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1
Chen, Jian, Zhong Qi Yue y Si Jing Liu. "An Innovative Approach of Drilling Process Monitoring for Slope Characterization in Mountainous Regions". Applied Mechanics and Materials 226-228 (noviembre de 2012): 2088–92. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2088.
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In Hong Kong, there are so many drill works for landslide prevention, such as drilling holes for soil nailing. To recognize the geotechnical condition of slope in detail based on these drillholes, we have developed and invented the drilling process monitoring (DPM) technique to accurately and quickly quantify and characterize the mechanical strength distribution beneath the slope surface. This technique is associated with the conventional air-driven rotary-percussive drilling machines with down-the-hole hammer. This drilling machine is manually portable to quickly form holes of upto 100 m deep in sloping ground. Such ground can comprise any kinds of geomaterials from soft or loose geomaterials such as caverns, clay or sand to extremely hard or strong geomaterials such concrete or granite. Therefore, we have proposed an innovative approach by using DPM method to accurately and quickly quantify the ground conditions in slopes in mountainous regions. It is trusted that the proposed approach will be able to upgrade our current slope engineering practice in mountainous regions.
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Donati, Davide, Doug Stead y Lisa Borgatti. "The Importance of Rock Mass Damage in the Kinematics of Landslides". Geosciences 13, n.º 2 (9 de febrero de 2023): 52. http://dx.doi.org/10.3390/geosciences13020052.
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The stability and kinematics of rock slopes are widely considered to be functions of lithological, structural, and environmental features. Conversely, slope damage features are often overlooked and considered as byproducts of slope deformation. This paper analyzes and discusses the potential role of slope damage, its time-dependent nature, and its control on both the stability of rock slopes and their kinematics. The analysis of several major landslides and unstable slopes, combined with a literature survey, shows that slope damage can play an important role in controlling short- and long-term slope stability. Seasonal and continuously active events cause permanent deformation within the slope due to the accumulation of slope damage features, including rock mass dilation and intact rock fracturing. Rock mass quality, lithology, and scale control the characteristics and complexity of slope damage, as well as the failure mechanism. The authors propose that the role of slope damage in slope kinematics should always be considered in slope stability analysis, and that an integrated characterization–monitoring–numerical modelling approach can enhance our understanding of slope damage, its evolution, and the controlling factors. Finally, it is emphasized that there is currently a lack of guidelines or frameworks for the quantitative assessment and classification of slope damage, which requires a multidisciplinary approach combining rock mechanics, geomorphology, engineering geology, remote sensing, and geophysics.
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Moradi, Shirin, Thomas Heinze, Jasmin Budler, Thanushika Gunatilake, Andreas Kemna y Johan Alexander Huisman. "Combining Site Characterization, Monitoring and Hydromechanical Modeling for Assessing Slope Stability". Land 10, n.º 4 (15 de abril de 2021): 423. http://dx.doi.org/10.3390/land10040423.
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Rainfall-induced landslides are a disastrous natural hazard causing loss of life and significant damage to infrastructure, farmland and housing. Hydromechanical models are one way to assess the slope stability and to predict critical combinations of groundwater levels, soil water content and precipitation. However, hydromechanical models for slope stability evaluation require knowledge about mechanical and hydraulic parameters of the soils, lithostratigraphy and morphology. In this work, we present a multi-method approach of site characterization and investigation in combination with a hydromechanical model for a landslide-prone hillslope near Bonn, Germany. The field investigation was used to construct a three-dimensional slope model with major geological units derived from drilling and refraction seismic surveys. Mechanical and hydraulic soil parameters were obtained from previously published values for the study site based on laboratory analysis. Water dynamics were monitored through geoelectrical monitoring, a soil water content sensor network and groundwater stations. Historical data were used for calibration and validation of the hydromechanical model. The well-constrained model was then used to calculate potentially hazardous precipitation events to derive critical thresholds for monitored variables, such as soil water content and precipitation. This work introduces a potential workflow to improve numerical slope stability analysis through multiple data sources from field investigations and outlines the usage of such a system with respect to a site-specific early-warning system.
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Alves, H. M. R., M. M. L. Volpato, T. G. C. Vieira, D. A. Maciel, T. G. Gonçalves y M. F. Dantas. "CHARACTERIZATION AND SPECTRAL MONITORING OF COFFEE LANDS IN BRAZIL". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (23 de junio de 2016): 801–3. http://dx.doi.org/10.5194/isprs-archives-xli-b8-801-2016.
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In Brazil, coffee production has great economic and social importance. Despite this fact, there is still a shortage of information regarding its spatial distribution, crop management and environment. The aim of this study was to carry out spectral monitoring of coffee lands and to characterize their environments using geotechnologies. Coffee fields with contiguous areas over 0.01 km2 within a 488.5 km<sup>2</sup> region in the south of Minas Gerais state were selected for the study. Spectral data from the sensors OLI/Landsat 8 and the Shuttle Radar Topography Mission from 2014 to 2015 were obtained, as well as information on production areas, surface temperature, vegetation indexes, altitude and slope, were gathered and analyzed. The results indicate that there is great variation in the NDVI and NDWI values, with means ranging from 0.21 to 0.91 (NDVI) and 0.108 to 0.543 (NDWI). The altitude ranged from 803 to 1150 m, and the surface temperature from 20.9°C to 27.6°C. The altitude and the surface temperature distribution patterns were correlated with the vegetation indexes. The slope classes were very homogeneous, predominantly with declivities between 8 to 20 %, characterized as wavy relief. This study made possible the characterization and monitoring of coffee lands and its results may be instrumental in decision-making processes related to coffee management.
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Alves, H. M. R., M. M. L. Volpato, T. G. C. Vieira, D. A. Maciel, T. G. Gonçalves y M. F. Dantas. "CHARACTERIZATION AND SPECTRAL MONITORING OF COFFEE LANDS IN BRAZIL". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (23 de junio de 2016): 801–3. http://dx.doi.org/10.5194/isprsarchives-xli-b8-801-2016.
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In Brazil, coffee production has great economic and social importance. Despite this fact, there is still a shortage of information regarding its spatial distribution, crop management and environment. The aim of this study was to carry out spectral monitoring of coffee lands and to characterize their environments using geotechnologies. Coffee fields with contiguous areas over 0.01 km2 within a 488.5 km<sup>2</sup> region in the south of Minas Gerais state were selected for the study. Spectral data from the sensors OLI/Landsat 8 and the Shuttle Radar Topography Mission from 2014 to 2015 were obtained, as well as information on production areas, surface temperature, vegetation indexes, altitude and slope, were gathered and analyzed. The results indicate that there is great variation in the NDVI and NDWI values, with means ranging from 0.21 to 0.91 (NDVI) and 0.108 to 0.543 (NDWI). The altitude ranged from 803 to 1150 m, and the surface temperature from 20.9°C to 27.6°C. The altitude and the surface temperature distribution patterns were correlated with the vegetation indexes. The slope classes were very homogeneous, predominantly with declivities between 8 to 20 %, characterized as wavy relief. This study made possible the characterization and monitoring of coffee lands and its results may be instrumental in decision-making processes related to coffee management.
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Burjánek, Jan, Valentin Gischig, Jeffrey R. Moore y Donat Fäh. "Ambient vibration characterization and monitoring of a rock slope close to collapse". Geophysical Journal International 212, n.º 1 (3 de octubre de 2017): 297–310. http://dx.doi.org/10.1093/gji/ggx424.
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Guo, Yongxing, Jianjun Fu, Longqi Li y Li Xiong. "Fiber Bragg grating sensor-based monitoring strategy for slope deformation in centrifugal model test". Sensor Review 39, n.º 1 (21 de enero de 2019): 71–77. http://dx.doi.org/10.1108/sr-10-2017-0218.
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Purpose Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability mechanisms. Simply observing the slope landslide before and after a centrifugal model test cannot reveal the processes involved in real-time deformation. Electromagnetic sensors have severed as an existing method for real-time measurement, however, this approach has significant challenges, including poor signal quality, interference, and complex implementation and wiring schemes. This paper aims to overcome the shortcomings of the existing measurement methods. Design/methodology/approach This work uses the advantages of fiber Bragg grating (FBG) sensors with their small form-factor and potential for series multiplexing in a single fiber to demonstrate a monitoring strategy for model centrifugal tests. A slope surface deformation displacement sensor, FBG anchor sensor and FBG anti-slide piling sensor have been designed. These sensors are installed in the slope models, while centrifugal acceleration tests under 100 g are carried out. Findings FBG sensors obtain three types of deformation information, demonstrating the feasibility and validity of this measurement strategy. Originality/value The experimental results provide important details about instability mechanisms of a slope, which has great significance in research on slope model monitoring techniques and slope stability.
