The countermeasure is intended as an alternative to the more effective target/citywide emergency evacuation when these crisis relocation programs would not be possible due to travel and time constraints. Maneuvers similar, but not identical, to "Duck and Cover" are also taught as the response to other sudden destructive events, the maneuvers that are advisable in an earthquake or tornado, in the comparable situation where preventive emergency evacuation is similarly not an option, again, due to time constraints. In these analogously powerful events, "Drop, Cover and Hold on" likewise prevents injury or death if no other safety measures are taken.