Accounting for Cascading Failures

Collapsed buildings, damaged roads, and broken power lines are direct impacts of natural hazard events. However, it’s the indirect impacts that can cause widespread, inequitable, and longer lasting issues. Much of Aotearoa New Zealand’s infrastructure is interdependent – a water supply pumping station may not be directly damaged but becomes inoperable because it needs electricity from now-severed power lines. Such “cascading failures” are rarely considered in risk analyses thereby underestimating impacts and missing opportunities for mitigation.

Early career researcher Tom Logan of the University of Canterbury is collaborating with Rebecca Peer and Conrad Zorn to better quantify cascading failures. They’re working on a Te Hiranga Rū QuakeCoRE project entitled, “Enhancing risk assessment by understanding cascading failures through interdependent urban infrastructure.” The Canterbury Lifelines Utilities Group and the Christchurch City Council’s Coastal Hazards Adaptation Planning team are partners in the research.

The researchers have built a model of topography and infrastructure networks in Christchurch using high-resolution, real-world data. Earthquake, tsunami, flood scenarios are applied to determine likely impacts. The model is then taken a step further to incorporate indirect impacts from cascading failures. This accounts, for example, for supermarkets rendered inaccessible as well as those directly damaged.