Geohazard Risk Research Articles

Risk assessment of geohazards along Cheng-Kun railway using fuzzy AHP incorporated into GIS

This article presents a case study on the risk assessment of geohazards along Cheng-Kun railway line. Cheng-Kun railway passes through a region of highly varied elevation and faults and the operation of Cheng-Kun railway has been frequently interrupted owing to geological disasters. A hybrid method via integrating triangular fuzzy number (TFN) and the analytic hierarchy process (AHP) (here after simply call TFN-AHP) into a geographic information system (GIS) is employed in this study to perform the geohazards assessment. The assessment results showed that TFN-AHP with GIS can effectively predict the distribution of geohazards risk in the study region within the last 10 years. The results also showed that the TFN-AHP method is more efficient in identifying high-risk areas compared with using original AHP. Based on the assessment results, prospective management measures to prevent risk are recommended.

Radar Remote Sensing to Supplement Pipeline Surveillance Programs through Measurements of Surface Deformations and Identification of Geohazard Risks

This research focused on the quantitative assessment of the surface deformation velocities and rates and their natural and man-made controlling factors as the potential risks along the seismically active 70 km section of buried oil and gas pipeline in Azerbaijan using Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) and Small Baseline Subset (SBAS) remote sensing analysis. Both techniques showed that the continuous subsidence was prevailing in the kilometer range of 13–70 of pipelines crossing two seismic faults. The ground uplift deformations were observed in the pipeline kilometer range of 0–13. Although both PS-InSAR and SBAS measurements were highly consistent in deformation patterns and trends along pipelines, they showed differences in the spatial distribution of ground deformation classes and noisiness of produced results. High dispersion of PS-InSAR measurements caused low regression coefficients with SBAS for the entire pipeline kilometer range of 0–70. SBAS showed better performance than PS-InSAR along buried petroleum and gas pipelines in the following aspects: the complete coverage of the measured points, significantly lower dispersion of the results, continuous and realistic measurements and higher accuracy of ground deformation rates against the GPS historical measurements. As a primary factor of ground deformations, the influence of tectonic movements was observed in the wide scale analysis along 70 km long and 10 km wide section of petroleum and gas pipelines; however, the largest subsidence rates were observed in the areas of agricultural activities which accelerate the deformation rates caused by the tectonic processes. The diverse spatial distribution and variation of ground movement processes along pipelines demonstrated that general geological and geotechnical understanding of the study area is not sufficient to find and mitigate all the critical sites of subsidence and uplifts for the pipeline operators. This means that both techniques outlined in this paper provide a significant improvement for ground deformation monitoring or can significantly contribute to the assessment of geohazards and preventative countermeasures along petroleum and gas pipelines.

Assessing the Economic Risk of Building Damage due to the Tunneling-Induced Settlement Using Monte Carlo Simulations and BIM

Due to the increasing use of underground space to align with sustainability needs, geohazard risk assessments have become a valuable tool for decision-making. One common issue in relation to urban geohazard assessments relates to ground movements due to tunneling affecting adjacent buildings. A framework for assessing costs related to subsequent building damage, using integrated data, statistics and considering the uncertainties involved, is presented in this paper. The proposed methodology provides an integration of Monte Carlo simulations to support uncertainty estimations with an analysis for building-damage cost risk due to tunneling-induced settlements. The analysis involves analytical models using green-field conditions and a typically used building damage assessment method. BIM is capable of collating, combining and visualizing information with advanced analysis techniques into a risk-based tool. The resulting tool provides a clear way of assessing building-damage costs risk due to tunneling-induced settlements. This uses a BIM-based environment and incorporates 3D visualizations and an integrated analysis via MATLAB to reveal and highlight hazardous areas and the severity of economic risk along the tunneling route. This informs the need for additional ground investigations or secondary analyses to ensure engineering processes reduce or remove the risk of economic damage and advance sustainable decision-making.

