California Code, Health and Safety Code - HSC § 19162

(b)(1) Notwithstanding the provisions of Section 19100, 19150, or any other provision of law, the governing body of any city, city and county, or county may, by ordinance, establish building seismic retrofit standards applicable to the seismic retrofit of any buildings identified pursuant to paragraph (2) of subdivision (a) of Section 19161 by the city, city and county, or county as being potentially hazardous to life in the event of an earthquake. Any standards established pursuant to this section shall apply until the effective date of building standards adopted by the California Building Standards Commission relating to the retrofit of existing buildings, if any, at which time the standards adopted by the commission as amended by the city, county, or city and county pursuant to Section 17958.5 shall apply.

(2) A local ordinance establishing building seismic retrofit standards applicable to soft story residential structures adopted before January 1, 2006, shall remain in full force and effect until the effective date of building standards adopted by the California Building Standards Commission relating to the retrofit of existing buildings unless the city, county, or city and county after January 1, 2006, adopts an ordinance pursuant to paragraph (1).