Seismic risk assessment of natural gas networks at the urban scale

Modern societies have shown to be heavily dependent on critical infrastructures, which provide essential services and contribute significantly to social and economic evolution. The natural gas network plays a crucial role in a post-disaster event and, if damaged, it can have a severe impact on recovery and ultimately on community resilience. This paper focuses on the evaluation of the seismic risk of urban natural gas networks. A physical-based model is developed to simulate the effects of pipeline damage induced by the ground shaking and soil deformation. The gas network modeling, calibration, and flow updating are automated through a python-based simulation tool. The proposed analysis allows to estimate network damage in terms of gas leaks and pipe breaks. In addition to the inherent vulnerability of the pipelines, the dependency to the built environment is considered by removing network components that are located inside buildings completely damaged. This information is then used to identify branches that are possibly out of service and to quantify the risk in terms of users not supplied. The methodology provides an effective tool to identify the gas network vulnerabilities at the urban level and to further study countermeasures that can overall improve community resilience.