Tsunami Fragility Functions for Road and Utility Pole Assets Using Field Survey and Remotely Sensed Data from the 2018 Sulawesi Tsunami, Palu, Indonesia

The 2018 Sulawesi tsunami caused widespread impacts in Palu City, Indonesia, including to components of infrastructure lifeline networks. Lifeline networks are key to the operation of society and are particularly crucial during post-disaster relief and recovery efforts. Understanding their vulnerability to tsunami hazards is important for disaster risk reduction, but is an understudied topic. This study uses field survey and remotely sensed data to develop a single dataset, used to create tsunami fragility functions for road and utility pole assets in Palu. Tsunami inundation depths were estimated at component locations from a spatial interpolation of field measured flow depths and wave run-up. Component attributes and geometries exposed to tsunami inundation were compiled from both field surveys and remote sensing on satellite imagery and ‘street view’ imagery, which included component construction material, capacity (roads) and height (poles). Roads demonstrate a 0.16 probability of exceeding complete damage at 2 m inundation depth, while utility poles see a 0.47 probability. The probability of exceeding complete damage at 2 m inundation depth for concrete, asphalt, collector and local roads is 0.34, 0.17, 0.19 and 0.13 respectively, and for concrete, steel, steel 5 m height utility poles is 0.42, 0.48, 0.49 and 0.47 respectively. When comparing the synthesised tsunami fragility functions to those from other global events, Palu roads were more vulnerable at 2 m inundation depth (0.16) compared to roads exposed to the 2011 Tohoku tsunami in Japan (0.06) and 2015 Illapel tsunami in Chile (0.05).