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A catastrophic rock planar slide occurred in the parish of Palmeira de Faro, Esposende (N Portugal), on November 23, 2022, in the middle of the night, killing two people while they were asleep in the first floor of a building close to the affected cut slope. The collapsed slope presented a maximum height of about 23 m, and was excavated in a granitic rock mass strongly weathered, in some areas by mechanical means and, locally, with the support of blasting. The displaced material, with an estimated volume of 2000 m3, described an oblique trajectory with respect to the dip direction of the slope with a maximum length of about 44.6 m. The direction of the trajectory could be explained by the strong structural control of the instability trough three discontinuity sets which delimit the slid rock mass causing multiple damage on the above-mentioned building. Although further detailed studies are necessary to elucidate the causes of the landslide, the unfavorable geological conditions, the anomalous accumulated rainfall during the previous two months (more than double than in the historic records), and some excavations apparently performed on the cut slope could be related to this instability. Therefore, this recent landslide highlights the important influence of the rock mass structure on the development of rock planar slides. [ABSTRACT FROM AUTHOR]

Slope failures, subsidence, earthworks, consolidation of waste dumps, and erosion are typical active deformation processes that pose a significant hazard in current and abandoned mining areas, given their considerable potential to produce damage and affect the population at large. This work proves the potential of exploiting space-borne InSAR and airborne LiDAR techniques, combined with data inferred through a simple slope stability geotechnical model, to obtain and update inventory maps of active deformations in mining areas. The proposed approach is illustrated by analyzing the region of Sierra de Cartagena-La Union (Murcia), a mountainous mining area in southeast Spain. Firstly, we processed Sentinel-1 InSAR imagery acquired both in ascending and descending orbits covering the period from October 2016 to November 2021. The obtained ascending and descending deformation velocities were then separately post-processed to semi-automatically generate two active deformation areas (ADA) maps by using ADATool. Subsequently, the PS-InSAR LOS displacements of the ascending and descending tracks were decomposed into vertical and east-west components. Complementarily, open-access, and non-customized LiDAR point clouds were used to analyze surface changes and movements. Furthermore, a slope stability safety factor (SF) map was obtained over the study area adopting a simple infinite slope stability model. Finally, the InSAR-derived maps, the LiDAR-derived map, and the SF map were integrated to update a previously published landslides' inventory map and to perform a preliminary classification of the different active deformation areas with the support of optical images and a geological map. Complementarily, a level of activity index is defined to state the reliability of the detected ADA. A total of 28, 19, 5, and 12 ADAs were identified through ascending, descending, horizontal, and vertical InSAR datasets, respectively, and 58 ADAs from the LiDAR change detection map. The subsequent preliminary classification of the ADA enabled the identification of eight areas of consolidation of waste dumps, 11 zones in which earthworks were performed, three areas affected by erosion processes, 17 landslides, two mining subsidence zone, seven areas affected by compound processes, and 23 possible false positive ADAs. The results highlight the effectiveness of these two remote sensing techniques (i.e., InSAR and LiDAR) in conjunction with simple geotechnical models and with the support of orthophotos and geological information to update inventory maps of active deformation areas in mining zones. [ABSTRACT FROM AUTHOR]

This article proposed a new method to estimate the diameter of jet grouting columns. The method uses the largest data collection of column diameters measured to date and includes a large amount of new data that fills the existing gap of data for high injection energies. The dataset was analysed using a deep neural network that took into account the problem's key parameters (i.e. type of soil, soil resistance, type of jet and specific energy in the nozzle). As a result, three different neural networks were selected, one for each type of jet, according to the errors and consistency associated with each. Finally, using the trained networks, a number of design charts were developed to determine the diameter of a jet grouting column as a function of the soil properties and the jet system. These charts allow generating an optimal jet grouting design, improving the prediction of the diameter of jet columns especially in the high energy triple fluid. [ABSTRACT FROM AUTHOR]

Alaşehir-Sarıgöl sub-basin (ASSB) in Türkiye faces severe water stress mainly due to intensive agricultural irrigation. This has led to declining groundwater levels, aquifer compaction, and subsequent land subsidence. This study aims to evaluate the roles of tectonic activity and groundwater withdrawal in land-subsidence and investigate additional factors like faults and soft soil thickness. The P-SBAS algorithm was applied, using 98 and 123 Sentinel-1 SAR images in ascending and descending orbits, respectively, from 2016 to 2020. Independent Component Analysis separated long-term displacements from seasonal variations in the InSAR time series data. InSAR analysis showed displacement rates up to −6.40 cm/year. Results reveal a direct correlation between InSAR displacement and soft soil thickness, highlighting aquitard layer compaction due to groundwater withdrawal and piezometric head depletion as the primary causes of land subsidence. It was not possible to disentangle the multi-year displacements with different rates, i.e., to isolate the displacements caused by tectonic activity from displacements due to the soft soil compaction induced by groundwater withdrawal. Nonetheless, the analysis identified two spatiotemporal displacement trends: one linked to long-term, linear plastic compaction of the aquitard due to groundwater withdrawal and the other involving long-term displacements with seasonal rebounds caused by yearly water level fluctuations. • Groundwater extraction fosters land subsidence in the eastern Gediz river basin. • FastICA identified three uncorrelated components, explaining over 99% of eigenvalues. • A direct relationship between subsidence and soft soil thickness is detected. • Subsurface faults significantly impact land subsidence distribution patterns. [ABSTRACT FROM AUTHOR]

The permanent training of professionals in any area of knowledge is a challenge to be achieved today. With highperforming professionals is no different, they must master a wide range of disciplines ranging from human relationships to the domain of enterprise risk management. The research presents an analysis of the practical application of the concepts of information architecture, informational spaces and multimodality as a proposal to meet these demands of training of these professionals. The applied methodology was applied research, using questionnaires directed to professionals of high performance, to collect the data. The results of the research demonstrate a good acceptance of the model, initially with 94% of the evaluations concentrated between grades 8 to 10, concepts from good to great for the questions asked. The research indicates that the multimodality applied in the professional training can significantly help the reach of the information needs of the student, so that he can carry out his daily technical and managerial activities. [ABSTRACT FROM AUTHOR]

Finding new ways to quantify discontinuity persistence values in rock masses in an automatic or semi-automatic manner is a considerable challenge, as an alternative to the use of traditional methods based on measuring patches or traces with tapes. Remote sensing techniques potentially provide new ways of analysing visible data from the rock mass. This work presents a methodology for the automatic mapping of discontinuity persistence on rock masses, using 3D point clouds. The method proposed herein starts by clustering points that belong to patches of a given discontinuity. Coplanar clusters are then merged into a single group of points. Persistence is measured in the directions of the dip and strike for each coplanar set of points, resulting in the extraction of the length of the maximum chord and the area of the convex hull. The proposed approach is implemented in a graphic interface with open source software. Three case studies are utilized to illustrate the methodology: (1) small-scale laboratory setup consisting of a regular distribution of cubes with similar dimensions, (2) more complex geometry consisting of a real rock mass surface in an excavated cavern and (3) slope with persistent sub-vertical discontinuities. Results presented good agreement with field measurements, validating the methodology. Complexities and difficulties related to the method (e.g., natural discontinuity waviness) are reported and discussed. An assessment on the applicability of the method to the 3D point cloud is also presented. Utilization of remote sensing data for a more objective characterization of the persistence of planar discontinuities affecting rock masses is highlighted herein. [ABSTRACT FROM AUTHOR]

Liquefaction is an effect for which a saturated soil suffers a severe loss of shear strength due to an increase of pore-water pressure. This effect, which generally affects loose granular soils, is usually produced by cyclic loading such as that the induced by earthquakes. In Spain, three different national standards plus Eurocode can currently be applied in the assessment of potential liquefaction of a soil site. In this research, a comparative study of the similarities and differences between these standards has been performed. Moreover, to improve understanding of the differences between standards, the factor of safety against liquefaction has been obtained for three real cases in the province of Alicante. According to the obtained results, it can be concluded that the safety factor can present significant differences depending on the code used. [ABSTRACT FROM AUTHOR]

