High-resolution Photogrammetry Research Articles

Lithostructural Control in the Development of Potholes in the Rock Bed of the Carnaúba River, Seridó Geopark, NE Brazil

Granitic forms resulting from turbulent flow, with hydraulic vortices, characterize the rocky bed of the lower course of the Carnaúba River, in a geosite of the Seridó Geopark, in the Seridó Oriental microregion, Northeast Brazil. These forms constitute a variety of types of potholes that individually represent various stages of evolution, in addition to reflecting the variation in the erosive potential of river flow throughout the Quaternary. From a bibliographical review, fieldwork (quantification and measurements of the potholes), high-resolution photogrammetry and morphostructural analysis of the generated cartographic products, it was possible to establish a correlation between the preferential orientation of the potholes and the direction of the planes of weakness, as well as the classification of potholes by morphometric parameters. In this work it was demonstrated that the efficiency of hydraulic vortices is associated with discontinuity structures and the mineralogical composition of granite facies, with abrasive erosion being responsible for sculpting potholes, with different dimensions and geometries. In the rocky bed of the Carnaúba River, the small potholes deepen and their diameter evolves into cylindrical shapes as the turbulent vertical flow increases, eventually becoming sigmoidal. The lateral potholes, located on the walls of the river channel, are deeper than they are wide, and represent a destructive phase of evolution.

Rockfall Analysis from UAV-Based Photogrammetry and 3D Models of a Cliff Area

The application of Unmanned Aerial Vehicles (UAVs), commonly known as drones, in geological, geomorphological, and geotechnical studies has gained significant attention due to their versatility and capability to capture high-resolution data from challenging terrains. This research uses drone-based high-resolution photogrammetry to assess the geomechanical properties and rockfall potential of several rock scarps within a wide area of 50 ha. Traditional methods for evaluating geomechanical parameters on rock scarps involve time-consuming field surveys and measurements, which can be hazardous in steep and rugged environments. By contrast, drone photogrammetry offers a safer and more efficient approach, allowing for the creation of detailed 3D models of a cliff area. These models provide valuable insights into the topography, geological structures, and potential failure mechanisms. This research processed the acquired drone imagery using advanced geospatial software to generate accurate orthophotos and digital elevation models. These outputs analysed the key factors contributing to rockfall triggering, including identifying discontinuities, joint orientations, kinematic analysis of failures, and fracturing frequency. More than 8.9 × 107 facets, representing discontinuity planes, were recognised and analysed for the kinematic failure modes, showing that direct toppling is the most abundant rockfall type, followed by planar sliding and flexural toppling. Three different fracturation grades were also identified based on the number of planar facets recognised on rock surfaces. The approach used in this research contributes to the ongoing development of fast, practical, low-cost, and non-invasive techniques for geomechanical assessment on vertical rock scarps. In particular, the results show the effectiveness of drone-based photogrammetry for rapidly collecting comprehensive geomechanical data valid to recognise the prone areas to rockfalls in vast regions.

High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces

Photogrammetry, reconstructing three-dimensional (3D) models from overlapping two-dimensional (2D) photos, finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects, for example rock fractures. Fracture properties are important for determining the mechanical stability, permeability, strength, and shear behavior of the rock mass. Photogrammetry can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture, which controls the fluid flow, hydromechanical and shear behavior of the rock mass. This research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface. A workflow has been developed to define the physical aperture of a fracture using photogrammetry. Three blocks of Kuru granite (25 cm × 25 cm × 10 cm) with an artificially induced fracture, were investigated. For scaling 3D models, 321 markers were used as ground control points (GCPs) with predefined distances on each block. When the samples were well-matched in their original positions, the entire block was photographed. Coordinate data of the GCPs were extracted from the 3D model of the blocks. Each half was surveyed separately and georeferenced by GCPs and merged into the same coordinate system. Two fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical aperture. Accuracy assessment of the photogrammetric reconstruction showed a 20–30 μm digital control distance accuracy when compared to known distances defined between markers. To attain this accuracy, the study found that at least 200 scale bars were required. Furthermore, photogrammetry was employed to measure changes in aperture under normal stresses. The results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers (LVDTs), with differences ranging from 1 μm to 8 μm.

