For the purpose of this chapter the following definitions shall apply unless the context clearly indicates or requires a different meaning.
"CIVIL EMERGENCY." Shall mean either:
(1) A riot of unlawful assembly characterized by the use of actual force or violence or any threat to use force if accompanied by immediate power to execute such force by three or more persons acting together without authority of law; or
(2) Any natural disaster or man-made calamity including a 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 on 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, except persons officially designated to duty with reference to civil emergency. ('74 Code, § 130.06)(Ord. 69-15, passed 11-17-69)