IAEG/AEG Annual Meeting Proceedings, San Francisco, California, 2018 - Volume 1

The purpose of this study was to characterize the rock mass at the Mount Rushmore National Memorial (MORU) site that exhibits the sculptures of four American presidents (Washington, Jefferson, Roosevelt, and Lincoln) carved in granite rock. In addition to granite, quartz-mica schist and minor outcrops of pegmatite are present within the memorial site. We used both the Rock Mass Rating System (RMR) and Rock Quality System (Q-system) to characterize the rock mass. For collecting the data required for rock mass characterization, we divided the MORU site into four regions. Field investigations for each region included detailed mapping of the discontinuities (orientation, spacing, continuity, aperture, nature of infilling material, presence/absence of water), estimating Rock Quality Designation, and collecting rock samples for laboratory testing. Additionally, we evaluated the degree of rock weathering for each region. In the laboratory, we determined unconfined compressive strength and second-cycle slake durability index values for the granite and schist samples. Both the RMR and Q-systems indicate the granite, schist, and pegmatite classify as fair to good rock. The granite and schist are moderately to highly weathered whereas the pegmatite is moderately to completely weathered. The second-cycle slake durability test results indicate a slight potential for undercutting of granite by schist. Considering the importance of the sculptures, we recommended that differential weathering between schist and granite rock from which the sculptures are carved be monitored on a long-term basis by periodically measuring the depth of undercutting using a tape measure and by maintaining a photographic record.

Since water impoundment of the Three Gorges reservoir, more than 200 large-scale existing landslides have reactivated in the reservoir area. It has been extensively recognized that seepage and uplift water pressure following rise and drawdown of the reservoir water played important roles in reactivation of these landslides, while variation of residual strength of landslides’ slip zones which were immersed by the reservoir water and its contribution to these landslides’ reactivation has been paid little attention. To explore this, residual strength of five large-scale landslides’ slip zones in the reservoir area, which were composed of clayey soils with significant amount of gravel, was experimentally investigated after being soaked for different periods. It was found that a significant reduction in residual strength of the landslides’ slip zones occurred after being soaked for around 30 days, and very minor reduction occurred after being soaked for a longer period. This indicates that reduction in residual strength of their slip zones may contribute to the landslides’ reactivation which occurred during early time of the reservoir’s operation. Particle size analysis and water chemical analysis of the slip zones’ materials after being soaked suggest that residual strength reduction of the landslides’ slip zones may be mainly attributed to slaking of coarse particles, followed by hydration of clay minerals, dissolution of calcite and hydrolysis of feldspar due to soaking.

The Lotus Pond landslide developed in a large-scale cataclinal slope on the right bank of Yangtze River. It has been reactivated by impounding of the Three Gorges Reservoir. Based on geological survey and experimental tests, deformation characteristics and failure mechanism have been ascertained. The Lotus Pond landslide is a successive landslide formed by three periods of sliding at different elevations; the three slides have similar shapes in the longitudinal profile. The toes of the later slides thrust and overlie the heads of the early slides on circular rupture surfaces. However, the successive slides exhibit different failure mechanisms, namely, buckling, planar slide, and “toe-break” mechanisms.

The topographic and climatic conditions of Hong Kong result in frequent landslides within the natural hillsides surrounding much of the urbanized and developed area. When failures do occur and in view of the high-risk levels associated with retrogression/reactivation of landslide scars, urgent repair works comprising of debris clearance and minor trimming back and shotcreting of landslide scars are frequently undertaken. Although effective in terms of reducing further landslide risk in the short term, these approaches have resulted in many unsightly concrete ‘scars’ within otherwise naturally vegetated slopes. To counter these impacts and enhance slope stability in a more sustainable and aesthetic manner, soil bioengineering techniques have recently been implemented within natural terrain catchments on Lantau Island that were subject to intense landsliding and subsequent emergency works in 2008. This paper discusses the design and implementation of some of the techniques implemented for landslide scar.

Slope design of highway construction projects in Algeria has always been a difficult engineering problem. The study site has a complex geological setting with notable regional seismic events, faults and slope instability. The designed slope is situated over a marl bedrock, Maastrichtian (late Cretaceous) to Paleocene in age, which comprises a monotonous series of marls, locally covered by the recent topsoil layer, fill deposits and the quaternary cover comprising clay-matrix conglomerates which include sandstone gravels and blocks and interbedded layers of resistant travertines. This study describes the stability analysis of a highway slope before and after the reinforcement by a pile wall and prestressed anchor cables using finite element program in two-dimensional problems, i.e. computation of the factors of safety (FOS) and location of the critical slide surface and simulated the various stages of execution of work and the situations for the structural design.

