Any lawful use, structure or lot existing at the date of passage of the ordinance codified in this title or subsequent amendment thereto, and located in a zone in which the use, structure or lot would not be permitted under the terms of this title, is declared to be a legal nonconformance. It is the intent of this title to permit these legal nonconformances to continue until terminated by voluntary act or by catastrophic event, and to encourage their conversion to conformance where possible. (Zoning ordinance dated 6/3/03 Art. XIV (part))