# Seismic Resilience in Critical Infrastructures: A Power Station Preparedness Case Study
## 3 Methodology
### Phase 1--Investigation of the Power Station  
This phase establishes a thorough understanding of the power station's configuration. The objectives are to pinpoint the geographic location and the associated seismic risk, identify the primary components and the subcomponents, and characterize their mechanical and operational interdependencies.  
Power Station LocationDetailed geographic and seismic zoning are established, forming the basis for evaluating potential seismic risks. The location serves as a critical factor in determining the risk exposure. The detailed analysis is based on the location of the power station and consideration of site effects.  
Assessing seismic threats and their occurrence probabilities involves analyzing the likelihood and potential severity of seismic risks associated with the power station's  
Figure 2: Main phases of the methodology.  
geographic location. The assessment categorizes the threats into primary earthquake events and secondary seismic events.  
1. Primary Earthquake Event--it is crucial to identify the occurrence probabilities of earthquake events and their associated ground motion at the site. Hazard maps and other available data, such as historical seismic records or local geological surveys, can support this step. If required, probabilistic seismic hazard analysis (PSHA) models may be employed to quantify the likelihood of earthquakes impacting the power station, considering factors such as fault locations, seismic activity rates, and ground motion attenuation [46].
2. Secondary Seismic Events--review of possible subsequent events that can be triggered as a result of the earthquake, such as: * Amplification--evaluating the soil and geological conditions to determine the site's susceptibility to seismic amplification.
* Slope Stability--assessing the probability of landslides and slope failure due to seismic shaking.
* Liquefaction--analyzing soil liquefaction potential based on soil composition, groundwater levels, and historical liquefaction occurrences.
* Tsunami--determination of the occurrence probability and characteristics of tsunami events, utilizing historical data, simulations, and other pertinent information.
* Power station structure and vulnerability.  
Structural and Component Analysis--the power station structure and layout must be thoroughly investigated to identify the facility's main components and subcomponents. Additionally, this step must include the determination of the functional and mechanical interdependencies between components and establishing how the failure of one could affect another. This step also includes the functionality investigation of the components in routine and emergency conditions.  
Components Vulnerability definition--fragility curve parameters are identified and associated with each essential component and subcomponent within the system. These parameters are typically obtained from established sources such as the Hazus technical manual [47] and the FEMA database [48] or previous research [49; 50; 51]. However, in cases where suitable fragility curves are unavailable, this step may be supported by collaboration with structural engineers, alongside the utilization of historical damage data, empirical studies, and analytical models [52; 53], or by the development of specific fragility curves [54; 55].