NADIR AND OBLIQUE UAV PHOTOGRAMMETRY TECHNIQUES FOR QUANTITATIVE ROCK FALL EVALUATION IN THE RIMROCKS OF SOUTH-CENTRAL MONTANA

As our cities expand into geologically sensitive areas across the greater Rocky Mountain region and beyond, quantitative methods of assessment are increasingly critical for the development of evidence-based alternatives to avoid or mitigate geologic hazards. Unmanned Aerial Vehicle (UAV) photogrammetry can improve these geologic investigations by enabling remote visual inspection, measurement, and spatial analysis while eliminating many of the physical access limitations that contribute to field sampling bias and human error. UAV photogrammetry technology was employed to evaluate fragmental rock fall hazards at two locations in the Rimrocks region of south-central Montana, Zimmerman Trail Road and Phipps Park. At these sites, active retrogressive rock slope instability caused by differential erosion has produced damaging rock fall. Nadir and oblique imagery of the 35-acre Zimmerman Trail Road and 13-acre Phipps Park study areas was acquired with a DJI Phantom 4 Pro UAV and processed into digital photogrammetry with Pix4Dmapper. Remote methods of analysis were employed to measure the orientation of discontinuities in rock fall source areas and to quantify rock fall susceptibility. At Zimmerman Trail Road, photogrammetry data products were used to numerically differentiate rock fall hazard zones along the 0.3-mile long rock slope in accordance with the detailed Rock Fall Hazard Rating System (Pierson, 1991). At Phipps Park, photogrammetry was used to measure the size, run out distance, and change in elevation of high energy rock fall and to generate 2D and 3D slope profiles, which were used to model potential future rock fall. The methods and findings demonstrate how nadir and oblique UAV photogrammetry can be used to implement quantitative, defensible approaches for evaluating rock fall susceptibility and run out potential in geologic investigations of fragmental rock fall hazard areas

Debris-Slide Susceptibility Modelling Using GIS Technology in the Great Smoky Mountains National Park

Debris-slides are one of the most frequently occurring geological hazards in metasedimentary rocks of the Anakeesta ridge in Great Smoky Mountains National Park (GRSM), which often depends on the influence of multiple causing factors or geo-factors such as geological structures, slope, topographic elevation, land use, soil type etc. or a combination of these factors. The main objective of the study was to understand the control of geo-factors in initiating debris-slides using different knowledge and data-driven methods in GIS platform. The study was performed in three steps: (1) Evaluation of geometrical relationship between geological discontinuity and topographic orientation in initiation of debris-slides, (2) Preparation of knowledge-driven debris-slide susceptibility model, and (3) Preparation of data-driven debris-slide susceptibility models and compare their efficacy. Performance of the models were evaluated mostly using area under Receiver Operating Characteristic (ROC) curve, which revealed that the models were statistically significant

Sedimentological characterization of Antarctic moraines using UAVs and Structure-from-Motion photogrammetry

In glacial environments particle-size analysis of moraines provides insights into clast origin, transport history, depositional mechanism and processes of reworking. Traditional methods for grain-size classification are labour-intensive, physically intrusive and are limited to patch-scale (1m2) observation. We develop emerging, high-resolution ground- and unmanned aerial vehicle-based ‘Structure-from-Motion’ (UAV-SfM) photogrammetry to recover grain-size information across an moraine surface in the Heritage Range, Antarctica. SfM data products were benchmarked against equivalent datasets acquired using terrestrial laser scanning, and were found to be accurate to within 1.7 and 50mm for patch- and site-scale modelling, respectively. Grain-size distributions were obtained through digital grain classification, or ‘photo-sieving’, of patch-scale SfM orthoimagery. Photo-sieved distributions were accurate to <2mm compared to control distributions derived from dry sieving. A relationship between patch-scale median grain size and the standard deviation of local surface elevations was applied to a site-scale UAV-SfM model to facilitate upscaling and the production of a spatially continuous map of the median grain size across a 0.3 km2 area of moraine. This highly automated workflow for site scale sedimentological characterization eliminates much of the subjectivity associated with traditional methods and forms a sound basis for subsequent glaciological process interpretation and analysis

Deltaic deposits at Aeolis Dorsa: Sedimentary evidence for a standing body of water on the northern plains of Mars

