Every city office shall become vacant upon the happening of any of the following events before the expiration of the term of such office.
(a) For any reason specified by state law as grounds for creating a vacancy;
(b) If the officer of the city shall absent himself continuously from the city for more than sixty (60) days without the permission of the Council;
(c) In the case of members of the Council, where such officer shall miss four (4) consecutive regular meetings of the Council, or twenty-five (25) per cent of such meetings in any fiscal year of the city, unless such absences shall be excused by the Council and the reason therefor entered in the proceedings of the Council;
(d) If the officer shall be convicted of any act constituting misconduct in office under the provisions of this charter.