HomeMy WebLinkAbout1975-04-01; City Council; 3283-1; Geologic and Seismic Safety of the General PlanAgenda B il No. 3283 - ^ppiement #1 >"-,— " Date; April
Referred to:
SubjectZGeologric and Seismic Safety Element of the General Submitted by:
Plan (GPA-30) '
Applicant: city of Carlsiad
Statement of the Matter: The city Council at your adjourned meeting of March 10
1975, directed the City Attorney to prepare the necessary documents approving
the Geologic and Seismic Safety Element of the General Plan (GK&-30) . The
resolution approving the Element and a copy of the final draft, incor-
porating the minor changes directed by the Council, are attached.
Exhibit:
1. Geologic and Seismic Safety Element (Text marked Exhibit A, dated March
1975, and maps marked Exhibit B, dated July, 1973)
2. Planning Commission Resolution No. 1126 recommending approval of the
Geologic and Seismic Safety Element of the General Plan (GPA-30)
3. City Council Resolution No. 3&3*S" amending General Plan.
+
Staff Recommendations to City Manager: .
Staff recommends that the Geologic and Seismic Safety Element of the General
Plan be approved for reasons outlined in Planning Commission Resolution No.
1126. If the City Council concurs, your action is to adopt Resolution
~
AS No.Date: April 1, 1975
City Manager's Recommendation
Concur with staff recommendation.
Council Action
4-1-75 Resolution #3625 was adopted, approving the Geologic and Seismic
Safety Element of the General Plan (GPA-30).
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RESOLUTION NO. 3625
A RESOLUTION OF THE CITY COUNCIL OF THE
CITY OF CARLSBAD, CALIFORNIA, AMENDING
THE GENERAL PLAN BY THE ADOPTION OF GENERAL
PLAN AMENDMENT (GPA-30) ADOPTING A GEOLOGIC
AND SEISMIC SAFETY ELEMENT AS A PART OF THE
GENERAL PLAN OF THE CITY OF CARLSBAD.
WHEREAS, the City of Carlsbad has undertaken a comprehen-
sive review of the General Plan in order to adopt all the elements
mandated by the State Planning Act, including a Geologic and
Seismic Safety Element; and
WHEREAS, the Planning Commission did on the 14th day of
January, 1975 hold a duly noticed public hearing as prescribed
by law to consider adopting said element (General Plan Amendment
No. 30) consisting of a text entitled "Geologic and Seismic
Safety Element"dated March 1975 as revised through March 13, 1975
and related maps prepared by Burkland & Associates and dated
July, 1973. Said documents are marked Exhibits A and B, respec-
tively, are on file with the City Clerk and are incorporated
by reference herein; and
WHEREAS, the element provides a General Plan Amendment
of the City of Carlsbad to be called the "Geologic and Seismic
Safety Element", which consists of an overall goal, objectives,
policies, guidelines and action programs that:
1. Identify geologic and seismic problems in the study
area; and
2. Introduce additional mitigative planning measures
into the development review practices of the City.
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WHEREAS, said amendment has met the requirements of the
City of Carlsbad Environmental Protection Ordinance of 1972 by
including a section on environmental impact considerations; and
WHEREAS, at said public hearing the Planning Commissioners
received the recommendations, objections and comments of all
individuals and parties who desired to be heard, and at the
conclusion of said hearings the Planning Commission did find
the following facts and reasons to exist which in their judgment
made said amendment necessary to carry out the intent of the
General Plan:
1. The adoption of the Geologic and Seismic Safety
Element is essential for the General Plan to be comprehensive
and effective; and
2. The Geologic and Seismic Safety Element meets the
requirements of State of California law relating to seismic
safety; and
3. The Geologic and Seismic Safety Element provides
the City of Carlsbad with a comprehensive document identifying
the seismic and geologic phenomena of the City; and
WHEREAS, the Planning Commission did adopt Resolution
No. 1126 recommending that the City Council adopt said element;
and
WHEREAS, the City Council has held a series of public
hearings to consider said plan and received and considered the
recommendations, objections and comments of all persons desiring
to be heard;
2.
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NOW, THEREFORE, BE IT RESOLVED by the City Council of
the City of Carlsbad as follows:
'• 1. That the above recitations are true and correct.
2. That the General Plan of the City of Carlsbad is
hereby amended by the adoption of a Geologic and Seismic Safety
Element consisting of a text dated March, 1975, marked
Exhibit A, and related maps dated July, 1973, marked Exhibit A,
both in a form on file in the office of the City Clerk and incor-
porated by reference herein.
PASSED, APPROVED AND ADOPTED at a regular meeting of
Carlsbad City Council held on the 1st day of April ,
by the following vote, to wit:
AYES: Councilmen Frazee, Chase, Lewis, Skotnicki
Counci Iwoman Casler
NOES: None
ABSENT: None
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/( 6-^r~*^-d d. ^'f ££\scf ,' I *^ V J^M"*^ _*»
ROBERT C. FRAZEE, ; May or
ATTEST :
^^y/l •/ ^ ///y// /^^^A^c^ " *• (s/tf^tfst^^
MARjGAKET E. ADAMS,/ City Clerk
(SEAL)
3.
the
1975
and
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W iQ,
CITY
<*
CARLSBAD
REVISION CATE
MARCH 1975
TABLE OF CONTENTS
Page
List of Tables . i
Distribution List . . 11
Summary. 11-1
Section 1. INTRODUCTION . . . . .1
A. Authority for the Geologic & Seismic
Safety Element ............. 2
B. Risk Evaluation . . .... . . .... 2
C. General Plan Relationships , .. .... ... 4
Section 2. SUMMARY OF'FINDINGS . . . . . .... ., . . 6
Section 3. GOAL AND OBJECTIVES. . .... . . ..... 9
Section 4. POLICIES, GUIDELINES & ACTION PROGRAMS ... 10
Section 5, BIBLIOGRAPHY . . . . ... ..... . . . . 15
Section 6. APPENDICES ......... . . ...... A-l
A. Geotechnical Investigations ...... A-1
1. Descriptive Geology. . . . . . . . . A-2
2. Engineering Geology ........ A-10
3. Seismic Hazards A-l8
4. Geotechnical Interpretations .... A-26
B. Glossary B-T
C. Summary of State Laws Relating to Seismic
Safety . . . . . . . . . . . . . .... C-T
D. Maps. . . . '. . . . . . ...» . . . .0
Seismic Hazards Ma?p . . ..... . . . D
Geotechnical Hazards Kap . D
Land Use Feasibility Map ....... 0
<c o.
List of Tables
Page.\ .
Table I - Slope Stability Related to Development . . . . A-13
Table II - Approximate Relationship of Earthquake
Magnitude to Intensity. ........... A-21
Table III - Suggested Investigation Procedures tor
Common Geotechnical Problems A-29
Geologic S Seismic Safety Element Distribution List
The following organizations or persons were extended
the opportunity to critique the draft element for the
purpose of maximizing the level of public and professional
input to the element:
Citizen S Professional Advisory Committee:
Mr. Allan Kelly, Chairman
Mr. Baylor Brooks .
Mr. Charles Rice
Mr. Ray Wai ton
Mr. Philip Benton
Mr. Bob Ladwig
Mr. George Long
Mr. Jack Kubota •
Mr. Frank Leeds
Mr. Robert Chaney .
Mrs. Liz Fiddler
Mr. Allan McDougall
Mr. "J" "C" Fikes
Professional:
American Institute of Architects, San Diego Section
-Southern Califqrnia Testing Lab, Inc. -~- Dennis Hannan
Structural tngineers Association • •
Scripps Institute of Oceanography, Dr. M. P. Kennedy
San Diego 'State University, Geology Department, Robert McEuen
San Diego Association of Geologists* Richard Threet
Governmental: '....•-''
Comprehensive Planning .Organization, Ruth Potter
San Diego County Planning Department, Mike Wright
San Diego Coast Regional Commission, Elene Johnston
City Staff: . .
