Rare but conceivable: Determining the likelihood of meteors and other infrequent events

Abstract

AbstractIn the aftermath of a rare but devastating disaster, there is a tendency to overestimate how frequent such an event may be, hence a tendency to overestimate the risk associated with such an event. Those concerned with process safety will acknowledge that though rare, events like meteors, hurricanes, and airplane crashes that can impact chemical plants are conceivable. Typically, though, they have nothing more than feelings to decide whether these events are likely enough to be considered “credible.” This compiles data from the literature for several “meteors,” both natural and man‐made, that often become a cause of general concern after such an event occurs: meteors, earthquakes, and tsunamis; tornadoes and hurricanes; and airplane crashes, pipeline ruptures, train derailments, and truck crashes. It provides data and describes approaches to estimating the frequency of such events at a specific facility based on its location. With these frequencies, process risk analysts can then determine which, if any, of these events is sufficiently likely to warrant further attention.