Understanding the uniaxial tensile behaviour of rocks and its water-induced variation are key issues for designing effective mining and civil engineering structures and for assessing numerous geotechnical hazards. However, these aspects remain poorly analysed because conducting uniaxial direct pull tests is a difficult and time-consuming laboratory task that requires the use of sophisticated equipment and complex rock sample preparation and processing. This work attempts to expand knowledge by determining several tensile properties of three porous limestone lithotypes under dry and water-saturated conditions through two different approaches: by conducting direct tensile tests and by means of indirect methods (i.e. Brazilian and point load tests). The results revealed that water saturation generated important reductions in their uniaxial tensile strength (UTS), tensile elastic modulus (E t), Brazilian tensile strength (BTS) and point load strength index (I s(50)). In addition, their petrological characteristics and mineralogical composition are used to discuss the main causes of the observed tensile softening. Furthermore, highly accurate correlation functions were established between the direct tensile strength parameters (UTS and E t) and the indirect ones (BTS and I s(50)) for the whole set of tested rocks. The proposed relationships are a novel and useful contribution to geomechanics because they enable the estimation of pure tensile parameters using alternative, cheap, rapid and versatile tests. • Water saturation leads to important decreases in tensile properties of limestones. • Relations among tensile strength parameters are analysed by curve fitting. • Uniaxial tensile behaviour can be accurately estimated using indirect methods. [ABSTRACT FROM AUTHOR]

Aragonés, L.; Tomás, R.; Cano, M.; Rosillo, E., and López, I., 2017. Influence of maritime construction within protected archaeological sites along coastal areas: Los Baños De La Reina (Alicante), Spain. A multidisciplinary study was made assessing the impact of the construction of a harbour on an existing Roman fish farm, which was excavated in the first century BC and placed in Alicante, on the SE coast of Spain. The effect of the harbour on the wave frequencies and the velocity of the streams has been modelled for the different building stages, using the SMC (Sistema de Modelado Costero) software, including consideration of the local maritime climate and bathymetry. The results show that the predominant wave frequencies and the stream velocities increased considerably after harbour construction and, as a result, created new turbulence areas within the influence area of the Roman fish farm. The presence of hydrodynamic bioindicators confirms this result. The lithological structure of the rock mass from which the pools were excavated clearly favours the differential erosion and the subsequent failure of the area, which is now exposed to the impact of ocean waves. The activity of some lithophaga organisms can also increase the degradation of the rock mass. Consequently, a joint analysis of the geological, biological, and maritime information available suggests the degradation of the Roman fish farm located in this area was strongly exacerbated by the construction of the harbour. [ABSTRACT FROM AUTHOR]

Earth Observations (EO) encompasses different types of sensors (e.g., Synthetic Aperture Radar, Laser Imaging Detection and Ranging, Optical and multispectral) and platforms (e.g., satellites, aircraft, and Unmanned Aerial Vehicles) and enables us to monitor and model geohazards over regions at different scales in which ground observations may not be possible due to physical and/or political constraints. EO can provide high spatial, temporal and spectral resolution, stereo-mapping and all-weather-imaging capabilities, but not by a single satellite at a time. Improved satellite and sensor technologies, increased frequency of satellite measurements, and easier access and interpretation of EO data have all contributed to the increased demand for satellite EO data. EO, combined with complementary terrestrial observations and with physical models, have been widely used to monitor geohazards, revolutionizing our understanding of how the Earth system works. This Special Issue presents a collection of scientific contributions focusing on innovative EO methods and applications for monitoring and modeling geohazards, consisting of four Sections: (1) earthquake hazards; (2) landslide hazards; (3) land subsidence hazards; and (4) new EO techniques and services. [ABSTRACT FROM AUTHOR]

Beijing is one of the most water-stressed cities in the world. Due to over-exploitation of groundwater, the Beijing region has been suffering from land subsidence since 1935. In this study, the Small Baseline InSAR technique has been employed to process Envisat ASAR images acquired between 2003 and 2010 and TerraSAR-X stripmap images collected from 2010 to 2011 to investigate land subsidence in the Beijing region. The maximum subsidence is seen in the eastern part of Beijing with a rate greater than 100 mm/year. Comparisons between InSAR and GPS derived subsidence rates show an RMS difference of 2.94 mm/year with a mean of 2.41 ± 1.84 mm/year. In addition, a high correlation was observed between InSAR subsidence rate maps derived from two different datasets (i.e., Envisat and TerraSAR-X). These demonstrate once again that InSAR is a powerful tool for monitoring land subsidence. InSAR derived subsidence rate maps have allowed for a comprehensive spatio-temporal analysis to identify the main triggering factors of land subsidence. Some interesting relationships in terms of land subsidence were found with groundwater level, active faults, accumulated soft soil thickness and different aquifer types. Furthermore, a relationship with the distances to pumping wells was also recognized in this work. [ABSTRACT FROM AUTHOR]

Rock mass classification systems are widely used tools for assessing the stability of rock slopes. Their calculation requires the prior quantification of several parameters during conventional fieldwork campaigns, such as the orientation of the discontinuity sets, the main properties of the existing discontinuities and the geo-mechanical characterization of the intact rock mass, which can be time-consuming and an often risky task. Conversely, the use of relatively new remote sensing data for modelling the rock mass surface by means of 3D point clouds is changing the current investigation strategies in different rock slope engineering applications. In this paper, the main practical issues affecting the application of Slope Mass Rating (SMR) for the characterization of rock slopes from 3D point clouds are reviewed, using three case studies from an end-user point of view. To this end, the SMR adjustment factors, which were calculated from different sources of information and processes, using the different softwares, are compared with those calculated using conventional fieldwork data. In the presented analysis, special attention is paid to the differences between the SMR indexes derived from the 3D point cloud and conventional field work approaches, the main factors that determine the quality of the data and some recognized practical issues. Finally, the reliability of Slope Mass Rating for the characterization of rocky slopes is highlighted. [ABSTRACT FROM AUTHOR]

ABSTRACT It is widely known that differential land subsidence in a valley significantly controls its fluvial dynamics. Nevertheless, major uncertainty exists about the way in which alluvial forms respond to this process. In this study, morphological and lithostratigraphic data have been combined with advanced differential interferometry ( A-DInSAR) to detect changes in alluvial landform elevations and to verify the existence of a differential subsidence pattern influenced by active sedimentary dynamics. For this purpose, the middle reach of the Segura River valley (Vega Media of the Segura River), in southeast Spain, was chosen as the study area. The Vega Media of the Segura River is an alluvial area affected by subsidence processes in close conjunction with depositional conditions, ground-water withdrawals and faults. A high scale mapping of the main younger sedimentary units was carried out by combining multi-temporal aerial photographs, high-resolution digital elevation models derived from LIDAR data, global navigation satellite system data and fieldwork. In addition, lithostratigraphic descriptions were obtained from geotechnical drilling and trenching. Finally, ground surface displacements, measured using A-DInSAR for the periods 1995-2005 and 2004-2008, allowed the determination of elevation rates and ground deformation associated with the different alluvial units. The results from this analysis revealed four typical deformational behaviours: non-deformational units (cemented alluvial fans and upper fluvial terraces); slightly deformable units (lower terraces and old abandoned meanders); moderately deformable units (lateral accretion zones and abandoned meanders before channelisation in 1981); and highly deformable areas (recently active meanders associated with artificial cutoffs by channelisation, non-active floodplains and spilling zones). [ABSTRACT FROM AUTHOR]