Engineering Department, Tim Flanagan, Dan Grothj Russell Morrison
Fire Department, G. W. Anear
Building Department, R. S. Osburn, Ray Green
Planning staff
/^ . rV iii
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SUMMARY
i
In 1971, the Seismic Safety Element became a required
element of the General Plan for all Cities and Counties in
the State of California. Its overall purpose is to prescribe
programs aimed at reducing geologic and seismic risk in the
City of Carlsbad by:
(1) Identifying geologic and seismic problems
in the study area;
(2) Adopting policies which introduce addi-
tional mitigative planning measures into
the development review practices of the
City.
On August 8, 1974, the Carlsbad City Council appointed
the Citizens and Professionals Advisory Committee on Seismic
Safety and Geologic Hazards. The Committee's charge was to
advise the City of Carlsbad staff during the formulation of
a Geologic & Seismic Safety Element, and to assist in the
preparation of this element of the General Plan. The
Geologic & Seismic Safety Element incorporates procedures
to minimize the loss of human life and property damage from
seismic and geologic phenomena into the planning process
of the City of Carlsbad.
The major topics addressed in the element are as
follows:
(1) Evaluation of the state-of-the-art and
existing data on the subject;
(2) Identification of an overall goal for
reducing geologic and seismic risk;
(3) General guidelines regarding the level
or nature of acceptable risk;
(4) Policies and guidelines for present and
future programs aimed at reducing geologic
and seismic risk to existing and proposed
structures; *
(5) Generalized geologic mapping which discloses
known hazardous sites as of July, 1973.
Section 1
I INTRODUCTION1 .
The California Division of Mines and Geology estimates
that in California before the year 2000, unless significant
measures are taken, approximately $20 billion in earthquake-
related damage could occur and the loss of life could be In
the thousands. However, most of this loss is preventable if
T5measures are taken now. Every city and county in California
must meet this challenge of reducing geologic and seismic
risk by giving' serious consideration to the meaning and con-
tent of the seismic safety element.
The purpose of the Geologic & Seismic Safety Element
is to prescribe programs aimed at reducing the present geo-
logic and seismic risk in the City of Carlsbad by adopting
policies intended to further improve planning, building, and
development practices. The element will serve as an Infor-
mational resource in the evaluation of development proposals.
The objective is to reduce the level of geologic and seismic
risk by identifying problems and introducing additional mftt-
gative planning measures into the development practices of
the City. The major sections of the element include the
following: (1) Background data and findings on the City's
geology indicating types of programs'needed; (2) Goal and
objectives to guide the creation of geologic and seismic pro-
grams;and (3) Policies, guide!ines, and action programs for
geologic and seismic safety implementation.
A. Authority for the Geologic and Seismic Safety Element
In response to public concern calling for affirmative
action to reduce the loss of life and widespread structural
damage from earthquakes, Section 65302 of the California
Government Code was amended in 1971 to require the addition
of a Seismic Safety Element as part of the General Plan of
each community. Subsection (f) of Section 65302 requires
that co_unt:i_es and cities prepare:
...a seismic safety element consisting of
an identification and appraisal of seismic
hazards such as susceptibility to surface
ruptures from faulting, to ground shaking,
to ground failures, and to effects of seis-
mically induced waves such as tsunamis and
seiches.
The seismic safety element shall also include
an appraisal of mudslides, landslides, and
slope stability as necessary geologic hazards .
that must be considered simultaneously with
other hazards, such as possible surface rup^
tures from faulting, ground shaking, ground
failure, and seismically induced waves.
B. Risk Evaluation and Guidelines
There is some risk involved in almost every human
activity. The basic objective of seismic risk is to reduce
the loss of life and property damage due to seismic activity
to an acceptable level. Since it is not possible to „
eliminate all risk to life and property, each community
must decide what level of risk it is willing to accept.
The Council of Intergovernmental Relations guidelines
w . .
for the Seismic Safety Element defines "acceptable risk" as
. - .
follows: •
The level of risk below which no specific
action by local government is deemed to be
necessary to protect life and property.
/ The determination of acceptable risk is applicable
not only to future planning decisions, but it is applicable
also to the evaluation of risks associated with existing
buildings and land uses. High risks in existing structures
may be lowered to a level of acceptable risk by means of
physical alteration (a structural hazard abatement program),
relocation and/or demolition of existing structures, and
the change of levels of use of structures (from high to low
occupancy). The following general guidelines will serve
as a framework for decision-making in determining the level
of acceptable risk: .
1. Emergency services and public utilities required
to provide emergency services during disasters
should have a very low level of risk. These
include hospitals, medical clinics, fire and
police stations, power plants, water and sewerage
facilities, telephone lines, electrical lines,
major highways, dams, reservoirs, etc.
' 2. Structures of involuntary use, i.e. nursing homes,
convalescent homes, schools, etc., where the
individual has no choice in using the facility,
should require a level of acceptable risk that
is very low.-
3. High occupancy buildings should be required to
have a low risk exposure. These include large
office buildings, theaters, churches, large
industrial and shopping centers, multKstory, multi-
occupancy buildings, etc.
The entire Geologic & Seismic Safety Element is an
attempt to recognize and define risks within the limits of
•present knowledge and prescribe programs to mitigate or
lessen that risk. In structures where the risk could involve
the loss of life, measures such as building occupancy limita-
tion, renovation or removal programs should be undertaken.
A recommendation for a structural hazards abatement program
is given in Section 4. Additionally, it is recommended that
in all future development proposals, consideration be given
to the long range physical and economic impact to the City in
the event of a geologic or seismic occurrence.
C, General Plan Relationships
The Geologic.and Seismic Safety Element contributes
information on the comparative safety of using lands for
various purposes, types of structures, and occupancies. It
provides essential information pertaining to Land Use, Housing,
Open Soace, Circulation and Safety Elements. The Safety
Element must include a response plan for all types of disas-
ters and emergencies that might occur in the City. Therefore,
an earthquake and emergency response plan should become a
portion of the safety Element with input on geologic and
seismic hazards being drawn from the Geologic and Seismic
Safety Element. The Geologic and Seismic Safety Element 1s
also related to various environmental factors, as follows:
* Physical - geologic hazards can be a prime determinant
of land use capability
* Social - may provide basis of evaluating costs of
social disruption, including the possible
loss of life due to earthquakes and Identifies
means of mitigating social impact
* Economic - cost and benefits of using or not using
areas related to potential damage or cost
of overcoming hazards
1 ' • •' ("' ' • 5
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In addition, the Geologic and Seismic Safety Element
, t
f provides a basis for evaluating'environmental impacts of
proposed projects in relation to slope stability, possible
structure failure, etc.
c
Section 2
I SUMMARY OF .FINDINGS
The City of Carlsbad contracted with Burkland and
Associates, Engineering Geologists, for the preparation of
a geotechnical report and related maps. Burkland and Asso-
ciates' responsibility was to gather and evaluate the geologic
.- - •' *and seismic characteristics of the Carlsbad study area.
The data is provided in the report, "Geotechnical Investi-
gations for General Plan Revisions, Carlsbad, California",
and is on file in the City Planning Department. Assistance
was also provided by a Citizen and Professional Advisory
Committee on Geology and Seismic Safety. This background
forms the basis for the policies and implementation program
recommended in Section 4.
The following summary findings were presented by
Burkland and Associates based on their research, study,
and evaluation of the Carlsbad study area:
1. On the basis of existing geotechnical
information, approximately 85% of the
study area could be utilized for urban
activity following routine geotechnical
investigations of individual development
sites. *
See map, pg. 8, Carlsbad Study Area
** » 'Percentages stated throughout the findings are
estimates of general geographic distribution, and
are based on available data.
2. About 15% of the study area has geologic
conditions which would require that detailed
geotechnical investigations be conducted at
individual development sites to determine
feasibility for urban use.
3. There are no known active faults in the
study area. There are at least six faults
in the study area which have not yet been,
investigated for potential activity.
4. Erosion and siltation are existing geotechnical
problems.
5. Potential geotechnical problems include slope
instability, excavation of hard rock, drainage,
flooding, compressible soils, and secondary
seismic effects.
