For the purposes of this chapter, the terms "rock festival" and "such event" mean, unless the context clearly indicates a different meaning, an actual, or a reasonably foreseeable, assembly of one thousand (1,000) or more people which does or did continue, or can reasonably be expected to continue, for a period of eighteen (18) or more consecutive hours upon private property which does not contain an established place of worship and at which the principal source of entertainment is, was or will be musical in nature.