Evaluating liquefaction exposure of road networks to support decision-making

This article discusses different approaches to evaluate liquefaction exposure across road networks and inform decision-making processes regarding asset management, emergency preparation and response planning. Using the New Zealand State Highway network, liquefaction exposure is assessed based on ground shaking from two sources: (1) various return period shaking intensities from the National Seismic Hazard Model and (2) a suite of specific earthquake scenarios. The first approach considers the likelihood of liquefaction exposure at each location conditional on different levels of ground shaking, suitable for assessing individual network components. The second approach presents liquefaction exposure for a specific earthquake scenario, capturing the extent of exposure across a network. In addition, it offers a new indicator, the number of events (NoE), identifying network sections that could be affected by liquefaction manifestation across multiple earthquake scenarios. For both approaches, the extent of potential exposure (number of affected 100 m-segments) and the level of network disruption (number of affected links representing segments between intersections) are estimated at both national and regional scales. While the national-scale assessment helps to quantify liquefaction exposure across the entire network, providing valuable insight for asset management, the regional-scale assessments identify potential worst-case scenarios, identify locations affected by multiple events and allow for more informed emergency management decision-making. Future research should expand the multi-scenario approach, incorporate network related aspects, such as criticality or redundancy, and consider recurrence intervals for scenario weighting or perform a full probabilistic liquefaction hazard analysis to enhance the evaluation of potential impacts and to further support decision-making.