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Provenzano, Giuseppe, Antonis Zervos, Mark E. Vardy y Timothy J. Henstock. "Characterization of shallow overpressure in consolidating submarine slopes via seismic full waveform inversion". Quarterly Journal of Engineering Geology and Hydrogeology 53, n.º 3 (20 de enero de 2020): 366–77. http://dx.doi.org/10.1144/qjegh2019-019.
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Pore pressures higher than hydrostatic correspond to localized reductions of the level of shear stress required to induce lateral mass movement in a slope, and therefore play a key role in preconditioning submarine landsliding. In this paper, we investigate whether multi-channel seismic reflection data can be used to infer potentially destabilizing pore-pressure levels at a resolution and sensitivity useful for in-situ slope stability characterization. We simulate the continuous deposition of sediment on consolidating slopes in two scenarios, with combinations of sedimentation rate and permeability distribution leading to disequilibrium compaction. Ultra-high-frequency (UHF; 0.2–2.5 kHz) seismic reflection data are computed for each model and a stochastic full waveform inversion (FWI) method is used to retrieve the sub-seabed properties from the computed seismograms. These are then interpreted as time–depth variations in the effective stress (σʹ) regime, and therefore local overpressure ratio and factor of safety, using a combination of p-wave velocity to σʹ transforms. The results demonstrate that multi-channel UHF seismic data can provide valuable constraints on the distribution of physical properties in the top 50 m below seabed at a sub-metric scale, and with a sensitivity useful to infer destabilizing excess pore pressure levels.Thematic collection: This article is part of the Measurement and monitoring collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring
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Li, Feng, Wen Tao Zhang, Fang Li y Yan Liang Du. "Fiber Optic Inclinometer for Landslide Monitoring". Applied Mechanics and Materials 166-169 (mayo de 2012): 2623–26. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2623.
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As a main parameter reflecting the security status of slope, internal displacement monitoring has been an important issue to geotechnical engineering. An optical inclinometer is demonstrated, which utilizes FBG sensors attached to the casing of a conventional inclinometer. Three arrays of sensors at an interval of 90 degrees are glued to the outside of inclinometer. The authors carried out model experiment, in which characterization of the sensor revealed good agreement with theory and conventional displacement measurements. Meanwhile, angle monitoring result was rewarding, monitoring value of 44.3 and 29.5 degrees corresponding to the actual value of 45 and 30 degrees respectively.
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Vanneschi, Claudio, Matthew Eyre, Mirko Francioni y John Coggan. "The Use of Remote Sensing Techniques for Monitoring and Characterization of Slope Instability". Procedia Engineering 191 (2017): 150–57. http://dx.doi.org/10.1016/j.proeng.2017.05.166.
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Morgenstern, N. R., A. E. Fair y E. C. McRoberts. "Geotechnical engineering beyond soil mechanics—a case study". Canadian Geotechnical Journal 25, n.º 4 (1 de noviembre de 1988): 637–61. http://dx.doi.org/10.1139/t88-076.
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Geotechnical engineering embraces soil mechanics, rock mechanics, and engineering geology. In practice it employs a wide variety of techniques ranging from site mapping and characterization to advanced theoretical analysis and performance monitoring. This paper draws on the development of the Alberta oil sands as a case study to illustrate the breadth of application of geotechnical engineering in large-scale resource developments.A description of the resource base and common extractive procedures used in the Alberta oil sands is given. The geological setting and geotechnical characterization of the Athabasca deposit are summarized. Detailed discussions are presented on geotechnical contributions to surface mining and slope stability, waste handling and tailings dam construction, and in situ recovery processes. The substantial opportunities for geotechnical engineering to contribute to both safe and economical operations in the extractive industries are emphasized. Key words: oil sands, mining, slope stability, monitoring, dredging, shear strength, tailings dam, overburden, liquefaction, pore pressures, geotechnical engineering.
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Sutton, Isaac A. y Nicholas E. Jones. "Measures of fish community size structure as indicators for stream monitoring programs". Canadian Journal of Fisheries and Aquatic Sciences 77, n.º 5 (mayo de 2020): 824–35. http://dx.doi.org/10.1139/cjfas-2019-0268.
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Characterization of community size structure presents an alternative to taxa-based approaches commonly applied to assess lotic ecosystem health. However, few studies have explored the relationship between community size structure and land use stresses in lotic systems. In the present study, we investigated use of metrics including mean body size, body size range, size diversity, size evenness, and the size spectrum slope as indicators of land use disturbance in streams. We also explored the effects of sampling intensity (one- versus three-pass electrofishing) on these size-based variables. We found significant decreases in size range and diversity with increased urban cover. In contrast, mean body size, size evenness, and size spectrum slopes were unrelated to variation in land use. Fewer than 25% of samples collected conformed to the power law model predicted for size distributions in aquatic ecosystems. However, increased departure from the power law form was related to agricultural cover and the use of three-pass electrofishing.
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Damiano, Emilia. "Effects of layering on triggering mechanisms of rainfall-induced landslides in unsaturated pyroclastic granular soils". Canadian Geotechnical Journal 56, n.º 9 (septiembre de 2019): 1278–90. http://dx.doi.org/10.1139/cgj-2018-0040.
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Rainfall-induced landslides are widespread in shallow layered granular soil deposits. In many cases, slope instability is related to the decrease of suction during rainwater infiltration. However, the contrasts in the unsaturated hydraulic properties of the soils deeply affect the infiltration process, thus influencing slope failure. Coarse-textured soil layers embedded between finer ones may initially confine the process within the overlying finer layers, delaying the infiltration and eventually inducing lateral flow diversion. Nonetheless, depending on the state variables at the beginning of rainfall as well as on rainfall characteristics, the coarser layers may or may not have a positive effect on stability. The results of research based on advanced geotechnical characterization, physical and numerical modeling, and field monitoring have been analyzed to investigate the effects of layering on slope stability.
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Le, Thi-Cuc, Yun-Chin Wang, David Y. H. Pui y Chuen-Jinn Tsai. "Characterization of Atmospheric PM2.5 Inorganic Aerosols Using the Semi-Continuous PPWD-PILS-IC System and the ISORROPIA-II". Atmosphere 11, n.º 8 (4 de agosto de 2020): 820. http://dx.doi.org/10.3390/atmos11080820.
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A semi-continuous monitoring system, a parallel plate wet denuder and particle into liquid sampler coupled with ion chromatography (PPWD-PILS-IC), was used to measure the hourly precursor gases and water-soluble inorganic ions in ambient particles smaller than 2.5 µm in diameter (PM2.5) for investigating the thermodynamic equilibrium of aerosols using the ISORROPIA-II thermodynamic equilibrium model. The 24-h average PPWD-PILS-IC data showed very good agreement with the daily data of the manual 5 L/min porous-metal denuder sampler with R2 ranging from 0.88 to 0.98 for inorganic ions (NH4+, Na+, K+, NO3−, SO42−, and Cl−) and 0.89 to 0.98 for precursor gases (NH3, HNO3, HONO, and SO2) and slopes ranging from 0.94 to 1.17 for ions and 0.87 to 0.95 for gases, respectively. In addition, the predicted ISORROPIA-II results were in good agreement with the hourly observed data of the PPWD-PILS-IC system for SO42− (R2 = 0.99 and slope = 1.0) and NH3 (R2 = 0.97 and slope = 1.02). The correlation of the predicted results and observed data was further improved for NH4+ and NO3− with the slope increasing from 0.90 to 0.96 and 0.95 to 1.09, respectively when the HNO2 and NO2− were included in the total nitrate concentration (TN = [NO3−] + [HNO3] + [HONO] + [NO2−]). The predicted HNO3 data were comparable to the sum of the observed [HNO3] and [HONO] indicating that HONO played an important role in the thermodynamic equilibrium of ambient PM2.5 aerosols but has not been considered in the ISORROPIA-II thermodynamic equilibrium model.
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Fukunaga, Atsuko, John Burns, Brianna Craig y Randall Kosaki. "Integrating Three-Dimensional Benthic Habitat Characterization Techniques into Ecological Monitoring of Coral Reefs". Journal of Marine Science and Engineering 7, n.º 2 (28 de enero de 2019): 27. http://dx.doi.org/10.3390/jmse7020027.
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Long-term ecological monitoring of reef fish populations often requires the simultaneous collection of data on benthic habitats in order to account for the effects of these variables on fish assemblage structure. Here, we described an approach to benthic surveys that uses photogrammetric techniques to facilitate the extraction of quantitative metrics for characterization of benthic habitats from the resulting three-dimensional (3D) reconstruction of coral reefs. Out of 92 sites surveyed in the Northwestern Hawaiian Islands, photographs from 85 sites achieved complete alignment and successfully produced 3D reconstructions and digital elevation models (DEMs). Habitat metrics extracted from the DEMs were generally correlated with one another, with the exception of curvature measures, indicating that complexity and curvature measures should be treated separately when quantifying the habitat structure. Fractal dimension D64, calculated by changing resolutions of the DEMs from 1 cm to 64 cm, had the best correlations with other habitat metrics. Fractal dimension was also less affected by changes in orientations of the models compared to surface complexity or slope. These results showed that fractal dimension can be used as a single measure of complexity for the characterization of coral reef habitats. Further investigations into metrics for 3D characterization of habitats should consider relevant spatial scales and focus on obtaining variables that can complement fractal dimension in the characterization of reef habitats.