Fotogrametria de um icnofóssil escavado por preguiças-gigantes (Megaichnus major)

Photogrammetry of an excavated ichnofossil by giant sloths (Megaichnus major). During the Pliocene and Pleistocene, the extinct giant mammals that lived in South America had the burrowing behavior that, in the search for shelter and refuge, produced large ichnofossils called Megaichnus (paleoburrows). Megaichnus are biogenic structures in the form of tunnels and halls excavated by Folivora (Megaichnus major) and Cingulata (Megaichnus minor). On the ceiling and walls of these paleoburrows, it is possible to observe traces of excavation of these animals. Photogrammetry was performed by imaging M. major to generate the Three-Dimensional Digital Model (3DM). The paleoburrow is located in the Municipality of Doutor Pedrinho (Santa Catarina State) and was excavated in the sandstone of the Taciba Formation (Permian). The photographs were processed to generate the 3DM and the virtual reality interface with 3D glasses. The 3DMs are available for viewing on the Sketchfab website through the links (GoPro 4; https://skfb.ly/6RYyn) and (Nikon D60; https://skfb.ly/ooprJ). 3DM allows easy access to the ichnofossils, making it possible to study them remotely from anywhere in the world. The construction of 3DMs of the paleoburrows, through high-resolution photogrammetry, is an innovative proposal, and allows wide dissemination of knowledge about these structures. Keywords: paleoburrows, Quaternary, megafauna, 3D imaging.

Fantastic Marine Creatures From the Late Renaissance: Pietro Tacca’s fountains in Florence’s Piazza della Santissima Annunziata

In the 1550s Florence’s water supply was upgraded through the construction of a new aqueduct. Prior to that, water needs were supported by the remnants of a Roman aqueduct and by wells and cisterns. The new infrastructure increased the amount of available water and allowed for the construction of fountains in the city’s main squares, with themes principally derived from Greek and Roman mythologies. In 1641 the twin Mostri Marini (‘Marine Monsters’) fountains designed by Pietro Tacca were installed in the Piazza dellaSantissima Annunziata. The bronze and stone statues presented fantasy creatures whose flexuous shapes suggested moving fluid. But while these statues complemented the square, they were not originally planned for the location, having been intended for placement in the main Tuscan harbour town of Livorno. This study draws on high-resolution photogrammetry to analyse the structures with this specific digital survey being presented for the first time.

Relaunching the TY tracksite: tridactyl dinosaur footprints from the Lower Jurassic of southern Africa

ABSTRACT Comprising more than 350 dinosaur footprints and at least 38 trackways, the TY tracksite described herein is located close to the border of NW Lesotho, near Teyateyaneng (TY), and is probably identical to the site originally mentioned by Dornan in 1908. The tridactyl footprints are exposed as natural casts on a cliff overhang and a fallen block at the base of the cliff in the uppermost Elliot Formation (Sinemurian, Lower Jurassic). High-resolution photogrammetry and zoom lenses facilitated the detailed ichnological documentation of the otherwise inaccessible overhang. The tracks vary greatly in morphology, likely due to moisture fluctuations in the tracking surface during their formation. Repeated wetting and drying of the track-bearing sediment is indicated by the cross-cutting relationship of the several generations of desiccation cracks and tracks. Two footprint size classes can be distinguished, with the smaller class being Grallator-like and the larger class being assignable to Eubrontes. All tracks are likely attributable to bipedal, small to moderately large theropod dinosaurs that roamed the drylands of the region c. 190 million years ago. Our ichnological account turns this aesthetic TY footprint site into an apt geoheritage destination with scientific and educational value for all.

