RCW 42.14.050

In the event that the executive head of any city or town is unavailable by reason of a catastrophic incident to exercise the powers and discharge the duties of the office, then those members of the city or town council or commission available for duty shall by majority vote select one of their number to act as the executive head of such city or town. In the event that a catastrophic incident reduces the number of city or town councilmembers or commission members, then those members available for duty shall have full power to act by majority vote of those present.