6. Those portions of the study area underlain by
deep, soft, saturated soils are susceptible
to the seismic hazards of liquefaction, lurch
cracking, lateral spreading and local subsidence.
7-. The beach areas are susceptible to the seismic
hazard of tsunami, and the lagoon areas are
susceptible to the seismic hazard of seiche.
8. No Special Studies zones as required by the
Alquist-Priolo Geologic Hazards Act have been
-delineated within the City by the State Geologist,
and, based on the information developed in
this study, none are expected. .
A more detailed analysis of the geotechnical problems
of the Carlsbad study area is presented in Appendix A, The
majority of the information presented is based on the
geotechnical report prepared by Burklahd and Associates.
8
Bueno Vista Lonoon
Aguo Hedionda Lagoo
Baliquifos Lagoon
Olivenhoin Road
CARLSBAD STUDY AREA
>*»•,
Section 3
GOAL AND OBJECTIVES
Goal The Geologic and Seismic Safety Element goal is
to minimize the loss of life, injury to health,
and destruction of property in the City of
Carlsbad by implementing necessary planning
and development policy recommendations that
give consideration to potential geologic and
seismic occurrences and their long range impact
on the community.
Objectives - To accomplish the above goal, the following general
objectives outline overall programs:
1. Establish a project review process that
allows consideration of seismic and geo-
logic hazards at the earliest possible
point in the development process, preferably
before comprehensive engineering work has
commenced.
.2. Develop a program to identify existing
hazardous structures in the City of Carlsbad.
These structures shall be abated or modified
within a reasonable period of time, or their
usage or occupancy modified when loss of
1ife is a factor.
3. Sponsor a public information program in
cooperation with the County of San Diego
to increase public awareness of geologic
and seismic hazards.
4. Institute policies and programs that
observe physical constraints in the
City of Carlsbad regarding seismic and
geologic problems and integrate them into
the planning and development review process.
o*•—.<-">
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Section 4
'< POLICIES, GUIDELINES & ACTION PROGRAMS
The following policies, guidelines, and action programs
are deemed necessary to carry out the goal and objectives
of the Geologic & Seismic Safety Element. Basically, they
are aimed at reducing the risks associated with seismic
and geologic hazards as identified in this element.
Policies
1. It shall be the policy of the City of Carlsbad to
utilize the guidelines contained in the Geologic
& Seismic Safety Element when reviewing development
proposals to determine the presence of any geologic
and/or seismic problems, and to make recommendations
for appropriate mitigative measures at the earliest
possible point in the development review process.
2. It shall be the policy of the City of Carlsbad to
follow through with the action programs outlined
in the Geologic & Seismic Safety Element as soon
as possible by adopting a work program* and by
establishing priorities and time schedules for
implementing the programs.
Guidelines
1. Appraisal of Individual Development Projects:
a. The City Engineer may waive soils report requirements if other
reports and/or investigations conducted in the vicinity of the
development site have indicated the soils conditions are stable
and further investigations are not necessary. Routine soils reports
shall be conducted at all development sites prior to grading orconstruction unless, Map #6, (Land Use Feasibility) contained here-
in, or specific conditions known to the City Engineer, requires
a more specific or detailed geologic investigation.
t -b. Detailed geologic inyestinations shall be conducted
at sites where the construction of critical struc-*
tures (high occupancy structures and those which
must remain in operation during emergencies)
Tl
and structures over four stories are under consideration
c. The maps contained in Appendix D (Seismic Hazards,
Geotechnical Hazards, and Land Use Feasibility), in
addition to Table III, page 29 of the Appendix,
shall be used as generalized guidelines in determining
the type of geotechnical report to be required as
well as the extent of the report.
*
d. Section 11549.5 (c,d) of the Business and Professional
Code makes a provision that subdivision maps may be
denied if a project site is not physically suitable
for either the type or density of a proposed develop-
ment. This provision should be enforced, where
applicable, based on information contained in the;
Geologic & Seismic Safety Element.
2. Evaluation of Slope Stability in the Development Review
Process:
a. A qualified professional shall review grading plans
and inspect areas of excavation during and after
grading to evaluate slope stability. It is impera-
tive in areas of known landslides to ascertain
slope stability before and after development. The
following determinations should be made in cases
where known landslides exist: depth to slide
plane, rock types, presence of clay seams, ground-
water conditions, stability under earthquake
conditions.
b. Areas where slope stability is a problem shall be:
investigated and evaluated by qualified professionals
on an individual basis, and appropriate remedial
measures taken. Table I, page 13 of the Appendix,
which relates development activities to slope
stability problems, shall be used as a guideline
for determining appropriate remedial measure(s).
3. Measures to Alleviate and Remedy the Problems of
Erosion and Siltation in the Development Review Process:
a. Investigation and evaluation of individual proposed
building and development sites will be necessary to
determine which measure(s) will be most appropriate
in each situation. The following are recommended
guidelines to reduce the rates and effects of
erosion and siltation:
(1) leave soil and vegetation undisturbed, wherever
possible
* (Effective March 1, 1975, the section number will be changed to 66474
c,d)
(2) contour and plant slopes
(3) chemically treat soils to increase stability and
resistance to erosion
(4) construct retaining structures on slopes
! (5) construct weirs and check dams on streams
(6) open lagoons to the ocean
(7) construct silt traps and settling basins in
drainage systems
(8) construct protective structures along the base
of sea cliffs
b. Surface water should be diverted away from cut and
fill slopes in the La Jolla Group rocks and soils
because of their susceptibility to erosion. Silt
traps and settling basins should be provided down-
slope of any grading and construction in the La
Jolla Group, if deemed necessary by the City Engineer..
(See Appendix, page A-6).
4. Consideration of Seismic Design in Construction:
a. Individual project structural engineers should be
aware of the ground response characteristics of
the site in their design and construction speci-
fications .
b. When critical structures (high occupancy struc-
tures and those which must remain in operation
during emergencies) are being considered, geo-
technically qualified professionals should make
recommendations regarding appropriate design
criterion.
c. Critical structures shall be prohibited directly
across known fault locations.
Action Programs
1 . Review and Revision of Development Regulations and
Procedures : ' '
a. All applicable City codes, ordinances, and policies
shall be reviewed and revised, where necessary, to
insure compatibility with the Geologic & Seismic
Safety Element, e.g. grading ordinance, environ-
mental protection ordinance
13
b. Procedures shall be established to efficiently
process required geotechnical reports. All reports
dealing with geology should be produced, reviewed,
and approved by geotechnically competent persons.
However, only in those cases where City staff
cannot adequately review and assess geologic
reports should outside consulting help be sought.
2. Preparation of Application for National Flood Insurance:
The City of Carlsbad shall undertake a program as soon
as possible for the mapping of all flood plain and flood-
way areas within tht: study area. In addition, an appli-
cation shall be prepared for the National Flood Insurance
program. Flood plain overlay zoning shall be applied
to appropriate areas within the City.
3. Dangerous Buildings Abatement Program and Related
P u b1i c In forma t i on Dissemination:
a. Existing hazardous structures shall be posted
as soon as possible with appropriate bilingual
warning signs to adequately inform the public
of the risk involved.
b. A program to identify and evaluate existing
hazardous structures shall be undertaken.
This work should include the assistance of a
structural engineer experienced in this field.
The following structures shall be identified:
(1) Structures,built prior to 1933;
(2) Structures built prior to 1958, which exhibit
identifiable hazard to human life;
(3) Public buildings, especially one with emergency
service potential; and
(4) Major public utilities.
Hazardous structures shall be abated or modified
when loss of life is a potential factor. If the
demolition of residential structures is required,
an adequate housing relocation program shall be
instituted.
In addition, recommendations should be addressed
to unreinforced masonry, aged and dilapidated
structures and structurally unstable architectural
appendages and ornaments, such as parapets or marques.