Inferred oviraptorosaur footprints in the Apenninic Carbonate Platform: New tools for the identification of trackmakers from the Sezze ichnosite (lower-middle Cenomanian; central Italy)

Herein we apply a new approach to the study of theropod footprints with elongated metatarsal traces from the Upper Cretaceous (lower-middle Cenomanian) Sezze ichnosite (Latium, central Italy). In this study, we combine traditional methods and new tools (i.e., close-range digital photogrammetry, sUAS – small Unmanned Aerial System, Principal Component Analysis, and Cluster Analysis) to identify the osteological features of the foot mirrored in the traces, analyse the differential depth of impressions and reconstruct the anatomical structure of the trackmaker foot. The use of close-range photogrammetry allows us to improve the ichnological interpretation and analysis, focusing on anatomical features such as phalangeal pads and claw traces. A dataset consisting of measurements of 66 foot skeletons of theropods and the five best preserved elongated footprints with metatarsal trace was subjected to Principal Component Analysis and Cluster Analysis, to investigate the morphospace occupied by the principal clade of theropods and find the most likely trackmaker among known taxa. The results indicate the clade of Oviraptorosauria as the more consistent producers for the Sezze theropod footprints, opening new questions about the clade dispersal and on the complex paleobiogeography of the Appenninic Carbonate Platform in the Late Cretaceous. The integrated multidisciplinary approach (high-resolution photogrammetry and morphometric analysis) confirms the utility of the new technological methodologies for the ichnological study.

The use of high-resolution photogrammetry for the survey and analysis of rock-climbing walls

Abstract. In climbing, the routes that lead through a wall are mainly represented in two-dimensional maps. These climbing maps, also called "topos," help climbers and alpinists to plan their routes and find a way through the complex structures of a vertical or partially overhanging rock face. Today, a trend towards more realistic visualization techniques can be seen, where 3D representations are used for different geometric and topographic features (Kolecka, 2012). In this paper the focus is on 3D visualization and high-resolution data capturing at rock walls. Unmanned Aerial System (UAS) - based data collection has been conducted to collect digital images that are used to generate various outputs using a photogrammetry workflow. The photogrammetric processing of digital imagery results in dense 3D point clouds, digital surface models (DSM), textured 3D models and orthophotos of the test sites. How accurately is it possible to survey a vertical rock and how high the spatial resolution of the outputs will end up being is answered in this paper. After the data collection and the photogrammetric processing, a 3D climbing guide is created to answer the question if an enhanced visualization of climbing routes can be achieved. There are certain morphological features within the rock face that play a major role in climbing. For one, the climbing holds are important for climbers to continue the movement upwards. Other important factors are the dip angle and the dip direction of different rock facets. In this thesis the 3D point cloud is clustered into different sized facets, that share the same dip angle which is the angle of the center point of a cluster to a horizontal plane and the same dip direction which is the orientation of such a facet(Thanh, 2008). Using the analysis results, an automated climbing route construction is performed.

Analysis of Depth Cameras for Proximal Sensing of Grapes.

This work investigates the performance of five depth cameras in relation to their potential for grape yield estimation. The technologies used by these cameras include structured light (Kinect V1), active infrared stereoscopy (RealSense D415), time of flight (Kinect V2 and Kinect Azure), and LiDAR (Intel L515). To evaluate their suitability for grape yield estimation, a range of factors were investigated including their performance in and out of direct sunlight, their ability to accurately measure the shape of the grapes, and their potential to facilitate counting and sizing of individual berries. The depth cameras’ performance was benchmarked using high-resolution photogrammetry scans. All the cameras except the Kinect V1 were able to operate in direct sunlight. Indoors, the RealSense D415 camera provided the most accurate depth scans of grape bunches, with a 2 mm average depth error relative to photogrammetric scans. However, its performance was reduced in direct sunlight. The time of flight and LiDAR cameras provided depth scans of grapes that had about an 8 mm depth bias. Furthermore, the individual berries manifested in the scans as pointed shape distortions. This led to an underestimation of berry sizes when applying the RANSAC sphere fitting but may help with the detection of individual berries with more advanced algorithms. Applying an opaque coating to the surface of the grapes reduced the observed distance bias and shape distortion. This indicated that these are likely caused by the cameras’ transmitted light experiencing diffused scattering within the grapes. More work is needed to investigate if this distortion can be used for enhanced measurement of grape properties such as ripeness and berry size.

Performance Assessment of Reference Modelling Methods for Defect Evaluation in Asphalt Concrete.

