# Seismic Resilience in Critical Infrastructures: A Power Station Preparedness Case Study
## 4 Case Study
### Damage Assessment and Failure Analysis  
The power station structure and component analysis illustrated the vulnerabilities of earthquake impacts. By employing fragility curves for various subcomponents and conducting a Fault Tree Analysis (FTA), the methodology derives the damage probabilities for the station's main components. The summary of these damage probabilities, as detailed in Table 5, reveals varying levels of seismic vulnerability across components. The average damage probability of a component is 0.098, with a standard deviation of 0.0753, indicating the potential variability and risk distribution across the power station's components.  
Following the failure probabilities of the power station's critical components, an estimate of the overall damage probability for the entire power station is achievable. A fundamental principle of this analysis is that damage to any single component, defined as significant enough to disrupt the station's operations, contributes to the overall damage probability. For a determined PGA of 0.2 g, the total damage probability, calculated using an FTA specific to the power station, is derived to be 0.5732. It is crucial to note that this analysis treated the subcomponents as unanchored, heightening their vulnerability to seismic events, a concern that will be further discussed.  
The sensitivity level for slope stability, defined as negligible, indicates that no countermeasures are required. The risk of liquefaction was identified for foundations shallower than 20 m. However, the power station was constructed in accordance with Israeli codes, which mandate conservative construction practices to safeguard and ensure the ongoing performance of critical infrastructure in regions susceptible to soil liquefaction. This means the design and construction of the power station took into account the possibility of soil liq  
Figure 10: Fragility curves for gas and steam turbines.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Power Station Component** & **Damage Probability \({}^{\star}\)** \\ \hline Gas Turbines & \(7.68\times 10^{-5}\) \\ Steam Turbines & 0.0416 \\ Steam Boiler & 0.0109 \\ GIS (Gas-Insulated Switchgear) & 0.1020 \\ PRMS (Pressure Regulating and Metering Station) & 0.0824 \\ Water Treatment Facility & 0.2312 \\ Water storage Tank & 0.1570 \\ Oil storage Tank & 0.1570 \\ \hline \hline \end{tabular} \({}^{\star}\)Damage probabilities are calculated based on a PGA of 0.2 g.  
\end{table}
Table 5: Power station main components and their determined probabilities of damage.  
uefaction, incorporating foundations deeper than 20 m to mitigate this risk. By complying with existing regulations and building codes and proactively considering the potential for soil liquefaction during the design and construction stages, the associated risks have been effectively reduced.  
The tsunami scenario identified for the power station site forecasts a maximum predicted inundation height between 2.5 m and 5.0 m. To mitigate this risk, a tsunami protection wall was constructed along the perimeter of the power station. This barrier consists of precast foot wall units, each standing 9.2 m high with a base width of 3.4 m. Each unit costs approximately ILS 30,870 (around USD 8500), resulting in a total expenditure of about ILS 17 million (roughly USD 4.6 million) for the entire wall. Notably, the investment in tsunami protection represents less than 0.5% of the total construction cost of the power station, indicating a cost-effective measure to safeguard against potential tsunami impacts. This mitigation strategy highlights the practicality and cost-effectiveness of integrating protective measures against natural disasters in critical infrastructure projects. The power station significantly increases its resilience in tsunami scenarios by allocating less than 0.5% of the total construction budget to a tsunami protection wall, ensuring operational continuity and safety.