The extraction of underground minerals in hilly regions is highly susceptible to landslides, which requires the application of InSAR techniques to monitor the surface displacement. However, repeated mining for multiple coal seams can cause a large displacement beyond the detectable gradient of the traditional InSAR technique, making it difficult to explore the relationship between landslides and subsurface excavations in both temporal and spatial domains. In this study, the Tengqing landslide in Shuicheng, Guizhou, China, was chosen as the study area. Firstly, the large-gradient surface displacement in the line of sight was obtained by the fusion of SAR offset tracking and interferometric phase. Subsequently, a multi-segment logistic model was proposed to simulate the temporal effect induced by repeated mining activities. Next, a simplified probability integral method (SPIM) was utilized to invert the geometry of the mining tunnel and separate the displacement of the mining subsidence and landslide. Finally, the subsurface mining parameters and in situ investigation were carried out to assess the impact of mining and precipitation on the kinematic process of Tengqing landslides. Results showed that the repeated mining activities in Tengqing can not only cause land subsidence and rock avalanches at the top of the mountain, but also accelerate the landslide displacement. The technical approach presented in this study can provide new insights for monitoring and modeling the effects of repeated mining-induced landslides in mountainous areas. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an analysis of the performance of the Coherent Pixel Technique for urban subsidence monitoring using TerraSAR-X data. Repeated observations for the period comprised between July 2008 and September 2009 have been used. For this purpose the city of Murcia has been selected as a test-site because it is affected by subsidence due to groundwater exploitation. The obtained results are compared with those obtained from ERS/ENVISAT data belonging to the same period and validated with pre-existing information. Subsidence data reveal average rates of subsidence for the whole area up to −5mm/year with local values that reach −35mm/year. These results are analyzed with respect to the main factors that control subsidence mechanisms: the thickness of the compressible layer, the presence of pumping wells, and the water table variation. Finally a local analysis of several buildings and infrastructures is presented. Therefore the usefulness of X-band radar technology, not only to improve the knowledge of this kind of regional phenomenon, but also to study its effects on local areas such as buildings and infrastructures is demonstrated. [Copyright &y& Elsevier]

Abstract: Differential SAR Interferometry (DInSAR) is a remote sensing technique with the well-proven ability to monitor ground deformations. In this work we have applied an advanced DInSAR technique – the Coherent Pixels Technique (CPT) – , to study subsidence phenomena due to the excessive pumping of groundwater in the Vega Media of the Segura River (SE Spain) from 1993 to the present. The settlement map retrieved with DInSAR shows settlement of up to 8 cm at some points of the study area and has been compared with other data provided by ground instruments to analyse the relationship with ground deformation. A correlation has been observed between these measurements and the observations from on-site testing of piezometric groundwater fluctuations and borehole extensometric settlement. However, the distribution of damaged buildings, well points and basements does not show a clear relationship with measured subsidence values because the occurrence of damage also depends on the structural state of the buildings and the characteristics of their foundations. In addition, the distribution of pumping wells is not indicative of the distribution of the volume of water withdrawal which is the real conditioning factor of piezometric level changes. It can be concluded that the results obtained provide very useful spatial and temporal data about this phenomenon in an urban area at a low cost. The data can be used for forecasting purposes and helps to define zones with future ground settlement problems if the same conditions are repeated. This technique has also allowed the monitoring of ground subsidence in the Vega Media of Segura River for a period (1993–1995) where no instrument information was available. [Copyright &y& Elsevier]

Steep fill–bedrock interfaces usually appear in many filling soil infrastructures, such as airports, houses, and road embankments in mountainous areas, when the excavation of rock slopes is constrained. These interfaces are prone to be tensioned up to failure, which easily triggers landslides of fill slopes. The anchor system buried in the fill soil, named radial cable system, was proposed for effectively enhancing the stability of steep fill–bedrock interfaces. At the interface, the steel ropes of the anchor section cable were equally divided into three subcables with a radial distribution. The pullout performance, failure evolution, and branching effect of the radial cable coupled with anchor plates were studied by a pullout test (in a laboratory setup) and a numerical simulation. The results showed that (1) the ultimate pullout capacities (Pu) of the radial cables were 193.53%–312.94% (for the 7 mm diameter of the anchor plate) and 141.25%–247.50% (for the 10 mm diameter of the anchor plate) greater than those of the single cables; (2) the pullout performance of the radial cable was significantly improved with an increase in the diameter of the anchor plate, and the optimal radial inclined angle of subcables coupled with anchor plates was 15°; (3) the soil surrounding the radial cable showed a progressive failure pattern, and its failure area was basically a symmetric conical; and (4) the radial cable can better reinforce the steep fill–rock interface than the conventional cable, as verified by a hill-fill project. The results of this study provide some new and important guidelines for the design and application of the radial cable system. [ABSTRACT FROM AUTHOR]

The San Luis Potosi metropolitan area has suffered considerable damage from land subsidence over the past decades, which has become visible since 1990. This paper seeks to evaluate the effects of groundwater withdrawal on land subsidence in the San Luis Potosi Valley and the development of surface faults due to the differential compaction of sediments. For this purpose, we applied the Coherent Pixels Technique (CPT), a Persistent Scatterer Interferometry (PSI) technique, using 112 Sentinel-1 acquisitions from October 2014 to November 2019 to estimate the deformation rate. The results revealed that the deformation areas in the municipality of Soledad de Graciano Sánchez mostly exhibit subsidence values between −1.5 and −3.5 cm/year; whereas in San Luis Potosi these values are between −1.8 and −4.2 cm/year. The PSI results were validated by five Global Navigation Satellite System (GNSS) benchmarks available, providing a data correlation between the results obtained with both techniques of 0.986. This validation suggests that interferometric derived deformations agree well with results obtained from GNSS data. The strong relationship between trace fault, land subsidence,e and groundwater extraction suggests that groundwater withdrawal is resulting in subsidence induced faulting, which follows the pattern of structural faults buried by sediments. [ABSTRACT FROM AUTHOR]

The integration of data from different sources can be very helpful in understanding the mechanism, the geometry, the kinematic, and the area affected by complex instabilities, especially when the available geotechnical information is limited. In this work, the suitability of different techniques for the study of a deep-seated landslide affecting a bridge in Alcoy (Spain) is evaluated. This infrastructure presents such severe damage that has rendered the bridge unusable, which prevents normal access to an important industrial area. Differential SAR Interferometry (DInSAR) and terrestrial Light Detection and Ranging (LiDAR) remote sensing techniques have been combined with ground displacement monitoring techniques, such as inclinometers and conventional geological and geotechnical investigation, electrical-seismic tomography, damage, and topographic surveys, to determine the boundaries, mechanism, and kinematics of the landslide. The successful case study that is illustrated in this work highlights the potential and the need for integrating multi-source data for the optimal management of complex landslides and the effective design of remedial measurements. [ABSTRACT FROM AUTHOR]

This work describes a new procedure aimed to semi-automatically identify clusters of active persistent scatterers and preliminarily associate them with different potential types of deformational processes over wide areas. This procedure consists of three main modules: (i) ADAfinder, aimed at the detection of Active Deformation Areas (ADA) using Persistent Scatterer Interferometry (PSI) data; (ii) LOS2HV, focused on the decomposition of Line Of Sight (LOS) displacements from ascending and descending PSI datasets into vertical and east-west components; iii) ADAclassifier, that semi-automatically categorizes each ADA into potential deformational processes using the outputs derived from (i) and (ii), as well as ancillary external information. The proposed procedure enables infrastructures management authorities to identify, classify, monitor and categorize the most critical deformations measured by PSI techniques in order to provide the capacity for implementing prevention and mitigation actions over wide areas against geological threats. Zeri, Campiglia Marittima–Suvereto and Abbadia San Salvatore (Tuscany, central Italy) are used as case studies for illustrating the developed methodology. Three PSI datasets derived from the Sentinel-1 constellation have been used, jointly with the geological map of Italy (scale 1:50,000), the updated Italian landslide and land subsidence maps (scale 1:25,000), a 25 m grid Digital Elevation Model, and a cadastral vector map (scale 1:5000). The application to these cases of the proposed workflow demonstrates its capability to quickly process wide areas in very short times and a high compatibility with Geographical Information System (GIS) environments for data visualization and representation. The derived products are of key interest for infrastructures and land management as well as decision-making at a regional scale. [ABSTRACT FROM AUTHOR]