The British Geological Survey (BGS) formally incorporated engineering geology as one of its key activities by creating the Engineering Geology Unit (EGU) in 1967. From 1968 an engineering geological survey of the proposed site of the new town of Milton Keynes in the south Midlands of England was carried out, as part of a government initiative to build new towns to accommodate an increasing population. This involved analysis of extensive site investigation data and the production of an engineering geological map and a table of summarized geotechnical data for each geological formation. This work led to a much more extensive project for the then proposed Third London Airport in the estuary of the River Thames in South Essex, in south east England and two further mapping projects in development areas adjacent to the Firth of Forth and Cromarty Firth in Scotland. These projects were completed during the 1970s and early 1980s. The experience gained on these projects was then used in a series of urban geological/engineering geological mapping projects in urban areas of England, Scotland and Wales. The paper discusses the engineering geological mapping techniques developed in the first two decades of engineering geological survey and research at the BGS and where this work led in subsequent years.

The east-west trending, south-facing slope in Rockville, Washington County, Utah is well known for experiencing large-size rockfalls, including the fatal rockfall of December 2013 that destroyed a home and killed two people. The stratigraphic units present in the area include the well-indurated, Upper Triassic, Shinarump Conglomerate Member (cliff-forming unit) of the Chinle Formation that caps the less-resistant, Lower Triassic, Moenkopi Formation (slope-forming unit). We performed a detailed study to investigate the factors that contribute to rockfall occurrence and the associated risk in the Rockville area. To accomplish this objective, we selected four representative sites along the slope and a few supplemental sites for additional data. The results of our study indicate that the main factors contributing to rockfall occurrence include unfavorable orientation of discontinuities, differential weathering resulting in undercutting, and regional climate (infrequent, high precipitation events; freeze-thaw cycles) whereas those contributing to rockfall risk include high slopes, presence of gullies that channelize rockfall debris, and proximity of homes to the toe of the slope. The results also show that the western portion of the study area poses the highest risk due to the presence of higher slopes, larger exposure of the Shnabkaib Member (the weaker rock unit) resulting in undercutting, higher number of deep gullies, and the higher number of residences closer to the slope toe.

A cut slope, located in front of the Faculty of Social Sciences and Humanity (FSSK) building, Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor failed after a heavy rainfall in November 2012. The main objectives of this study are to assess and characterize the landslide hazards to identify the geological parameters contributing towards the hazards and to recommend suitable risk mitigation measures. The study has been carried out by discontinuity survey, soil and rock testings and kinematic stability analysis. The studied slope is made up of predominantly of highly to completely weathered phyllite, graphitic phyllite and quartzite. The phyllite is generally weak rock and has very low durability, while graphitic phyllite and quartzite are generally medium strong rocks with low durability. The slope is dissected by at least 5 sets of discontinuities (mainly joints and foliations), which exerted profound control on the geometry of the slope failure. Kinematic stability analyses indicated that the slope is unstable and have undergone planar, wedge and/or combined modes of failure. To mitigate the risk for retrogressive failure, the slope has been stabilized with active netting (wire mesh with soil nails). The slope is also equipped with sufficient drainage system to control surface runoff and vegetation cover by applying hydroseeding method. This study has shown a typical example of the importance of geological studies in identifying the root causes for a failure of weathered cut slope and recommended methods for stabilization and remediation of a failed weathered cut slope in a wet tropical country such as Malaysia.

During the construction of many roads, slope stability problems can occur, resulting in a delayed completion of the construction as well as an increased final budget. However, there is still limited data collected that reveals the actual costs of geotechnical issues. The Diezma landslide, affecting the A-92 highway (Granada, SE Spain), is a great example of this situation. The construction project, which was started in 1988, did not identify the geotechnical instabilities of this zone, thus no preventive measures were recommended. The landslide-induced disruption of the highway involved economic losses related to the implementation of corrective measures and to indirect costs. In this paper, an evaluation of direct and indirect costs induced by the landslide is developed, and as a result, the potential cost savings of an adequate geotechnical survey are obtained.

Since the 19th century, the warming rate in the European Alpine region has been twice as high as the average global rate. Warming-related permafrost degradation has been shown to cause a reduction of bedrock bearing capacities, potentially leading to the destabilization and eventually to the failure of high-alpine infrastructure. The presented study investigates permafrost-related changes of bedrock properties and their stability-relevant effects on high-alpine infrastructures. The Kitzsteinhorn summit and its highly frequented cable car station (3029 m a.s.l., Austria) is home to the interdisciplinary Open Air Lab Kitzsteinhorn (OpAL), where the consequences of climate change, based on a long-term monitoring of surface, subsurface and atmospheric parameters are investigated. In a rock-ice mechanical model, degradation of permafrost causes changes in rock fracture toughness and rock friction, affects ice fracturing and creep as well as the behavior of rock-ice interfaces. A first numerical distinct element model of the mechanical behavior of rock slope and the infrastructure was set up, based on OpAL datasets and a civil engineering assessment of the cable car setup. By conducting a thorough rock mechanical model sensitivity analysis, it was tested how individual model parameters affect the rock slope stability below the cable car summit station. The accurate knowledge of the most sensitive parameters and their empirical variation range generates a better process understanding of destabilisation in permafrost-affected rock walls. This facilitates efficient stabilization measures for affected high-alpine infrastructures. Here we show, that the stability of infrastructure on permafrost-affected bedrock is not only passively determined by mechanical changes in the underlying frozen rock mass, but infrastructure also actively affects thermal conditions and rock stability in a relevant way.

