For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
CIVIL EMERGENCY.
(1) A riot or unlawful assembly characterized by the use of actual force of violence or any threat to use force by three or more persons acting together without authority of law; or
(2) Any natural disaster or man-made calamity including flood, conflagration, cyclone, tornado, earthquake or explosion within the corporate limits of the city resulting in the death or injury of persons or the destruction of property to such an extent that extraordinary measures must be taken to protect the public health, safety and welfare.
CURFEW. A prohibition against any person or persons walking, running, loitering, standing or motoring upon any alley, street, highway, public property or vacant premises within the corporate limits of the city during the hours in which a curfew has been imposed, excepting persons officially designated to duty with reference to said civil emergency.
(‘85 Code, § 29.25(a))