The deterioration of road conditions and increasing repair deficits pose challenges for the maintenance of reliable road infrastructure, and thus threaten, for example, safety and the fluent flow of traffic. Improved and more efficient procedures for maintenance are required, and these require improved knowledge of road conditions, i.e., improved data. Three-dimensional mapping presents possibilities for large-scale collection of data on road surfaces and automatic evaluation of maintenance needs. However, the development and, specifically, evaluation of large-scale mobile methods requires reliable references. To evaluate possibilities for close-range, static, high-resolution, three-dimensional measurement of road surfaces for reference use, three measurement methods and five instrumentations are investigated: terrestrial laser scanning (TLS, Leica RTC360), photogrammetry using high-resolution professional-grade cameras (Nikon D800 and D810E), photogrammetry using an industrial camera (FLIR Grasshopper GS3-U3-120S6C-C), and structured-light handheld scanners Artec Leo and Faro Freestyle. High-resolution photogrammetry is established as reference based on laboratory measurements and point density. The instrumentations are compared against one another using cross-sections, point–point distances, and ability to obtain key metrics of defects, and a qualitative assessment of the processing procedures for each is carried out. It is found that photogrammetric models provide the highest resolutions (10–50 million points per m2) and photogrammetric and TLS approaches perform robustly in precision with consistent sub-millimeter offsets relative to one another, while handheld scanners perform relatively inconsistently. A discussion on the practical implications of using each of the examined instrumentations is presented.

Reassessing classic evidence for warm-based Cryogenian ice on the western Laurentian margin: The “striated pavement” of the Mineral Fork Formation, USA

Determining the extent and nature of ancient glacial deposits is fundamental to understanding Earth’s climate in the Cryogenian Period. Although the detailed study of sedimentary facies has allowed significant insights, it typically fails to produce high confidence interpretations for the past position of grounded ice, its thermal regime and flow direction, which are of fundamental importance to any glaciological reconstruction. When correctly identified, Cryogenian subglacially striated surfaces (pavements) unequivocally indicate grounded ice, a warm-based thermal regime and flow direction. However, they are globally rare and open to misinterpretation. Despite a discontinuous belt of Cryogenian strata, stretching thousands of kilometres from Alaska to California, the only purported Cryogenian pavements from the North American continent or the western margin of the Laurentian palaeocontinent occur in the Big Cottonwood Canyon area, Utah. We critically reappraise the only uncontested pavement from this area, presenting a detailed description derived from new high resolution photogrammetry and traditional field observations. These suggest that the purported pavement is unlikely to be a Cryogenian feature, but is instead a recent erosional phenomenon consistent with other structurally controlled features within the surrounding modern landscape. Our reinterpretation questions whether grounded Cryogenian ice reached the Utah – Idaho region and whether the lower reaches of the Mineral Fork Formation record glacially influenced deposition or non-glacial, rift-related sedimentation that transitions upwards into glacial conditions.

Lateral thermokarst patterns in permafrost peat plateaus in northern Norway

Abstract. Subarctic peatlands underlain by permafrost contain significant amounts of organic carbon. Our ability to quantify the evolution of such permafrost landscapes in numerical models is critical for providing robust predictions of the environmental and climatic changes to come. Yet, the accuracy of large-scale predictions has so far been hampered by small-scale physical processes that create a high spatial variability of thermal surface conditions, affecting the ground thermal regime and thus permafrost degradation patterns. In this regard, a better understanding of the small-scale interplay between microtopography and lateral fluxes of heat, water and snow can be achieved by field monitoring and process-based numerical modeling. Here, we quantify the topographic changes of the Šuoššjávri peat plateau (northern Norway) over a three-year period using drone-based repeat high-resolution photogrammetry. Our results show thermokarst degradation is concentrated on the edges of the plateau, representing 77 % of observed subsidence, while most of the inner plateau surface exhibits no detectable subsidence. Based on detailed investigation of eight zones of the plateau edge, we show that this edge degradation corresponds to an annual volume change of 0.13±0.07 m3 yr−1 per meter of retreating edge (orthogonal to the retreat direction). Using the CryoGrid3 land surface model, we show that these degradation patterns can be reproduced in a modeling framework that implements lateral redistribution of snow, subsurface water and heat, as well as ground subsidence due to melting of excess ice. By performing a sensitivity test for snow depths on the plateau under steady-state climate forcing, we obtain a threshold behavior for the start of edge degradation. Small snow depth variations (from 0 to 30 cm) result in highly different degradation behavior, from stability to fast degradation. For plateau snow depths in the range of field measurements, the simulated annual volume changes are broadly in agreement with the results of the drone survey. As snow depths are clearly correlated with ground surface temperatures, our results indicate that the approach can potentially be used to simulate climate-driven dynamics of edge degradation observed at our study site and other peat plateaus worldwide. Thus, the model approach represents a first step towards simulating climate-driven landscape development through thermokarst in permafrost peatlands.