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Nguyen, H. T., T. M. Fernandez-Steeger, T. Wiatr, D. Rodrigues y R. Azzam. "Use of terrestrial laser scanning for engineering geological applications on volcanic rock slopes – an example from Madeira island (Portugal)". Natural Hazards and Earth System Sciences 11, n.º 3 (14 de marzo de 2011): 807–17. http://dx.doi.org/10.5194/nhess-11-807-2011.
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Abstract. This study focuses on the adoption of a modern, widely-used Terrestrial Laser Scanner (TLS) application to investigate volcanic rock slopes in Ribeira de João Gomes valley (Funchal, Madeira island). The TLS data acquisition in May and December 2008 provided information for a characterization of the volcanic environment, detailed structural analysis and detection of potentially unstable rock masses on a slope. Using this information, it was possible to determine specific parameters for numerical rockfall simulations such as average block size, shape or potential sources. By including additional data, such as surface roughness, the results from numerical rockfall simulations allowed us to classify different hazardous areas based on run-out distances, frequency of impacts and related kinetic energy. Afterwards, a monitoring of hazardous areas can be performed in order to establish a rockfall inventory.
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Hussain, Yawar, Martin Cardenas-Soto, Salvatore Martino, Cesar Moreira, Welitom Borges, Omar Hamza, Renato Prado et al. "Multiple Geophysical Techniques for Investigation and Monitoring of Sobradinho Landslide, Brazil". Sustainability 11, n.º 23 (26 de noviembre de 2019): 6672. http://dx.doi.org/10.3390/su11236672.
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Geophysical methods have a varying degree of potential for detailed characterization of landslides and their dynamics. In this study, the application of four well-established seismic-based geophysical techniques, namely Ambient Noise Interferometry (ANI), Horizontal to Vertical Spectral Ratio (HVSR), Multi-Channel Analysis of Surface Waves (MASW) and Nanoseismic Monitoring (NM), were considered to examine their suitability for landslide characterization and monitoring the effect of seasonal variation on slope mass. Furthermore, other methods such as Ground Penetrating Radar (GPR) and DC Resistivity through Electrical Resistivity Tomography (ERT) were also used for comparison purpose. The advantages and limitations of these multiple techniques were exemplified by a case study conducted on Sobradinho landslide in Brazil. The study revealed that the geophysical characterization of the landslide using traditional techniques (i.e., GPR, ERT and MASW) were successful in (i) the differentiation between landslide debris and other Quaternary deposits, and (ii) the delineation of the landslide sliding surface. However, the innovative seismic based techniques, particularly ambient noise based (HVSR and ANI) and emitted seismic based (NM), were not very effective for the dynamic monitoring of landslide, which might be attributed to the short-time duration of the data acquisition campaigns. The HVSR was also unsuccessful in landslide site characterization i.e., identification of geometry and sliding surface. In particular, there was no clear evidence of the light seasonal variations, which could have been potentially detected from the physical parameters during the (short-time) ambient noise and microseismic acquisition campaigns. Nevertheless, the experienced integration of these geophysical techniques may provide a promising tool for future applications.
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Calvari, Sonia, Federico Di Traglia, Gaetana Ganci, Flora Giudicepietro, Giovanni Macedonio, Annalisa Cappello, Teresa Nolesini et al. "Overflows and Pyroclastic Density Currents in March-April 2020 at Stromboli Volcano Detected by Remote Sensing and Seismic Monitoring Data". Remote Sensing 12, n.º 18 (16 de septiembre de 2020): 3010. http://dx.doi.org/10.3390/rs12183010.
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Between 28 March and 1 April 2020, Stromboli volcano erupted, with overflows from the NE crater rim spreading along the barren Sciara del Fuoco slope and reaching the sea along the NW coast of the island. Poor weather conditions did not allow a detailed observation of the crater zone through the cameras monitoring network, but a clear view of the lower slope and the flows expanding in the area allowed us to characterize the flow features. This evidence was integrated with satellite, GBInSAR, and seismic data, thus enabling a reconstruction of the whole volcanic event, which involved several small collapses of the summit cone and the generation of pyroclastic density currents (PDCs) spreading along the slope and on the sea surface. Satellite monitoring allowed for the mapping of the lava flow field and the quantification of the erupted volume, and GBInSAR continuous measurements detected the crater widening and the deflation of the summit cone caused by the last overflow. The characterization of the seismicity made it possible to identify the signals that are associated with the propagation of PDCs along the volcano flank and, for the first time, to recognize the signal that is produced by the impact of the PDCs on the coast.
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Oppikofer, T., M. Jaboyedoff, L. Blikra, M. H. Derron y R. Metzger. "Characterization and monitoring of the Åknes rockslide using terrestrial laser scanning". Natural Hazards and Earth System Sciences 9, n.º 3 (26 de junio de 2009): 1003–19. http://dx.doi.org/10.5194/nhess-9-1003-2009.
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Abstract. Terrestrial laser scanning (TLS) provides high-resolution point clouds of the topography and new TLS instruments with ranges exceeding 300 m or even 1000 m are powerful tools for characterizing and monitoring slope movements. This study focuses on the 35 million m3 Åknes rockslide in Western Norway, which is one of the most investigated and monitored rockslides in the world. The TLS point clouds are used for the structural analysis of the steep, inaccessible main scarp of the rockslide, including an assessment of the discontinuity sets and fold axes. TLS acquisitions in 2006, 2007 and 2008 provide information on 3-D displacements for the entire scanned area and are not restricted like conventional survey instruments to single measurement points. The affine transformation matrix between two TLS acquisitions precisely describes the rockslide displacements and enables their separation into translational components, such as the displacement velocity and direction, and rotational components, like toppling. This study shows the ability of TLS to obtain reliable 3-D displacement information over a large, unstable area. Finally, a possible instability model for the upper part of Åknes rockslide explains the measured translational and rotational displacements by a combination of southward planar sliding along the gneiss foliation, gravitational vertical settlement along the complex, stepped basal sliding surface and northward toppling toward the opened graben structure.
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Martino, S. y P. Mazzanti. "Integrating geomechanical surveys and remote sensing for sea cliff slope stability analysis: the Mt. Pucci case study (Italy)". Natural Hazards and Earth System Sciences 14, n.º 4 (11 de abril de 2014): 831–48. http://dx.doi.org/10.5194/nhess-14-831-2014.
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Abstract. An integrated approach to the geomechanical characterization of coastal sea cliffs was applied at Mt. Pucci (Gargano promontory, Southern Italy) by performing field-based geomechanical investigations and remote geostructural investigations via a terrestrial laser scanner (TLS). The consistency of the integrated techniques allowed to achieve a comprehensive and affordable characterization of the main joint sets on the sea cliff slope. The observed joint sets were considered to evaluate the proneness of the slope to rock failures by attributing safety factor (SF) values to the topple- and wedge-prone rock blocks under three combined or independent triggering conditions: (a) hydrostatic water pressures within the joints, (b) seismic action, and (c) strength reduction due to weathering of the joint surfaces. The combined action of weathering and water pressures within the joints was also considered, resulting in a significant decrease in the stability. Furthermore, remote survey analyses via InfraRed Thermography (IRT) and Ground Based Synthetic Aperture Radar Interferometry (GBInSAR) were performed to evaluate the role of the surveyed joint sets in inducing instabilities in the Mt. Pucci sea cliff. The results from the remote surveys: (i) GBInSAR monitoring revealed permanent displacements coupled to cyclic daily displacements, these last ones detected in certain sectors of the cliff wall; (ii) the thermal images allowed us to identify anomalies that correspond well to the main joints and to the slope material released due to recent collapses.
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Loiotine, Lidia, Gioacchino Francesco Andriani, Michel Jaboyedoff, Mario Parise y Marc-Henri Derron. "Comparison of Remote Sensing Techniques for Geostructural Analysis and Cliff Monitoring in Coastal Areas of High Tourist Attraction: The Case Study of Polignano a Mare (Southern Italy)". Remote Sensing 13, n.º 24 (12 de diciembre de 2021): 5045. http://dx.doi.org/10.3390/rs13245045.