14
4. Collection, Maintenance, an.d Update of Geologic and
Seismic Information:
a. The City of Carlsbad shall expand its data base
in geology and related disciplines and should,
in addition, cooperate in a region-wide program,
/ if one is established. The City's program will
I include the compilation of information produced
through site study investigations. Study site
locations shall be identified on a map as they
occur. The program will, as a minimum, include
the collection of soils, geologic, seismic, and
environmental impact reports to be incorporated
into a uniform information system or data bank.
b. Because knowledge in the geotechnical field is
rapidly expanding, the information contained in
the Geologic & Seismic Safety Element should
be reviewed on a regular and frequent (annual)
basis. This element should be comprehensively
revised every five years or when substantially
new scientific evidence becomes available.
c. Because of the generalized nature of the enclosed
geotechnical maps (dated July 1973), additional
geologic field reconnaissance and mapping should
be undertaken, .
d. The City of Carlsbad should encourage the Inter-
national Conference of Building Officials to make
changes in the Uniform Building Code that will
recognize the Structural Engineers Association of
California Seismology Committee's recommendations
and other new technology. This should be accom-
plished in cooperation with the County of San
Diego.
D
15
Section
BIBLIOGRAPHY
1. Abbott, P. L., 1963, Tertiary Marine Enbayments of the
Vista Region, Unpublished Senior Research, San Diego
State Uni versity.
2. Bandy, Orville L., 1951, Upper Cretaceous Foraminifera
From the Carlsbad Area, San Diego County, California,
Journal of Paleontology, Vol. 25.
3. Berg, Glen V., The Skopje, Yugoslavia Earthquake,
(American Iron and Steel Institute:New York), 1963.
4. Blanc, R. P., 1968, Natural Slope Stability as Related
To Geology, San Clemente Area, Orange and San Diego
Counties, California, California Division of Mines
and Geology, Special Report 98.
5. Brune, James N., 1973, Seismic Risk at Rancho• S-arr.Die-go,•.•
Scripps Institute of Oceanography, U. S. San Diego.
6. , 1973, Seismic Risk From Earthquakes In
or Near San Diego, Scripps Institute of Oceanography,
IEC. San Diego.
7. , 1973, Seismic Hazard At Hens haw Dam,
Scripps Institute of Oceanography, U. C. San Diego.
8. California Department of Water Resources, 1967, Ground-
water Occurrence' and Quality, San Diego Region, Depart-
ment of Water Resources Bulletin, Vol. 106-2.
9. ,1963, San
Diego County Flood Hazard Investigation, .Bulletin 112,
Appendix A, Regional Flood Frequency Analysis.
10. • ' . . , 1965, Hydro^
logic Data, Vol. 5, Southern Cal., Appendix C,
Groundwater Measurements.
11. ____^___^ , 1969, Hydro*
"logic Data, Bulletin 130-67, Vol. 5, Southern Cal.,
Appendices: A - Climatological Data, B - Surface
Water Measurements, C - Groundwater Measurements,
D - Surface Water Quality, E - Groundwater Quality,
F - Waste Water Data.
(C • O '6
12. California Department of Water Resources, 1971, Hydr o -
logic Data. Bull. 130-69, Vol. 5, Southern Cal.
13. _, 1969, Interim
Report on Study of Beach Nourishment Along the Southern
California Coastline, Southern District.
14. , 1963, County
Report No. 3, San Diego County.
15. California Division of Mines and Geology, Bulletin 198,
Urban Geology, Master Plan for California, Sacramento,
California, 1973.
16. California Council on Intergovernmental Relations, General
Plan Guidelines, September 20, 1973.
17. Comprehensive Planning Organization, Model Seismic Safety
Element, February, 1974.
18. Cooper-Clark and Associates, 1973, Geotechnlcal Aspects
for the Proposed San Diego Region Model Seismic Safety
Element for the Comprehensive Planning Organization
of the San Diego Region, California. "~
19. Ellis, A. J., 1919, Geology and Groundwaters of the
Western Part of San Diego County, U. S. Geological
Survey, Water Supply Paper, Vol. 446.'
20. Emery, K. 0., 1941, Rate of Surface Retreat of Sea Cliffs
Based on Dated Inscription, Science, Vol. 93.
2T. Environmental Development Agency, 1973, Natural Resource
Inventory of San Diego County, San Diego County.
22. Euge, K. M., Miller, D. G., and Palmer, L. A., 1973,
Evidence for^a Possible On-Shore Extension of the
Rose Canyon Fault in the Vicinity of Oceanside,
Calfornia, Geological Society of America Abstracts,
Vol. 5, No. 1.
23. Fairbanks, H. W., 1893, Geology of San Diego County;
Also Portions of Orange and San Bernardino Counties,
California Division of Mines and Geology, Report of
the State Mineralogist, Vol. 11.
24. Fife, D. L., Minch, J. A. and Crampton, P., 1967, Late
Jurassic, Age of the Santiago Peak Volcanics, CaTlforntcu
Geological Society of America Bulletin, Vol. 78. """"""
' 17
25. Flawn, Peter T., Environmental Geology: Conservation,
Land-Use Planning, and Resource Management.(Harper
& Row": New York), 1970/ '.
26. Ganus, William J., 1973, Problems Related to the Evalua-
tion of Groundwater Resources of the Crystalline Rock
/ Area. San Diego County, California, in Association of
I Engineering Geologists Guidebook.
27. Geotechnical Investigation for General Plan Revisions,
Carlsbad, California, Burkland and Associates, July,
1973.
28. Grading Codes Advisory Board and Building Code Committee,
1973, Geology and Earthquake Hazards - Planners Guide
to the Seismic Safety Element, Association of Engineering
Geologists, Southern California Section.
29. Greensfelder, R. W., 1973, Crustal Movement Investigations
in California, California Division of Mines and Geology,
Special Pub!ication No. 37.
30. Hannan, Dennis L., Reconnaissance Mapping of Tertiary-
• Quaternary Faulting in Oceanside-Carlsbad, California*
The Geological Society of America Abstract, Vol. 6,
No. 3, February, 1974.
31. Hart, Michael W., 1973, Landslide Provinces of San Diego
County, California, in Association of.Engineering
Geologists Guidebook.
32. Hertlein, L. G., 1954, Geology of Oceanside - .San-01 ego-
Coastal Area, Southern California, California Division
of Mines and Geology Bulletin, Vol. 170. •
33. Housner, G. W., 1970, Analysis of Ground Motlons^at San
Onofre Nuclear Generating Station, April 9, 1968,
Seismological Society of America Bulletin, Vol. 60.
34. Hungtington Beach, City of, Geotechnical Inputs, prepared
by Leighton-Yen and Associates, February, 1974.
35. Inglewood, City of, Seismic Safety Element, Allan Colman,
Director. •
36. Jahns, R. H., 1954, Geology of the Peninsular Range
Province, Southern California and Baja California,
California Division of Mines and Geology, Bulletin,
Vol. 170.
37. Joint Committee on Seismic Safety to the California
State Senate Legislature, Meeting the Earthquake
Challenge, Parts 1, 2, 3, Final Report to the
California State Legislature, February, 1974.
/
38. Kennedy, Michael P.. and Moore, G. W. , 1971 .- Stratigraphic
Relations of Upper Cretaceous and Eocene Formations,
San Diego Coastal Area, California, American Association
of Petroleum Geologists Bulletin, Vol. 55.
39. Kennedy, Michael P., 1973, Bedrock Lithologies, San Diego
Area, California, San Diego Association of Geologists
and the Association of Engineering Geologists, 1973
Field Trip Guidebook.
40. __ _ _ , 1971, Stratigraphy and Structure of
the Area Between Oceanside and San Diego, California,
Geologic Road Log, University of California, Riverside,
Miscellaneous Contribution No. 1.
41. Larsen, E. S., Jr., 1948, Batholith and Associated Rocks
of Corona, Elsinore and San Luis Rey Quadrangles,
Southern California, Geological Society of America
Memoir No. 29. ~~
42. _ _ _ , 1954, The Batholitfrof Southern
California, California Division of Mines and Geology,
Vol. 170.
43. Li ska, R. D., 1964, Geology and Biostratigraphy of letter*
box Canyon, San Diego County, Unpublished Master's
Thesis, San Diego State University.