Hybrid measurement techniques used to a study of historic cast iron suspension bridge

Traditional measurement techniques consist of discrete measurements and they are time-consuming. Moreover, information obtained by means of these methods is limited to over a dozen points located on the examined bridge. The latest measurement methods such as laser scanning and digital photogrammetry enable to obtain quasi-continuous surface of the tested bridge. It consists of many millions of points with known spatial coordinates. The tested structure is a historic suspension bridge in the town of Ozimek in Poland. Nowadays the bridge is intended for pedestrian traffic across Mala Panew river. It was built in 1827 and it is the oldest cast iron suspension bridge in continental Europe. In the analyzed case, the measurements were performed with the use of terrestrial laser scanning (a FARO Focus 3DX130) and high-resolution photogrammetry (Canon 650D camera with the lens of fixed focus of 85 mm and the GigaPano turntable). The obtained results indicate that the differences between the two methods are within a few millimeters, which should be considered satisfactory. The advantage of the presented measurement methods is minimizing time of fieldwork and obtaining a 3D model of the bridge with millimeter accuracy.

Assessing the spatial distribution of coral bleaching using small unmanned aerial systems

Small unmanned aerial systems (sUAS) are an affordable, effective complement to existing coral reef monitoring and assessment tools. sUAS provide repeatable low-altitude, high-resolution photogrammetry to address fundamental questions of spatial ecology and community dynamics for shallow coral reef ecosystems. Here, we qualitatively describe the use of sUAS to survey the spatial characteristics of coral cover and the distribution of coral bleaching across patch reefs in Kāneʻohe Bay, Hawaii, and address limitations and anticipated technology advancements within the field of UAS. Overlapping sub-decimeter low-altitude aerial reef imagery collected during the 2015 coral bleaching event was used to construct high-resolution reef image mosaics of coral bleaching responses on four Kāneʻohe Bay patch reefs, totaling ~ 60,000 m2. Using sUAS imagery, we determined that paled, bleached and healthy corals on all four reefs were spatially clustered. Comparative analyses of data from sUAS imagery and in situ diver surveys found as much as 14% difference in coral cover values between survey methods, depending on the size of the reef and area surveyed. When comparing the abundance of unhealthy coral (paled and bleached) between sUAS and in situ diver surveys, we found differences in cover from 1 to 49%, depending on the depth of in situ surveys, the percent of reef area covered with sUAS surveys and patchiness of the bleaching response. This study demonstrates the effective use of sUAS surveys for assessing the spatial dynamics of coral bleaching at colony-scale resolutions across entire patch reefs and evaluates the complementarity of data from both sUAS and in situ diver surveys to more accurately characterize the spatial ecology of coral communities on reef flats and slopes.

