A casualty loss is a type of tax loss that is a suden, unexpected, or unusual event. Damage or loss resulting from progressive deterioration of property through a steadily operating cause would not be a casualty loss. “Other casualty” are events similar to “fire, storm, or shipwreck.” It is generally held that wherever force is applied to property which the owner-taxpayer is either unaware of because of the hidden nature of such application or is powerless to act to prevent the same because of the suddenness thereof or some other disability and damage results.