Blockchain technology possibilities are analysed in the context of RDC-Arq requirements form the point of view of archivists' perception about digital documents authenticity and integrity. In particular, this article sought to explore software security features used for digital documents management by archivists. It was considered how that software is been used to preserve the authenticity and integrity of digital documents, and the professional opinion about how it contributes to preserve the chain of custody. Finally, a comparative between blockchain technology and the RCD-Arq features is elaborated from the perspective of the archivists participating in the research. The research shows that blockchain technology have good potential for maintening the authenticity and integrity of digital documents, highlighting the importance of following RDCArq guidelines. [ABSTRACT FROM AUTHOR]

Geomechanics classifications are used to perform a preliminary assessment of rock slope stability for different purposes in civil and mining engineering. Among all existing rock mass classifications, slope mass rating (SMR) is one of the most commonly used for slopes. Although SMR is a geomechanics classification applied worldwide, often some misapprehensions and inaccuracies are made when professionally and scientifically used. Nearly all these miscalculations involve the influence of slope geometry and the dip and direction of the discontinuities. These problems can be overcome by a systematic assessment of SMR, which allows users to understand and visualize the relative orientation between discontinuities and slope. To fulfil this purpose, a complete and detailed definition of the angular relationships between discontinuities and slope are included in this paper, clarifying the assessment of the SMR parameters. Additionally, a Matlab-based open-source software for SMR (SMRTool) calculation is presented, avoiding miscalculations by automating the calculations and showing the graphical representation of slope and discontinuities. Finally, a general explanation of the method for the use of SMR is reviewed, stressing the common source of errors when applying this classification. The performance, benefits and usefulness of SMRTool are also illustrated in this paper through a specific case study. [ABSTRACT FROM AUTHOR]

It is not the aim of this work to include all rocks, as reference books on petrography mention over one thousand types of rocks (Goodman [5]), but to upload some main rocks classified in an accepted classification system. Rock-mechanic subjects aim to analyse the behaviour of rocks and rock masses. MC described part of the rock specimens, wrote and revised the manuscript along with the website and created the behavioural datasheet and collected most of the mechanical values of the rock samples. [Extracted from the article]

Abstract Technological progress in remote sensing has enabled digital representation of terrain through new techniques (e.g. digital photogrammetry) and instruments (e.g. 3D laser scanners). However, the use of old aerial images remains important in geosciences to reconstruct past landforms and detect long-term topographic changes. Administrations have recently expressed growing interest in sharing photogrammetric datasets on public repositories, providing opportunities to exploit these resources and detect natural and anthropogenic topographic changes. The SfM-MVS photogrammetric technique was applied to scanned historical black and white aerial photos of the Serra de Fontcalent (Alicante, Spain), as well as to recent high-quality digital aerial photos. Ground control points (GCPs) extracted from a LiDAR-derived three-dimensional point cloud were used to georeference the results with non-linear deformations. Two point clouds obtained with SfM-MVS were compared with the LiDAR-derived reference point cloud. Based on the result, the quality of the models was analysed through the comparison of the stages on stable areas, i.e., lands where no variations were detected, and active areas, with quarries, new infrastructures, fillings, excavations or new buildings. This study also indicates that errors are higher for old aerial photos (up to 5 m on average) than recent digital photos (up to 0.5 m). The application of SfM-MVS to open access data generated 3D models that enhance the geomorphological analysis, compared to stereophotogrammetry, and effectively detected activities in quarries and building of landfills. Highlights • Existing techniques enable the use of historical and recent aerial photos to reconstruct DEMS • An area of interest is reconstructed using historical printed and digital aerial photos, obtained from readily available resources, through Structure-from-Motion • An airbone LiDAR derived point cloud was used as a benchmark and for the extraction of ground control points • Three different stages of the landform were analysed and compared • The quality of the reconstruction and the capability of monitoring changes were analysed [ABSTRACT FROM AUTHOR]

The article presents the discussion on global population facing a high probability of land subsidence. Topics include natural or anthropogenic triggers resulting from solid or fluid mobilization underground; reducing aquifer-system storage capacity, causing earth fissures, damaging buildings, and civil infrastructure; and raising awareness and informing decision-making by evaluating potential global subsidence due to groundwater depletion.

Anti-slide piles have been widely applied in many practical projects around the world. In this work, a novel upper-hollow drainage anti-slide pile (UDAP) is selected to evaluate its working performance and mechanism by means of a physical model test and a numerical simulation. The physical model test indicates that UDAPs exhibit an excellent drainage performance, and the earth pressure and the pore water pressure around them dramatically decrease. The catchment holes placed on the lateral and upslope sides of the UDAPs have the same effects, and their drainage capacity improves with depth. The numerical simulation results of the UDAP arranged in the Quchi landslide (China) indicates that the retaining effect of the UDAPs is significantly better than that of the conventional anti-slide piles (CAPs). The landslide thrust and deformation are reduced due to the decrease of groundwater table and the consequent pore water pressure reduction due to the drainage effect of the UDAPs. Furthermore, the deflection and internal force of the UDAPs are significantly lower than those of the CAPs. The retaining effect of the continuous and interval arrangement scheme of the UDAPs is almost identical. Furthermore, the value of the internal force and the law of variation of the UDAPs and CAPs are basically the same. Therefore, the results of this paper can provide an important basis for the future research, design, popularization and application of the UDAPs. [ABSTRACT FROM AUTHOR]

The Daguangbao mega-landslide (China), induced by the 2008 Wenchuan earthquake (M w = 7.9), with an area of approximately 8 km 2 , is one of the largest landslides in the world. Experts predicted that the potential risk and instability of the landslide might remain for many decades, or even longer. Monitoring the activity of such a large landslide is hence critical. Terrain Observation by Progressive Scans (TOPS) mode from the Sentinel-1 satellite provides us with up-to-date high-quality Synthetic Aperture Radar (SAR) images over a wide ground coverage (250 × 250 km), enabling full exploitation of various InSAR applications. However, the TOPS mode introduces azimuth-dependent Doppler variations to radar signals, which requires an additional processing step especially for SAR interferometry. Sentinel-1 TOPS data have been widely applied to earthquakes, but the performance of TOPS data-based time series analysis requires further exploitation. In this study, Sentinel-1 TOPS data were employed to investigate landslide post-seismic activities for the first time. To deal with the azimuth-dependent Doppler variations, a processing chain of TOPS time series interferometry approach was developed. Since the Daguangbao landslide is as a result of the collapse of a whole mountain caused by the 2008 Mw 7.9 Wenchuan earthquake, the existing Digital Elevation Models (DEMs, e.g. SRTM and ASTER) exhibit height differences of up to approximately 500 m. Tandem-X images acquired after the earthquake were used to generate a high resolution post-seismic DEM. The high gradient topographic errors of the SRTM DEM (i.e. the differences between the pre-seismic SRTM and the actual post-seismic elevation), together with low coherence in mountainous areas make it difficult to derive a precise DEM using the traditional InSAR processing procedure. A re-flattening iterative method was hence developed to generate a precise TanDEM-X DEM in this study. The volume of the coseismic Daguangbao landslide was estimated to be of 1.189 ± 0.110 × 10 9 m 3 by comparing the postseismic Tandem-X DEM with the preseismic SRTM DEM, which is consistent with the engineering geological survey result. The time-series results from Sentinel-1 show that some sectors of the Daguangbao landslide are still active (and displaying four sliding zones) and exhibiting a maximum displacement rate of 8 cm/year, even eight years after the Wenchuan earthquake. The good performance of TOPS in this time series analysis indicates that up-to-date high-quality TOPS data with spatiotemporal baselines offer significant potential in terms of future InSAR applications. [ABSTRACT FROM AUTHOR]