A fundamental long-standing question regarding Mars history is whether the flat and low-lying northern plains ever hosted an ocean. The best opportunity to solve this problem is provided by stratigraphic observations of sedimentary deposits onlapping the crustal dichotomy. Here, we use high-resolution imagery and topography to analyze a branching network of inverted channel and channel lobe deposits in the Aeolis Dorsa region, just north of the dichotomy boundary. Observations of stacked, cross-cutting channel bodies and stratal geometries indicate that these landforms represent exhumed distributary channel deposits. Observations of depositional trunk feeder channel bodies, a lack of evidence for past topographic confinement, channel avulsions at similar elevations, and the presence of a strong break in dip slope between topset and foreset beds suggest that this distributary system was most likely a delta, rather than an alluvial fan or submarine fan. Sediment transport calculations using both measured and derived channel geometries indicate a minimum delta deposition time on the order of 400  years. The location of this delta within a thick and widespread clastic wedge abutting the crustal dichotomy boundary, unconfined by any observable craters, suggests a standing body of water potentially 105 km2 in extent or greater and is spatially consistent with hypotheses for a northern ocean

Rock fractures analysis using Structure from Motion technology: new insight from Digital Outcrop Models

Fractures are one of the most important features of the rocks of the upper crust since they strongly influence their physical and chemical behavior and reflect their tectonic history. For this reason, fracture study plays a key role in different branches of the geosciences. Notwithstanding, the quantification of the features and parameters describing fractures could be unsatisfactory using the standard field techniques because they are mainly based on direct-contact methodologies that are affected by errors, as orientation bias and trace censoring, and scarce representativeness, due to the limited possibility of acquiring information of outcrops partially or totally inaccessible. Recently new remote sensing technologies, such as Terrestrial Laser Scanner (TLS) and Digital Photogrammetry (DP), can help to overcome these limitations. Whereas TLS could be very expensive and difficult to use in geological study, DP permits to obtain similar results in an easier way due to cheaper and lighter equipment and more straightforward procedures. Moreover, DP becomes even more useful when combined with Unmanned Aerial Vehicle (UAV) because permits to acquire digital images from positions inaccessible to humans, allowing to analyze geological objects from points of view previously unimaginable. The images acquired from the ground and/or by the UAV can be then processed using different digital algorithms, such as Structure from Motion (SfM), that permit to create 3D model of the studied outcrop. In geosciences, the 3D model representing the surface of the outcrop is often called Digital Outcrop Model (DOM). Despite DOMs can be really useful in different branches of geosciences, their applications are quite well limited because the procedures of their development and sampling/analysis are scarcely analyzed in literature. It is important to highlight that whereas the UAV-based SfM approach is fairly discussed in literature for simple flat areas, is scarcely treated for application to near vertical and not-planar slopes. Moreover, the validity of some procedures of fracture sampling on 3D model, with special regards to the automatic ones, that have been recently presented in literature, is not well treated for real cases of study. The scarce knowledge about these approaches could cause different troubles to the scientific-users: from the application of avoidable time-consuming routine, to the acquisition and interpretation of erroneous data. This research aims to contribute to the scientific knowledge of the use of digital photogrammetry for fractured rock mass analysis, creating and defining new approaches and procedures for the development, analysis and application of DOMs. Here, a workflow for the fracture analysis of steep rocky outcrops and slopes using the 3D DOM is presented. In particular, the following steps are discussed: (i) image acquisition; (ii) development of 3D model; (iii) sampling of DOM; (iv) quantification and parametrization of the 3D measures; (v) application of the 3D quantitative data and parameters to different case of study. Four different cases of study were selected to validate the proposed method: the upper Staffora Valley and Ponte Organasco (Northern Apennines, Italy), Ormea (Ligurian Alps, Italy), and Gallivaggio (Western Alps, Italy) cases of study. However, this methodology could not completely replace the 'direct-contact' field activity, because some information as roughness, infilling and aperture of fractures cannot be measured satisfactory, and because, where possible, field control measures to validate the 3D data are necessary. However, this methodology could be considered as a new necessary procedure for rock-fracture studies because it allows to overcome the inevitable errors of the ground-based traditional methodology and because the DOMs are always available for the analysis, promoting data sharing and comparison, two fundamental principles on which science have and will have to be basedFractures are one of the most important features of the rocks of the upper crust since they strongly influence their physical and chemical behavior and reflect their tectonic history. For this reason, fracture study plays a key role in different branches of the geosciences. Notwithstanding, the quantification of the features and parameters describing fractures could be unsatisfactory using the standard field techniques because they are mainly based on direct-contact methodologies that are affected by errors, as orientation bias and trace censoring, and scarce representativeness, due to the limited possibility of acquiring information of outcrops partially or totally inaccessible. Recently new remote sensing technologies, such as Terrestrial Laser Scanner (TLS) and Digital Photogrammetry (DP), can help to overcome these limitations. Whereas TLS could be very expensive and difficult to use in geological study, DP permits to obtain similar results in an easier way due to cheaper and lighter equipment and more straightforward procedures. Moreover, DP becomes even more useful when combined with Unmanned Aerial Vehicle (UAV) because permits to acquire digital images from positions inaccessible to humans, allowing to analyze geological objects from points of view previously unimaginable. The images acquired from the ground and/or by the UAV can be then processed using different digital algorithms, such as Structure from Motion (SfM), that permit to create 3D model of the studied outcrop. In geosciences, the 3D model representing the surface of the outcrop is often called Digital Outcrop Model (DOM). Despite DOMs can be really useful in different branches of geosciences, their applications are quite well limited because the procedures of their development and sampling/analysis are scarcely analyzed in literature. It is important to highlight that whereas the UAV-based SfM approach is fairly discussed in literature for simple flat areas, is scarcely treated for application to near vertical and not-planar slopes. Moreover, the validity of some procedures of fracture sampling on 3D model, with special regards to the automatic ones, that have been recently presented in literature, is not well treated for real cases of study. The scarce knowledge about these approaches could cause different troubles to the scientific-users: from the application of avoidable time-consuming routine, to the acquisition and interpretation of erroneous data. This research aims to contribute to the scientific knowledge of the use of digital photogrammetry for fractured rock mass analysis, creating and defining new approaches and procedures for the development, analysis and application of DOMs. Here, a workflow for the fracture analysis of steep rocky outcrops and slopes using the 3D DOM is presented. In particular, the following steps are discussed: (i) image acquisition; (ii) development of 3D model; (iii) sampling of DOM; (iv) quantification and parametrization of the 3D measures; (v) application of the 3D quantitative data and parameters to different case of study. Four different cases of study were selected to validate the proposed method: the upper Staffora Valley and Ponte Organasco (Northern Apennines, Italy), Ormea (Ligurian Alps, Italy), and Gallivaggio (Western Alps, Italy) cases of study. However, this methodology could not completely replace the 'direct-contact' field activity, because some information as roughness, infilling and aperture of fractures cannot be measured satisfactory, and because, where possible, field control measures to validate the 3D data are necessary. However, this methodology could be considered as a new necessary procedure for rock-fracture studies because it allows to overcome the inevitable errors of the ground-based traditional methodology and because the DOMs are always available for the analysis, promoting data sharing and comparison, two fundamental principles on which science have and will have to be base