MAPPING AND MONITORING GROUND INSTABILITIES WITH SENTINEL-1 DATA: THE EXPERIENCE OF SERNAGEOMIN

Abstract. The application of Satellite Differential SAR interferometry (DInSAR) has become a reliable solution as a tool for mapping and monitoring geohazards. Few years ago, the main applications of these techniques were devoted to science. However, nowadays, the easy access to SAR imagery and the maturity of the techniques to exploit these type of data has widened the user’s spectrum from only scientists to professional and decision makers. The advent of Sentinel-1 satellites has significantly contributed to this achievement. In particular, in the field of geohazard risk management, Sentinel-1 has solved one of the main constraining factors that hindered the operational use of interferometric techniques in the past: the lack of systematic acquisition plans. In this context, Sentinel-1 assures worldwide coverage with short temporal baselines (6 to 24 days). This has supposed a definitive step towards the implementation of DInSAR based techniques to support decision makers against geohazards. In this work, we show the first experiences of the remote sensing unit of the Geological and Mining Survey of Chile (Sernageomin) with Sentinel-1 data. Three different case studies in different areas of the Chilean territory are presented. The examples illustrate how DInSAR based techniques can provide different levels of information about geohazard activity in different environments.

Detection of Cover Collapse Doline and Other Epikarst Features by Multiple Geophysical Techniques, Case Study of Tarimba Cave, Brazil

Reliable characterization of the karst system is essential for risk assessment where many associated hazards (e.g., cover-collapse dolines and groundwater pollution) can affect natural and built environments, threatening public safety. The use of multiple geophysical approaches may offer an improved way to investigate such cover-collapse sinkholes and aid in geohazard risk assessments. In this paper, covered karst, which has two types of shallow caves (vadose and fluvial) located in Tarimba (Goias, Brazil), was investigated using various geophysical methods to evaluate their efficiency in the delineation of the geometry of sediments filled sinkhole. The methods used for the investigation were Electrical Resistivity Tomography (ERT), Seismic Refraction Survey (SRS), Seismic Refraction Tomography (SRT) and the Very Low Frequency Electromagnetic (VLF-EM) method. The study developed several (2D) sections of the measured physical properties, including P-wave velocity and electrical resistivity, as well as the induced current (because of local bodies). For the analysis and processing of the data obtained from these methods, the following approaches were adopted: ERT inversion using a least-square scheme, Karous-Hjelt filter for VLF-EM data and time-distance curves and Vp cross-sections for the SRS. The refraction data analysis showed three-layered stratigraphy topsoil, claystone and carbonate bedrock, respectively. The findings obtained from ERT (three-layered stratigraphy and sediment-filled doline), as well as VLF-EM (fractured or filled caves as a positive anomaly), were found to be consistent with the actual field conditions. However, the SRS and SRT methods did not show the collapsed material and reached the limited the depth because of shorter profile lengths. The study provides a reasonable basis for the development of an integrated geophysical approach for site characterization of karst systems, particularly the perched tank and collapse doline.

Influence of the initial CH4-hydrate system properties on CO2 capture kinetics

Recovering methane from natural gas hydrate deposits using carbon dioxide injection is currently of great environmental and energetic interest as it shows potential for producing an energy resource while mitigating CO2 emissions through CO2 sequestration. This work investigates the exchange kinetic between CH4 and CO2 (or CO2-N2(v)) in synthetic hydrates, with an emphasis on the impact of CH4 hydrate formation conditions (e.g. driving force Δp) on the subsequent exchange reactions. Different driving forces Δp are utilized and show that the exchange kinetic is improved by a factor of ~3 when the exchange is performed with low Δp CH4 hydrates, for which there is a higher relative amount of free H2O(liq) (277 K); the kinetic is further improved when stirring is applied. Isobaric CH4 hydrates exhibit a fast primary hydrate dissociation and CH4 release, followed by a slower exchange kinetic, possibly limited by solid-state exchange diffusion or secondary CO2-rich hydrate formation within the stability field of CH4 hydrates. Upon exposure to a mixed CO2-N2(v) gas stream, secondary hydrate production is governed by the effective Δp remaining after dissolution of the gas mixture, and results in an even slower exchange reaction rate. These results may help optimizing recovery processes in field trial experiments, where both hydrates and liquid water coexist, and aid in predicting the risk of geo-hazards induced by unstable secondary hydrate formation. Furthermore, the exchange kinetic dependencies highlighted here are important as they affect the overall energy efficiency and energy cost of CH4 recovery processes in gas hydrate field trials.

The development of China national geohazard information system

Geohazards caused significant damages to people and economical properties. The prevention and mitigation of geohazards in China is facing great challenges. To solve the problem, establishing a national geohazard information system is important in accessing the distribution of geohazards, optimizing the efforts of prevention and mitigation, and improving the public awareness and risk reduction capabilities. After two decades’ of development, China national geohazard information system have upgraded from client-server (C/S) to browser-server (BS) architecture, and now to the micro-service based architecture, more than 320 thousands of geohazards which were mainly collected through field surveys and the routine field inspections have been saved in the database; through the information system, data acquisition and integration, classified storage, efficient data processing, real-time statistics and data services have been achieved and standardized by numerous technical specifications. In this paper, the current status of China national geohazard information system, including the development progress, database architecture, system functionality and data applications are introduced, and expected to provide references of establishing an efficient and comprehensive geohazard information system to improve the geohazard risk reduction capabilities for the countries or regions suffering from geohazards.

