These regulations shall govern the exercise of city,
county and state agency responsibilities to identify and
map seismic hazard zones and to mitigate seismic hazards
to protect public health and safety in accordance with
the provisions of Public
Resources Code, Section 2690 et seq. (Seismic Hazards
Mapping Act).
Authority cited: Public
Resources Code Section 2695
Reference: Public
Resources Code Section 2695(a)(1)and (3)-(5)
(a) "Acceptable Level"
means that level that provides reasonable protection of
the public safety, though it does not necessarily ensure
continued structural integrity and functionality of the
project.
(b) "Lead Agency" means
the city, county or state agency with the authority to
approve projects.
(c) "Registered civil
engineer" or "certified engineering
geologist" means a civil engineer or engineering
geologist who is registered or certified in the State of
California.
Authority cited: Public
Resources Code Section 2695
Reference: Public
Resources Code Sections 2690-2696.6
(a) The Department of Conservation, Division of Mines
and Geology, shall prepare one or more State-wide
probabilistic ground shaking maps for a suitably defined
reference soil column. One of the maps shall show ground
shaking levels which have a 10% probability of being
exceeded in 50 years. These maps shall be used with the
following criteria to define seismic hazard zones:
(1) Amplified shaking hazard zones shall be delineated
as areas where historic occurrence of amplified ground
shaking, or local geological and geotechnical conditions
indicate a potential for ground shaking to be amplified
to a level such that mitigation as defined in Public Resources Code
Section 2693(c) would be required.
(2) Liquefaction hazard zones shall be delineated as
areas where historic occurrence of liquefaction, or local
geological, geotechnical and ground water conditions
indicate a potential for permanent ground displacements
such that mitigation as defined inPublic Resources Code
Section 2693(c) would be required.
(3) Earthquake-induced landslide hazard zones shall be
delineated as areas where Holocene occurrence of
landslide movement, or local slope of terrain, and
geological, geotechnical and ground moisture conditions
indicate a potential for permanent ground displacements
such that mitigation as defined inPublic Resources Code
Section 2693(c)would be required.
(b) Highest priority for mapping
seismic hazard zones shall be given to areas facing
urbanization or redevelopment in conjunction with the
factors listed in Section
2695(a)(2)(A), (B), (C) and (D) of the Public Resources
Code.
Authority cited: Public
Resources Code Section 2695
Reference: Public
Resources Code Section 2695(a)(1)
(a) The Mining and Geology Board shall provide an
opportunity for receipt of public comments and
recommendations during the 90-day period for review of
preliminary seismic hazard zone maps provided by the Public Resources Code
Section 2696. At least one public hearing shall be
scheduled for that purpose.
(b) Following the end of the review period, the Board
shall forward its comments and recommendations, with
supporting data received, to the State Geologist for
consideration prior to revision and official issuance of
the maps.
Authority cited: Public
Resources Code Section 2696
Reference: Public
Resources Code Section 2696
The following specific criteria for project approval
shall apply within seismic hazard zones and shall be used
by affected lead agencies in complying with the provisions of the Act:
(a)A project shall be approved
only when the nature and severity of the seismic hazards
at the site have been evaluated in a geotechnical report
and appropriate mitigation measures have been proposed.
(b) The geotechnical report shall
be prepared by a registered civil engineer or certified
engineering geologist, having competence in the field of
seismic hazard evaluation and mitigation. The
geotechnical report shall contain site-specific
evaluations of the seismic hazard affecting the project,
and shall identify portions of the project site
containing seismic hazards. The report shall also
identify any known off-site seismic hazards that could
adversely affect the site in the event of an earthquake.
The contents of the geotechnical report shall include,
but shall not be limited to, the following:
(1) Project description.
(2) A description of the geologic and geotechnical
conditions at the site, including an appropriate site
location map.
(3) Evaluation of site-specific seismic hazards based
on geological and geotechnical conditions, in accordance
with current standards of practice.
(4) Recommendations for appropriate mitigation
measures as required in Section
3724(a), above.
(5) Name of report preparer(s), and signature(s) of a
certified engineering geologist and/or registered civil
engineer, having competence in the field of seismic
hazard evaluation and mitigation.
(c)Prior to approving the
project, the lead agency
shall independently review the geotechnical report to
determine the adequacy of the hazard evaluation and
proposed mitigation measures and to determine the
requirements of Section 3724(a),
above, are satisfied. Such reviews shall be conducted by
a certified engineering geologist or registered civil
engineer, having competence in the field of seismic
hazard evaluation and mitigation.
Authority cited: Public
Resources Code Section 2695
Reference: Public
Resources Code Section 2695(a)(3)(A), (B), and (C)
See also: Guidelines
for Evaluating and Mitigating Seismic Hazards in
California
For a specific project, the lead
agency may determine that the geological and
geotechnical conditions at the site are such that public
safety is adequately protected and no mitigation is
required. This finding shall be based on a report
presenting evaluations of sites in the immediate vicinity
having similar geologic and geotechnical characteristics.
The report shall be prepared by a certified engineering
geologist or register civil engineer, having competence
in the field of seismic hazard evaluation and mitigation.
The lead agency shall
review submitted reports in the same manner as in Section 3724(c) of this
article. The lead agency
shall also provide a written commentary that addresses
the report conclusions and the justification for applying
the conclusions contains in the report to the project
site. When the lead agency
makes such a finding, it may waive the requirement of a
geotechnical report for the project. All such waivers shall be
recorded with the county recorder and a separate copy,
together with the report and commentary, filed with the
State Geologist within 30 days of the waiver.
Where to file a waiver
Authority cited: Public
Resources Code Section 2695
Reference: Public
Resources Code Section 2697(a)(5)
See also: Guidelines
for Evaluating and Mitigating Seismic Hazards in
California, Chapter 7
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