, their characteristics, and contributing factors is crucial for decision-making regarding mitigation strategies for infrastructure projects. These characteristics depend on the geomorphology of the area, climate, and proximity to water bodies and anthropogenic activity. Some geomorphological features are shared between some western Canadian regions, particularly within the Canadian Interior Plains (Interior Plains). This paper synthesizes the failure mechanisms, kinematics, triggering events, and contributing factors associated with 11 landslides in the Interior Plains, with detailed qualitative descriptions of two of them. The paper discusses the commonalities of bedrock formations that contain thin sub-horizontal and continuous deposits of weak materials as the main geomorphological predisposing factor for landslides in this region. The findings show commonalities in the effect of seasonal fluctuations in the characteristics of water bodies in contact with these landslides, driving episodes of landside reactivation, acceleration and deceleration. Importantly, anthropogenic activity as a trigger for the initiation of some of these landslides suggests a high susceptibility of certain slopes in the Interior Plains to instability resulting from relatively small changes in in-situ stresses. This information becomes critical for assessing the landslide susceptibility of valley slopes in this region for infrastructure planning, design, and operation.
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Urgilez Vinueza, Alexandra, Jessica Robles, Mark Bakker, Pablo Guzman e Thom Bogaard. "Characterization and Hydrological Analysis of the Guarumales Deep-Seated Landslide in the Tropical Ecuadorian Andes". Geosciences 10, n. 7 (10 luglio 2020): 267. http://dx.doi.org/10.3390/geosciences10070267.
Testo completoAbstract (sommario):
The high landslide risk potential along the steep hillslopes of the Eastern Andes in Ecuador provides challenges for hazard mitigation, especially in areas with hydropower dams and reservoirs. The objective of this study was to characterize, understand, and quantify the mechanisms driving the motions of the Guarumales landslide. This 1.5 km2 deep-seated, slow-moving landslide is actively moving and threatening the “Paute Integral” hydroelectric complex. Building on a long time series of measurements of surface displacement, precipitation, and groundwater level fluctuations, we analyzed the role of predisposing conditions and triggering factors on the stability of the landslide. We performed an analysis of the time series of measured groundwater levels and drainage data using transfer functions. The geological interpretation of the landslide was further revised based on twelve new drillings. This demonstrated a locally complex system of colluvium deposits overlying a schist bedrock, reaching up to 100 m. The measured displacement rates were nearly constant at ~50 mm/year over the 18 years of study. However, the measurement accuracy and time resolution were too small to identify possible acceleration or deceleration phases in response to hydro-meteorological forcing. The groundwater and slope drainage data showed a lagged response to rainfall. Finally, we developed a conceptual model of the Guarumales landslide, which we hope will improve our understanding of the many other deep-seated landslides present in the Eastern Andes.