The complete characterization of rock masses implies the acquisition of information of both, the materials which compose the rock mass and the discontinuities which divide the outcrop. Recent advances in the use of remote sensing techniques – such as Light Detection and Ranging (LiDAR) – allow the accurate and dense acquisition of 3D information that can be used for the characterization of discontinuities. This work presents a novel methodology which allows the calculation of the normal spacing of persistent and non-persistent discontinuity sets using 3D point cloud datasets considering the three dimensional relationships between clusters. This approach requires that the 3D dataset has been previously classified. This implies that discontinuity sets are previously extracted, every single point is labeled with its corresponding discontinuity set and every exposed planar surface is analytically calculated. Then, for each discontinuity set the method calculates the normal spacing between an exposed plane and its nearest one considering 3D space relationship. This link between planes is obtained calculating for every point its nearest point member of the same discontinuity set, which provides its nearest plane. This allows calculating the normal spacing for every plane. Finally, the normal spacing is calculated as the mean value of all the normal spacings for each discontinuity set. The methodology is validated through three cases of study using synthetic data and 3D laser scanning datasets. The first case illustrates the fundamentals and the performance of the proposed methodology. The second and the third cases of study correspond to two rock slopes for which datasets were acquired using a 3D laser scanner. The second case study has shown that results obtained from the traditional and the proposed approaches are reasonably similar. Nevertheless, a discrepancy between both approaches has been found when the exposed planes members of a discontinuity set were hard to identify and when the planes pairing was difficult to establish during the fieldwork campaign. The third case study also has evidenced that when the number of identified exposed planes is high, the calculated normal spacing using the proposed approach is minor than those using the traditional approach. [ABSTRACT FROM AUTHOR]

Many bridges and other structures worldwide present a lack of maintenance or a need for rehabilitation. The first step in the rehabilitation process is to perform a bridge inspection to know the bridge′s current state. Routine bridge inspections are usually based only on visual recognition. In this paper, a methodology for bridge inspections in communication routes using images acquired by unmanned aerial vehicle (UAV) flights is proposed. This provides access to the upper parts of the structure safely and without traffic disruptions. Then, a standardized and systematized novel image acquisition protocol is applied for data acquisition. Afterwards, the images are studied by civil engineers for damage identification and description. Then, specific structural inspection forms are completed using the acquired information. Recommendations about the need of new and more detailed inspections should be included at this stage when needed. The suggested methodology was tested on two railway bridges in France. Image acquisition of these structures was performed using an UAV for its ability to provide an expert assessment of the damage level. The main advantage of this method is that it makes it possible to safely accurately identify diverse damages in structures without the need for a specialised engineer to go to the site. Moreover, the videos can be watched by as many engineers as needed with no personal movement. The main objective of this work is to describe the systematized methodology for the development of bridge inspection tasks using a UAV system. According to this proposal, the in situ inspection by a specialised engineer is replaced by images and videos obtained from an UAV flight by a trained flight operator. To this aim, a systematized image/videos acquisition method is defined for the study of the morphology and typology of the structural elements of the inspected bridges. Additionally, specific inspection forms are proposed for every type of structural element. The recorded information will allow structural engineers to perform a postanalysis of the damage affecting the bridges and to evaluate the subsequent recommendations. [ABSTRACT FROM AUTHOR]

The mapping and classification of active landslides in high mountainous regions provide crucial information about the location and types of geohazards. Additionally, this process plays a vital role in ensuring the safety of the geological environments in mountainous towns. In this study, we presented a refined InSAR approach for mapping and classifying active landslide hazards in Deqin County, Tibetan Plateau, China. The study area is characterized by a high altitude and extremely rugged terrain. Consequently, conventional InSAR methods are limited in precisely estimating landslide deformation owing to severe atmospheric delays. To this end, we first propose a block-based linear model to correct tropospheric artifacts. This model considers the spatial variability of the atmosphere and provides an opportunity to accurately estimate heterogeneous atmospheric delays over high mountainous areas without any external data. Compared with the traditional global-window linear model and the GACOS approach, the new method demonstrated outstanding performance in reducing atmospheric artifacts. Second, based on the knowledge mapping of landslide types, we proposed a semi-automatic procedure to map and classify landslides using InSAR-derived displacements and auxiliary data (i.e., C-index and high-resolution optical images). Our results obtained from ascending and descending Sentinel-1 images revealed, for the first time, that there were 317 active landslides in Deqin County between May 2017 and June 2021. Among these, 10.7% were associated with slide activity, 7.9% with fall deformation, and the majority (81.4%) with flow movement. These results were cross-verified and evaluated using an a priori inventory map obtained from the visual interpretation of optical images and geological field surveys. This study demonstrates that InSAR can accurately map and classify active landslides over difficult mountainous terrains, provided the associated phase errors are effectively restrained. • A refined InSAR approach is developed to map active landslides in high mountain terrains. • A new strategy is proposed to mitigate the atmospheric artifacts in high mountain region. • A semi-automatic procedure is developed to identify and classify different types of landslides. • Three types of landslides are illustrated in terms of deformation spatiotemporal patterns. [ABSTRACT FROM AUTHOR]

The effect of exposure to high temperature on rock strength is a topic of interest in many engineering fields. In general, rock strength is known to decrease as temperature increases. The most common test used to evaluate the rock strength is the uniaxial compressive strength test (UCS). It can only be carried out in laboratory and presents some limitations in terms of the number, type and preparation of the samples. Such constrains are more evident in case of rocks from historical monuments affected by a fire, where the availability of samples is limited. There are alternatives for an indirect determination of UCS, such as the point load test (PLT), or non-destructive tests such as the Schmidt's hammer, that can also be performed in situ. The aims of this research are: (i) measuring the effect of high temperatures and cooling methods on the strength and hardness of a limestone named Pedra de Borriol widely used in several historic buildings on the E of Spain, and (ii) studying the possibility of indirectly obtaining UCS by means of PLT and Leeb hardness tests (LHT), using Equotip type D. Limestone samples were heated to 105 (standard conditions), 200, 300, 400, 500, 600, 700, 800 and 900 ºC and cooled slowly (in air) and quickly (immersed in water). After that, UCS, PLT and LHT tests were performed to evaluate the changes as temperature increases. Results show decreases over 90% in UCS, of between 50 and 70% in PLT index and smaller than 60% in LHT index. Insignificant differences between cooling methods were observed, although slowly cooled samples provide slightly higher values than quickly cooled ones. The results indicate that LHT can be used to indirectly estimate UCS, providing an acceptable prediction. Research on correlating strength parameters in rocks after thermally treated is still scarce. This research novelty provides correlations to predict UCS in historic buildings if affected by a fire, from PLT and non-destructive methods such as LHT whose determination is quicker and easier. [ABSTRACT FROM AUTHOR]

The study of land subsidence has recently been expanded due to its increased occurrence and magnitude worldwide. This paper develops and applies an optimal control model of groundwater extractions under conditions of land subsidence. We include, in a traditional groundwater management model, two types of negative externalities associated with land subsidence: damage to infrastructure and to economic activities, and the loss of aquifer storage capacity. Using a two-stage optimal control method, characterized by two sub-problems corresponding to the phase before and after the occurrence of subsidence, we find the economically sustainable paths of groundwater extractions and water table levels under the existence of land subsidence impacts. The theoretical results indicate that the presence of land subsidence dictates the optimal paths of groundwater withdrawals and water table levels. The model has been applied to the Alto Guadalentín over-exploited aquifer system in the Segura River Basin of Spain. The empirical outcomes indicate that by following the optimal paths, groundwater extractions should be curtailing to avoid reaching the critical water level at which subsidence takes place. Results suggest that regional net present value of welfare over the planning period, under the two land subsidence scenarios, is reduced by nearly 1–5%, compared to the no land subsidence scenario. Furthermore, under subsidence, even with relatively small impacts of both types of externalities, groundwater optimal extractions are kept at levels that avoid these externalities. These outcomes clearly call for government intervention in order to reduce groundwater withdrawals in aquifers with propensity to face undesirable subsidence effects. • LS due to aquifers overused causes major social costs with irreversible impacts. • LS has not received proper attention by regulators and the economic damages are not accurately assessed. • This paper develops a groundwater optimization model including negative externalities of LS. • In presence of subsidence, even with small impacts, groundwater management is necessary. • The results call for government intervention to curtail groundwater withdrawals to face LS. [ABSTRACT FROM AUTHOR]

