A matrix based framework for rapid landslide risk assessment

The appendices to this paper set out matrices intended for rapid assessment of the risk to life from landslide. Matrix based flowcharts are provided for the general case, and for cases where the element at risk is mobile (e.g. people in a vehicle or on foot) and where the elements at risk are static (e.g. in a building). Where time is critical or where there are large numbers of hazards or elements at risk to assess, there can be a need for landslide risk assessment to be undertaken rapidly and efficiently. In these cases landslide risk assessment is used primarily as a screening tool to inform quick and efficient decision making. Examples include the assessment of risk to life following a disaster event such as an earthquake or extreme rainfall event or where triage of a large number of hazards is required to quickly identify those hazards that need to be prioritised for further assessment and mitigation. Such risk assessment systems have been in widespread use in Australia for some time, most notably the Transport for New South Wales Guide to Slope Risk Assessment (formerly NSW Roads and Maritime Service), currently at Version 4 (RMS 2014). This system has been in use for more than 20 years and serves to ensure systems are in place to identify landslide and geotechnical hazards affecting the road network and to then provide a screening tool to inform road authorities as to which landslide and geotechnical hazards on their road network should be prioritised for risk mitigation. A rapid risk assessment system partially adapted from RMS 2014 is presented here which is intended to have broad application to most scenarios for which rapid assessment of risk to life from landslide is required. The system takes into account the number of people exposed to the landslide hazard, the number of hazards to which they are exposed and whether they are moving past the hazard (e.g. walking or in a vehicle) or stationary (e.g. in a building) in order to arrive at a risk level estimated on a 5-point scale between Very High and Very Low. This paper sets out the basis of the appended matrix based risk assessment system.