(a) If a city councilmember is absent without permission from all regular city council meetings for 60 days consecutively from the last regular meeting he or she attended, his or her office becomes vacant and shall be filled as any other vacancy.
(b) Notwithstanding subdivision (a), if a city council meets monthly or less frequently than monthly and a city councilmember is absent without permission from all regular city council meetings for 70 days consecutively from the last regular meeting he or she attended, his or her office becomes vacant and shall be filled as any other vacancy.