Landslides are among the most important and frequent natural calamities that cause severe socio-economic and human losses. After earthquakes, landslides are responsible for the greatest number of casualties and the largest amount of damage to man-made structures. On average, southern Italy is affected by a high spatial density of landslides due to its complex geological setting, which often predisposes it to slope instability phenomena under both natural and anthropogenic influences. Structurally complex formations are widespread in the southern Apennines and are characterized by high heterogeneity and very poor mechanical properties. Thus, these formations represent one of the main factors contributing to the predisposition of slopes to landsliding. In this paper, landslide-induced damage was investigated and analyzed in an area within the municipality of Agnone (Molise region), which is affected by a complex landslide that involves a structurally complex formation. The approaches used were based on six different methods that have previously been described in the literature, and a comparison of the results was made. Data regarding the damage, which consists largely of cracks observed in buildings and at the ground, were compiled through field surveys. The results were critically analyzed to note the advantages and constraints of each classification scheme. The aim of the work was to apply and compare different approaches in order to test the best and most accurate procedures for assessing damage due to landslides at the scale of individual buildings as well as to provide an objective assessment of the degree of landslide damage to structures and facilities. [ABSTRACT FROM AUTHOR]

Timely and effective post-disaster assessment is of significance for the design of rescue plan, taking disaster mitigation measures and disaster analysis. Field investigation and remote sensing methods are the common ways to perform post-disaster assessment, which are usually limited by dense cloud coverage, potential risk, and tough transportation etc. in the mountainous area. In this paper, we employ the 2017 catastrophic Xinmo landslide (Sichuan, China) to demonstrate the feasibility of using spaceborne synthetic aperture radar (SAR) data to perform timely and effective post-disaster assessment. With C-band Sentinel-1 data, we propose to combine interferometric coherence to recognize the stable area, which helps us successfully identify landslide source area and boundaries in a space-based remote sensing way. Complementarily, X-band TanDEM-X SAR data allow us to generate a precise pre-failure high-resolution digital elevation model (DEM), which provides us the ability to accurately estimate the depletion volume and accumulation volume of Xinmo landslide. The results prove that spaceborne SAR can provide a quick, valuable, and unique assistance for post-disaster assessment of landslides from a space remote sensing way. At some conditions (bad weather, clouds, etc.), it can provide reliable alternative. [ABSTRACT FROM AUTHOR]

The accurate evaluation of landslide-induced damage is a necessity for planning of proper and effective mitigation measures. It requires the implementation of field investigations to identify structural failures to more effectively trace landslide boundaries. Many methods have been proposed to classify landslide-induced damage of buildings. The existing methods demonstrate several advantages and drawbacks depending on the parameters considered, as lack of some important features and difficulties in applicability. A new classification approach of landslide-induced damage of facilities is proposed, which specifically focuses on assessing of damage degree and its relationship to the ground motion intensity and impact severity. The new approach is designed in two steps: a chart utilized during surveys to quantify cracks on structures and ground surface; ana posterioriranking of structures performed using a cell-grid matrix. Furthermore, a damage recording scheme useful for field surveying is proposed. This approach considers several parameters derived from different existing methodologies by smoothing out drawbacks and homogenizing the considered features. The resulting approach provides a new procedure of landslide-induced damage assessment adoptable in case of private dwellings, as it does not require internal accessibility, and it is exploitable for different landslide events and for different kinds of structures and facilities. [ABSTRACT FROM AUTHOR]

More than 5000 landslides with different kinds of deposit-bedrock interface morphologies developed in Three Gorges Reservoir area (TGR) after its first impoundment. In this paper, the Outang landslide, a typical accumulation landslide with a chair-like deposit-bedrock interface (CLDBI) located in the Three Gorges Reservoir area (TGR) of China, is taken as an example. More than 6 years of multi-technique monitoring data shows that cumulative displacements over time present a step-like pattern, characterized by the gradual increasing of total displacements with altitude. The factors affecting the slope movement at the upper and the lower parts of the landslide are rainfall and reservoir water, separately. In this work a novel drainage anti-slide pile (DASP) is proposed, and the drainage performance of this DASP is verified and studied through physical model test. To this aim, three different environmental scenarios have been simulated by ABAQUS to evaluate the reinforcement effect induced on the landslide when using the proposed DASP. The model revealed that the optimum solution for the stabilization of the slope consists in the construction of single-row DASPs in the upper part of the landslide. These results provide practical experience and enlightenment on common measures to landslide prevent in TGR using the DASPs. [ABSTRACT FROM AUTHOR]

In the last two decades, advanced differential interferometric synthetic aperture radar (A-DInSAR) techniques have experienced significant developments, which are mainly related to (i) the progress of satellite SAR data acquired by new missions, such as COSMO-SkyMed and ESA's Sentinel-1 constellations; and (ii) the development of novel processing algorithms. The improvements in A-DInSAR ground deformation time series need appropriate methodologies to analyse extremely large datasets which consist of huge amounts of measuring points and associated deformation histories with high temporal resolution. This work demonstrates A-DInSAR time series exploitation as valuable tool to support different problems in engineering geology such as detection, characterization and modelling of land subsidence mechanisms. The capabilities and suitability of A-DInSAR time series from an end-user point of view are presented and discussed through the analysis carried out for three test sites in Europe: the Oltrepo Pavese (Po Plain in Italy), the Alto Guadalentín (Spain) and the London Basin (United Kingdom). Principal component analysis has been performed for the datasets available for the three case histories, in order to extract the great potential contained in the A-DInSAR time series. [ABSTRACT FROM AUTHOR]

Groundwater resources are under stress in many regions of the world and the future water supply for many populations, particularly in the driest places on Earth, is threatened. Future climatic conditions and population growth are expected to intensify the problem. Understanding the factors that control groundwater storage variation is crucial to mitigate its adverse consequences. In this work, we apply satellite-based measurements of ground deformation over the Tertiary detritic aquifer of Madrid (TDAM), Central Spain, to infer the spatio-temporal evolution of water levels and estimate groundwater storage variations. Specifically, we use Persistent Scatterer Interferometry (PSI) data during the period 1992–2010 and piezometric time series on 19 well sites covering the period 1997–2010 to build groundwater level maps and quantify groundwater storage variations. Our results reveal that groundwater storage loss occurred in two different periods, 1992–1999 and 2005–2010 and was mainly concentrated in a region of ∼200 km 2 . The presence of more compressible materials in that region combined with a long continuous water extraction can explain this volumetric deficit. This study illustrates how the combination of PSI and piezometric data can be used to detect small aquifers affected by groundwater storage loss helping to improve their sustainable management. [ABSTRACT FROM AUTHOR]