44. Lung, R. and Procter, R., Editors, 1966, Engineering
Geology in Southern Cal ifornia , Association of Engin-
eering Geologists , Special Publication.
45. Lyle, John, Editor, 1971, The Coastal Lagoons of San
Diego County, Laboratory for Exp<
California Polytechnic Institute
46. McEven, R. B. and Pinckney, C. J., 1972, Seismic Risk
in San Diego, Transcript of the San Diego Society
• of Natural History, Vol. 17, No. 4.
47. Merriam, R. H., 1951, Groundwater in the Bedrock in
Western San Diego County, California Division of
Mines and Geology, Bulletin, Vol. 159.
48. Miller, W. J., 1935, Geomgrphology of the SouthernPeninsular Range of California, Geological Society
of American Bulletin, Vol. 46.
49. Moore, G. W. 1972, Off-Shore Extension of the^Rose
Canyon Fault, San Diego, U. S. Geological Survey
Professional Paper 800-C.
50. Nichols, D. R. and Buchanan-Banks, J. M., 1974, Setsroic
Hazards and Land-Use Planning, U. S. Geological Survey»
Circular 690.
51. Nichols, D. R., and Campbell, C. C., Editors, 1974,
Environmental Planning and .Geology, U. S. Department
of Housing and Urban Development and U. S. Department
of the Interior'.
52. Nordstrom, C. £., 1973, Beach and Cliff Erosion in San
; Pieao County, California, San Diego Association of
'i Geologists and the Association of Engineering Geology,
1973 Field Trip Guidebook.
53. Peterson, G. L., 1970, Geology of Peninsular Ranges,
California Division of Mines and Geology, Mineral
Information Series, Vol. 23.
54. San Diego Coast Regional Commission, 1974, Coastal
Geology and Geological Hazards, unpublished.
55. San Diego, County of, Seismic Safety Element, October*
1974".
56. San Diego, City of, Seismic Safety Element. 1974.
57. Storie, R. E., 1933, Classification and Evaluation of
the Soils of Western San Diego County, California
Agricultural Experiment Station Bulletin, Vol. 552.
58. Tri-Cities, Seismic Safety and Environmental Resources
Study for the General Plan, El Cerrito. Richmond,
and San Pablo, California, September 1, 1973, Dean
Armstrong, Project Director.
59. U. S. Army Corps of Engineers, 1957, Oceanside, Ocean
Beach, Imperial Beach and Coronado, San Diego, •
California, Beach Erosion Control Study, 84th Congress,
Second Session, House Document No. 399.
60. , 1966, Technical Report
No. 4, Shore Protection Planning and Design.
61. , Los Angeles District,
July. 1973, Floodplain Information for Buena Vista
Creek, Pacific Ocean to Vista, San Diego County"!
California.
62. , Los Angeles District,
July, 1973, Floodplain Information for Agua Hedtondar
Creek, Pacific Ocean to Buena, San Diego County,
California.
63. -..,...* '-os Angeles District,
April. 1971, Floodplain Information for San ftarcos
Creek and Vicinity of San Marcos, San Diego County,
California.
20
64. U. S. Department of Agriculture, Soil Conservation Service
Soil Survey for the San DJego Area, California, December,
1973.
65. U. S. President, Office of Emergency Preparedness, Disaster
Preparedness, Supt. of Documents, #4102-0006, 1972.
66. Vaughan, T. W., 1932. Rate of Sea Cliff Recession on the
Property of the Scripps Institute of Oceanography at
La J o 1 1 a , California, Science, Vol. 75.
67. Woodford, A. 0., 1925, The San Onofre Breccia, University
of California Publications in Geological Sciences,
Vol. 15.
68. Woodward-Gizienski & Associates and F. Beach Leighton &
Associates, Seismic Safety Study for the City of San
Diego, May 17, 1974.
69. Ziony, J. I., and Buchanan, J. M., 1972, Preliminary Report
on Recency of Faulting in the Greater San Diego Area,
California, U. S. Geological Survey, Open File Report
No . 1 .
c
0
A-T
Section 6
APPENDIX A
GEOTECHNICAL INVESTIGATIONS
The geotechnical background information presented in
this section was prepared primarily fay Burkland and Asso-
ciates, Engineering Geology consultants. The data upon
which their information is based were obtained in the
following manner:
1. Research and review of pertinent geologic,
soils, seismic and geotechnical studies
and maps. (Refer to #27, Bibliography).
2. Studies of stereo "aerial photographs,
Including black and white, color, high
altitude color and false-color infrared,
27
and satellite photography.
3. Surface reconnaissance of the study area,
with particular attention given to areas
with existing and potential geotechnical
problems.
4. Consultation with geotechnical experts
acquainted with the problems of the study
.27
area.
,r**X
>«*• ' W A-2
Section 6
APPENDIX A
!• Descriptive Geology
a. Topography
The study area can be divided into three distinct
topographic areas. The beach comprises less than 13. of the
City, and the terrace about 3Q%. Approximately 70$ of the
City consists of rolling hills.
The beach is very narrow. Its width does not exceed
500 feet, and is generally less than 200 feet. Approximately
a third of the coastal boundary, from Batiquitos Lagoon to
Palomar Airport Road, is sea cliffs which range from 40 to
60 feet high.
The terrace gently and uniformly declines in a
westerly direction. Maximum elevation ranges from about 40 feet
in the west to about 400 feet in the east. The terrace is cut
by the channels of four west-draining streams, three of which
empty into lagoons. A fifth west-draining stream does not
cut the terrace, but empties into one of the lagoons.
In the area of rolling hills, elevation ranges from
about 100 feet to about 1,000 feet, but 80% of the area is
less than 500 feet. Greatest relief is along the eastern
. ,
iw A 3
boundary of the study area. Here the hills are steepest,
with sharp, incised drainage divides.
5. Geologic Units, Rock Types and Soils
Map 1 GEOLOGY and Map 2 SOILS delineate the generalized
geologic and soils units occurring in the study area.* The
legend and table on each map identify the general characteris-
tics of the units. These maps are for reference use only.
They should not be used as substitutes for geotechnical inves-
tigations at proposed development sites.
(1 J Santiago Peak Volcanics (Jmv)
(They are sometimes referred to as the Black
Mountain Formation) These metavol cam" c rocks
occur predominantly in the eastern portion .of
the study area, particularly in the southeast
corner, and also in the central and northern
portion. They are fine to coarse grained, ,
Tight greenish-grey to black in color, generally
occur in outcrops on the surfaces of rounded
hills, and are locally highly fractured.
These rocks weather to light brown to red-brown
rocky silt loams (S1L) containing all sizes of
boulders. These soils are usually less than 10
feet deep, and are often expansive, that is,
they expand in the presence of moisture.
These maps are available in the Carlsbad City Planning Department
A-4
(2) Green Valley Tonal He (Kto)
This is a grey medium-grained igneous rock which
occurs in the eastern and northeastern portions
of the study area, where the topography is rela-
tively rugged. There are numerous boulders and
outcrops of this rock on the surface, Indicating
its resistance to weathering.
It weathers to reddish-brown, fine to coarse
grained sandy loams (SL1 and SL2) which can be
expansive. This soil is generally less than 10
feet deep, but it may locally extend to depths
of 25 to 30 feet.
(3)Granodiorites (Kgr)
These are light to medium pinkish-grey, massive*
igneous rocks which occur predominantly in the
rugged boulder strewn terrain of the southeast
portion of the study area.
These rocks decompose into clays (Cl), rocky
silt loams (S1L), fine to coarse sandy loams
(SL1 and SL2), and are light to dark reddtsh-
brown. Depth is quite variable, but usually
less than 10 feet. However, in some areas of
highly developed fracture systems, soils reay
extend to depths of 30 to 4-0 feet or more*
Some of these soils are likely to be expansive.'
'****>
(4) Lusardi Formation (Ks2)
This ia a massive conglomerate rock occurring
mainly in the east central part of the study
area. It consists of various sizes and colors
of cobbles and boulders in a light reddish-brown
sand matrix.
