Updating Active Deformation Inventory Maps in Mining Areas by Integrating InSAR and LiDAR Datasets

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.This research was funded by the ESA-MOST China DRAGON-5 project (ref. 59339) and funded by a Chinese Scholarship Council studentship awarded to Liuru Hu (Ref. 202004180062)

Sentinel-1 A-DInSAR approaches to map and monitor ground displacements

Persistent scatterer interferometry (PSI) is a group of advanced interferometric synthetic aperture radar (SAR) techniques used to measure and monitor terrain deformation. Sentinel-1 has improved the data acquisition throughout and, compared to previous sensors, increased considerably the differential interferometric SAR (DInSAR) and PSI deformation monitoring potential. The low density of persistent scatterer (PS) in non-urban areas is a critical issue in DInSAR and has inspired the development of alternative approaches and refinement of the PS chains. This paper proposes two different and complementary data-driven procedures to obtain terrain deformation maps. These approaches aim to exploit Sentinel-1 highly coherent interferograms and their short revisit time. The first approach, called direct integration (DI), aims at providing a very fast and straightforward approach to screen-wide areas and easily detects active areas. This approach fully exploits the coherent interferograms from consecutive images provided by Sentinel-1, resulting in a very high sampling density. However, it lacks robustness and its usability lays on the operator experience. The second method, called persistent scatterer interferometry geomatics (PSIG) short temporal baseline, provides a constrained application of the PSIG chain, the CTTC approach to the PSI. It uses short temporal baseline interferograms and does not assume any deformation model for point selection. It is also quite a straightforward approach, which improves the performances of the standard PSIG approach, increasing the PS density and providing robust measurements. The effectiveness of the approaches is illustrated through analyses performed on different test sites.This work has been partially funded by AGAUR, Generalitat de Catalunya, through a grant for the recruitment of early-stage research staff (Ref: FI_B 00741) and through the Consolidated Research Group RSE, “Remote Sensing” (Ref: 2017-SGR-00729). It has been also partially funded by the Spanish Ministry of Economy and Competitiveness through the DEMOS project “Deformation monitoring using Sentinel-1 data” (Ref: CGL2017-83704-P) and by AGAUR.Peer ReviewedPostprint (published version

ADAtools: Automatic Detection and Classification of Active Deformation Areas from PSI Displacement Maps

This work describes the set of tools developed, tested, and put into production in the context of the H2020 project Multi-scale Observation and Monitoring of Railway Infrastructure Threats (MOMIT). This project, which ended in 2019, aimed to show how the use of various remote sensing techniques could help to improve the monitoring of railway infrastructures, such as tracks or bridges, and thus, consequently, improve the detection of ground instabilities and facilitate their management. Several lines of work were opened by MOMIT, but the authors of this work concentrated their efforts in the design of tools to help the detection and identification of ground movements using synthetic aperture radar interferometry (InSAR) data. The main output of this activity was a set of tools able to detect the areas labelled active deformation areas (ADA), with the highest deformation rates and to connect them to a geological or anthropogenic process. ADAtools is the name given to the aforementioned set of tools. The description of these tools includes the definition of their targets, inputs, and outputs, as well as details on how the correctness of the applications was checked and on the benchmarks showing their performance. The ADAtools include the following applications: ADAfinder, los2hv, ADAclassifier, and THEXfinder. The toolset is targeted at the analysis and interpretation of InSAR results. Ancillary information supports the semi-automatic interpretation and classification process. Two real use-cases illustrating this statement are included at the end of this paper to show the kind of results that may be obtained with the ADAtools.This work has received funding from the Shift2Rail Joint Undertaking under the European Union's Horizon 2020 research and innovation programme, with grant agreement No 777630, project MOMIT, “Multi-scale Observation and Monitoring of railway Infrastructure Threats”. It has been also partially funded by Interreg-Sudoe program of the EU, through the project RISKCOAST (Ref: SOE3/P4/E0868)

Imaging land subsidence in the Guadalentín River Basin (SE Spain) using Advanced Differential SAR Interferometry