Industrial land expansion in rural China threatens environmental securities

China’s rural industrialization has been a major driver for its rapid economic growth during the recent decades, but its myriad environmental risks are yet to be fully understood. Based on a comprehensive national land-use data set, our study shows that the area of China’s rural industrial land (RIL) quadrupled during 1990–2015, reaching 39338 km2 in 2015, comparable to urbanization in magnitude but with a much greater degree of landscape fragmentation which implies stronger ecological and environmental impacts. About 91% of the protected areas in the central China were within 50 km from rural industrial land, thus exposed to industrial disturbances. Accelerated rural industrial land expansion, particularly in regions under high geo-hazard risks, led to dramatically increased environmental risks, threatening the safety and health of both rural industrial workers and residents. Moreover, negative effects from rural industrial land expansion could partially offset the crop production growth in recent decades. The underprivileged rural population in the west bears a disproportionally large share of the increased environmental risks. China urgently needs to design and implement sustainable policies to restrict and reshape its rural industrialization. This study aims to inspire policy makers and researchers to rethink the current model of industrial expansion and improve rural industrial land planning, which is important for achieving the sustainable development goals of China.

Hydrogeological and geophysical properties of the very-slow-moving Ripley Landslide, Thompson River valley, British Columbia

Landslides along a 10 km reach of Thompson River south of Ashcroft, British Columbia, have repeatedly damaged vital railway infrastructure, while also placing public safety, the environment, natural resources, and cultural heritage features at risk. Government agencies, universities, and the railway industry are focusing research efforts on a representative test site — the very-slow-moving Ripley Landslide — to manage better the geohazard risk in this corridor. We characterize the landslide’s form and function through hydrogeological and geophysical mapping. Field mapping and exploratory drilling distinguish 10 hydrogeological units in surficial deposits and fractured bedrock. Electrical resistivity tomography, frequency domain electromagnetic conductivity measurements, ground-penetrating radar, seismic pressure wave refraction, and multispectral analysis of shear waves; in conjunction with downhole measurement of natural gamma radiation, induction conductivity, and magnetic susceptibility provide a detailed, static picture of soil moisture and groundwater conditions within the hydrogeological units. Differences in electrical resistivity of the units reflect a combination of hydrogeological characteristics and climatic factors, namely temperature and precipitation. Resistive earth materials include dry glaciofluvial outwash and nonfractured bedrock; whereas glaciolacustrine clay and silt, water-bearing fractured bedrock, and periodically saturated subglacial till and outwash are conductive. Dynamic, continuous real-time monitoring of electrical resistivity, now underway, will help characterize water-flow paths, and possible relationships to independently monitor pore pressures and slope creep. These new hydrogeological and geophysical data sets enhance understanding of the composition and internal structure of this landslide and provide important context to interpret multiyear slope stability monitoring ongoing in the valley.

Continental-slope instability triggered by seepage: An experimental approach

ABSTRACT Mass-transport complexes (MTCs), mass-transport deposits (MTDs), and associated facies and features are widely recognized in continental slopes around the world. In most current stratigraphic models of MTCs and MTDs, these submarine sediment failures are related to aquifer outflow (sapping, seepage) along continental slope fronts that originated during relative sea-level fall. We test a hypothetical scenario that is favored during early forced regression using reduced-scale physical simulation. A major underground subaerial hydraulic gradient is assumed to flow towards the basin depocenter as a function of relative sea-level fall. We developed an experimental apparatus with slope angles varying between 15 and 30° to test this concept. Hydraulic gradients, aquifer outflow velocities, and triggered collapses induced by the seepage effect were recorded at various positions of the slope. Analysis shows that steeper slope gradients require lower seepage velocities (and shear stresses) to trigger collapse, but gentler slopes remain unchanged. Experimental data are compatible with a seepage effect that could potentially trigger mass failure and the formation of MTCs during relative sea-level fall. The features produced in the experiment have geometries comparable to natural environments, and the experimental seepage velocities are of an order of magnitude similar to those monitored in submarine aquifers. The experimental results advance understanding of mass transport in continental slopes by introducing and testing new methods, and also provide new insights into potential submarine geohazard risks where tectonic uplift operates along some coastal regions.

