As used in this act:
1. ”Emergency” means any occasion or instance for which, in the determination of the President of the United States or the Governor of the State of Oklahoma, federal or state assistance is needed to supplement state and local efforts and capabilities to save lives, protect property, public health and safety, or to lessen or avert threat of a catastrophe in any part of the state;
2. “Man-made disaster” means a disaster caused by acts of man including, but not limited to, an act of war, terrorism, chemical spill or release, or a power shortage that requires assistance from outside the local political subdivision; and 3. "Unavailable" means absent from the place of session, other than on official business of the Legislature, or unable, for physical, mental or legal reasons, to exercise the powers and discharge the duties of a legislator, whether or not such absence or inability would give rise to a vacancy under existing constitutional or statutory provisions.