Aquifer overexploitation can lead to the irreversible loss of groundwater storage caused by the compaction or consolidation of unconsolidated fine-grained sediments resulting in land subsidence. Advanced Differential SAR Interferometry (A-DINSAR) is particularly efficient to monitor progressive ground movements, making it an appropriate method to study depleting aquifers undergoing overexploitation and land subsidence. The Guadalentín River Basin (Murcia, Spain) is a widely recognized subsiding area that exhibits the highest rates of groundwater-related land subsidence recorded in Europe (>10 cm/yr). The basin covers an extension of more than 500 km2 and is underlain by an overexploited aquifer-system formed by two contiguous hydraulically connected units (Alto Guadalentín and Bajo Guadalentín). Although during the last years the piezometric levels have partially stabilized, the ongoing aquifer-system deformation is evident and significant, as revealed by the A-DInSAR analysis presented. In this work, we submit the first vertical and horizontal (E-W) decomposition results of the LOS velocity and displacement time series of the whole Guadalentín Basin obtained from two datasets of Sentinel-1 SAR acquisitions in ascending and descending modes. The images cover the period from 2015 to 2021 and they were processed using the Parallel Small BAseline Subset (P-SBAS) implemented by CNRIREA in the Geohazards Exploitation Platform (GEP) on-demand web tool, which is funded by the European Space Agency. The output ascending and descending measurement points of P-SBAS lie on the same regular grid, which is particularly suited for the geometrical decomposition. Time series displacements are compared to a permanent GNSS station located in the Bajo Guadalentín basin.This study has received funding in framework of the RESERVOIR project (Sustainable groundwater RESources managEment by integrating eaRth observation deriVed monitoring and flOw modelIng Results), funded by the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) programme supported by the European Union (Grant Agreement 1924; https://reservoir-prima.org/). The study has also been supported by the Grant FPU19/03929 (funded by MCIN/AEI/10.13039/501100011033 and by “FSE invests in your future”); the Project CGL2017-83931-C3-3-P (funded by MCIN/ AEI/10.13039/501100011033 and by “ERDF A way of making Europe”); the ESA-MOST China DRAGON-5 Project (ref. 59339) and the SARAI Project PID2020-116540RB-C22 (funded by MCIN/AEI/10.13039/501100011033). Copernicus Sentinel-1 IW SAR data were provided and processed in ESA’s Geohazards Exploitation Platform (GEP), in the framework of the GEP Early Adopters Programme

Sentinel-1 DInSAR for Monitoring Active Landslides in Critical Infrastructures: The Case of the Rules Reservoir (Southern Spain)

We thank the editors and four anonymous reviewers for helpful comments and suggestions that improved the manuscript.Landslides in reservoir contexts are a well-recognised hazard that may lead to dangerous situations regarding infrastructures and people’s safety. Satellite-based radar interferometry is proving to be a reliable method to monitor the activity of landslides in such contexts. Here, we present a DInSAR (Differential Interferometric Synthetic Aperture Radar) analysis of Sentinel-1 images that exemplifies the usefulness of the technique to recognize and monitor landslides in the Rules Reservoir (Southern Spain). The integration of DInSAR results with a comprehensive geomorphological study allowed us to understand the typology, evolution and triggering factors of three active landslides: Lorenzo-1, Rules Viaduct and El Arrecife. We could distinguish between rotational and translational landslides and, thus, we evaluated the potential hazards related to these typologies, i.e., retrogression (Lorenzo-1 and Rules Viaduct landslides) or catastrophic slope failure (El Arrecife Landslide), respectively. We also observed how changes in the water level of the reservoir influence the landslide’s behaviour. Additionally, we were able to monitor the stability of the Rules Dam as well as detect the deformation of a highway viaduct that crosses a branch of the reservoir. Overall, we consider that other techniques must be applied to continue monitoring the movements, especially in the El Arrecife Landslide, in order to avoid future structural damages and fatalities.A Spanish “Sistema de Garantía Juvenil” research contract, founded by the Junta de Andalucía and the European Social Funds, supported the work of Cristina Reyes-Carmona. Spanish “Ramón y Cajal” grant supported part of the work of Jorge Pedro Galve. This work has been partially funded by the Spanish Ministry of Economy and Competitiveness through the DEMOS project “Deformation monitoring using Sentinel-1 data” (Ref: CGL2017-83704-P) and the LITHOSURF project “Respuesta de la topografía y la red de drenaje a procesos litosféricos y climáticos en el sur de Iberia” (Ref: CGL2015-67130-C2-1-R). This work has been partially developed in the framework of the RISKCOAST project (Ref: SOE3/P4/E0868) funded by the Interreg SUDOE program (3rd call for proposals)

Geotechnics for rockfall assessment in the volcanic island of Gran Canaria (Canary Islands, Spain)