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Rock slope failures in urban areas may represent a serious hazard for human life, as well as private and public property, even on the occasion of sporadic episodes. Prevention and mitigation measures indispensably require a proper rock mass characterization, which is often achieved by means of time-consuming, costly and dangerous field surveys. In the last decades, remote sensing devices such as high-resolution digital cameras, laser scanners and drones have been widely used as supplementary techniques for rock slope analysis and monitoring, especially in poorly accessible areas, or in sites of large extension. Although several methods for rock mass characterization by means of remote sensing techniques have been reported in specific studies, there are very few contributions that focused on comparing the different methods in an attempt to establish their advantages and limitations. With this study, we performed digital photogrammetry, Terrestrial Laser Scanning and Unmanned Aerial Vehicle surveys on a cliff located in a popular tourist attraction site, characterized by complex geological and geomorphological settings, as well as by disturbance elements such as vegetation and human activities. For each point cloud, we applied geostructural analysis by means of semi-automatic methods, and then compared multi-temporal acquisitions for cliff monitoring. By quantitative comparison of the results and validation by means of conventional geostructural field surveys, the pros and cons of each method were outlined in attempt to depict the conditions and goals the different techniques seem to be more suitable for.
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Kelln, Curtis, Jitendra Sharma, David Hughes y Gabriel Gallagher. "Deformation of a soft estuarine deposit under a geotextile reinforced embankment". Canadian Geotechnical Journal 44, n.º 5 (1 de mayo de 2007): 603–17. http://dx.doi.org/10.1139/t07-007.
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This paper presents a case history of a geotextile reinforced highway embankment constructed on a soft estuarine deposit installed with prefabricated vertical drains. The case history documents the geotechnical site characterization, embankment construction, and monitoring program. The loading response of the soft estuarine soil was monitored during construction using hydrostatic profile gauges, settlement plates, pneumatic piezometers, and slope inclinometers. Settlements of up to 1.3 m were measured under the 4 m high embankment. The deformation behaviour was interpreted qualitatively from the monitoring data using the general framework of elastic-plastic soil models. The effectiveness of the monitoring program is also briefly discussed. The paper provides performance details that make this case history useful to researchers studying the loading response of soft soils under a geotextile reinforced embankment.Key words: case history, embankment, soft clay, vertical drainage, reinforcement.
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Gao, Yang, Zhen Qi Hu, Jing Li, Wu Xiao, Ji Yong Zeng y Zhi Dong Jiang. "The Index System and Methods of Monitoring Damaged Cultivated Land Quality in Mining Area Based on Agricultural Land Classification". Applied Mechanics and Materials 409-410 (septiembre de 2013): 56–63. http://dx.doi.org/10.4028/www.scientific.net/amm.409-410.56.
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Damaged cultivated land reclamation in mining area is one of the important ways to remediate the cultivated land in China. In the study, Index system of monitoring damaged cultivated land quality in mining area was established on the basis of agricultural land classification indexes. Collapse depth, excavation depth, cover occupation height, density of fractures, and the additional slope are added to reflect the characterization of micro topographic. Methods which are used to monitoring damaged cultivated land quality are summarized according to the condition of mining area. The connection between gradation of agricultural land (upper level) and damage level (lower level) is established. These measures could make the results of land reclamation management effectively and directly serve the update of agricultural land grading results.
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Romeo, Saverio, Antonio Cosentino, Francesco Giani, Giandomenico Mastrantoni y Paolo Mazzanti. "Combining Ground Based Remote Sensing Tools for Rockfalls Assessment and Monitoring: The Poggio Baldi Landslide Natural Laboratory". Sensors 21, n.º 8 (8 de abril de 2021): 2632. http://dx.doi.org/10.3390/s21082632.
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Nowadays the use of remote monitoring sensors is a standard practice in landslide characterization and monitoring. In the last decades, technologies such as LiDAR, terrestrial and satellite SAR interferometry (InSAR) and photogrammetry demonstrated a great potential for rock slope assessment while limited studies and applications are still available for ArcSAR Interferometry, Gigapixel imaging and Acoustic sensing. Taking advantage of the facilities located at the Poggio Baldi Landslide Natural Laboratory, an intensive monitoring campaign was carried out on May 2019 using simultaneously the HYDRA-G ArcSAR for radar monitoring, the Gigapan robotic system equipped with a DSLR camera for photo-monitoring purposes and the DUO Smart Noise Monitor for acoustic measurements. The aim of this study was to evaluate the potential of each monitoring sensor and to investigate the ongoing gravitational processes at the Poggio Baldi landslide. Analysis of multi-temporal Gigapixel-images revealed the occurrence of 84 failures of various sizes between 14–17 May 2019. This allowed us to understand the short-term evolution of the rock cliff that is characterized by several impulsive rockfall events and continuous debris production. Radar displacement maps revealed a constant movement of the debris talus at the toe of the main rock scarp, while acoustic records proved the capability of this technique to identify rockfall events as well as their spectral content in a narrow range of frequencies between 200 Hz to 1000 Hz. This work demonstrates the great potential of the combined use of a variety of remote sensors to achieve high spatial and temporal resolution data in the field of landslide characterization and monitoring.
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Rianna, Guido, Luca Comegna, Luca Pagano, Luciano Picarelli y Alfredo Reder. "The Role of Hydraulic Hysteresis on the Hydrological Response of Pyroclastic Silty Covers". Water 11, n.º 3 (26 de marzo de 2019): 628. http://dx.doi.org/10.3390/w11030628.
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A significant part of the recent geotechnical literature concerning pyroclastic soils is focused on the characterization of the hydrological effects of precipitations and their implications for the stability conditions of unsaturated sloping covers. Recent experience shows that suction-induced strength reduction is influenced by various factors including hydraulic hysteresis. A deeper insight into the hysteretic water retention behavior of these materials and its effects upon their response to dry/wetting conditions is a major goal of this paper, which exploits the data provided by the monitoring of a volcanic ash. Based on the parameters retrieved from data calibration, the hydrological response of a virtual slope subject to one-dimensional rainfall infiltration is investigated by numerical analyses and compared with the results obtained through the usually adopted non-hysteretic approaches. The analysis demonstrates that considering the hysteretic behavior may be crucial for a proper evaluation of the conditions leading to slope failure.
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Ronchetti, F., L. Borgatti, F. Cervi, C. Gorgoni, L. Piccinini, V. Vincenzi y A. Corsini. "Groundwater processes in a complex landslide, northern Apennines, Italy". Natural Hazards and Earth System Sciences 9, n.º 3 (18 de junio de 2009): 895–904. http://dx.doi.org/10.5194/nhess-9-895-2009.
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Abstract. The hydrogeological characteristics of roto-translational slides in flysch are complex, due to the inherent anisotropy and heterogeneity of rock masses and related deposits. The paper deals with the hydrogeological characterization of a reactivated roto-translational slide affecting Cretaceous flysch rocks, located in the northern Apennines of Italy. Continuous monitoring of groundwater levels, in-situ permeability and pumping tests, hydrochemical and physical analyses and Uranine tracers were the adopted prospecting methods. In this research hydrological monitoring and investigation are summarized in order to define a hydrogeological conceptual model of the landslide source area. Results showed that two overlaying hydrogeological units exist at the slope scale: the first is unconfined, but highly compartmentalized, and hosted in the fractured and dismembered rock slide body. The second is confined and lays in the undisturbed flysch below the sliding surface. The groundwater level in the confined hydrogeological unit is twenty meters higher than the groundwater level in the uppermost one. Moreover, the groundwater chemistry characterization revealed a rising of deep fluids in the landslide area.
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Stratiev, Dicho S., Svetoslav Nenov, Ivelina K. Shishkova, Rosen K. Dinkov, Kamen Zlatanov, Dobromir Yordanov, Sotir Sotirov et al. "Comparison of Empirical Models to Predict Viscosity of Secondary Vacuum Gas Oils". Resources 10, n.º 8 (10 de agosto de 2021): 82. http://dx.doi.org/10.3390/resources10080082.
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This work presents characterization data and viscosity of 34 secondary vacuum gas oils (H-Oil gas oils, visbreaker gas oils, and fluid catalytic cracking slurry oils) with aromatic content reaching up to 100 wt.%. Inter-criteria analysis was employed to define the secondary VGO characteristic parameters which have an effect on viscosity. Seven published empirical models to predict viscosity of the secondary vacuum gas oils were examined for their prediction ability. The empirical model of Aboul-Seud and Moharam was found to have the lowest error of prediction. A modification of Aboul-Seoud and Moharam model by separating the power terms accounting for the effects of specific gravity and average boiling point improves the accuracy of viscosity prediction. It was discovered that the relation of slope of viscosity decrease with temperature enhancement for the secondary vacuum gas oil is not a constant. This slope increases with the average boiling point and the specific gravity augmentation, a fact that has not been discussed before.