Drakensberg is a steep, mountainous terrain, where rockfalls widely occur along the slopes of the V-shaped valleys. Rockfall events, often responsible for casualties and fatalities, have occurred in the past and occur sporadically in that mountain range. In this study rockfall accumulation zones were mapped, and a data set of 208 rockfall boulders was developed. The falling blocks’ measured size range from 1 m3 to 4 × 103 m3 and the shape for the majority of the blocks is either cube or prism. A good agreement between the measured cumulative distribution and a fit by a power-law distribution, for volumes larger than 20 and 50 m3 is noticed. The rockfall trajectory paths, maximum run-out distances, involved kinetic energies, and rockfall velocities were estimated, based on rockfall analysis. A pseudo 3D rockfall analysis based on the shadow angle principle was applied to account for the lateral disperse of the falling blocks. The outcome of the rockfall analysis revealed that Giant’s Castle Main Camp is susceptible to rockfall hazard.

The Fontaínhas scarp, located on the right bank of the Douro River between D. Luis and D. Maria Pia bridges, presents an historical record of slope failures since 19th century is extremely important for risk management of that area as well as for the surrounding streets. In order to help future decision-making processes related to interventions on the escarpment, a study was performed, in 2011, to characterize the stability conditions of the scarp, based on existing bibliographic information, detailed field inspections and identification of risk situations. Aiming to systematize the problems identified in the field, the study area was subdivided in five sectors, considering the existence of important stabilization works, the type and distribution of the constructions (residential areas and ruins), the slope morphology and the vegetation (type and distribution) as criteria. Taking into account the characterization carried out for each sector, a remedial measures proposal for the risk situations identified in the field was suggested to the city council of Oporto, with the least possible impact on the landscape. Thus, this paper focuses on the characterization carried out on the escarpment as well as the description of the respective proposal.

Rock falls are a major cause for concern at the Magdalena Colliery, where mining of bituminous coal has been going on for the past twelve years. Potential keyblocks are the result of numerous joint intersections that result in many unstable blocks that fall off the roof, when the weight exceeds the support capacity. Several attempts have been made in the past to accurately predict rock fall occurrence. This paper describes the use of the computer program JBlock to simulate keyblocks in the roof at Section 1, Panel 417 at the Magdalena Colliery and to predict the probability of occurrence of rock falls. Scanline mapping was undertaken in the roof followed by cluster analysis in DIPS to determine the major joint sets for input into the JBlock program in order to identify potentially unstable keyblocks. Laboratory tests were also conducted on selected samples in order to determine the geotechnical properties of the material and also to carry out a rock mass classification. The program tested the generated keyblocks for the current support system and a proposed support system, which was based on the rock mass classification. Results obtained show that the current support system is inadequate at Section 1, Panel 417.

Geomechanical behavior changes caused by supercritical (sc) CO₂ in an analogue reservoir formation and in borehole cement are described after physical and mechanical evaluations. To simulate reservoir conditions, rock and cement specimens were conditioned during 5 weeks with scCO₂ at 333 K, brine at 16 MPa of hydrostatic pressure. Geomechanical experiments, such as traditional triaxial compression test and Brazilian tests, were executed with untreated and treated samples. First, results of the effects of CO₂ injection are presented through changes in physical and mechanical properties, as well as visual evaluations of the sandstone matrix and pore structure.

Some of the most serious landslide movements in Greece are often observed in the upper zone of weathered flysch and can be classified as composite landslides. This paper describes the landsliding behavior of highly weathered and tectonically decomposed flysch in a characteristic landslide in Western Greece, focusing on its physical and mechanical parameters, such as moisture content, clay percentage and shear strength. Back analysis was carried out in order to estimate the cohesion and angle of friction at the time of failure. The behavior of the flysch formation was also examined with the use of shear-related tests. All results were cross-examined, and it was concluded that weathered flysch in Western Greece is a landslide-prone material with small amounts of clay minerals, and its sliding behavior is mainly controlled by the rising of the water table and the tectonic activity.

The purpose of this paper is to assess the areas that are most susceptible to landslide occurrence along the Rio-Santos Highway in São Sebastião—SP (Brazil) based on the integration of the physiographic compartmentation and the geomechanical characterization of the study area. To produce physiographic compartmentation, the study area was subjected to photointerpretation to identify areas with homogenous textures and similar geomorphologic features. Moreover, DEM, slope maps and landslide scar mapping were used to complement the geomorphologic characterization of the region. A geological and geotechnical survey was used to obtain the parameters to classify rock masses according to the RMR classification and Q-System. Four units were delineated and described based on their geological, geotechnical and geomorphologic aspects. The units considered to be the most susceptible to the occurrence of shallow landslides are III and IV.

