Geohazards comprise a subgroup of natural hazards associated with geotechnical, hydrotechnical, tectonic, snow and ice, and geochemical processes that can pose a threat to worker and public safety, asset integrity, and asset management lifecycle cost. Like for most types of threats, the risks from geohazards can be assessed qualitatively or quantitatively and used to inform a geohazard management program. Most mining companies use risk matrices to aid in the assessment, prioritisation, communication and management of corporate risks. These matrices use standardised descriptions of likelihood and consequence to help users assess risks of negative outcomes to health, safety, the environment, assets, and reputation, and are tailored to each organisations types of risk exposure and level of risk tolerance. Geohazards and related geotechnical failures can represent low-probability, high-consequence events that plot in the highest risk zones of most corporate risk matrices. Variability in spatial and temporal probabilities for people and infrastructure exposed to geohazards can have a large influence on risk exposure, and this can be challenging to assess and communicate effectively with some risk matrices. Risk is scale-dependent: the business risk due to rockfall from a single slope along a mine access road is vastly different than the total risk due to rockfalls from all slopes along that road, yet guidance is often missing on how the risks from these scenarios should be plotted on a risk matrix. These and other pitfalls associated with use of corporate risk matrices for informed geohazard management are explored.
Mineral exploration projects in tropical environments can be exposed to a range of geohazards, including landslide, rockfall, debris flow, flooding, and subsidence. Understanding the geohazard types present, and their potential consequences at a proposed drill pad or camp site, is critical to managing the projects geohazard risks. During the early stages of exploration, typical datasets used to map and evaluate geohazards, such as stereo airphotos and airborne LiDAR data, are often not available; as a result, engineers and geologists must rely on reconnaissance-level desktop studies and field observations of the geomorphology to estimate the risk of geohazard exposure. In order to effectively estimate geohazard risk at individual sites in a systematic manner, an evidence-based system was developed employing a standard risk equation. The components of the field-based geohazard risk assessment system include identifying the geohazard type and estimating the annual probability of occurrence at a specific location, estimating the spatial probability of the geohazard reaching the elements at risk, estimating the vulnerability of the elements at risk to the geohazard, and estimating the temporal probability that the elements at risk would be present when a geohazard occurs. This approach enables credible geohazard threats to be rated and facilitates appropriate risk management approaches suitable for each location and geohazard type. In parallel with the geohazard risk ratings, geohazard risk can be managed through more detailed assessment, awareness training, engineering measures, relocation of drill sites and infrastructure, and trigger action response plans. This paper presents a case study that employs the methodology at a greenfield exploration project site in tropical jungle in mountainous terrain.