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Yan, Yajing, Yongshuai Yan, Guizhang Zhao, Yanfang Zhou y Zhoufeng Wang. "Combined ERT and GPR Data for Subsurface Characterization of Weathered Hilly Slope: A Case Study in Zhejiang Province, Southeast China". Sustainability 14, n.º 13 (22 de junio de 2022): 7616. http://dx.doi.org/10.3390/su14137616.
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Rain-triggered landslides frequently threaten public safety, infrastructure, and the economy during typhoon seasons in Zhejiang Province. Landslides are complex structural systems, and the subsurface features play a significant role in their stability. Their early identification and the evaluation of potential danger in terms of the rupture surface and unstable body are essential for geohazard prevention and protection. However, the information about the subsurface acquired by conventional exploration approaches is generally limited to sparse data. This paper describes a joint application of ground-penetrating radar (GPR) with a 100 MHz antenna and the electrical resistivity tomography (ERT) method with the Wenner configuration to identify the stratum structure and delineate the potentially unstable body of a clay-rich slope, the results of which were further verified using borehole data and field observation. The acquired results from the GPR and ERT surveys, consistent with each other, indicate two stratigraphic layers comprising silty clay and silty mudstone. Moreover, the potential rupture zone very likely exists in the highly weathered mudstone in the depth range of 3–7 m, and the average depth is 5 m. In addition, the thickness of the unstable mass is greater on the east and crest parts of the slope. Conclusively, the optimum combination of ERT and GPR is reliable for conducting rapid and effective delineation of subsurface characteristics of clayey slopes for risk assessment and mitigation during the typhoon season.
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Weigand, Maximilian, Florian M. Wagner, Jonas K. Limbrock, Christin Hilbich, Christian Hauck y Andreas Kemna. "A monitoring system for spatiotemporal electrical self-potential measurements in cryospheric environments". Geoscientific Instrumentation, Methods and Data Systems 9, n.º 2 (5 de agosto de 2020): 317–36. http://dx.doi.org/10.5194/gi-9-317-2020.
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Abstract. Climate-induced warming increasingly leads to degradation of high-alpine permafrost. In order to develop early warning systems for imminent slope destabilization, knowledge about hydrological flow processes in the subsurface is urgently needed. Due to the fast dynamics associated with slope failures, non- or minimally invasive methods are required for inexpensive and timely characterization and monitoring of potential failure sites to allow in-time responses. These requirements can potentially be met by geophysical methods usually applied in near-surface geophysical settings, such as electrical resistivity tomography (ERT), ground-penetrating radar (GPR), various seismic methods, and self-potential (SP) measurements. While ERT and GPR have their primary uses in detecting lithological subsurface structure and liquid water/ice content variations, SP measurements are sensitive to active water flow in the subsurface. Combined, these methods provide huge potential to monitor the dynamic hydrological evolution of permafrost systems. However, while conceptually simple, the technical application of the SP method in high-alpine mountain regions is challenging, especially if spatially resolved information is required. We here report on the design, construction, and testing phase of a multi-electrode SP measurement system aimed at characterizing surface runoff and meltwater flow on the Schilthorn, Bernese Alps, Switzerland. Design requirements for a year-round measurement system are discussed; the hardware and software of the constructed system, as well as test measurements are presented, including detailed quality-assessment studies. On-site noise measurements and one laboratory experiment on freezing and thawing characteristics of the SP electrodes provide supporting information. It was found that a detailed quality assessment of the measured data is important for such challenging field site operations, requiring adapted measurement schemes to allow for the extraction of robust data in light of an environment highly contaminated by anthropogenic and natural noise components. Finally, possible short- and long-term improvements to the system are discussed and recommendations for future installations are developed.
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Thiessen, Kendall J., Marolo C. Alfaro y James A. Blatz. "Measuring the load–deformation response of rockfill columns by a full-scale field test on a natural riverbank". Canadian Geotechnical Journal 48, n.º 7 (julio de 2011): 1032–43. http://dx.doi.org/10.1139/t11-019.
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A full-scale field test loading of a riverbank stabilized with rockfill columns was used to measure the load–deformation characteristics of the reinforced slope. The test site is located on the natural banks of the Red River in the city of Winnipeg. Rockfill column technology has evolved from granular shear key methods for stabilizing slopes. The relatively weak lacustrine clays are stabilized with compacted columns of limestone rockfill. The columns typically extend through the clay stratum and are anchored in the underlying till. The project involved an extensive site investigation, and soils characterization program in preparation for the field test. Eleven 2.1 m diameter columns were tested by loading the bank with 1920 t of fill. The deformations were measured with standard and in-place inclinometers. The pore-water pressure response of the in situ soils was continuously monitored with vibrating wire piezometers. The results have shown that shear stresses are mobilized along the entire length of the column when subjected to loading, and that complete densification is important in minimizing deformations. This paper discusses the design and construction of the field test and presents the results of the monitoring programs.
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Bery, Andy Anderson y Rosli Saad. "Enhanced Horizontal and Vertical Resolution in 4-D Electrical Resistivity Tomography for Environmental Slope Study in Penang Island". Applied Mechanics and Materials 661 (octubre de 2014): 73–80. http://dx.doi.org/10.4028/www.scientific.net/amm.661.73.
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This paper presents 4-D high resolution electrical resistivity tomography study for slope monitoring using two optimized (modified) arrays of the Wenner-Schlumberger and Pole-Dipole. These optimized resistivity arrays give a total of 2052 number of datum points from each data acquisition set. These two optimized were used because they have more datum points compared to their original arrays. Perhaps these optimized arrays were able to resolve the subsurface structures from surface areas. Inversion results from the computer (mathematical models) suggested that these optimized arrays were able to give in imaging the Earth’s subsurface structures and characterization at different period of time. Furthermore, in this paper, we are presented merging data levels in order to give high resolution in electrical resistivity tomography. Even though the time taken for data acquisition using this technique is twice, the outcome is compromised and reliable which helpful in the Earth’s subsurface interpretation.
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Martino, S. y P. Mazzanti. "Analysis of sea cliff slope stability integrating traditional geomechanical surveys and remote sensing". Natural Hazards and Earth System Sciences Discussions 1, n.º 4 (31 de julio de 2013): 3689–734. http://dx.doi.org/10.5194/nhessd-1-3689-2013.
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Abstract. An integrated approach to the geomechanical characterization of coastal sea cliffs was demonstrated at Mt. Pucci (Gargano promontory, Southern Italy) by performing direct traditional geomechanical and remote geostructural investigations via Terrestrial Laser Scanner (TLS). The consistency of the integrated techniques allowed us to achieve a comprehensive and affordable characterization of the main joint sets on the sea cliff slope. The observed joint sets were observed to evaluate the susceptibility of the slope to rock falls by attributing safety factors (SFs) to the topple- and wedge-prone rock blocks under three triggering conditions: (a) filling with static water, (b) seismic action, and (c) weathering of joint surfaces. The results of the susceptibility analysis for the topple-prone blocks show that the critical height of water filling of the joint is up to 50 cm and that the critical pseudo-static acceleration values vary in the range of 0.16–0.3 g depending on the block geometry and slope face orientation. For the wedge blocks, the critical height of water filling of the joint is generally up to several centimeters, and the critical pseudo-static acceleration values vary in the range of 0.05–0.8 g depending on the block geometry and slope face orientation. Moreover, the unstable conditions of the blocks due to weathering generally represent 60% of the joint degradation of the intact rock. The combined action of weathering and static water fill was also considered, resulting in a significant decrease of the SFs. Specifically, unstable conditions are associated with water levels lower than 47% of the water levels observed in intact joints, even if less than 60% of the weathering is attributed to the joints. Furthermore, remote survey analyses via Thermal InfraRed Camera and Terrestrial SAR Interferometry (TInSAR) were performed to evaluate the role of the surveyed joint sets in inducing instabilities in the Mt. Pucci sea cliff. The results of this study can be summarized as follows: (i) the thermal images allowed us to identify anomalies that correspond well to the main joints and to the slope material released due to recent collapses; and (ii) TInSAR monitoring revealed permanent displacements greater than 1 mm, and cyclic daily displacements of up to 1.2 mm were detected in certain sectors and were attributed to thermal variation of the rock mass.
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Hojat, Azadeh, Diego Arosio, Vladislav Ivov Ivanov, Laura Longoni, Monica Papini, Marco Scaioni, Greta Tresoldi y Luigi Zanzi. "Geoelectrical characterization and monitoring of slopes on a rainfall-triggered landslide simulator". Journal of Applied Geophysics 170 (noviembre de 2019): 103844. http://dx.doi.org/10.1016/j.jappgeo.2019.103844.
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Boubazine, Leila, Abderahmene Boumazbeur, Riheb Hadji y Kessasra Fares. "Slope failure characterization: A joint multi-geophysical and geotechnical analysis, case study of Babor Mountains range, NE Algeria". Mining of Mineral Deposits 16, n.º 4 (30 de diciembre de 2022): 65–70. http://dx.doi.org/10.33271/mining16.04.065.