Fluvial evacuation of landslide material from bedrock-confined channels under controlled experimental conditions

The supply of sediment from hillslopes to channels is rarely constant, with discrete events (e.g., landslides) known to transfer large volumes of sediment in geologically-short periods of time, especially in tectonically active areas. Understanding the rates and patterns of subsequent sediment evacuation is important for understanding variability of landscape evolution, as well as mitigating the risk of geohazards associated with bed aggradation and the loss of channel capacity to convey flood waters. Here, we performed a series of controlled laboratory flume experiments to explore the controls on sediment transport after a single sediment input in scenarios with (i) different initial input volumes (4–25 kg) under constant flow conditions (40 l/s), (ii) a constant initial input volume (12 kg) under different flow magnitudes (5–60 l/s), and (iii) a repeat of the input sediment volumes in scenario (i) but with the same volume of water delivered using a ramped hydrograph (0–60–0 l/s). We find the presence of sediment piles impacts the flow hydraulics, with a backwater effect developing upstream of the pile that causes a flow acceleration around the location of the pile. For a given discharge, larger sediment piles have a greater impact on the flow hydraulics, which in turn induces higher rates of sediment transport and erosion of the pile. In all cases, sediment remains at the initial pile input location for the duration of the sediment evacuation, acting to protect the bed from erosion. We highlight the role of geomorphic-hydraulic interactions in controlling the sediment evacuation, and suggest there is an optimal combination of pile size and flow conditions (flow magnitude and hydrograph shape) for accelerated rates of sediment transport, which are important for the short-term and long-term channel dynamics and the landscape evolution variability.

The long-term evolution of landslide activity near the epicentral area of the 2008 Wenchuan earthquake in China

The Wenchuan earthquake triggered numerous landslides and damaged vast areas of vegetation. Strong mountain earthquakes have long-term impacts on the activities of subsequent landslides. It is crucial for long-term geohazard risk assessment to investigate the spatio-temporal evolution of post-earthquake landslides. We used multi-year images from 2008 to 2018 to track the reactivation of coseismic landslides and newly occurring landslides to evaluate the influence of the Wenchuan earthquake on subsequent rain-induced landslides. With the aid of a GIS platform combined with field investigations, we analyzed the temporal and spatial evolutions of landslide activities over the past ten years and the factors controlling these changes. In addition, the process of vegetation recovery at landslide sites in the epicentral area was detected based on multi-year Landsat TM data after the Wenchuan earthquake. We observed that the total area of active landslides decreased significantly with time. In the first 5 years (2008–2013), the vegetation recovered quickly but was not well rehabilitated, and post-seismic landslides generally maintained high activity levels. Due to progressive revegetation and consolidation, most of the coseismic deposits along the hillslopes gradually stabilized. Subsequently (2013–2018), landslide activity weakened and mainly occurred in high and steep areas with poor vegetation recovery, particularly in proximity to the drainage network. Decreasing occurrence of rain-induced landslides was closely related to vegetation recovery in both time and space, and vegetation recovery could promote the reduction in post-earthquake landslide activities. We also proposed a quantitative model for the landslide rate in the epicentral area of the Wenchuan earthquake, which shows that the enhanced landslide rate reached its peak after the earthquake and will decrease to the pre-earthquake level in 25 years. The evolution of the post-seismic landslide activity can be categorized into four stages: high active period (2008–2013), low active period (2013–2018), recovery period (2018–2033), and stable period (after 2033).

Remote Sensing data for the investigation of geo-hazard: EO4GEO project and the knowledge sharing challenges

The improved capabilities of Remote Sensing in data acquisition, analysis and implementation of standardized products lead decision makers and managers to a better understanding and assessment against geo-hazard. But since geo-hazard pose potential risks to people, assets and the environment the better knowledge to deal with the huge amount and the high quality of Earth Observation data is required. EO4GEO Project represents the latest challenge to define a standard methodology for the creation of integrated application using EO data and services to carry out geo-hazard risk monitoring, assessment and mitigation options.

Risk Assessment of Earthquake-Triggered Geohazards Surrounding Wenchuan, China

AbstractThe great 2008 Wenchuan earthquake in China was a painful disaster. Accordingly, the management and mitigation of the risk of future earthquake-triggered geohazards remain a critical respon...