This rock generally weathers easily into light
brown to red-brown, cobbly, bouldery clays (Cl),
loams (Lo), loamy sands (LSI) and sandy loams
(SL2). The soil mantle is generally less than
10 feet deep, and these soils are not likely to
be expansive.
(5) Point Loma Formation (Ksl)
This formation is a sequence of interbedded
dark grey, fine grained shales, and light buff,
fine to medium grained sandstones, and buff*
fine grained siltstones. It occurs mostly in
the central portion of the study area. Where
seen in outcrops along El Camino Real , the
shale beds are usually 2 to 3 feet thick, and
and sandstone beds are about 6 inches' to 1 foot
thick.
This formation weathers to clays (LI), loams (to),
and loamy sands (LSI) which are fine .-to medium
grained and vary from light brown to dark grey in
color. These soils are usually less than 10 feet
deep. Some of them may be expansive.
• - •' - • ....... ." A- 6,««*»•
,(67 Intrusive Dac^'te (Tv)
There is one minor exposure of this rock in the
northeast corner of the study area. It has been
quarried in the past.
It is a hard rock, greenish-grey in color. It
weathers to a brown, fine sandy loam (SIT) which
is approximately 2 to 3 feet thick, and is pro-
bably not expansive.
(7) La Jolla Group (Ts)
This is the most frequently occurring geologic
unit in the study area. . The predominant rock
types in this Group are sandstones and siltstones
which are light buff to yellow fn color. The
beds are generally massive, 10 to 25 feet thick.
Locally, dark grey-green beds of claystones are
interbedded with the sandstones. Groundwater
generally occurs just above the claystones, and
in landslides in this Group the slide plane is
usually in the claystones.
The La Jolla Group weathers to a complex of inter-
mixed, usually light brown to dark grey, fine to
coarse grained soils. These soils include clays
(Cl), loams (Lo), loamy sands (SL1), and they
are usually less than 10 feet deep. Some of
these soils are expansive.
A- 7
(8) Linda Vista Te.rrace Deposits (Qt)
This geologic unit is located predominantly in
the western portion of the study area, is flat
lying, gently inclined to the west, and forms
the mesa-like areas of the study area. The
terrace deposits are reddish-brown in color,
and consist mostly of loosely cemented sands
and gravels with some clays. The thickness of
this unit ranges from less than 1 foot In some
areas, to at least 50 feet in others.
Weathering of the terrace deposits forms tan to
reddish-brown clays (Cl), loams (Lo), foamy sands
(LSI), gravelly loams (GL), and gravelly loamy
sands (LS2). The soils are usually less than
10 feet deep. Some of them may be locally
expansive.
(9) Quaternary Alluvial Deposits (Qal)
The alluvial deposits are soils which occur in
the valleys and lagoons, and along the beaches.
The maximum reported thickness of this unit is
200 feet. These deposits are varied and complex
in color, texture, and composition because of
their various origins (C1L, Lo, LSI, Say SL2, Rro)
Some of these soils are expansive. In general*
the alluvium west of El Carol no • Real is much
A-8
(*~* (**• ' • ' •'-w . W
softer and more compressible than that to the
east. The upper 20 feet of alluvium in the
lower reaches of the stream valleys, and in
and around the lagoons, consists of compressible
organic silts and sands.
c. Surface Water and Groundwater
(1) Surface Watc»*
Surface water in the study area is too meager
and undependable to be considered an exploitable
resource.
The Water Resources Division of the U. S. Geological
Survey studied the flood potential of the streams
in the study area. The areas susceptible to
flooding are those underlain by alluvium, the
lower reaches of the four main drainage basins,
and the lagoons. These areas are shown on Map
* • ' • .
3, FLOODING.
» • '"
Most of the streams are intermittent, and drain
into the three lagoons: Buena Vista, Agua Hedion-
da and Batiquitos. Only Agua Hedionda is a tidal
lagoon open to the ocean. It is periodically
dredged to a depth of 12 feet by the San Diego
Gas and Electric Company to their facility at
the mouth of the lagoon. Buena Vista and Bati-
quitos Lagoons contain brackish water; the degree
This map is available in the Carlsbad City Planning Department
of salinity varies seasonally with the amount of
rainfall. The lagoons have been utilized in the
past for sewage disposal, and the head of Buena
Vista Lagoon has been artifically filled.
At the present rate of siltation, with debris
originating mainly from construction projects
in their drainage basins, it.will be perhaps ten
to twenty years before Buena Vista Lagoon and
Batiquitos Lagoon are filled in, according to a
report by California Polytechnic Institute in
1971. If these lagoons are to be preserved, a
comprehensive program of erosion and siltation
control would have to be undertaken. Recommended
programs to control erosion, are given in Section 5,
(A) (2).
(2) Groundwater
Data from the California Department of Water
• . " •
Resources indicate that the only sources of ground-
water in the study are the alluvial deposits and
the La Oolla Group rocks. About 80% of the ground-
water is in the alluvial deposits and the remainder
is in the La Jolla Group.
Groundwater is currently being used for rural
domestic and agricultural purposes. Chemical
analysis performed by the Department of Water
c
Resources (see bibliography - 8,11) show
dissolved salts and minerals make the water
of questionable quality for domestic use,
but is considered adequate for most agri-
cultural purposes.
Department of Water Resources data indicate
that nowhere in the study area could a high
yield well, one producing at least500
gallons per minute, be developed.
2« Engineering Geology
a. Landslides and slope stability - The downslope
movement of earth materials is a normal geologic process
by which hill slopes are flattened and stream channels
widened. The rate of downslope movement ranges from rapid,
as in rock falls, to slow and imperceptible, as fn soil
creep. Almost all slopes are involved in some form of move-
ment. Most of these movements are of little consequence, but
there are areas in which slope movements pose a major geologic
hazard. Recognition of areas susceptible to large scale
movement, and appropriate planning and design can greatly
reduce the possibility of damage to property and risk to life.
W
'Landslide areas in the study area have been identified
through studies of stereo aerial photography of various
27
dates and scales, and field reconnaissance. These
landslide areas are mainly on the north-facing slopes
along creek channels, and in almost all cases are asso-
ciated with steep slopes in rocks of the La Oolla Group.
(Refer to Appendix A, Section 1, Descriptive Geology,
for an analysis of the characteristics of the La JolTa
Group). A few landslide areas are in granitic and
metavolcanic rocks where weathering has created deep
soils.
Instability of natural slopes can be considered a.,
relatively minor problem. However, slope instability
is a significant 'problem in road cuts and other man-
made slopes. Generally, small-scale slides and sloughing
can be seen in most road cuts including those of un- .
improved roads in the eastern portion of the study area.
All areas under consideration for any kind of develop-
ment, construction or excavation, should be thoroughly inves
tigated and evaluated by engineering geologists, and soil
and foundation engineers. A qualified expert should review
grading plans and inspect areas of excavation during and
after grading to evaluate slope stability. It is imperative
A-l?
in areas of known landslides to ascertain slope stability
before and after development. The following determinations
should be made: depth to slide plane, rock types, presence
of clay seams, groundwater conditions, stability under
earthquake conditions.
Areas where slope instability is now a problem should
be investigated and evaluated by engineering geologists and/or
soil and foundation engineers, on an individual basis, and
appropriate remedial measures taken. Table I, page 17 relates
development activities to slope .stability problems and indi*
cates remedial measures.
b. Erosion - Erosion is a normal geologic process whereby
earth ma.terial s are loosened, worn away, decomposed or dis-
solved, removed from one place and transported to another,
sometimes many miles from their source. Precipitation, running
water, wav.es, temperature, and winds are all agents of erosion.
Ordinarily, erosion proceeds so slowly that it is impercep-
tible; but, when the natural equilibrium of the environment
is changed, the rate of erosion can be greatly accelerated.
This can create aesthetic as well .as engineering problems,
although not necessarily posing a threat to life or property.
There are three major erosion problems in the study
area. They are: (1) accelerated erosion in the soft rocks
of the La Jolla Group; (2) siltation of the lagoons;and
(3) beach and sea cliff erosion.