The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate.This work was carried out in the framework of two projects funded by the European Commission, Directorate-General Humanitarian Aid and Civil Protection (ECHO): SAFETY (Sentinel-1 for geohazard prevention and forecasting. Ref. ECHO/SUB/2015/718679/Prev02) and U-GEOHAZ (Geohazard Impact Assessment for Urban Areas. Grant Agreement No. 783169). This work has been partly funded by the University of Alicante in the framework of Quality Improvement Grant of PhD Program in Materials, Structures and Soil Engineering: Sustainable Construction, Salvador de Madariaga Mobility Program from the Spanish Ministry of Science (PRX18/00020) and the Industrial PhD Project GEODRON (IND2017/AMB-7789). We also appreciate the contribution of the MACASTAB project (Ref.: MAC/3.5b/027). The laboratory tests were carried out in the Laboratories of Building and Public Works from the Canarian Government. The methodology is also developed in the framework of the RISKCOAST project (Ref: SOE3/P4/E0868) funded by the European Regional Development Fund - Interreg programme (3rd call for proposals)

Piezometric and ground deformation relationship at Almonte-Marismas aquifer (Andalucía, Spain)

[EN] Groundwater is one of the most important hydric resources of the Spain territory. Nevertheless, heavy groundwater withdrawal generates severe consequences, being land subsidence one of them. The Interferometric Synthetic Aperture Radar (InSAR) technique have been recently exploited to detect and monitor aquifer related deformations. In the present work, relationship between piezometric levels drawdowns and land subsidence has been studied for the higher withdrawals areas within Almonte-Marismas aquifer system (which holds the Doñana Natural Space). Four datasets of radar satellite images, obtained from Sentine-1 satellite, have been processed using the InSAR technique in the period 2014 - 2020. Results show that in some of these areas, like those surrounding El Rocío and Matalascañas villages, the correlation between these two variables is high.[ES] El agua subterránea es uno de los recursos hídricos más importantes en el territorio español. La gran cantidad de agua que se retira de ellos puede tener graves consecuencias, entre las que destaca, en algunos acuíferos, la subsidencia del terreno. La técnica de interferometría radar (InSAR), ha sido desarrollada en las últimas décadas para detectar y monitorear las deformaciones relacionadas con los acuíferos. En este trabajo se estudia la posible relación existente entre la variación de los niveles piezométricos y el movimiento del terreno en zonas con grandes extracciones del acuífero Almonte-Marismas (sobre el que se ubica el Espacio Natural de Doñana). Para ello, se han analizado los datos de deformación del terreno obtenidos del satélite Sentinel-1 en el periodo 2014-2020 Los resultados muestran que, en alguna de estas zonas, como las cercanas a las poblaciones de El Rocío y Matalascañas, la correlación entre ambas variables es alta.Este trabajo es parte de las actividades subvencionadas dentro del Sistema Nacional de Garantía Juvenil (PEJ2018-002477), financiado por la Fundación Tripartita para la Formación en el Empleo, la iniciativa YEI (Youth Employment Initiative) y el Fondo Social Europeo (FSE). Los datos Copernicus Sentinel-1 se obtuvieron y procesaron en la plataforma GEP de la ESA en el marco del GEP Early Adopters Programme. Agradecemos al IGME y a la CHG por proporcionar los datos de piezometría, así como a la Junta de Andalucía por suministrar los datos meteorológicos.González-Jiménez, M.; Guardiola-Albert, C.; Aguilera-Alonso, H.; Béjar- Pizarro, M.; Herrera, G.; Ezquerro, P.; López-Vinielles, J.... (2021). Estudio de la relación entre la piezometría y la deformación del terreno en el acuífero Almonte-Marismas (Andalucía, España). En Proceedings 3rd Congress in Geomatics Engineering. Editorial Universitat Politècnica de València. 102-108. https://doi.org/10.4995/CiGeo2021.2021.12675OCS10210

Rapid characterisation of the extremely large landslide threatening the Rules Reservoir (Southern Spain)

