The general court shall have full power and authority to provide 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 in periods of emergency resulting from disaster caused by enemy attack, and to adopt such other measures as may be necessary and proper for insuring continuity of the government of the commonwealth and the governments of its political subdivisions.