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Purpose. The research purpose is to apply an original combined approach to the study of landslide occurrence in the Tarzoust region, based on geophysical approaches. This is extremely important because landslides damage roads and buildings in many parts of North Africa, especially in the city of Tarzoust, NE Algeria. Significant slope failures have resulted in serious disasters in the region. Methods. In this study we use Vertical Electric Soundings (VES) and Seismic Refraction Method (SRM) for underground exploration, as well as Electrical Resistivity Tomography (ERT) to support the latter two methods. Findings. The clayey nature of the terrain is confirmed, very often covered by a mantle of superficial colluvium formations. The depth of the bedrock and shear surface has been precisely determined. The ERT reveals that the terrain has already experienced instability in the past. Originality. The originality of this study is in the combination of data from various sources and different approaches for the purpose of planning the deployment and use of land. Practical implications. Our approach has proven that the combination of geological and geotechnical data with geophysical deterministic methods can help engineers and decision-makers in land management. Our recommendations consist of topographic, inclinometric and piezometric monitoring for slip development and the effectiveness of reinforcement measures for new housing, and equipment programs for regional planning.
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Cignetti, Martina, Danilo Godone, Aleksandra Wrzesniak y Daniele Giordan. "Structure from Motion Multisource Application for Landslide Characterization and Monitoring: The Champlas du Col Case Study, Sestriere, North-Western Italy". Sensors 19, n.º 10 (22 de mayo de 2019): 2364. http://dx.doi.org/10.3390/s19102364.
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Structure from Motion (SfM) is a powerful tool to provide 3D point clouds from a sequence of images taken from different remote sensing technologies. The use of this approach for processing images captured from both Remotely Piloted Aerial Vehicles (RPAS), historical aerial photograms, and smartphones, constitutes a valuable solution for the identification and characterization of active landslides. We applied SfM to process all the acquired and available images for the study of the Champlas du Col landslide, a complex slope instability reactivated in spring 2018 in the Piemonte Region (north-western Italy). This last reactivation of the slide, principally due to snow melting at the end of the winter season, interrupted the main road used to reach Sestriere, one of the most famous ski resorts in north-western Italy. We tested how SfM can be applied to process high-resolution multisource datasets by processing: (i) historical aerial photograms collected from five diverse regional flights, (ii) RGB and multi-spectral images acquired by two RPAS, taken in different moments, and (iii) terrestrial sequences of the most representative kinematic elements due to the evolution of the landslide. In addition, we obtained an overall framework of the historical development of the area of interest, and distinguished several generations of landslides. Moreover, an in-depth geomorphological characterization of the Champlas du Col landslide reactivation was done, by testing a cost-effective and rapid methodology based on SfM principles, which is easily repeatable to characterize and investigate active landslides.
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Das, Sourav y Antoinette Tordesillas. "Near Real-Time Characterization of Spatio-Temporal Precursory Evolution of a Rockslide from Radar Data: Integrating Statistical and Machine Learning with Dynamics of Granular Failure". Remote Sensing 11, n.º 23 (25 de noviembre de 2019): 2777. http://dx.doi.org/10.3390/rs11232777.
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This study builds on fundamental knowledge of granular failure dynamics to develop a statistical and machine learning approach for characterization of a landslide. We demonstrate our approach for a rockslide using surface displacement data from a ground based radar monitoring system. The algorithm has three key components: (i) identification of a regime change point t 0 marking the departure from statistical invariance of the global velocity field, (ii) characterization of the clustering pattern formed by the velocity time series at t 0 , and (iii) classification of velocity patterns for t > t 0 to deliver a measure of risk of failure from t 0 and estimates of the time of emergent and imminent risk of failure. Unlike the prevailing approach of analysing time series data from one or a few chosen locations, we make full use of data from all monitored points on the slope (here 1803). We do not make a priori assumptions on the monitored domain and base our characterization of the complex spatial patterns and associated dynamics only from the data. Our approach is informed by recent developments in the physics and micromechanics of failure in granular media and is configured to accommodate additional data on landslide triggers and other determinants of landslide risk readily.
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Avian, Michael, Christian Bauer, Matthias Schlögl, Barbara Widhalm, Karl-Heinz Gutjahr, Michael Paster, Christoph Hauer et al. "The Status of Earth Observation Techniques in Monitoring High Mountain Environments at the Example of Pasterze Glacier, Austria: Data, Methods, Accuracies, Processes, and Scales". Remote Sensing 12, n.º 8 (15 de abril de 2020): 1251. http://dx.doi.org/10.3390/rs12081251.
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Earth observation offers a variety of techniques for monitoring and characterizing geomorphic processes in high mountain environments. Terrestrial laserscanning and unmanned aerial vehicles provide very high resolution data with high accuracy. Automatic cameras have become a valuable source of information—mostly in a qualitative manner—in recent years. The availability of satellite data with very high revisiting time has gained momentum through the European Space Agency’s Sentinel missions, offering new application potential for Earth observation. This paper reviews the status of recent techniques such as terrestrial laserscanning, remote sensed imagery, and synthetic aperture radar in monitoring high mountain environments with a particular focus on the impact of new platforms such as Sentinel-1 and -2 as well as unmanned aerial vehicles. The study area comprises the high mountain glacial environment at the Pasterze Glacier, Austria. The area is characterized by a highly dynamic geomorphological evolution and by being subject to intensive scientific research as well as long-term monitoring. We primarily evaluate landform classification and process characterization for: (i) the proglacial lake; (ii) icebergs; (iii) the glacier river; (iv) valley-bottom processes; (v) slope processes; and (vi) rock wall processes. We focus on assessing the potential of every single method both in spatial and temporal resolution in characterizing different geomorphic processes. Examples of the individual techniques are evaluated qualitatively and quantitatively in the context of: (i) morphometric analysis; (ii) applicability in high alpine regions; and (iii) comparability of the methods among themselves. The final frame of this article includes considerations on scale dependent process detectability and characterization potentials of these Earth observation methods, along with strengths and limitations in applying these methods in high alpine regions.
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Kuźmicz, Agnieszka, Arti Goyal, Stanisław Zola, Marek Jamrozy, Marek Dróżdż, Waldemar Ogłoza, Michał Siwak, Daniel E. Reichart, Vladimir V. Kouprianov y Daniel B. Caton. "Optical Variability of Eight FRII-type Quasars with 13 yr Photometric Light Curves". Astrophysical Journal Supplement Series 263, n.º 1 (1 de noviembre de 2022): 16. http://dx.doi.org/10.3847/1538-4365/ac9622.
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Abstract We characterize the optical variability properties of eight lobe-dominated radio quasars (QSOs): B2 0709+37, FBQS J095206.3+235245, PG 1004+130, [HB89] 1156+631, [HB89] 1425+267, [HB89] 1503+691, [HB89] 1721+343, and 4C +74.26, systematically monitored for a duration of 13 yr since 2009. The quasars are radio-loud objects with extended radio lobes that indicate their orientation close to the sky plane. Five of the eight QSOs are classified as giant radio quasars. All quasars showed variability during our monitoring, with magnitude variations between 0.3 and 1 mag for the least variable and the most variable QSOs, respectively. We performed both structure function (SF) analysis and power spectral density (PSD) analysis for the variability characterization and search for characteristic timescales and periodicities. As a result of our analysis, we obtained relatively steep SF slopes (α ranging from 0.49 to 0.75) that are consistent with the derived PSD slopes (∼2–3). All the PSDs show a good fit to single power-law forms, indicating a red-noise character of variability between timescales of ∼13 yr and weeks. We did not measure reliable characteristic timescales of variability from the SF analysis, which indicates that the duration of the gathered data is too short to reveal them. The absence of bends in the PSDs (change of slope from ≥1 to ∼0) on longer timescales indicates that optical variations are most likely caused by thermal instabilities in the accretion disk.
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Azedou, Ali, Said Lahssini, Abdellatif Khattabi, Modeste Meliho y Nabil Rifai. "A Methodological Comparison of Three Models for Gully Erosion Susceptibility Mapping in the Rural Municipality of El Faid (Morocco)". Sustainability 13, n.º 2 (12 de enero de 2021): 682. http://dx.doi.org/10.3390/su13020682.