This study models landslide susceptibility on a watershed scale and estimates soil loss resulting from landslide derived sediment within 30 m of Strahler 3rd order or higher streams in the Drift Creek/Siletz watershed. Landslide derived sediment has been suspected of decreasing water quality, suspending water treatment plant operations, and degrading ecology in the Drift Creek/Siletz watershed by the Oregon Department of Environmental Quality (DEQ). The watershed has been designated as “Impaired by Unknown Stressors” by the MidCoast Watersheds Council Biological Monitoring Results Survey (2013). Logistic regression was used to determine the most significant variables contributing to landslide occurrence and to create a watershed scale landslide susceptibility map with area under the ROC curve of 0.8761. The most significant variables are slope angle, terrain elevation, soil erodibility factor, and plan curvature (curvature perpendicular to slope direction). Soil loss estimates were made by using the U.S. Department of Agriculture RUSLE 2 equation in ArcGIS to accommodate the many different spatial factors in the calculation. The watershed wide average annual soil loss estimate agrees with published findings for watersheds of similar size and physiographical location. Four Upper Drift Creek landslide deposits within 30 m of the stream network showed the highest average annual soil loss estimates (281.5 tons/acre/year combined). These landslide deposits coincide with recent logging activity. Logging activity and the time for forest re-growth appears to substantially influence soil loss in the Drift Creek/Siletz watershed.

Database of large-scale bedrock landslides of the Central Asian region embracing the Pamir, the Tien Shan, and the Dzungaria mountain systems has been compiled. Collected rockslides range in volume from nearly 1 × 106 m3 to ca. 10 × 109 m3 with the affected areas from several hectares to more than 100 km2. More than 950 landslide features have been identified and quantitative parameters (area of the deposits, total area affected, volume, runout, height drop, etc.) of about 62% of them have been measured up to now. Most of case studies are prehistoric. Statistical analysis of this database with regard to the confinement conditions demonstrates that total affected area and its ratio with height drop characterize rockslide mobility better than runout and angle of reach. Higher mobility of secondary rock avalanches associated with momentum transfer within rockslide debris in comparison with rock avalanches of other types is confirmed statistically. These results can be useful for landslide hazard assessment both in Central Asia and in other mountainous regions.

Landslide susceptibility maps are effective tools for the mitigation of risks caused by such geological events. In line with recent scientific trends and thanks to the availability of detailed geological data, landslide susceptibility modeling, by means of statistical methodologies, has gained increasing consideration. The present work is based on a methodology widely employed in the field of ecology to draw prediction maps for the occurrence probability of certain species (MaxEnt). The study area is located in Palma Campania, a town sited in the peri-vesuvian area (in the province of Napoli, southern Italy) and characterized by a significant presence of pyroclastic soils, affected by several landslide events, one of which killed eight people in 1986. In this work, eleven geomorphological and geological predisposing factors were selected, based on previous experiences of landslides in peri-vesuvian areas and following several field surveys. Results were critically evaluated using a validation dataset (Receiver Operating Characteristic—ROC curves), by means of Sensitivity-Specificity graphs estimating Area Under Curve (AUC), and other tests such as the Jackknife and response curves, which highlighted the major role played by a number of factors. The consistent agreement between our results and the existing official map demonstrates the validity of the adopted procedure for emergency and land planning.

Santorini Island constitutes one of most unique geological structures as it compromises a distinctive Miocene volcano. Rockfalls and landslides are widespread phenomena in Santorini due to orientation and steepness of the cliffs which are mainly formed as high elevated lava domes with loose material inside, extruded by sticky, slow-flowing dacite lava. Especially, landslide events in high vulnerable areas can cause significant environmental and socioeconomic impacts. Following a landslide hazard, comprehensive and reliable information on the geotechnical and geometric properties but also on the actual consequences of the phenomenon is mandatory. Today, the evolution of geoscience enables the use of innovative tools such as Unmanned Aerial Vehicles (UAVs) to address emergency response in disastrous situations. As a result, landslide identification and monitoring of large areas can be accomplished economically and timely. During the last decade, the UAV platform has become a useful and reliable research tool in emergency situations such as landslide monitoring. The current research performs a semi-automated method to evaluate and quantify site-specific landslide hazard in the area of Red Beach on the island of Santorini, Greece. Red Beach shows very high tourist activity during the whole year, so it is mandatory for safety reasons to establish guidance to eliminate landslide hazard in prone areas. Considering the availability of high spatial and spectral datasets, multitemporal change detection techniques were performed between two different datasets acquired in February and September of 2017 with a UAV platform. The methodology implemented in the current research revealed the accumulation area of failure, flow direction but also allowed the quantification of the mass movement in the area of interest. The outcome of the current research aims to highlight the usefulness of photogrammetry and UAV platforms to assess and mitigate the potential negative consequences of landslide hazard.

From November 20th, 2016, to November 25th, 2016, Liguria Region (northwestern Italy) experienced prolonged and intense rainfall. The rainfall sequence occurred following two main phases. The second phase mainly hit the western sector of the region, reaching its peak on November 24th. Rainfall was particularly abundant within the Arroscia valley, where the 5–days cumulative rainfall locally exceeded 50% of the mean annual precipitation. In this paper, we document the rainstorm magnitude, presenting a first inventory of the rainfall–induced ground effects within the Arroscia Valley. The mapping was performed by means of extensive field work that was partly supported by satellite imageries. More than 250 landslides affected the upper sector of the valley, while in the downstream reach, widespread flood-related forms and processes resulting from the abundant precipitation were mapped. The results of this study are expected to be helpful for future research on both landslide– and flood–related channel change susceptibility and risk scenarios evaluation.