A-T3
TABLE I - SLOPE STABILITY RELATED TO DEVELOPMENT
DEVELOPMENT
ACTIVITY
Excavation
and Grading
POTENTIAL STABILITY
HAZARDS
undercut slopes
oversteepencd slopes
fill placed on slopes
placement of uncompacted
fill
MEASURES TO MINIMIZE
STABILITY HAZARDS
minimal excavation and grading
wherever possible
cut and fill slopes 2:1 or flatter
depending on analysis of local
conditions
key compacted fill into underlying
materials
Removal of
Vegetation
Alteration
of Drainage
increased saturation of
soils and rocks
increased surface runoff
accelerated erosion and
sedimentation
natural drainage concentrated
in restricted areas
concentrated rainfall runoff
from impervious surfaces
(roofs, pavements, etc.)
resulting in local accel-
erated erosion and sedimen-
tation
locally increased saturation
of soils and rocks from lawn
watering, septic tank leach
fields, swimming pools, etc.
leave vegetation intact wherever
possible
plant appropriate vegetation on
slopes and cleared areas
design around natural drainage
wherever possible
divert surface runoff away from
slopes into natural or constructed
drainage channels
design drainage systems with weirs,check dams, and settling basins
install subsurface drains where
' necessary
minimal construction of impervious
pavements
locate leach fields, etc. away from
steep slopes
Construction inappropriate location of
buildings, swimming pools,
etc.
design and locate structures in
accordance with properties of
underlying soils and rocks,
considering weight loading andwater saturation effects
locate structures away from steep
slopes
• A-14V . '
The soft rocks of the La Jolla Group are fine-grained",
friable and poorly cemented. These characteristics make them
highly susceptible to accelerated erosion. In areas where
underlying soil and vegetation have been removed, such as in
road cuts and excavations, and where these rocks have been
exposed to high intensity rainfalls, a "badlands" topography
has been developing. Badlands topography is characterized
by the formation of an intricate maze of narrow ravines, and
sharp crests and pinnicles. Where La Jolla Group rocks
have been used as fill material, and vegatal cover isabsent
or inadequate, they have been subject to accelerated erosion
and the development of badlands characteristics.
t ,
Eroded materials are transported through natural and
artificial drainage channels, into stream channels and
finally into the lagoons. Silt carried into the lagoons
remains suspended in the water for .some time where it con-
stitutes a pollutant, altering the normal balance of plant
and animal life. It eventually settles to the bottom where
it alters bottom contours and decreases the depth of the
water.
San Diego Gas & Electric Company dredges the outer
lagoon of Agua Kedionda Lagoon every 3 to 4 years to have
access to adequate quantities of cooling water. Ten to
twenty years ago, dredging was necessary only every 6 to
45
8 years. This is partially due to the Increased volume
of cooling water being used by SD6AE.
Field reconnaissance revealed a lack of erosion
* .
control measures in areas under development or
QW A-15
recently developed. At present there are no regulatory
controls over the problems of erosion and siltation.
In the normal erosion/deposition cycle of the Califor-
nia coast, storm waves carry beach sand out to sea from
October to April, and it is redeposited by longshore currents
from April to October. The sand supply is also partially
replenished by streams carrying sediments into the coastal
area.
In recent years, coastal erosion has continued unabated
while deposition has been severely altered. Breakwaters and
jetties which have been constructed along the coast break
up longshore currents and prevent the deposition of sand on
beaches. The closing off of lagoons, and the construction
of-dams on streams has diminished the. amount of stream^borne
sediments available for beach building.
Since 1960, the beaches of the study area have been
lowered approximately three feet. 20,32,59,60,66 Jhe IQSS
of beach sand, which would ordinarily serve to '.diminish the
force of storm waves, has allowed accelerated erosion of
the sea cliffs by storm waves. The rate of sea cliff retreat
in the study area is estimated to be between 1 and 1 T/2 feet
per year.
There are several measures which can be taken to
alleviate and remedy the problems of erosion and siltation.
Investigation and evaluation of individual affected areas
and proposed building and development sites would be necessary
* ' • ''..-•.
^ ^ A-16
to decide which measure(s) would be most appropriate in
each situation. The following measures can be employed
to reduce the rates and effects of erosion and siltation:
1. Leave soil and vegetation undisturbed
/ wherever possible '
2. Contour and plant slopes
3. Chemically treat soils to increase their
stability and resistance to erosion
4. Construct silt traps and settling basins
in drainage systems
5. Construct weirs and check dams on streams
s
6. Construct retaining structures on slopes
7. Open up lagoons to the ocean
8. Construct protective structures along
base of sea cliffs
Beach erosion is a highly complex problem for which
no general remedies can be prescribed* The situation at
each beach would have to be thoroughly investigated before
corrective measures could be recommended.
c. Excavation characteristics of rocks and soils - The•
rocks and soils of the study area can be divided into two
distinct groups according to their excavation characteristics.
The first group occurs in about 85% of the study area and
consists of the La Jolla Group, Linda Vista, Terrace Deposits,
Lusardi Formation, Point Loma Formation, and Alluviuai, (Refer
to Appendix A, Descriptive Geology) The second group occurs
in about 15% of the study area and consists of hard igneous
and metamorphic rocks and their residual soils.
fl 1 7
All of the rocks and soils in the first group can be
excavated with ordinary earth moving equipment. Locally,
in the Lusardi Formation and Point Loma Formation, hard
rock may be encountered that would require hard rock exca-
vation techniques. The only major geotechnical problem to
be encountered in this group is the necessity of providing
appropriate drainage structures for groundwater and surface
water. Slope instability is a relatively minor problem in
excavations in this group.
The La Jolla Group rocks and soils are susceptible
to accelerated erosion, therefore, surface water should be
diverted away from cut and fill slopes in this material.
Silt traps and settling basins should be provided down-
slope of any grading and construction in the La Jolla Group,
It' has been customary engineering practice to 'Strip-
shallow Terrace Deposits during grading, thereby exposing
the underlying La Jolla Group rocks. In this case, the
precautions indicated above for control of drainage and
erosion would apply.
In the Alluvium, shallow groundwater occurs in the
lagoon areas and lower alluvial valleys. In some places,
shoring or other specialized techniques would be needed
during excavation. Adequate drainage would have to be
provided for excavation and construction in these areas.
Provision should be made for control of surface water*
including the possibility of flooding in the lower alluvial
valleys. The existence of soft compressible soils in the
lower alluvial valleys and areas around the lagoons would
cause fills to be subject to settlement.
The rocks of the second group are generally hard,
and require ripping and blasting to excavate. Trenching
for utility lines is difficult and costly, and mass grading
is usually not feasible. In some areas, particularly in
granites, weathering has decomposed these rocks into soils
for a considerable distance below the surface. The existence
of these soils would create stability problems in cut slopes.
Except where deeply weathered soils occur, steep slopes would
generally be stable, as long as naturally occurring planes
of weakness in geologic structures are not undercut. Boulders
are very common in areas of deeply weathered soils. They
would require blasting for removal during excavation.
In all cases, investigations should be conducted by
engineering geologists and soil and.foundation, engineers,
at individual development sites prior to excavation.
3. Seismic Hazards - Refer to Seismic Hazards Map, AppendixD
a. Faults and Earthquake History - There are no proven active
faults in the study area. An active fault is one along which
there has been displacement during the last 11,000 years.
There are at least six faults in the study area which have
been located and mapped through analysis of aerial photographs
27and geologic field reconnaissance. These faults would have
to be thoroughly investigated to determine whether they are
active, inactive, or potentially active. An inactive fault
is one along which there has been no displacement for at least
3 million years. A potentially active fault is one along which
there has been displacement during the last 3 million years,
but not during the last 11,000 years, and along which there
may be displacement in the future.
There is one potentially active fault within a radius
of 25 miles of the study area. It is the Rose Canyon Fault,
4.Qapproximately 5 miles offshore. It has been suggested that
the Rose Canyon Fault is a part of a zone of faulting which
includes the Newport-Inglewood Fault and the Vallecito and
San Miguel Faults in Baja California. The Newport-Inglewood
Fault was the source of the 1933 Long Beach earthquake
(magnitude 6.3). Epicenters of earthquakes in the range of
Intensity V to VI have been located near the Rose Canyon
Fault System. (Refer to Table II, for intensity effects.)
