definition
strict definition
damaged by unknown cause
Major structural, functional, or cosmetic damage occurs to a structure, and its cause has not been determined.
A structure is damaged by unknown cause(s) when major structural, usage-impairing, or cosmetic damage occurs, and the cause(s) is/are not yet determined.
The damage can impair use, affect structural parts, or be primarily cosmetic, provided it is major. The event describes an observed loss whose cause remains unresolved.
When an explosion is established but its origin is unknown, damaged by explosion identifies the known mechanism. This definition applies where the cause of the damage itself has not been determined.