SEQUENCE STRATIGRAPHIC CONTROLS ON RESERVOIR-SCALE MECHANICAL STRATIGRAPHY OF SHALLOW-WATER CARBONATES

Studies on mechanical stratigraphy of shallow-water carbonates have shown that the distribution of fractures can be controlled by depositional facies, sedimentary cycles/sequences, and diagenesis. Understanding the role of these sedimentary controls is therefore crucial in the characterization of matrix-tight reservoirs, where fractures may represent the main conduits for fluid flow. Nonetheless, the relation between fracture distribution and sedimentary controls is not always investigated at scales that are relevant to reservoir and fluid-flow characterization. In this dissertation, is provided a solution to this problem by integrating sequence stratigraphic analysis with the multi-scale fracture characterization of two carbonate platform exposures outcropping in the Sorrento Peninsula (southern Italy). These outcrops represent the surface analogue of subsurface hydrocarbon reservoirs of the Basilicata region (southern Italy), and consist of nearly vertical cliffs (hundreds of meters wide and high) exposing shallow-water limestones and dolostones, crossed by several sub-vertical fractures ranging in height from few centimetres up to few tens of metres. Due to the partial inaccessibility of this cliff, field measures have been combined with remote sensing on virtual outcrop models. The study allowed to identify the key control exerted by sedimentary sequences on the thickness of mechanical units and the position of their boundaries, which implies that sequence stratigraphy can be used to predict the distribution of large-scale fractures. The applicability of this concept has been tested on a subsurface dataset from the Basilicata region. Performing a sequence stratigraphic analysis on image logs calibrated with core data, the main mechanical boundaries were predicted in a portion of fractured stratigraphic units. The thickness of predicted mechanical units showed a clear relation to the distribution of fractures. Indeed, in the investigated stratigraphic interval, an increase in the mean thickness of mechanical units corresponds to an increase in the mean spacing of fractures, of a comparable order of a magnitude. The main outcome of this study is the proposal of a new approach to estimate large-scale fracture intensity in carbonate reservoirs, based on the evaluation of the thickness of mechanical units through sequence stratigraphy

