**1. Introduction: using indicators to assess and manage resilience of critical infrastructures in SmartResilience and InfraStress projects**

The definition allows analyzing the behavior of an infrastructure exposed to an adverse event over a "scenario timeline" and simultaneously assessing the functionality of an infrastructure over the "resilience cycle" as shown in **Figure 1**. While the decomposition over the time-axis, i.e., defining the "phases" of the resilience cycle, may be trivial, decomposition over the functionality axis is non-trivial as

SmartResilience concept proposes the decomposition over a 5 5 resilience matrix,

The approach allows to represent the overall resilience cycle, and focus on single relevant issues. The issues, in turn, can be described by means of indicators and these can have values, thus, providing the possibility to quantitatively describe each

Phase I, understand risks, is applicable prior to an adverse event. It emphasizes emerging risks and includes their early identification and monitoring; e.g. what

Phase II, anticipate/prepare, also applicable before the occurrence of an adverse

Phase III, absorb/withstand, comes into action during the initial phase of the event and shall include the vulnerability analysis and the possible cascading/ripple effects; e.g. "how steep" is the absorption curve, and "how deep" down will it go? Phase IV, respond/ recover, is related to getting the adverse event under control

as soon as possible, influencing the "how long" will it last, question. Further, it

*The 5 5 resilience matrix, mapping the critical infrastructure system functionality over 5 phases of the*

*Possible outcomes of case of an infrastructure exposed to an adverse event: Between improvement and complete*

event. It includes planning and proactive adaptation strategies, possibly also

functionality might have different "dimensions" (see chapter 2.3). The

*Resilience and Situational Awareness in Critical Infrastructure Protection…*

defining 5 phases and 5 "dimensions".

*DOI: http://dx.doi.org/10.5772/intechopen.97810*

"cell" of the resilience matrix (**Figure 2**).

"smartness in preparation" [5].

**Figure 1.**

**Figure 2.**

*failure.*

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*resilience cycle.*

could the "adverse event" be? This is followed by.

Modern critical infrastructures are becoming increasingly smarter (e.g. the smart cities). Making the infrastructures smarter usually means making them smarter in the normal operation and use: more adaptive, more intelligent etc. But will these smart critical infrastructures behave smartly and be smartly resilient also when exposed to extreme threats, such as extreme weather disasters or terrorist attacks? If making an existing infrastructure smarter is achieved by making it more complex, would it also make it more vulnerable? Which aspect of resilience of a critical infrastructure will be affected the most? Its ability to anticipate, to prepare for, to adapt and withstand, respond to, or to recover? What are the resilience indicators (RIs) which one has to look at? These are the main questions tackled by the SmartResilience project [1] to which a methodology based on resilience indicators was developed, complete with the supporting "ResilienceTool" to handle both existing ("conventional") indicators suitable for assessing the resilience of critical infrastructure as well as new "smart" resilience indicators, e.g. those from Big Data (over 5,000 available in mid-2020). In the InfraStress project [2], the concept and the tools are developed further and integrated with the concept of situational awareness system (focus of the InfraStress project).
