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12.0 Glossary

Seismic Hazards Mapping Act: Legislation acted by the California legislature in April of
1997. Unlike the Alquist-Priolo Earthquake Fault Zoning Act, the Seismic Hazards Mapping
Act addresses non-surface fault rupture earthquake hazards, including liquefaction and
seismically induced landslides. The act requires the creation and publication of maps
showing areas where such impacts could occur.

Seismically induced settlement: The densification of soils resulting from seismic motion.
During strong ground-shaking, soil grains may become more tightly packed due to the
collapse of voids or pore spaces, resulting in a reduction in the thickness of the soil column.

Seismicity: The frequency or magnitude of earthquake activity in a given area.

Senescence: Growing old; aging (www.dictionary.com).

Sensitive Receptors: Sensitive receptors are people or institutions with people that are
particularly susceptible to illness from environmental pollution, such as the elderly, very
young children, people already weakened by illness (e.g., asthmatics), and persons engaged
in strenuous exercise.

Septic System: A sewage-treatment system that includes a settling tank through which
liquid sewage flows and in which solid sewage settles and is decomposed by bacteria in the
absence of oxygen. Septic systems are often used for individual-home waste disposal where
an urban sewer system is not available.

Setback: The horizontal distance between the property line and any structure.

Settlement: (1) The drop in elevation of a ground surface caused by settling or compacting.
(2) The gradual downward movement of an engineered structure due to compaction.
Differential settlement is uneven settlement, where one part of a structure settles more or at
a different rate than another part.

Shall: In accordance with Section 15005 of the State CEQA Guidelines, “shall” or “must”
identifies a mandatory element which all public agencies are required to follow.

Shatter: A splintered or fragmented condition.

Shears: The deformation of a rock in response to compressive stress resulting in the
formation of particular textures.

Shopping Center: A group of commercial establishments, planned, developed, owned, or
managed as a unit, with common off-street parking provided on the site.

Short-Term Noise: Noise from a temporary noise source that would occur for a limited
period of time such that a substantive reduction in the quality of the receptor’s environment
is not realized.

Should: In accordance with Section 15005 of the State CEQA Guidelines, “should” identifies
guidance provided by the Secretary for Resources based on policy considerations contained

R:\Projects\PAS\CEN\000306\Draft EIR\12.0_Glossary-051017.docx 12-71 Centennial Project
Draft EIR