The Lusi drone: A multidisciplinary tool to access extreme environments

Extreme and inaccessible environments are a new frontier that unmanned and remotely operated vehicles can today safely access and monitor. The Lusi mud eruption (NE Java Island, Indonesia) represents one of these harsh environments that are totally unreachable with traditional techniques. Here boiling mud is constantly spewed tens of meters in height and tall gas clouds surround the 100 m wide active crater. The crater is surrounded by a ∼600 m diameter circular zone of hot mud that prevents any approach to investigate and sample the eruption site. In order to access this active crater we designed and assembled a multipurpose drone.The Lusi drone is equipped with numerous airborne devices suitable for use on board of other multicopters. During the missions, three cameras can complete 1) video survey, 2) high resolution photogrammetry of desired and preselected polygons, and 3) thermal photogrammetry surveys with infra-red camera to locate hot fluids seepage areas or faulted zones. Crater sampling and monitoring operations can be pre-planned with a flight software, and the pilot is required only for take-off and landing. A winch allows the deployment of gas, mud and water samplers and contact thermometers to be operated with no risk for the aircraft. During the winch operations (that can be performed automatically), the aircraft hovers at a safety height until the tasks controlled by the winch-embedded processor are completed. The drone is also equipped with GPS-connected CO2 and CH4 sensors. Gridded surveys using these devices allowed obtaining 2D maps of the concentration and distribution of various gasses over the area covered by the flight path.The device is solid, stable even with significant wind, affordable, and easy to transport. The Lusi drone successfully operated during several expeditions at the ongoing active Lusi eruption site and proved to be an excellent tool to study other harsh or unreachable sites, where operations with more conventional methods are too expensive, dangerous or simply impossible.

Analysis of Landslide Evolution Affecting Olive Groves Using UAV and Photogrammetric Techniques

This paper deals with the application of Unmanned Aerial Vehicles (UAV) techniques and high resolution photogrammetry to study the evolution of a landslide affecting olive groves. The last decade has seen an extensive use of UAV, a technology in clear progression in many environmental applications like landslide research. The methodology starts with the execution of UAV flights to acquire very high resolution images, which are oriented and georeferenced by means of aerial triangulation, bundle block adjustment and Structure from Motion (SfM) techniques, using ground control points (GCPs) as well as points transferred between flights. After Digital Surface Models (DSMs) and orthophotographs were obtained, both differential models and displacements at DSM check points between campaigns were calculated. Vertical and horizontal displacements in the range of a few decimeters to several meters were respectively measured. Finally, as the landslide occurred in an olive grove which presents a regular pattern, a semi-automatic approach to identifying and determining horizontal displacements between olive tree centroids was also developed. In conclusion, the study shows that landslide monitoring can be carried out with the required accuracy—in the order of 0.10 to 0.15 m—by means of the combination of non-invasive techniques such as UAV, photogrammetry and geographic information system (GIS).

Application of a sediment connectivity GIS-based index in a basin undergoing glacier retreat: the case study of the Navizence catchment

The extent of the melting from retreating glacier can largely influence sediment transport processes at basin scale, affecting significantly the downstream fluvial system. The analysis of spatial sediment transport pathways and of different contributions of the sub-catchment as sediment sources allows the evaluation of the melting impacts on the potential sediment connectivity, i.e. the degree of connection that controls sediment fluxes between different segments of a landscape, in basins undergoing glacier retreat.The goal of this first study is inferring the effect of the connectivity changes on a basin with a sediment dynamic influenced by glacial features. Achieving this task was possible thank to a topography-based model of sediment connectivity (IC, Connectivity Index), as developed by Cavalli et al. (2013), was applied to Navizence catchment in the Southern Swiss Alps to analyze new potential connectivity pattern due to the retreat of the main glacial edifice (Zinal glacier). To analyze sediment connectivity evolution, two Digital Terrain Models (DTMs) were used: a current DTM, obtained from high resolution photogrammetry (2 m), describing the terrain at the time of the survey (2010); a post-glacial DTM, derived from application of the Slope Local Base Level (SLBL) (Jaboyedoff & Derron, 2005) technique to the current DTM, describing the terrain after forty years of glacier retreat. As a proxy of the impedance to sediment fluxes, a weighting factor derived from tabled values of hydraulic roughness (Manning's n) was applied. In order to evaluate the potential evolution of sediment connectivity in a glacierized environment, future lateral moraines, that would be formed after glacial retreat, were mapped and inserted into the DTM based on expert knowledge.Qualitative analysis of the variation of the geomorphologic index suggested that the degree of sediment connectivity in Zinal glacier is a key factor in controlling the release of sediment between hillslopes and main channel. It also emphasizes the role of lateral moraines development in influencing the future sediment fluxes from the glacial zone, acting as barriers for the downward sediment transport.

