Abnormal obsolescence means the loss of value of an asset, property or a piece of capital equipment due to the changes in tastes, circumstances or techniques which cannot be reasonably foreseen.
A specific equipment or asset may become obsolescence due to several factors such as consumers no longer want the good its produces or due to technical progress in other industries where the intermediate goods being produced is no longer needed.
New technique which is allow production will less labour, material or fuel may also lead to obsolescence. Besides that, non compliance with improved health and safety regulations may also lead to obsolescence.
Any natural catastrophe may lead to the property lose its value even without suffering from any damages.