Increasing geotechnical data confidence through the Integration of laser scanner face mapping data into the Sishen iron ore mine geotechnical database

A research report submitted in partial fulfilment of the requirements for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Mining Engineering at the University of the Witwatersrand, Johannesburg, 2018Face mapping is a simple but invaluable means of geological and geotechnical data acquisition whereby intact rock properties, rock mass properties, discontinuity properties and structural orientation can be assessed. Although traditionally done via direct contact with the mapping face through techniques such as line mapping or window mapping, remote face mapping using various digital techniques has become increasingly popular in recent years. Sishen Mine is a large open pit mining operation requiring a comprehensive geotechnical data set to evaluate pit wall design and stability with the necessary level of confidence. Geotechnical borehole data, face mapping data, geotechnical lab testing data and implicit structural models provide the main sources of this information. Although a large geotechnical borehole database has always been maintained at the mine, face mapping has in the past been restricted to sporadic and isolated stability assessments. In 2013 the mine acquired a Maptek 8810 terrestrial laser scanner with the resolution, photographic capabilities and software required to carry out geotechnical face mapping. The aims of this research project were to evaluate the capabilities of the Maptek scanner and system, set up a standard face mapping procedure, integrate face mapping data in the mine’s geotechnical database and compare face mapping acquired rock mass data with the mine’s existing borehole data set. Further potential uses for the laser scanner system and face mapping data were also explored throughout the course of the dissertation. A face mapping procedure was set up and faces were mapped from 86 individual scans, acquired between October 2015 and April 2017. The mapping data obtained from the scans was integrated into the Acquire Geological Data Management System, a purpose designed Structured Query Language (SQL) database system used for storing the mine’s geotechnical data. Open Database Connectivity (ODBC) database links with the Micromine Computer Aided Design (CAD) package allowed for spatial overlays of mapping data with other geotechnical data as well as survey and mine planning data. In terms of data analysis mapping parameters such as joint spacing, Rock Quality Designation and Rock Mass Rating could be directly compared with borehole logging values for the same rock types. The comparison indicated that in general borehole measurements tend to slightly under estimate joint spacing and rock mass rating values while face mapping assessments tend to slightly over estimate these values. This is due to various intricacies of the two data capture techniques that tend to skew the data in one way or the other. Face mapping data was compared with Sishen’s existing structural model, which is based mainly on interpretation and implicit data. Structural orientations and features correlate well between the implicit model and actual mapped values gathered during the data collection phase of this project. Within the geotechnical design process, having actual mapping data in combination with increased confidence in the structural model allows for better definition of geotechnical design sectors. Overall the face mapping and geotechnical analysis features of the Maptek 8810 terrestrial laser scanner make it an invaluable geotechnical data capture tool, providing a system is in place to store mapping data in a manner that allows for meaningful rock mass and structural information to be produced.XL201

Regional Structural Orientation of the Mount Sharp Group Revealed by In Situ Dip Measurements and Stratigraphic Correlations on the Vera Rubin Ridge

Ground‐based bedding orientation measurements are critical to determine the geologic history and processes of sedimentation in Gale crater, Mars. We constrain the dip of lacustrine strata of the Blunts Point, Pettegrove Point, and Jura members of the Murray formation using a combination of regional stratigraphic correlations and bed attitude measurements from stereo Mastcam images taken by the Mars Science Laboratory Curiosity rover. In situ bed attitude measurements using a principal component analysis‐based regression method reveal a wide range of dips and dip azimuths owing to a combination of high stereo errors, postdepositional deformation of strata (e.g., fracturing, rotation, and impact cratering), and different primary depositional dips. These constrain regional dips to be within several degrees of horizontal on average. Stratigraphic correlations between targets observed in the Glen Torridon trough and at the Pettegrove Point‐Jura member contact of Vera Rubin ridge (VRR) constrain dips to be between 3°SE and 2°NW, consistent with nearly flat strata deposited horizontally on an equipotential surface. The Jura member is determined to be stratigraphically equivalent to the northern portion of the Glen Torridon trough. Rover‐based dip magnitudes are generally significantly shallower than the orientation of VRR member contacts measured from High Resolution Imaging Science Experiment‐based traces, suggesting the sedimentary strata and VRR member contacts may be discordant

Integration of drone data and field investigations to investigate avalanche potential in steep cliffs, with examples from Western Norway

Masteroppgave i geovitenskapGEOV399MAMN-GEO