Ecological risk resonance of urbanization and its effect on geohazard disaster: the case of Freetown, Sierra Leone

Land use changes associated with urbanization may increase ecological risk and subsequent geohazard risk. Africa is particularly vulnerable at preset as, since 2005, the highest rates of rapid urbanization-associated forest degradation have occurred there. On August 14, 2017, a compound geohazard in Freetown, Sierra Leone, caused thousands of fatalities and destroyed hundreds of houses. Land use change is considered the main factor contributing to geohazard initiation. Here, we use Freetown as a case study to quantitatively assess the magnitude of the increase in ecological risk associated with land use changes. To achieve the aim, satellite images are used in the case study area from 2007 to 2017, the data are integrated into a geographic information system. A series of indices are then used based on the processed images to describe land use and ecological risk, including dynamic index, trend and state index, and ecological risk index. The results show that Freetown experienced a rapid urbanization process, together with an unbalanced increase in urban land and complex conversion of bare and grass land, from 2007 to 2017. Significantly degenerated forest was converted into urban land (2.77%), bare land (6.47%), and grassland (10.27%), while the ecological risk level increased from low to high. The ecological risk in the affected area of geohazard is found higher than that of the surrounding mountainous area. It indicates that vegetation may reduce the risk of disaster. This result is helpful for the trade-off between urban development and ecological protection and rational urban planning. For disaster resilience and sustainable development of Freetown, and also other rapidly urbanizing cities in mountainous areas, ecological protection must be incorporated into development planning.

Linking the Random Forests Model and GIS to Assess Geo-Hazards Risk: A Case Study in Shifang County, China

This study proposes an objective and accurate geo-hazards risk assessment method to address the challenge of increasingly severe hazards around the world. Previous studies mostly began from the perspectives of hazard and vulnerability, ignoring the role of survey data at disaster sites during risk assessments. The random forests (RF) model was applied in this study. Combined with detailed data from hazard sites, a geo-hazards risk assessment model was constructed, with the two dimensions of disaster hazard and vulnerability, was constructed. We analyzed the spatial pattern characteristics and the internal patterns of disaster risk and discussed the risk controlling factors and their contributions. The results showed the following. (1) The RF model, when combined with hazard, vulnerability conditions, and detailed data from disaster sites, can be used to zone and verify regional geo-hazards risks, providing a method for point-to-surface disaster risk mapping. (2) The RF-based geo-hazards risk assessment results were relatively consistent with the evaluation results from the support vector machine (SVM) model, but the accuracy and stability of the RF model were higher. (3) This method can be used to avoid the subjectivity in determining the weights and threshold values for indexes and can calculate the contribution of each index to geo-hazards risks.

Geohazards regionalization along highways in Shandong Province, China

The disturbance of the highway construction to the terrain and the natural environmental factors are the main causes of the geohazards along the highway. We collected geohazards along the highway in Shandong Province and put forward the comprehensive geohazard index to reflect the risk of geohazards along the highway. The index consists of an intensity index describing the development of geohazards and a sensitivity index describing the potential risk of geohazards. The article uses an incomplete additive language matrix to calculate the weight of each index and factor. Based on the Getis-Ord Gi* statistic tool, the spatial distribution of landslides and collapses, debris flows, ground collapses, and unstable slopes are analyzed, and the geohazard intensity index is calculated by spatial superposition. The relationship between slope gradient, rainfall, vegetation coverage, rock type and geohazards is analyzed, and the geohazard sensitivity index is calculated by spatial superposition. Based on the comprehensive geohazard index and geomorphological characteristics, Shandong Province is divided into 4 geohazard first-level regions and 11 geohazard second-level regions, providing a basis for highway planning and construction.

Declining geohazard activity with vegetation recovery during first ten years after the 2008 Wenchuan earthquake

Understanding the evolution of post-seismic geohazards with vegetation recovery is of great significance for long-term geohazard risk assessment. The Wenchuan earthquake in 2008 triggered numerous landslides and severely damaged the vegetation in the earthquake-stricken region. Between 2008 and 2017, we evaluated the vegetation recovery process, the evolution of rain-induced landslides and debris flows, and the relationship between them by analyzing satellite images and conducting detailed field investigations. Shortly after the earthquake, numerous landslides and debris flows were triggered by rainstorms and the vegetation was severely damaged near the epicenter. In the first 5 years (2008–2013) the vegetation recovered quickly but was not well rehabilitated. Rain-induced landslides and debris flows occurred actively but exhibited a clear declining trend in both frequency and magnitude. After 2013, the vegetation gradually recovered to the pre-seismic normal level in terms of quantity, but with higher variability and isolated spots to be further rehabilitated. Over this period, rain-induced geohazards mainly occurred in the catchments where the level of vegetation recovery was uneven, with occasional bare deposits. Therefore, a close relation is observed between declining rain-induced geohazards and the recovery of vegetation, in both time and space. The findings provide important information for post-seismic infrastructure re-construction and disaster risk reduction in future mountain earthquake events.

