GIS-based method to assess seismic vulnerability of interconnected infrastructure : a case of EU gas and electricity networks

Our study concerns the interconnected European Electricity and Gas transmission grid where we address two important issues of these interdependent critical infrastructures. First we assessed the response under seismic hazard for each independent network; then we analysed the increased vulnerability due to coupling between these two heterogeneous networks. We developed a probability reliability model that encompasses the spatial distribution of the network structures using a Geographic Information System (GIS). We applied the seismic risk assessment of individual network facilities and presented the results in the form of the system fragility curves of the (independent and dependant) networks in terms of various performance measures - connectivity loss, power loss, and impact on the population. We characterized the coupling behaviour between the two networks as a physical dependency: here the electricity grid, in part, depends on the gas network due to the generation capacity of gas-fired power plants. The dependence of one network on the other is modelled with an interoperability matrix, which is defined in terms of the strength of coupling; additionally we consider how the mechanical-structural fragility of the pipelines of the gas-source supply stream contributes to this dependence. In addition to network-wide assessment, damage was also evaluated at a local level by examining the performance status of each and every electricity distribution substation in the electricity grid. Finally, the comprehensive geographical distributions of performance loss at the European level can be visualized on a GIS tool; showing, as expected, that the highest direct damage in southeast Europe.