The problem of geological and landslide risk management is viewed as a series of events leading to risk reduction, including risk analysis, risk assessment, risk mapping, vulnerability evaluation, concept of acceptable risk, monitoring organization, engineering-technical methods, insurance and others. The methodology for landslide risk assessment and mapping for urban areas is developed. The construction of a landslide risk map in the territory of Moscow is suggested.

High frequency of landslides in Taiwan area is affected by its geography and geology background. Landslide hazard was significantly affected by the 1999 Chi-Chi earthquake (921 earthquake), as this event changed the geomaterial conditions. A sustainable urban development plan is essential for the landslide hazard management. It should consider political and economical factors except technical factors. Besides, the climate change impact to natural hazard becomes more and more significant in Taiwan area. The rainfalls are more concentrated and the temperature increased about 1.5° during last 100 years. The concentrated rainfalls might more significantly affect the landslides in the futures. The problem of landslide and debris flow risk management is seen as series of events leading to risk reduction, including Risk analysis, Risk assessment, Risk mapping, Vulnerability evaluation, Concept of acceptable risk, Monitoring organization, Engineering-technical methods, Insurance and others. The problem of monitoring organization for landslides and debris flow in Taiwan is considered and analyzed.

Landslide inventory maps are effective and easily understandable products both for experts, such as engineering geologists, and for nonexperts, including decision-makers, planners, and civil protection managers. At present, the Cinque Terre landscape suffers from the massive abandonment of cultivations on the terraces, with negative consequences for slope stability due to the increasing erosional processes. Each landform was digitized as a polygon using a GIS platform. Landslide detection was performed by a two-step method. The first step consisted of mapping landslides using orthophotos provided by Liguria Region, together with Google Earth imagery; the second step was a field verification study carried out between September and November 2015. Four hundred and five landslides were then identified and grouped into seven main typologies: a percentage distribution analysis of the different landslide types detected in Cinque Terre was then performed. A large number of debris slides (33.3%) indicates the vulnerability of dry-stone walls after large amounts of rainfall. Rockfalls (18.5%) are also frequent and especially concentrated along the eastern sector of the coastline. In addition, debris flows (12.6%) are widely distributed, especially along the western sector of Cinque Terre, among the Monterosso and Vernazza municipalities; these landslides were mainly triggered by the October 25th, 2011, meteorological event (382 mm of rainfall in 24 h recorded by the Monterosso al Mare weather station). Many landslides with complex evolutions (7% of the total) were detected along the coastline between Vernazza and Manarola; these events are historically well-known and extensively described in the literature.

Being located in a mountainous area in the heart of Central America, with a young and partially very soft volcanic geology under the influence of a humid tropical climate with high rainfall during the rainy season, the area of the Honduran capital city, Tegucigalpa, is highly prone to landslides. Due to rapid and uncontrolled urbanization, especially on the slopes that surround the city, there is a strong interaction between human activities and landslides, further increasing landslide occurrences and causing a high vulnerability of the poorest part of the population. We here employed a landslide inventory, a geological map, and a dataset of landslide related factors, generated from data that is freely available for the analysis of landslide susceptibility with the help of data mining techniques. An input dataset of 21 variables, such as lithology, landform and drainage characteristics, and road density, was pre-processed, explored, coded in the IBM SPSS Modeler software, and implemented for the prediction of landslide occurrences with Artificial Neural Networks (ANN), Bayesian Networks (BN), and Decision Trees (DT). Different techniques were applied to enhance the performance of the model predictions by preparing the dataset to make it mathematically more accessible. The models with the balanced dataset yielded promising overall correct predictions of landslide and non-landslide cases of 85% (ANN) to 90% (DT) and correct predictions of landslides of 35% (BN) to 63% (ANN).

The Cumberland Plateau of eastern Kentucky is a forested and landslide prone area dominated by narrow ridges, steep slopes, and, in many places, terrain disturbed by past and current coal mining. The bedrock geology of the region comprises flat-lying Paleozoic shales, sandstones, siltstones, and coals; the vegetation is temperate deciduous forest sustained by average annual precipitation of about 125 cm. We undertook a pilot project to develop an extensible airborne LiDAR based landslide mapping protocol and create landslide inventory maps of the Prestonsburg, Kentucky, 7.5-min quadrangle, which we will ultimately use to support landslide susceptibility models of the areas. Arcuate head scarps, bulging toes, displaced drainage paths, and hummocky topography define landslides throughout the study area. Supplementary topographic roughness, topographic curvature, and bedrock geology maps, along with aerial photographs and a focused program of field checking, helped to confirm mapped features as landslides. We will collect samples for geotechnical testing and combine the results with a LiDAR based DEM to create susceptibility maps using both the physics-based probabilistic computer code PISA-m and empirical logistic regression models. If successful, our protocol may be implemented statewide and the results made available through an online database, serving as a resource for residents and professionals.

