Definition: this is a sudden, natural or man-made situation where change and destruction may occur without prior knowledge or preparation. a sudden, violent event.

The answer is "it is called as Catastrophic Event".

Catastrophic Event refers to any characteristic or man-made occurrence, including fear based oppression, which brings about phenomenal levels of mass setbacks, harm, or interruption extremely influencing the populace, framework, condition, economy, national resolve, and additionally government capacities.