Land subsidence associated with groundwater overexploitation in the Alto Guadalentín Basin (Spain) aquifer system has been detected during the last decades. In this work, for the first time, we propose a new point cloud differencing methodology to detect land subsidence at basin scale, based on the multiscale model-to-model cloud comparison (M3C2) algorithm. This method is applied to two open-access airborne LiDAR datasets acquired in 2009 and 2016, respectively. First the internal edge connection errors in the different flight lines were addressed by means of a smoothing point cloud method. LiDAR datasets capture information from ground and non-ground points. Therefore, a method combining gradient filtering and cloth simulation filtering (CSF) algorithms was applied to remove non-ground points. The iterative closest point (ICP) algorithm was used for point cloud registration of both point clouds exhibiting a very stable and robust performance. The results show that vertical deformation rates are up to −14 cm/year in the basin from 2009 to 2016, in agreement with the displacement reported by previous studies. LiDAR results have been compared to the velocity measured by continuous GNSS stations and an InSAR dataset. For the GNSS-LiDAR and InSAR-LiDAR comparison, we computed a common 100 × 100 m grid in order to assess any similarities and discrepancies. The results show a good agreement between the vertical displacements obtained from the three different surveying techniques. Furthermore, LiDAR results were compared with the distribution of compressible soil thickness showing a clear relationship. The study underlines the potential of open-access and non-customized LiDAR to monitor the distribution and magnitude of vertical deformations in areas prone to be affected by groundwater-withdrawal-induced land subsidence. • A new approach is proposed to measure land subsidence using point cloud datasets. • Some difficulties derived when using wide-spread LiDAR datasets are overcome. • Vertical deformation rates up to −12 cm/year are measured between 2009 and 2016. • The relationship between subsidence and conditioning/triggering factors is studied. • The advantages and drawbacks of using LiDAR against InSAR are discussed. [ABSTRACT FROM AUTHOR]

A twenty-year period of severe land subsidence evolution in the Alto Guadalentín Basin (southeast Spain) is monitored using multi-sensor SAR images, processed by advanced differential interferometric synthetic aperture radar (DInSAR) techniques. The SAR images used in this study consist of four datasets acquired by ERS-1/2, ENVISAT, ALOS and COSMO-SkyMed satellites between 1992 and 2012. The integration of ground surface displacement maps retrieved for different time periods allows us to quantify up to 2.50 m of cumulated displacements that occurred between 1992 and 2012 in the Alto Guadalentín Basin. DInSAR results were locally compared with global positioning system (GPS) data available for two continuous stations located in the study area, demonstrating the high consistency of local vertical motion measurements between the two different surveying techniques. An average absolute error of 4.6 ± 4 mm for the ALOS data and of 4.8 ± 3.5 mm for the COSMO-SkyMed data confirmed the reliability of the analysis. The spatial analysis of DInSAR ground surface displacement reveals a direct correlation with the thickness of the compressible alluvial deposits. Detected ground subsidence in the past 20 years is most likely a consequence of a 100–200 m groundwater level drop that has persisted since the 1970s due to the overexploitation of the Alto Guadalentín aquifer system. The negative gradient of the pore pressure is responsible for the extremely slow consolidation of a very thick (> 100 m) layer of fine-grained silt and clay layers with low vertical hydraulic permeability (approximately 50 mm/h) wherein the maximum settlement has still not been reached. [ABSTRACT FROM AUTHOR]

Summary The purpose of this paper is to analyze the quasi-elastic deformational behavior that has been induced by groundwater withdrawal of the Tertiary detrital aquifer of Madrid (Spain). The spatial and temporal evolution of ground surface displacement was estimated by processing two datasets of radar satellite images (SAR) using Persistent Scatterer Interferometry (PSI). The first SAR dataset was acquired between April 1992 and November 2000 by ERS-1 and ERS-2 satellites, and the second one by the ENVISAT satellite between August 2002 and September 2010. The spatial distribution of PSI measurements reveals that the magnitude of the displacement increases gradually towards the center of the well field area, where approximately 80 mm of maximum cumulated displacement is registered. The correlation analysis made between displacement and piezometric time series provides a correlation coefficient greater than 85% for all the wells. The elastic and inelastic components of measured displacements were separated, observing that the elastic component is, on average, more than 4 times the inelastic component for the studied period. Moreover, the hysteresis loops on the stress–strain plots indicate that the response is in the elastic range. These results demonstrate the quasi-elastic behavior of the aquifer. During the aquifer recovery phase ground surface uplift almost recovers from the subsidence experienced during the preceding extraction phase. Taking into account this unique aquifer system, a one dimensional elastic model was calibrated in the period 1997–2000. Subsequently, the model was used to predict the ground surface movements during the period 1992–2010. Modeled displacements were validated with PSI displacement measurements, exhibiting an error of 13% on average, related with the inelastic component of deformation occurring as a long-term trend in low permeability fine-grained units. This result further demonstrates the quasi-elastic deformational behavior of this unique aquifer system. [ABSTRACT FROM AUTHOR]

Sediment budgets and morphological channel adjustments are closely related to changes in stream power. In ephemeral channels, whose geomorphic response depends on the magnitude and frequency of hydrological events isolated in time, such relationships are often difficult to establish. This study sought to quantitatively relate morphological adjustments to stream power along different reference channel reaches for the period 2018–2020 in the Azohía Rambla, a Mediterranean gravel-bed ephemeral stream in southeastern Spain. Very high resolution digital terrain models (VHR DTM) (at 1 to 2.5 cm pixel size), combined with ortophotographs and 3D point clouds, generated via SfM photogrammetry and terrestrial laser scanning (TLS) for pre- and post-event stages, together with ground-based surveys were used to estimate the spatial variability of morphological sediment budgets and to assess channel bed mobility and changes in net sediment flux during the study period in two spatial scenarios: reference channel reaches (RCRs) and pilot bed survey areas (PBSAs). The hydraulic variables (flow velocity, Froude number, shear stress, mean stream power and energy gradient, among other) were estimated using a 1D hydrodynamic model calibrated with field information. The high resolution maps allowed a spatially-explicit analysis of stream power and transport efficiency in accordance with the areas of erosion and deposition in each RCR. The incision and bed armoring processes showed different trends according to the stream power (ω), cumulative excess energy (ε c), and relative bed stability (RBS). The greatest morphological adjustments at the event scale coincided with ω values above 300 W m−2, ε c higher than 3 MJ, and RBS below 0.5. The relationships between the mean stream power gradient at peak flood discharges and the changes in bed elevation verified the bed aggradation (an average surface raising of 0.17 to 0.22 m for δω/δs of −6.2 to −14.5 W m−2 m−1) during the major flood and bed scour (average surface lowering of 0.16 to 0.19 m for δω/δs of 5.8 to 10.6 W m−2 m−1) in the moderated events at the bankfull and sub-bankfull stages. Furthermore, this study contributes new relevant data to the scarce existing literature on the relationships between stream power and morphosedimentary adjustments in a fluvial system highly sensitive and resilient to climate change, as is the case of ephemeral gravel-bed channels. [Display omitted] • Morphological channel adjustments are sensitive to changes in stream power. • Bed elevation was monitored at the event scale and very high spatial resolution. • Bedload controls sediment budgets in ephemeral gravel-bed streams. • Changes in bed stability related to stream power thresholds in ephemeral channels. [ABSTRACT FROM AUTHOR]

The construction of the Three Gorges Reservoir (TGR) has considerably increased landslide hazard due to the 30-m annual fluctuating reservoir water level. In this study, the influence of permeability on the stability of dual-structure landslide with different deposit-bedding interface (DBI) morphology were comprehensively investigated. A landslide database including 560 recorded dual-structure landslides was built for the statistical analysis. The DBI morphology, the slope structure and the permeability were classified and presented. The statistical analysis of the DBI morphological parameters indicates that the armchair type (AT) is the most popular in over-dip landslide, the curved type (CT) is very widespread in anaclinal landslide, the stepped type (ST) is the most common DBI morphology in over-dip landslide, and the linear type (LT) could be found widely at the under-dip landslide. Two conceptual models, downslide-locked model and locked model, were proposed according to the change rules of the dip angle of the DBI. The stability for these two conceptual models were analyzed and modeled as well as verified by specific case studies. The numerical results manifest that the permeability and the DBI morphology could pose significant impacts on the stability of the dual-structure landslide. Deepening our understanding of the effect of the fluctuating reservoir water level on the factor of safety (FOS) of the defined conceptual models, which are of paramount importance to improve the design of mitigation countermeasures and, consequently, to reduce fatalities and property losses in the TGR and many other analogous reservoir areas. • 560 landslides information in the Three Gorges Reservoir area was collected. • Two conceptual models corresponding to different DBI morphology were proposed. • The possible landslide mitigation countermeasures were discussed. [ABSTRACT FROM AUTHOR]

