What is the term for damage that occurs suddenly and accidentally as opposed to gradual damage?

The term that defines damage occurring suddenly and accidentally, as opposed to gradual or long-term damage, is "sudden damage." This classification is important in the context of insurance policies, as many coverages specifically address sudden and accidental events while excluding claims related to gradual deterioration. Sudden damage refers to occurrences that take place abruptly, such as a burst pipe or a fallen tree, which are typically insurable events under a property policy. In contrast, damage that develops over time, like wear and tear or mold growth, does not fall under this category and may not be covered by insurance, as such damage is expected and typically the responsibility of the property owner to manage.

Other terms, like accidental damage or immediate damage, could describe various scenarios but do not capture the essence of the sudden nature that distinguishes this concept. Negligent damage refers to damage that results from a lack of reasonable care, which is also not the primary focus of this question. Thus, "sudden damage" is the most accurate term for these events.