The General Assembly, in order to insure continuity of state and local governmental operations in periods of emergency only resulting from disasters occurring in this state caused by enemy attack on the United States, shall have the power to such extent as the General Assembly deems advisable. In the event there occurs in this state a disaster caused by enemy attack on the United States, the General Assembly shall immediately convene in the City of Jefferson or in such place as designated by joint proclamation of the highest presiding officers of each house, and shall have power

(1) To provide by legislative enactment for prompt and temporary succession to the powers and duties of public offices, of whatever nature and whether filled by election or appointment, the incumbents of which may become unavailable for carrying on the powers and duties of such offices, and

(2) To adopt by legislative enactment such other legislation as may be necessary and proper for insuring the continuity of governmental operations. Notwithstanding the power conferred by this section of the constitution, elections shall always be called as soon as possible to fill any elective vacancies in any office temporarily occupied by operation of any legislation enacted pursuant to the provisions of this section.