Recently, a large number of synthetic aperture radar (SAR) images has been introduced into landslide investigations with the growing launch of new SAR satellites, such as ALOS/PALSAR-2 and Sentinel-1. Therefore, it is appropriate to develop new approaches to retrieve three-dimensional (3D) displacements and long-term (> 10 years) displacement time series to investigate the spatio-temporal evolution and creep behavior of landslides. In this study, a new approach for the estimation of 3D and long-term displacement time series of landslides, based on the fusion of C- and L-band SAR observations, is presented. This method is applied to map 3D and long-term displacements (nearly 12 years) of the landslides in Gongjue County, Tibet in China; four sets of SAR images from different platforms (i.e., L-band ascending ALOS/PALSAR-1, C-band descending ENVISAT, and C-band ascending and descending Sentinel-1 SAR datasets) covering the period of January 2007 to November 2018 were collected and exploited. First, the assumption that the landslide moves parallel to its ground surface is used to produce 3D displacement rates and time series by fusing ascending and descending Sentinel-1 SAR images, from which the optimal sliding direction for each pixel of the slope is well estimated. Then, the long-term displacement time-series of the landslide between January 2007 and October 2018 in the estimated sliding direction is recovered by fusing L-band ALOS/PALSAR-1 and C-band Sentinel-1 SAR images. In order to fill the time gap of nearly four years between ALOS/PALSAR-1 and Sentinel-1 SAR images, the Tikhonov regularization (TR) method is developed to establish the observational equation. Moreover, to solve the problem arising from ALOS/PALSAR-1 and Sentinel-1 images with different wavelengths, incidence angles and flight directions, the measurements from ALOS/PALSAR-1 and Sentinel-1 images are both projected to the estimated optimal sliding direction to achieve a unified displacement datum. Our results from ascending and descending Sentinel-1 images suggest that the maximum displacement rates of the study area in the vertical and east-west directions from December 2016 to October 2018 were greater than 70 and 80 mm/year, respectively, and 2D displacement results reveal that the displacement patterns and movement characteristics of all the detected landslides are not identical in the study area. Specifically, the 3D displacement results successfully revealed the spatiotemporal displacement patterns and movement direction of each block of the Shadong landslide, and long-term displacement time series showed for the first time that the maximum cumulative displacement exceeds 1.3 m from January 2007 to October 2018. Moreover, the kinematic evolution and possible driving factors of landslides were investigated using 2D and 3D and long-term displacement results, coupled with hydrological factors and unidimensional constitutive models of the rocks. • New approaches are presented to estimate 3D and long-term landslide displacements. • Optimal sliding direction of the landslide is retrieved using 3D displacements. • InSAR reveals 12-year's displacement time series and its creep behavior of a landslide. • InSAR measurements suggest that the landslide was in a stable deformation stage. • Non-linear landslide movement is likely caused by the Jinsha River water level changes. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a study carried out on the bell tower of the Church of Santas Justa and Rufina in Orihuela in the Province of Alicante, Spain. The study was made to predict the evolution of its dynamic behaviour in relation to subsidence caused by variations in the level of the water table during periods of drought. Initial calibration of the developed numerical model was based on the dynamic characteristics of the tower in free vibration. The numerical model included details of both the structure and the surrounding terrain to a depth of ten meters, as indicated by geotechnical tests. Sensitivity studies were made of the terrain’s elastic characteristics with the aim of evaluating the dynamic amplification factor of the soil–structure interaction due to dynamic forces generated by the swinging of the bells in the tower. [Copyright &y& Elsevier]

Lanzhou is one of the cities with the higher number of civil engineering projects for mountain excavation and city construction (MECC) on the China's Loess Plateau. As a result, the city is suffering from severe surface displacement, which is posing an increasing threat to the safety of the buildings. However, up to date, there is no comprehensive and high-precision displacement map to characterize the spatiotemporal surface displacement patterns in the city of Lanzhou. In this study, satellite-based observations, including optical remote sensing and synthetic aperture radar (SAR) sensing, were jointly used to characterize the landscape and topography changes in Lanzhou between 1997 and 2020 and investigate the spatiotemporal patterns of the surface displacement associated with the large-scale MECC projects from 2015 December to March 2021. First, we retrieved the landscape changes in Lanzhou during the last 23 years using multi-temporal optical remote sensing images. Results illustrate that the landscape in local areas of Lanzhou has been dramatically changed as a result of the large-scale MECC projects and rapid urbanization. Then, we optimized the ordinary time series InSAR processing procedure by a "dynamic estimation of digital elevation model (DEM) errors" step added before displacement inversion to avoid the false displacement signals caused by DEM errors. The DEM errors and the high-precision surface displacement maps between December 2015 and March 2021 were calculated with 124 ascending and 122 descending Sentinel-1 SAR images. By combining estimated DEM errors and optical images, we detected and mapped historical MECC areas in the study area since 2000, retrieved the excavated and filling areas of the MECC projects, and evaluated their areas and volumes as well as the thickness of the filling loess. Results demonstrated that the area and volume of the excavated regions were basically equal to that of the filling regions, and the maximum thickness of the filling loess was greater than 90 m. Significant non-uniform surface displacements were observed in the filling regions of the MECC projects, with the maximum cumulative displacement lower than −40 cm. 2D displacement results revealed that surface displacement associated with the MECC project was dominated by settlements. From the correlation analysis between the displacement and the filling thickness, we found that the displacement magnitude was positively correlated with the thickness of the filling loess. This finding indicated that the compaction and consolidation process of the filling loess largely dominated the surface displacement. Our findings are of paramount importance for the urban planning and construction on the Loess Plateau region in which large-scale MECC projects are being developed. [ABSTRACT FROM AUTHOR]

• Prada limestone shows a steep drop in UCS even at low temperatures (T < 200 °C). • Important properties variation at 300 and 400 °C due to micro-fissure progression. • Severe thermal damage at 500 °C due to trans -granular micro-fissure connection. • Dramatic properties variation at 600 °C, even greater in water-cooled samples. • Best predictions of mechanical parameters using exponential and potential functions. Temperature and cooling methods strongly affect the stability of tunnels drilled in rock masses and so condition interventions for fire emergencies. Samples from two horizontal boreholes drilled in Prada limestone during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) are heated from 105 to 600 °C, and subsequently cooled with air or water to simulate fire extinguishing interventions. Changes in chemical composition and microstructure, physical properties (open porosity, volume, dry total weight, P and S-wave velocity), and mechanical properties (uniaxial compressive strength, elastic modulus, and Poisson's ratio) are analysed. Rock weakening is observed even at low temperatures (T < 300 °C). The influence of the cooling method appeared at intermediate temperatures of 300-400 °C and open porosity, P and S-wave velocities, and elastic modulus show greater variation for water-cooled samples. A temperature of 500 °C is of paramount importance for 'Prada' limestone as it leads to a dramatic increase in porosity and a notable decrease in P and S-wave velocities under both cooling methods. Trans-granular micro-crack progression is observed at 500 °C using scanning electron microscope (SEM), and water-cooled samples show a greater loss in uniaxial compressive strength (UCS), and this is due to micro-crack connections and growing fissures. Thermal damage at 600 °C is also greater when samples are quickly cooled. An ANOVA and a simple regression analysis are performed to discard the influence of the natural location of the borehole samples in the obtained experimental results. Finally, correlations to predict UCS and elastic modulus from volume, open porosity, and P-wave velocity after thermal treatment are proposed using simple exponential and potential functions to help make preliminary decisions after a tunnel fire. These predictive results on the effects of fire on Prada limestone will be considered for the definition of future fire intervention protocols in the Tres Ponts Tunnel. [ABSTRACT FROM AUTHOR]