When an active landslide is first identified in an artificial reservoir, a comprehensive study has to be quickly conducted to analyse the possible hazard that it may represent to such a critical infrastructure. This paper presents the case of the El Arrecife Landslide, located in a slope of the Rules Reservoir (Southern Spain), as an example of geological and motion data integration for elaborating a preliminary hazard assessment. For this purpose, a field survey was carried out to define the kinematics of the landslide: translational in favour of a specific foliation set, and rotational at the foot of the landslide. A possible failure surface has been proposed, as well as an estimation of the volume of the landslide: 14.7 million m3. At the same time, remote sensing and geophysical techniques were applied to obtain historical displacement rates. A mean subsidence rate of the landslide around 2 cm/year was obtained by means of synthetic aperture radar interferometry (InSAR) and ground-penetrating radar (GPR) data, during the last 5 and 22 years, respectively. The structure-from-motion (SfM) technique provided a rate up to 26 cm/year during the last 14 years of a slag heap located within the foot of the landslide, due to compaction of the anthropical deposits. All of this collected information will be valuable to optimise the planning of future monitoring surveys (i.e. differential global positioning systems, inclinometers, ground drilling, and InSAR) that should be applied in order to prevent further damage on the reservoir and related infrastructures.This work was mainly supported by the European Regional Development Fund (ERDF) through the project “RISKCOAST” (SOE3/P4/E0868) of the Interreg SUDOE Programme. The work of J.P.G., M.M-S., P.R. and J.M.A. was also supported by the “Ramón y Cajal” Programme (RYC-2017–23335) of the Spanish Ministry of Science, the project “MORPHOMED”—PID2019-107138RB-I00 / SRA (State Research Agency / https://doi.org/10.13039/501100011033) and the project “RADANDALUS” (P18-RT-3632) and B-RNM-305-UGR1818 of the FEDER / Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades

Research Group on Earth Observation, Geological Risks and Climate Change (OBTIER)

[EN] Within the framework of the IGME-CSIC Department of Geological Hazards and Climate Change, the OBTIER research group was created in July 2021 and currently has 22 members, including scientific and technical staff, as well as young people with contracts linked to competitive national and international research projects. The main objective of the group is to provide society with scientific information, methods, tools and solutions to mitigate the impact of geohazards and the effects of Climate Change. OBTIER is currently leading 6 competitive projects (4 European and 2 national), as well as several projects in agreement with other national and international administrations. It is an active member of the EuroGeoSurveys Earth Observation Expert Group and the ASGMI Geological Hazards Group. OBTIER offers society a wide range of capabilities on: earthquakes, tsunamis, landslides, land subsidence, volcanic eruptions, droughts and floods. In 2021, the group published an article in Science entitled: Mapping the global threat of land subsidence with significant media coverage around the world.Peer reviewe

Aplicación de técnicas de interferometría radar satélite al análisis de estabilidad de taludes en zonas mineras