This paper outlines the status of the landslide susceptibility modelling of the Sydney Basin region within the state of NSW, Australia. This area extends from Newcastle in the north to Batemans Bay in the south and west to include the Blue Mountains, an area of approximately 31,000 km2. The University of Wollongong NSW Landslide Inventory includes 1863 landslides (134 falls, 278 flows and 1451 slides) to date. The region supports approximately one quarter of the population of Australia. Individual susceptibility models for both slide category and flow category landslides have been developed for the entire Sydney Basin region. Rockfall Susceptibility has also been developed for portions of the Wollongong Local Government Area. The susceptibility models are suitable for use at local scale, Advisory level Local Government Area Development Control Plans. As the models cover the three dominant landslide types identified within the inventory, a trial Total Landslide Susceptibility model has now been developed. As each landslide susceptibility model is a 10 m pixel resolution numerical grid, with values ranging from 0 to 1, the total susceptibility model has been developed, quite simply, by summing the three individual models producing a Total Susceptibility numerical grid. However, classifying this grid into zones is not simple. Furthermore, the Australian regulatory requirements are varied and the outcomes often complex involving a spatial query of the total susceptibility grid and its three contributing landslide susceptibility grids.

Mudflow accidents have been described in Southeastern Brazil, some of them involving huge volumes of organic clay, causing economic losses and casualties. Usually, these mudflows occur in amphitheater-like headwaters of hilly areas of basement rocks. These amphitheaters are filled with layers of soft organic clay, characterized by low values of Nspt and UU shear strength, interfingered with or partially or totally covered by colluvium, with higher Nspt. The organic clay layer can reach 6 m in thickness. It overlies thin pebbly sand layers or silt-rich saprolites. This stratigraphy is a natural consequence of climate oscillations that have prevailed since the Upper Pleistocene/Holocene, causing advances or retreats of the fluvial system and, consequently, of the headwater zones. It is not easy to identify the triggering mechanism of these movements, but a retrogressive rupture model is possible, since these clays present some strength sensitivity. Groundwater uplift pressure on the less permeable organic clay is probably an important triggering mechanism for mudflows and it hinders the clay consolidation throughout the geological time. A detailed geomorphological mapping of a hydrographic basin near Belo Horizonte (State of Minas Gerais) helped identify several amphitheater-like headwaters with similar characteristics to those identified at accident sites. The description of outcrops, auger, cable percussion boring samples and geophysical surveys validated the above-mentioned stratigraphy, proving that this configuration is common in basement areas of southeastern Brazil. With the growth of Brazilian cities towards regions with these characteristics, greater care should be taken to prevent the repetition of mudflow accidents.

A study of slope stability in the Benguela and Lobito areas, in Western Angola, was carried out. Seven slopes are studied. Three of the slopes are located at the urban area of Lobito, the other three are situated at Catumbela and one is located in the Caota’s area. The majority of the slopes are essentially composed of intercalations of limestone and marls belonging to the Quissonde Formation of the Cretaceous period. The methodology adopted in this work was useful to identify and characterize the different stability problems of the slopes. The Rockfall Hazard Rating System (RHRS), established by Pierson et al. (1990), was used to define the potential hazard for the roadways users. RHRS permits an analysis of the rockfall on roadways with relative low costs and can be applied in undeveloped countries, where the measurements devices are limited or scarce. Different types of slopes failures have occurred such as rockfalls, flows and landslides. The main causes of the slope movements are rainfall, slope geometric modification, rapid urbanization and roadway construction without the necessary geological and geotechnical characterization. The areas, of the studied slopes belong to dry tropical climate of arid and semi-arid characteristics, nevertheless torrential rainfall episodes can occur and initiate hazardous landslides. The majority of results of RHRS for the different slopes lie between 300 and 500. The results analysis allowed the adoption of mitigation and prevention measures.

The rapid growth of performance and cost reduction of micro-electromechanical systems (MEMS) make it possible to apply inertial sensors to slope deformation monitoring. In this paper, we propose a slope deformation monitoring means that measures and tracks displacements and movements without external georeferencing. The inertial measurement unit (IMU) consists of triaxial accelerometers and gyroscopes, which measure linear acceleration and rotational rate, respectively. It can be deployed either on the slope surface or underground. Applying the inertial navigation algorithms, we can achieve not only the velocity but also the attitude and position of the observed target. Unlike most of the existing deformation geotechnical measuring methods, the provided method measures the deformation of a slope until it fails, and allows continuing movement surveillance after the failure, which facilitates the local authorities in the implementation of effective and sustainable mitigation measures. This method can be combined with global navigation satellite system (GNSS) to achieve a monitoring scheme for the whole process of slope deformation. Making use of the measurements appropriately, we can derive the deformation or displacement at different phases of the slope deformation process.