New perspectives on interdisciplinary earth science at the Dead Sea: The DESERVE project

The Dead Sea region has faced substantial environmental challenges in recent decades, including water resource scarcity, ~1m annual decreases in the water level, sinkhole development, ascending-brine freshwater pollution, and seismic disturbance risks. Natural processes are significantly affected by human interference as well as by climate change and tectonic developments over the long term. To get a deep understanding of processes and their interactions, innovative scientific approaches that integrate disciplinary research and education are required. The research project DESERVE (Helmholtz Virtual Institute Dead Sea Research Venue) addresses these challenges in an interdisciplinary approach that includes geophysics, hydrology, and meteorology. The project is implemented by a consortium of scientific institutions in neighboring countries of the Dead Sea (Israel, Jordan, Palestine Territories) and participating German Helmholtz Centres (KIT, GFZ, UFZ). A new monitoring network of meteorological, hydrological, and seismic/geodynamic stations has been established, and extensive field research and numerical simulations have been undertaken. For the first time, innovative measurement and modeling techniques have been applied to the extreme conditions of the Dead Sea and its surroundings. The preliminary results show the potential of these methods. First time ever performed eddy covariance measurements give insight into the governing factors of Dead Sea evaporation. High-resolution bathymetric investigations reveal a strong correlation between submarine springs and neo-tectonic patterns. Based on detailed studies of stratigraphy and borehole information, the extension of the subsurface drainage basin of the Dead Sea is now reliably estimated. Originality has been achieved in monitoring flash floods in an arid basin at its outlet and simultaneously in tributaries, supplemented by spatio-temporal rainfall data. Low-altitude, high resolution photogrammetry, allied to satellite image analysis and to geophysical surveys (e.g. shear-wave reflections) has enabled a more detailed characterization of sinkhole morphology and temporal development and the possible subsurface controls thereon. All the above listed efforts and scientific results take place with the interdisciplinary education of young scientists. They are invited to attend joint thematic workshops and winter schools as well as to participate in field experiments.

Insights into the evolution of the Yenkahe resurgent dome (Siwi caldera, Tanna Island, Vanuatu) inferred from aerial high-resolution photogrammetry

The Yenkahe dome (Tanna Island, Vanuatu) is one of the most spectacular examples of presently active post-caldera resurgence, exhibiting a very high uplift rate over the past 1000years (156mm/year on average). Although numerous inhabited areas are scattered around the dome, the dynamics of this structure and associated hazards remain poorly studied because of its remote location and dense vegetation cover. A high-resolution photogrammetric campaign was carried out in November 2011 over the dome. Georeferenced photographs were treated by “Structure from Motion” and “Multiple-view Stereophotogrammetry” methods to produce a 3D-digital surface model (DSM) of the area and its associated orthophotograph. This DSM is much more accurate than previously available SRTM and Aster digital elevation models (DEMs), particularly at minimal (coastline) and maximal altitudes (Yasur culmination point, ~390m). While previous mapping relied mostly on low resolution DEMs and satellite images, the high precision of the DSM allows for a detailed structural analysis of the Yenkahe dome, notably based on the quantification of fault displacements. The new structural map, inferred from the 3D reconstruction and morphological analysis of the dome, reveals a complex pattern of faults and destabilization scars reflecting a succession of constructive and destructive events. Numerous landslide scars directed toward the sea highlight the probable occurrence of a tsunami event affecting the south-eastern coast of Tanna. Simulations of landslide-triggered tsunamis show the short time propagation of such a wave (1–2min), which could affect coastal localities even following relatively small destabilized volumes (a few million cubic meters).

Insights into the evolution of the Yenkahe resurgent dome (Siwi caldera, Tanna Island, Vanuatu) inferred from aerial high-resolution photogrammetry

Insights into the evolution of the Yenkahe resurgent dome (Siwi caldera, Tanna Island, Vanuatu) inferred from aerial high-resolution photogrammetry