Probabilistic risk assessment of oil and gas infrastructures for seismic extreme events

Modern economy and society are constantly increasing dependent on a variety of critical infrastructures (CIs) over the last
decades. However an observation and review of the extreme events that occurred during the last two decades reveal that while the
interdependencies between the CIs are growing and getting more complex there is an increasing gap between the growing risk and
the actual preparedness. Therefore there is an utmost importance to ensure reliable and robust performance of critical
infrastructures on a continuous basis, particularly during and after the occurrence of extreme events. In this study a methodology
is developed to act as decision support tool for decision makers to appraise and mitigate the risk of CIs after the occurrence of
seismic events. The methodology analyzes the damage of critical infrastructures components by Fault-Tree-Analysis, Decision
Trees and Fragility Curves. Though the methodology is suitable for a variety of critical infrastructures, this study will focus on
critical Oil and Gas Network Systems, which are vital to the energy supply infrastructure of Israel. In order to assess the risk that
Oil and Gas Critical Infrastructures are exposed to in case of seismic extreme events, fragility curves are derived and adjusted to
different components of the Oil and Natural Gas systems. Subsequently, a variety of possible seismic scenarios are examined and
analyzed in order to determine the damage of the components. The overall expected damage of the Oil or Gas system is assessed
by considering the damage state of all components of the system. The expected damage states of the components disclose and
emphasize the most vulnerable parts of the system. Also discussed are guiding principles for decision makers to mitigate risk
based on benefit-cost ratio.