A new approach for identification of critical states of soil masses was elaborated. The mechanism of formation of the limiting state in a soil mass during the initiation of a landslide is considered. The equations for assessment of a soil mass limited state prior to landslide formation were obtained. Also the equation for calculation of a landslide slip surface depth was obtained, using slope morphological and soil strength parameters. The developed limit state criteria were tested on specific landslide slopes. The results of these calculations have shown a good agreement with the actual data. For example, the calculated depths of sliding surfaces for deep landslide sites in Moscow coincide with depths identified by inclinometer measurements with accuracy of 0.5 m. The derived equation is suitable for slopes composed of different soils, from weak loams to very strong lithified Sarmatian limy clays of Balchik (Bulgaria), which are characterized by structural strength equal to 1 MPa.

Traditionally, discontinuity measurements have been collected manually using a Brunton compass. Ground-based light detection and ranging (LiDAR) scanning has, in recent years, been included as a more efficient method of structural data collection. Emerging technology in the realm of unmanned aerial vehicles (UAVs) focuses on the use of aerial photogrammetry in order to collect data from regions that would be otherwise difficult or impossible to access, and has the added benefit of eliminating “shadow zones” (gaps in data) that are typically a limitation of terrestrial LiDAR methodology. This study compares discontinuity data acquisition via an unmanned aerial vehicle (UAV) to these established methods in order to determine if UAV technology can be used reliably to collect structural data. Two field sites in Virginia were scanned for this study—a cut slope in Deerfield along highway 629, and a shale pit in Cove Mountain. Approximately 300 Brunton compass measurements of orthogonal joint sets and bedding planes were taken at each site in order to provide a “control group” for orientation data. In addition, ground-based LiDAR scans and UAV photogrammetric data were collected at each location. Scans from the LiDAR unit and the UAV were converted into 3D point clouds for statistical comparison with manually collected data. Stereonets of each data set were also prepared for further comparison. Preliminary results indicate that discontinuity data collection from UAV closely matches the data collected using LiDAR or Brunton compass.

Debris flows are among the most hazardous landslides. Additionally, their relevance increases as a consequence of global climate change, a phenomenon, which has already been observed by other authors. In June 2015 two debris flows occurred due to a radar-inferred rainfall intensity of about 90 mm in 45 min near Oberstdorf (Bavaria, Germany) in the Northern Alps. The debris flows lead to damage costs of several million euros and more than 300 people were evacuated. To monitor geomorphic changes and a potential channel refill after the event, high resolution (5 cm grid size) digital elevation models (DEMs) were derived from terrestrial laser scanning (TLS) in May, July and August 2017 in the Roßbichelgraben, one of these channels. Therefore, the 800 m long channel was observed with 72–78 laser scan positions on each date and DEMs of difference (DoDs) with spatially variable uncertainty were calculated. Simultaneously, DEMs were derived by photogrammetric surveys using an unmanned aerial vehicle (UAV). Photos taken by the UAV were photogrammetrically reconstructed into point clouds using the structure from motion—multi-view stereo workflow (SfM-MVS). The results show a good correlation of detectable areas with geomorphic changes between both methods. However, the accuracy of the SfM-MVS derived DEMs remains uncertain in steep parts of the channel. Nevertheless, the current contribution demonstrated that SFM-MVS offers great potential for topographic surveying and is a promising tool to quantify geomorphic changes in the near future.

This research describes a methodology for acquiring, visualizing, and reconstructing three-dimensional representations of blocky rock masses based on the coordinates of dense surface points. In general, the surface points can be obtained with a variety of sensors and sensor platforms. The workflow described herein considers photogrammetric data sets acquired with Unmanned Aerial Vehicles (UAVs). In the overall, the steps for constructing high resolution 3D geological structural models are: (1) a photogrammetric survey of the investigation area is performed to obtain a true-color georeferenced 3D point cloud; (2) structural geologic measurements are extracted directly from the point cloud or associated digital terrain model (DTM); (3) the 3D rock structure is represented as a discrete fracture network (DFN); (4) identification, computing and visualization of blocks; and (5) on the basis of Block Theory, kinematically removable blocks are identified directly on the point cloud/DTM with embedded DFN and classified according to their criticality.

The relief of an area controls factors such as drainage conditioning, thalweg and interfluve determination, watershed delimitation, and microclimate. In turn, all of these components control the rock alteration process, and origin and formation of soils. For this reason, it is necessary to observe geomorphological features of geotechnical areas of study. One of the emerging technologies in planialtimetric surveys makes use of Unmanned Aerial Systems (UAS), which provide high-resolution aerophotogrammetric surveys. This paper aims to evaluate the efficiency of UAS and obtain geomorphologic data to be used in slope stability analysis. Focusing on low cost solutions able to provide high-quality products data form the automatic flight of an Almost Ready to Fly quadcopter was evaluated and post-processed with the aim of generating a digital surface model and an orthophoto. The 3-dimensional slope stability analysis was performed using SoilVision’s SVSlope software, with geotechnical features obtained from physic and mechanic laboratory tests and topographic data from high-resolution digital surface model generated from UAS flight data. It was observed that UAS were effective for the slope stability analysis, since besides providing high-resolution topography, it proved to be a low-cost tool for periodic data acquisition, used to monitor slope failure and validate predicted slope deformations.

