As used in this chapter:
(a) “City” and “county” includes the City and County of San Francisco.
(b) “Geotechnical report” means a report prepared by a certified engineering geologist or a civil engineer practicing within the area of his or her competence, which identifies seismic hazards and recommends mitigation measures to reduce the risk of seismic hazard to acceptable levels.
(c) “Mitigation” means those measures that are consistent with established practice and that will reduce seismic risk to acceptable levels.
(d) “Project” has the same meaning as in Chapter 7.5 (commencing with Section 2621), except as follows:
(1) A single-family dwelling otherwise qualifying as a project may be exempted by the city or county having jurisdiction of the project.
(2) “Project” does not include alterations or additions to any structure within a seismic hazard zone which do not exceed either 50 percent of the value of the structure or 50 percent of the existing floor area of the structure.
(e) “Commission” means the Seismic Safety Commission.
(f) “Board” means the State Mining and Geology Board.