En esta investigación se propone una metodología de análisis de estabilidad de taludes en zonas mineras basada en la combinación de técnicas de monitorización (remota e in situ) y modelización numérica, aplicable tanto a escala regional como local, y centrada en la aplicación de la interferometría radar satélite (InSAR) como principal técnica de monitorización. La aplicación de la metodología propuesta, cuyo fin último no es otro que el de reducir el riesgo asociado a la posible ocurrencia de roturas de talud (o simplemente a la existencia de inestabilidades de talud) en minería, facilita la interpretación de los resultados obtenidos con las diferentes técnicas aplicadas, y ofrece distintas posibilidades para la integración de los mismos, lo que permite aportar gran valor añadido a los datos InSAR satélite brutos. Además, la metodología puede utilizarse para realizar tanto análisis (predictivos) de inestabilidades de talud, como análisis (retrospectivos) de roturas de talud. El trabajo está estructurado en tres bloques. El primero de ellos describe cada una de las partes de la metodología desarrollada, incluyendo una descripción detallada de las técnicas de monitorización y modelización necesarias para aplicar el flujo de trabajo propuesto. El segundo, recoge los resultados obtenidos en tres zonas de estudio, seleccionadas principalmente atendiendo a criterios de aplicabilidad, tipología, complementariedad y disponibilidad de información. Finalmente, el tercer bloque resume las principales conclusiones de la investigación. La metodología consta de cuatro pilares: (i) aplicación de técnicas de monitorización multi-sensor (técnicas InSAR, técnicas de fotogrametría digital o SfM, y técnicas de navegación por satélite diferencial o DGNSS) multi-plataforma (satélite, aérea y terrestre), y de técnicas de validación de datos (validación de los resultados de monitorización), (ii) aplicación de métodos de análisis espaciotemporal de datos (análisis de los resultados de monitorización), (iii) aplicación de técnicas de modelización numérica (mediante modelización por elementos finitos o FEM), y (iv) aplicación de técnicas de integración de datos (integración de los resultados de monitorización y modelización). El segundo bloque presenta los resultados obtenidos tras aplicar la metodología en los tres casos de estudio considerados: la Sierra Minera de Cartagena-La Unión (Murcia), la mina de Las Cruces (Sevilla) y la mina de El Feixolín (León). Así, sobre la base de los trabajos llevados a cabo en la Sierra Minera, esta tesis documenta, por primera vez, la aplicación de técnicas FEM al análisis de estabilidad de taludes en zonas mineras a escala regional (análisis predictivo), así como la elaboración de mapas de peligrosidad por inestabilidad de taludes mediante la combinación de técnicas InSAR y FEM. Asimismo, gracias a los trabajos llevados a cabo en Las Cruces, este trabajo muestra las posibilidades que ofrece la combinación de técnicas InSAR, SfM y FEM a la hora de realizar análisis remotos (es decir, basados exclusivamente en la explotación de datos de teledetección) de roturas de talud en zonas de minería a cielo abierto a escala local (análisis retrospectivo). Por último, este estudio documenta por vez primera, en base a los trabajos realizados en El Feixolín, la aplicación de técnicas SfM a la monitorización de inestabilidades de talud en zonas mineras a escala local (análisis predictivo), poniendo además de manifiesto las ventajas asociadas a la adopción, para la gestión del riesgo por inestabilidad de taludes, de programas de monitorización basados en la combinación de técnicas InSAR y SfM. Estos trabajos han ayudado a demostrar la eficacia de la metodología propuesta para analizar, en los casos de estudio investigados, características geomorfológicas, áreas fuente, volúmenes movilizados, desplazamientos a lo largo de la línea de vista del satélite, aspectos sobre la predictibilidad de la rotura, diferencias de elevación, desplazamientos 3D, factores condicionantes y desencadenantes, y mecanismos de rotura. Aunque, en todos los casos, la aplicación de la metodología desarrollada en esta tesis se ha centrado en el análisis de inestabilidades y roturas de talud en zonas mineras, conviene señalar que dicha metodología puede utilizarse para analizar todo tipo de movimientos de ladera. ----------ABSTRACT---------- This research proposes a methodology for slope stability analysis in mining areas, based on the combination of (remote sensing and in situ) monitoring and numerical modeling techniques, applicable at both regional and local scales, and focusing on the application of satellite radar interferometry (InSAR) as the main monitoring technique. The application of the proposed methodology, its ultimate aim being none other than to reduce the risk associated with the possible occurrence of slope failure (or simply the existence of slope instabilities) in mining, facilitates the interpretation of the results obtained with the different techniques applied, and offers different possibilities for their integration, which allows to provide great added value to the raw satellite InSAR data. Furthermore, the methodology can be used to perform both (predictive) analyses of slope instabilities and (retrospective) analyses of slope failures. The work is structured in three sections. The first describes each part of the methodology developed, including a detailed description of the monitoring and modeling techniques needed to apply the proposed workflow. The second one gathers the results obtained in three study areas, selected mainly according to criteria of applicability, typology, complementarity, and availability of information. Finally, the third section summarizes the main conclusions of the research. The methodology consists of four pillars: (i) application of multi-sensor (InSAR techniques, digital photogrammetry techniques or SfM, and differential satellite navigation techniques or DGNSS), multi-platform (satellite, airborne and terrestrial) monitoring techniques, and of data validation techniques (validation of the monitoring results), (ii) application of spatiotemporal data analysis methods (analysis of the monitoring results), (iii) application of numerical modeling techniques (using finite element modeling techniques or FEM), and (iv) application of data integration techniques (integration of the monitoring and modeling results). The second section presents the results obtained by applying the methodology in the three case studies considered: Sierra Minera de Cartagena-La Unión (Murcia), Las Cruces mine (Seville) and El Feixolín mine (Leon). Thus, on the basis of the work conducted at Sierra Minera, this thesis reports for the first time the application of FEM techniques to perform slope stability analysis in mining areas on a regional scale (predictive analysis), as well as the elaboration of slope instability hazard maps by combining InSAR and FEM techniques. In addition, thanks to the study carried out at Las Cruces, this work shows the possibilities offered by the combination of InSAR, SfM and FEM techniques to perform remote analysis (i.e., based exclusively on the exploitation of remote sensing data) of slope failures in open-pit mining areas on a local scale (retrospective analysis). Finally, this study documents for the first time, based on the investigations conducted at El Feixolín, the application of SfM techniques to the monitoring of slope instabilities in mining areas on a local scale (predictive analysis), further highlighting the advantages associated with the adoption, for slope instability risk management, of monitoring programs based on the combination of InSAR and SfM techniques. The proposed methodology has proven to be effective for analyzing, in the investigated case studies, geomorphological features, source areas, mobilized volumes, displacements along the satellite line of sight, aspects on the failure predictability, elevation differences, 3D displacements, conditioning and triggering factors, and failure mechanisms. Although, in all cases, the application of the methodology developed in this thesis has focused on the analysis of slope instabilities and failures in mining areas, it should be noted that this methodology can likewise be used to analyze all types of instabilities and failures affecting natural and man-made slopes