An Assessment of Stress States in Passive Margin Sediments: Iterative Hydro-Mechanical Simulations on Basin Models and Implications for Rock Failure Predictions

Capturing the past and present hydro-mechanical behavior of passive margin sediments raises noticeable interest, notably in geo-hazard risk assessment and hydrocarbon exploration. In this work, we aim at assessing the stress states undergone by these sedimentary deposits through geological time. To do so, we use an iterative coupling between a basin simulator and a finite element mechanical solver. This method conciliates a computation of the full stress tensors with a dynamic and geologically detailed modelling of the sedimentation. It is carried out on a dedicated set of 2D synthetic basin models, designed to be representative of siliciclastic deposition in passive margins and integrating variations in their geological history. Contrary to common assumptions in operational basin modelling studies, our results imply that passive margin sedimentary wedges are multidimensional mechanical systems, which endure significant non-vertical stress without external tectonic input. Our results also highlight the variability of the stress states through space and time, with a strong control from the geometry and lithological heterogeneities of the deposits. Lastly, we used the simulation results to predict a location and timing for the development of weakness zones in the sedimentary stacks, as privileged areas for rock failure. The outcome underlines the influence of the basal tilt angle, with a slight tilt impacting the wedges stability to a similar extent as a substantial increase in sedimentation rate. Altogether, this study emphasizes the need for careful consideration of non-vertical stresses in basin simulations, including in passive tectonic contexts. It also suggests that the iterative coupling method employed is a promising way to match industrial needs in this regard.

The identification and mitigation of geohazards using shallow airborne engineering geophysics and land-based geophysics for brown- and greenfield road investigations

South Africa is a mineral-rich country with a diverse geology and a long history of mining. The rich history of mining activities includes the extraction of coal from the Ecca Group Sediments of the Karoo Supergroup (250 Ma), gold and uranium from the Witwatersrand Supergroup (2900 Ma), as well as platinum, uranium, tin and lead from the layered Bushveld Igneous Complex (BIC) (2150 Ma). The extraction of gold, copper, tin, lead and rare earth minerals also took place in the Archean rocks of Swazium age (3500–3000 Ma). The historical mining records have either not been accurately recorded or have been lost over time. This has resulted in significant geohazard risk during infrastructure development, especially in and around historical mining towns, such as Johannesburg and Ermelo. These geohazard risks require careful appraisal and quantification prior to any infrastructure design or construction. This case study aims to set out the development aspects of the Multi-Faceted Geophysical Modelling Systems approach, which was used by the South African National Roads Agency SOC Ltd (SANRAL) during an investigation of undermined ground for the historical coal-mining town of Ermelo in South Africa. The N11/N2 ring road was planned to go around Ermelo to ensure mobility between major routes, whilst still maintaining town access. The systems approach used a combination of airborne geophysics (Versatile Time Domain Electromagnetic System (VTEM TM ) and magnetics), generally used in mining exploration, land-based and borehole geophysics, borehole water testing, and ground-truthing. The approach was continuous and iterative, building on the data at hand and reducing unnecessary investigations while eliminating the possibility of anomalies being missed, as in the case of conventional discrete drilling. The investigation ensured that 100% of the route was comprehensively investigated with a high confidence in the geological and geophysical data, and concomitant mitigation of infrastructure risk. The Multi-Faceted Geophysical Modelling Systems approach was successfully used to identify a previously unknown 1 × 1 m mining stope cavity at 90 m depth and a 3 × 5 m access tunnel at 24 m depth in a timely and cost-effective manner. Seven reverse-circulation percussion boreholes confirmed the structural integrity of these underground cavities, as well as the structural geology along the centreline. Based on the great success achieved in identifying shallow anomalies, this Multi-Faceted Geophysical Modelling Systems approach is now being considered for field trails on the dolomitic formations and the Wild Coast greenfields road project where there are large historical slumps and many fault lines. Thematic collection: This article is part of the Ground-related risk to transportation infrastructure collection available at https://www.lyellcollection.org/cc/Ground-related-risk-to-transportation-infrastructure