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Erosion is the main threat to sustainable water and soil management in Morocco. Located in the Souss-Massa watershed, the rural municipality of El Faid remains an area where gully erosion is a major factor involved in soil degradation and flooding. The aim of this study is to predict the spatial distribution of gully erosion at the scale of this municipality and to evaluate the predictive capacity of three prediction methods (frequency ratio (FR), logistic regression (LR), and random forest (RF)) for the characterization of gullying vulnerability. Twelve predisposing factors underlying gully formation were considered and mapped (elevation, slope, aspect, plane curvature, slope length (SL), stream power index (SPI), composite topographic index (CTI), land use, topographic wetness index (TWI), normalized difference vegetation index (NDVI), lithology, and vegetation cover (C factor). Furthermore, 894 gullies were digitized using high-resolution imagery. Seventy-five percent of the gullies were randomly selected and used as a training dataset, whereas the remaining 25% were used for validation purposes. The prediction accuracy was evaluated using area under the curve (AUC). Results showed that the factor that most contributed to the prevalence of gullying was topographic (slope, CTI, LS). Furthermore, the fitted models revealed that the RF model had a better prediction quality, with the best AUC (91.49%). The produced maps represent a valuable tool for sustainable management, land conservation, and protecting human lives against natural hazards (floods).
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Gaffet, Stéphane, Yves Guglielmi, Frédéric Cappa, Claude Pambrun, Tony Monfret y David Amitrano. "Use of the simultaneous seismic, GPS and meteorological monitoring for the characterization of a large unstable mountain slope in the southern French Alps". Geophysical Journal International 182, n.º 3 (29 de junio de 2010): 1395–410. http://dx.doi.org/10.1111/j.1365-246x.2010.04683.x.
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Enríquez, Carlos, Juan Manuel Jurado, Alexandro Bailey, Danilo Callén, María José Collado, Gabriel Espina, Pablo Marroquín et al. "The UAS-Based 3D Image Characterization of Mozarabic Church Ruins in Bobastro (Malaga), Spain". Remote Sensing 12, n.º 15 (24 de julio de 2020): 2377. http://dx.doi.org/10.3390/rs12152377.
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In recent years, the application of geomatics tools in archaeology has proved to be very useful to obtain meaningful knowledge of the 3D reconstruction of archaeological remains and semantic classification of the 3D surface. These techniques have proven to be an effective solution for the 3D modeling and the extraction of many spatial features on an archaeological site. However, novel methodologies as well as new data exploitation strategies are required to exploit these geospatial data for natural and cultural heritage documentation, monitoring, and preservation. In this paper, we have studied unique archaeological ruins, a Mozarab church in Al-Andalus, using high-resolution RGB images, which was taken by a drone. Thus, a 3D reconstruction of the ruins and the surrounding environment is carried out in order to characterize it on a dense point cloud. Then, a digital elevation model (DEM) was calculated in order to identify critical slope lines, which are significant to determine where the structure of the church was built. Our results can be used for the development of an architectural project and thus a virtual recreation of these archaeological ruins was performed.
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Maierhofer, Theresa, Christian Hauck, Christin Hilbich, Andreas Kemna y Adrián Flores-Orozco. "Spectral induced polarization imaging to investigate an ice-rich mountain permafrost site in Switzerland". Cryosphere 16, n.º 5 (20 de mayo de 2022): 1903–25. http://dx.doi.org/10.5194/tc-16-1903-2022.
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Abstract. Spectral induced polarization (SIP) measurements were collected at the Lapires talus slope, a long-term permafrost monitoring site located in the western Swiss Alps, to assess the potential of the frequency dependence (within the frequency range of 0.1–225 Hz) of the electrical polarization response of frozen rocks for an improved permafrost characterization. The aim of our investigation was to (a) find a field protocol that provides SIP imaging data sets less affected by electromagnetic coupling and easy to deploy in rough terrains, (b) cover the spatial extent of the local permafrost distribution, and (c) evaluate the potential of the spectral data to discriminate between different substrates and spatial variations in the volumetric ice content within the talus slope. To qualitatively assess data uncertainty, we analyse the misfit between normal and reciprocal (N&R) measurements collected for all profiles and frequencies. A comparison between different cable setups reveals the lowest N&R misfits for coaxial cables and the possibility of collecting high-quality SIP data in the range between 0.1–75 Hz. We observe an overall smaller spatial extent of the ice-rich permafrost body compared to its assumed distribution from previous studies. Our results further suggest that SIP data help to improve the discrimination between ice-rich permafrost and unfrozen bedrock in ambiguous cases based on their characteristic spectral behaviour, with ice-rich areas showing a stronger polarization towards higher frequencies in agreement with the well-known spectral response of ice.
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Guan, Huade, Xinping Zhang, Oleg Makhnin y Zhian Sun. "Mapping Mean Monthly Temperatures over a Coastal Hilly Area Incorporating Terrain Aspect Effects". Journal of Hydrometeorology 14, n.º 1 (1 de febrero de 2013): 233–50. http://dx.doi.org/10.1175/jhm-d-12-014.1.
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Abstract Efforts in the past two decades on air temperature mapping based on sparse monitoring networks reveal that algorithms based on multiple linear regressions with geographical and topographical parameters perform promisingly. In this study, a multiple-regression model, previously for precipitation characterization using autosearched orographic and atmospheric effects (PCASOA), is applied to analyze spatial distribution of mean monthly daily maximum and minimum temperatures (at 33 stations) in Adelaide and the Mount Lofty Ranges (9000 km2), a coastal hilly area in South Australia. Terrain aspect (or slope orientation) is transformed and explicitly incorporated in the model, together with some other topographic variables. Overall, PCASOA captures 91% and 70% observed spatial variability for mean monthly maximum (Tmax) and minimum (Tmin) temperature, respectively. The regression also infers some physical processes influencing the air temperature distribution. The results indicate horizontal gradients of Tmax in the east–west and north–south directions, which can be related to the effects of dominant wind directions in the study area. The effect of terrain ruggedness on Tmax is likely related to the blockage of sea breeze in the complex terrain. Cold air drainage potential only influences Tmin during winter months in the study area. Terrain slope and aspect significantly contribute to interpreting Tmin spatial distribution and can be related to their sheltering effect from the dominant cool inland winds. They also contribute to interpreting Tmax spatial distribution, while the physical mechanism is not clear.
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Arbune, Anca A., Isa Conradsen, Damon P. Cardenas, Luke E. Whitmire, Shannon R. Voyles, Peter Wolf, Samden Lhatoo, Philippe Ryvlin y Sándor Beniczky. "Ictal quantitative surface electromyography correlates with postictal EEG suppression". Neurology 94, n.º 24 (12 de mayo de 2020): e2567-e2576. http://dx.doi.org/10.1212/wnl.0000000000009492.
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ObjectiveTo test the hypothesis that neurophysiologic biomarkers of muscle activation during convulsive seizures reveal seizure severity and to determine whether automatically computed surface EMG parameters during seizures can predict postictal generalized EEG suppression (PGES), indicating increased risk for sudden unexpected death in epilepsy. Wearable EMG devices have been clinically validated for automated detection of generalized tonic-clonic seizures. Our goal was to use quantitative EMG measurements for seizure characterization and risk assessment.MethodsQuantitative parameters were computed from surface EMGs recorded during convulsive seizures from deltoid and brachial biceps muscles in patients admitted to long-term video-EEG monitoring. Parameters evaluated were the durations of the seizure phases (tonic, clonic), durations of the clonic bursts and silent periods, and the dynamics of their evolution (slope). We compared them with the duration of the PGES.ResultsWe found significant correlations between quantitative surface EMG parameters and the duration of PGES (p < 0.001). Stepwise multiple regression analysis identified as independent predictors in deltoid muscle the duration of the clonic phase and in biceps muscle the duration of the tonic-clonic phases, the average silent period, and the slopes of the silent period and clonic bursts. The surface EMG-based algorithm identified seizures at increased risk (PGES ≥20 seconds) with an accuracy of 85%.ConclusionsIctal quantitative surface EMG parameters correlate with PGES and may identify seizures at high risk.Classification of evidenceThis study provides Class II evidence that during convulsive seizures, surface EMG parameters are associated with prolonged postictal generalized EEG suppression.
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Deng, J. H., C. F. Lee y X. R. Ge. "Characterization of the disturbed zone in a large rock excavation for the Three Gorges Project". Canadian Geotechnical Journal 38, n.º 1 (1 de febrero de 2001): 95–106. http://dx.doi.org/10.1139/t00-080.
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Excavation in a rock mass leads to the perturbation of the stress regime, often creating a stress-relieved, locally weakened zone known as the disturbed zone. This paper presents the results of in situ studies that were carried out both in the central rock barrier (or separation block) between the shiplift and the temporary shiplock and in the northern slope of the permanent shiplock of the Three Gorges Project. The vertical extent of the disturbed zone was determined jointly by cross-hole seismic wave penetration testing and borehole elastic modulus testing, and the horizontal extent was assessed by monitoring and evaluating the deformation characteristics. Compared with the undisturbed rock mass, the P-wave velocity of the disturbed zone was reduced by 3438% and the borehole elastic modulus by 1231%. The reductions were caused by the opening of primary structural planes or the extension of apertures due to local sliding along the structural planes. In the disturbed zone, no newly formed fractured planes were found. The observed disturbed zone was compared with the tensile stress zones and the shear-damaged zones calculated by the finite element method. A rock reinforcement scheme was recommended and implemented.Key words: disturbed zone, mechanical properties, brittle rock mass, excavation, finite element method, reinforcement.