Geomatic techniques based on digital images have become a very useful tool for landslide monitoring, quantifying landslide movements over a long period of time. One of these techniques is based on digital image correlation. Digital image correlation estimates 2D displacements by means of statistical techniques, automatically matching identical points in the two digital images. It may be applied using remote sensing or aerial images. Digital image correlation has been applied to multi-temporal aerial photographs at the Cerro Gordo landslide (Granada, Spain) which is badly affecting an urbanized area. This landslide consists of a main deep slide and several minor shallow slides, located around the head scarp or affecting some parts of the main landslide body. Slides involve existing landfills used for urban works as well as in situ materials (colluvial deposits and weathered schists). The period under study (2002–2010) has been divided into four subperiods of approximately two years each. Results provide horizontal displacement in the landslide area and surroundings which allow to assess the landslide movement evolution at different stages according to triggering factors and structural measures that were carried out to stabilize the affected area. Over the period of 2002–2004, displacement rates varied from 2 to 6 cm, meanwhile for the periods of 2004–2006 and 2006–2008 displacements continued with 4–6 cm rates. Then, the period of 2008–2010 generally shows a higher activity with more areas showing 6 cm displacement rates. Surface observations of these periods go along with both location and direction of displacements as shown by the results of digital image correlation techniques. Image correlation results have provided very useful information to understand the complex movements of the landslide as well as the effectiveness of the structural measures implemented.

Following the heavy snowfalls in the central and southern Italy at the end of winter 2017, the reactivation of many landslides in the Apennines area was observed. Some of them had already been subject to several seismic events, with main shocks on 08/24/2016 (M6.0) and 10/26/2016 (M5.9). This paper shows preliminary results concerning the Ponzano landslide activity (Civitella del Tronto—Italy), located in the central Italy at about 40 km from the 2016 main earthquakes areas. This landslide reactivated in the last days of February 2017 with displacements of more than 8 meters in the first few days, probably due to the fast snowmelt (about 1.2 m snowpack, accumulated in the middle of January). In accordance with the Department of Civil Protection, different monitoring systems have been foreseen in order to describe the behavior of the landslide and to monitor the oldest part of the village. To reach these goals, a near-real time monitoring approach was implemented by means of a robotized total station. Additionally, a series of UAV aerial surveys for a multi-temporal site analysis were accomplished. The first approach allowed to perform a continuous displacement monitoring (frequency of measurements 0.5 h ÷ 2 h) and to detect landslide movements due to spring rainfalls. The second one allowed us to perform a rapid mapping of the area immediately after the main reactivation, and its evolution after a few months. Thanks to a modular fixed wing multisensor UAV recently developed in our institute, it was possible to perform a survey using optical and multispectral sensors. In this work, we present the results obtained by both systems, and we describe how they can be used in the emergency scenarios and in subsequent landslide management phases.

Discontinuity analyses along rock slopes become more and more important due to increasing safety requirements, especially for steep slopes like in quarries. The focus of this work is to determine quantitative discontinuity parameters such as orientation, persistence, and spacing, in relation to the slope orientation. In applied projects, the question for an optimized workflow in terms of discontinuity evaluation often arises. An integral approach of discontinuity set extraction can be provided by the combination of the following methods: 1. a quantitative manual recording of discontinuities (scanline sampling), 2. a semi-automatic technique (stereo-photogrammetry with the software ShapeMetrix3D), and 3. an evaluation applying an automatized algorithm to the point cloud data obtained by terrestrial laser scanning (TLS). These methods are applied at several quarries located in Variscan granitoids in the southwestern part of the Bavarian Forest (Germany). This contribution aims to discuss the possibilities and limitations of each method for discontinuity set evaluation in the context of applied failure analysis. Knowing geological structure will help us to determine the geomechanical behavior of the rock mass comprehensively, objectively, and reproducibly in further research, as well as to save resources and time.

Three major Holocene rock avalanches have sculpted the morphology of Mount Pletzachkogel (Tyrol, Austria), and rock fall processes continue to show recent activity. Coalescing sets of discontinuities and block moulds exposed in the steep and rugged limestone cliffs exemplify the broad spectrum of rotational and translational block failure modes to which the mountain is prone. As personnel safety concerns strongly limit the ability to access the 200 m high rock cliffs to make traditional structural field measurements, Unmanned Aerial Vehicle (UAV) photogrammetric surveys were performed with a compact portable multicopter. The UAV survey provided a georeferenced point cloud and Digital Terrain Model of sufficient resolution and accuracy to permit efficient extraction of structural geologic measurements by using different open source software packages. This research focuses on comparing discontinuity measurements extracted from the point cloud using manual, semi-automated, and automated techniques, to field measurements made with a geologic compass. The overall workflow of digital image processing and related structural measurement extraction is described, together with data validation procedures. The workflow described herein provides an efficient means for obtaining comprehensive and accurate data sets that mitigate personnel access constraints, are fully auditable and archivable. With increased applications of UAVs for geologic mapping and documentation, such procedures are sure to see rapidly increasing deployment, particularly in alpine terrain.