**1. Introduction**

Natural hazards frequently cause disturbances for different types of critical infrastructures and, therefore, have a substantial impact on the safe and reliable operation of the respective infrastructures such as telecommunication, processes, and energy industry. Furthermore, the set of natural hazards can strongly affect the different types of transport infrastructures such as road, rail, waterways, and aviation.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In case of the electrical power industry, the impact, in particular of seismotectonic, hydrological, and meteorological hazards, is diversified. Examples are the energy production and the transmission and distribution lines of the suppliers where strong winds like tornados result in a disruption of the production (e.g., in case of wind turbines) or of the distribution lines due to trees fallen on overhead lines. An expected low water level may require the shutdown of a nuclear power plant because of potential core cooling problems.

Although this chapter focuses on natural hazards, it is important to list and characterize all types of hazards in order to enable the analyst to perform a complete screening of hazard

Natural Hazards: Systematic Assessment of Their Contribution to Risk and Their Consequences

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In **Table 1**, an overview of the different classes of internal and external hazards is given. **Tables 2**–**10** provide for all hazard classes mentioned in **Table 1** the binning of individual

combinations.

**I. External hazards 1.** *Natural hazards*

Class A: Seismotectonic hazards

Class C: Meteorological hazards Class D: Extraterrestrial hazards

**2.** *Man-made hazards* (Class Z)

**II.Internal hazards (Class I)**

**Table 1.** Overview of hazard classes, from [1].

A3 Surface faulting (fault capability) A4 Liquefaction, lateral spreading

**Table 2.** Class A hazards according to [2].

**Hazard Type of individual seism tectonic hazard**

A1 Earthquake (vibration ground motion (including long duration) A2 Vibration ground motion induced or triggered by human activity

A5 Dynamic compaction (seismically induced soil settlement) A6 Permanent ground displacement subsequent to earthquake

Class E: Biological hazards Class F: Geological hazards

Class H: Natural fires

**2.1. Systematic binning of hazards**

hazards to the different hazard classes.

Class B: Flooding and other hydrological hazards

Hazards can arise not only individually but often occur together with other events or hazards. The experience has shown that a variety of combinations of different types are possible. If and how frequently such hazard combinations do occur at a nuclear facility site depends on the site characteristics but also on the facility to be investigated and its design against various events.

In particular, for combinations of natural hazards with other events, the operating experience of the more recent past has shown that at least some of the huge amount of theoretically possible hazard combinations cannot be excluded to occur in principle. Some of these combinations represent—like individual hazards—low-frequency, high-damage events, others are more frequent, but the damage potential is much lower (so-called high-frequency, low-damage events).

For systematically considering all hazard combinations having the potential to impair the safe operation of an industrial facility, but enabling the analyst to exclude non-negligible combinations as well, the entire set of hazards, which can be anticipated at the site of the facility being analyzed, needs to be identified. In the second step, the individual hazards have to undergo a qualitative and quantitative screening process. In the third step, hazard combinations have to be identified starting from those individual hazards identified and not screened out by qualitative arguments. For these hazard combinations, again the screening has to be performed.