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Aslan, Gokhan, Michael Foumelis, Daniel Raucoules, Marcello De Michele, Severine Bernardie y Ziyadin Cakir. "Landslide Mapping and Monitoring Using Persistent Scatterer Interferometry (PSI) Technique in the French Alps". Remote Sensing 12, n.º 8 (20 de abril de 2020): 1305. http://dx.doi.org/10.3390/rs12081305.
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Continuous geodetic measurements in landslide prone regions are necessary to avoid disasters and better understand the spatiotemporal and kinematic evolution of landslides. The detection and characterization of landslides in high alpine environments remains a challenge associated with difficult accessibility, extensive coverage, limitations of available techniques, and the complex nature of landslide process. Recent studies using space-based observations and especially Persistent Scatterer Interferometry (PSI) techniques with the integration of in-situ monitoring instrumentation are providing vital information for an actual landslide monitoring. In the present study, the Stanford Method for Persistent Scatterers InSAR package (StaMPS) is employed to process the series of Sentinel 1-A and 1-B Synthetic Aperture Radar (SAR) images acquired between 2015 and 2019 along ascending and descending orbits for the selected area in the French Alps. We applied the proposed approach, based on extraction of Active Deformation Areas (ADA), to automatically detect and assess the state of activity and the intensity of the suspected slow-moving landslides in the study area. We illustrated the potential of Sentinel-1 data with the aim of detecting regions of relatively low motion rates that be can attributed to activate landslide and updated pre-existing national landslide inventory maps on a regional scale in terms of slow moving landslides. Our results are compared to pre-existing landslide inventories. More than 100 unknown slow-moving landslides, their spatial pattern, deformation rate, state of activity, as well as orientation are successfully identified over an area of 4000 km2 located in the French Alps. We also address the current limitations due the nature of PSI and geometric characteristic of InSAR data for measuring slope movements in mountainous environments like Alps.
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Amabile, Alessia, Annarita Pozzato y Alessandro Tarantino. "Instability of flood embankments due to pore-water pressure build-up at the toe: lesson learned from the Adige River case study". Canadian Geotechnical Journal 57, n.º 12 (diciembre de 2020): 1844–53. http://dx.doi.org/10.1139/cgj-2018-0372.
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A case study is presented of the Adige River embankment, a segment of which experienced instability of the landside slope due to the development of uplift pressures. Soil profile and hydromechanical properties of the embankment and foundation materials have been assessed via site investigation, laboratory testing, and field monitoring for two cross sections, within and outside the failure segment. The hydromechanical model developed thereof was first validated against its ability to reproduce the probability of failure for the two sections with a first-order, second-moment (FOSM)-based approach. Comparison of water flow regimes between the two sections was then used to highlight the importance of the hydraulic properties of the material on the landside for the development of uplift pressures at the toe of the embankment. The lesson learnt from this case study is that the hydraulic response of the ground on the landside may play a critical role on the stability of flood embankments and its characterization should therefore not be overlooked when planning site investigation.
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Rito, Gianpietro Di, Aleksander Suti y Roberto Galatolo. "Fault-tolerant control via four-leg inverter of a full-electric propulsion system for lightweight fixed-wing UAVs". IOP Conference Series: Materials Science and Engineering 1226, n.º 1 (1 de febrero de 2022): 012108. http://dx.doi.org/10.1088/1757-899x/1226/1/012108.
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Abstract The work deals with the development and the performance characterization of a novel control strategy for the detection, isolation and accommodation of coil faults in a three-phase Permanent Magnet Synchronous Motor (PMSM), used to drive the propeller of a modern lightweight fixed-wing UAV. The health-monitoring algorithms on motor currents (used to detect the open-circuit fault and to activate the control reconfiguration) are based on a slope method, associated to the evaluation of the current phasor trajectory in the Clarke plane. Actually, when an open-circuit fault occurs in PMSM driven by a standard three-leg converter, the typical circular trajectory of the current phasor in the Clarke plane collapses into a linear track and relevant torque ripples are generated. On the other hand, if the PMSM is driven by a four-leg converter, a control reconfiguration can be applied: the fourth leg of the power bridge is in stand-by when the system operates without faults, but it is enabled to regulate the current flowing at the central point of the Y connection of the 3-phase PMSM. The performances of the fault-tolerant algorithms are assessed via detailed nonlinear simulation of the propulsion system (including propeller loads, electrical faults, mechanical transmission compliance, digital signal processing and sensors errors). The results demonstrate that the health-monitoring algorithms and the fault-tolerant control strategies permit to obtain extremely small detection and isolation latencies, and negligible performance degradation in terms PMSM torque.
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Vouillamoz, Naomi, Sabrina Rothmund y Manfred Joswig. "Characterizing the complexity of microseismic signals at slow-moving clay-rich debris slides: the Super-Sauze (southeastern France) and Pechgraben (Upper Austria) case studies". Earth Surface Dynamics 6, n.º 2 (27 de junio de 2018): 525–50. http://dx.doi.org/10.5194/esurf-6-525-2018.
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Abstract. Soil and debris slides are prone to rapid and dramatic reactivation. Deformation within the instability is accommodated by sliding, whereby weak seismic energies are released through material deformation. Thus, passive microseismic monitoring provides information that relates to the slope dynamics. In this study, passive microseismic data acquired at Super-Sauze (southeastern France) and Pechgraben (Upper Austria) slow-moving clay-rich debris slides (“clayey landslides”) are investigated. Observations are benchmarked against previous similar case studies to provide a comprehensive and homogenized typology of microseismic signals at clayey landslides. A thorough knowledge of the various microseismic signals generated by slope deformation is crucial for the future development of automatic detection systems to be implemented in landslide early-warning systems. Detected signals range from short-duration (< 2 s) quake-like signals to a wide variety of longer-duration tremor-like radiations (> 2 s – several min). The complexity of seismic velocity structures, the low quantity and low quality of available signal onsets and non-optimal seismic network geometry severely impedes the source location procedure; thus, rendering source processes characterization challenging. Therefore, we constrain sources' locations using the prominent waveform amplitude attenuation pattern characteristic of near-source area (< about 50 m) landslide-induced microseismic events. A local magnitude scale for clayey landslides (ML−LS) is empirically calibrated using calibration shots and hammer blow data. The derived ML−LS returns daily landslide-induced microseismicity rates that positively correlate with higher average daily displacement rates. However, high temporal and spatial resolution analyses of the landslide dynamics and hydrology are required to better decipher the potential relations linking landslide-induced microseismic signals to landslide deformation.
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Ramírez, Sandra, Manuel Zarzo, Angel Perles y Fernando-Juan García-Diego. "Characterization of Temperature Gradients According to Height in a Baroque Church by Means of Wireless Sensors". Sensors 21, n.º 20 (19 de octubre de 2021): 6921. http://dx.doi.org/10.3390/s21206921.
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The baroque church of Saint Thomas and Saint Philip Neri (Valencia, Spain), which was built between 1727 and 1736, contains valuable paintings by renowned Spanish artists. Due to the considerable height of the central nave, the church can experience vertical temperature gradients. In order to investigate this issue, temperatures were recorded between August 2017 and February 2018 from a wireless monitoring system composed of 21 sensor nodes, which were located at different heights in the church from 2 to 13 m from the floor level. For characterizing the temperature at high, medium and low altitude heights, a novel methodology is proposed based on sparse Partial Least Squares regression (sPLS), Linear Discriminant Analysis (LDA), and the Holt-Winters method, among others, which were applied to a time series of temperature. This approach is helpful to discriminate temperature profiles according to sensor height. Once the vertical thermal gradients for each month were characterized, it was found that temperature reached the maximum correlation with sensor height in the period between August 10th and September 9th. Furthermore, the most important features from the time series that explain this correlation are the mean temperature and the mean of moving range. In the period mentioned, the vertical thermal gradient was estimated to be about 0.043 ∘C/m, which implies a difference of 0.47 ∘C on average between sensor nodes at 2 m from the floor with respect to the upper ones located at 13 m from the floor level. The gradient was estimated as the slope from a linear regression model using height and hourly mean temperature as the predictor and response, respectively. This gradient is consistent with similar reported studies. The fact that such gradient was only found in one month suggests that the mechanisms of dust deposition on walls involved in vertical thermal gradients are not important in this case regarding the preventive conservation of artworks. Furthermore, the methodology proposed here was useful to discriminate the time series at high, medium and low altitude levels. This approach can be useful when a set of sensors is installed for microclimate monitoring in churches, cathedrals, and other historical buildings, at different levels and positions.