At this time, published studies have not determined
if the Rose Canyon Fault is part of a larger fault which
extends continuously for 140 miles, or whether it is one
of the several shorter faults. If this hypothesis is confirmed
that the Rose Canyon Fault is part of the larger fault system,
there is a major cause for concern.5
There are four major active fault rones within TOO
miles of the study area. They are the Elsinore, AguavCalientev
San Jacinto and San Andreas Fault Zones. The energy of even
a high magnitude (7.0 or greater) earthquake centered on
(C
any of these faults would be attenuated by the time it reached
the study area. However, the study area is susceptible to
damage from secondary seismic effects. The extent of the
effects would depend on the response period of the structure
and its site. Table II, following, indicates the approximate
relationship of earthquake magnitude to earthquake intensity.
The threat of damage from earthquakes on the Rose
Canyon Fault and the most distant faults can be iiiinimized
if certain precautionary measures are taken. Routine geo-
technical investigations including generalized evaluations
of seismic hazards should be conducted at all proposed
development sites (See Table III, p.. 33). In addition,
detailed investigations should be conducted at sites where
the construction of critical structures (high occupancy
structures and those which must remain in operation during
emergencies) or; structures over four stories are under
consideration. Individual project structural engineers
should be aware of the ground response characteristies
of the site in their design and'construction specificaiiorrs
for all improvements. Critical structures should be
designed to withstand the effects of a 7.0 or 7.5 earthquake
centered on the Rose Canyon Fault. For other structures
a 6.5 earthquake on that fault can be considered by design
criterion earthquake.
b. Description and Assessment-of Primaryand Secondary
Seismic Effects - Seismic effects are classified as primary
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and secondary. The primary effect is ground rupture, also
called surface faulting. Secondary effects are the results
of ground motion during an earthquake. Those relevant to
the study area are liquefaction, lurch cracking, lateral
spreading, local subsidence, landslides, structural damage
due to ground vibration, seiche, tsunami, and regional
subsidence and uplift.
Primary effects are caused by movement along an
active fault. These movements can be sudden and severe as
in an earthquake, or slow and inrpercepti ble as in fault
creep. Movement on a fault can be horizontal, vertical*
or a combination of both. Usually the width of a ground
rupture zone is less than 20 feet in rock, but can be up
to 60 feet in soft, saturated soils.
Surface faulting tends to occur along lines of pre-
vious faulting. There are no known active faults in the
study area. The six faults which have been located and
mapped through studies of aerial photographs, and geologic
field reconnaissance should be thoroughly studied and eva-
luated for their potential for ground rupture before any
construction is undertaken in their vicinity. Critical
N structures should not straddle these faults, unless geologic
investigations conclude that they would be no hazard to
such structures.
Secondary effects pertinent to the study area are
liquefaction, lurch cracking, lateral spreading, and local
subsidence of soils (sometimes collectively referred to
as ground failure), landslides, vibrational damage, seiche,
tsunami and regional subsidence and uplift. Ratings of
potentials for secondary effects are provided only to
indicate relative likelihood of occurrence during an earth-
quake. More precise determination should be made by appro-
priate geotechnical investigations at proposed development
sites.
Liquefaction is a mechanism of ground failure. Soil
liquefaction is defined as the transformation of a granular
material from a soligWinto a liquefied state as a consequence
^ 55of increased pore-water pressures. It is caused by seismic
vibration of fine sand or silt which is saturated with water.
There are limited areas which must be considered potentially,
subject to liquefaction. They are the alluvial areas west
of El Camino Real, the areas in and around the lagoons, and
the areas along the beaches.
Lurch cracking is the development of all types and
sizes of fissures in the ground due to ground motion during
an earthquake. Sand boils and mud volcanoes often accompany
lurch cracking as groundwater is forced toward the surface.
The alluvial areas west of El Camino Real, the areas i.n
and around the lagoons, and the areas along the beaches are
considered potentially subject to lurch cracking.
Lateral Spreading is the movement of loose soils
over low-angle slopes into open areas during an earthquake.
The alluvial areas west of El Camino Real, the areas in and
around the lagoons, and the areas along the beaches are
considered to be potentially subject to lateral spreading.
A-24
Local subsidence can occur during an earthquake when
water is driven out of saturated soils causing them to become
more compact. The alluvial areas west of El Camino Real,
the areas in and around the lagoon, and the areas along the
beaches are considered potentially subject to subsidence,
Lands!ides, the movement of a mass of rock and/or
soil down a hillside or steep slope, and falls of loose rocks
and soils, can result from ground shaking duriny an earthquake.
Failures are common in old landslides and oversteepened
slopes such as roadcuts,building, sites, sea cliffs, and
stream-cut canyons. The weathered soils of the hard rock
areas and the slopes of the La Jolla Group are considered
potentially subject to landsliding problems.
Structural damage due to ground vibration 1s caused
by the transmission of earthquake vibrations from the ground
into the structures. The variables which determine the
extent of damage are (1) the characteristics of the under-
lying soils and/or rocks; (2) the design of the structure;
(3) the quality of materials and workmanship used In construc-
tion; (4) the location of the epicenter and magnitude of
the earthquake; and (5) the duration and intensity of Aground
shaking. The potential for structural damage due to ground
.
vibration in the study area is greatest in areas underlain
by deep, soft, saturated alluvial soils and least in areas
of hard bedrock.
A seiche is an oscillating wave in an enclosed or
restricted body of water generated by ground motion during
A-25
an earthquake. It can cause overflow of a lake, reservoir,
or lagoon. At this time, however, there is no imminent
danger from seiche hazards.
A tsunami is a high ocean wave generated by a
submarine earthquake or volcanic eruption. Such an event
anywhere in the Pacific Ocean could threaten inundation of
the beaches and lagoons in the study area with waves up to
10 to 15 feet high.
Under Public Law 80-373/August 1974, the National
Oceanic and Atmospheric Administration through the National
Ocean Survey, maintain a tsunami warning system.
At this time, based on available studies, it is
questionable whether movement along the offshore fault system
could cause a significant tsunami affecting the San Diego
coastal zone. However, it "is recommended that funding be
made available for a study to determine the tsunami run-up
for the San Diego region. Such a study might be undertaken .
by National Oceanic and Atmospheric Administration or by
Scripps Institute of Oceanography.
Regional subsidence and uplift during an earthquake
are caused by differential vertical movement along an active
fault. This occurs over large areas, and the amount of
subsidence or uplift is usually on the order of a few
inches to a few feet. It is generally not possible to assess
the hazard to individual locations; however, the study are*
can be expected to respond as a unit. Therefore this pheno-
menon is not considered to be a hazard in the study area>
A-26
Dams and Dam Failures - The sources of hazards from
dams are of three major types: .(1) failure of the dam struc-
ture during a seismic event; (2) overtopping caused by a
landslide into the reservoir; and (3) seiching, which was
described earlier.
The State Department of Water Resources is responsible
for the safety of dams in California, other than those fed-
erally owned. .
At present, based on available information, no hazar-
dous conditions exist, but a complete study should be made.
The Public Safety Element should observe any hazards which
may be identified. Particular attention should be given to
Calevaras and Squires Dam.
4.. GeotechnicaT Interpretation
a.«. Geotechnical Hazards - Refer to Geotechnical Hazards
Map, Appendix D
The. study area can be divided into seven areas on
the basis of the presence and severity of geologic and seis-
mic hazards. These hazards can be defined as geotechnical
hazards when evaluated in relation to land development.
The map delineates and the legend identifies the
general hazards present in each of the seven areas, and
their distribution throughout the study area. The table
. . '•'•'•,'
indicates the severity of the most significant geotechnical
hazards in each of the map areas.
After routine geotechnical investigations, about 852
of the study area may be utilized for urban activity utilizing
V " ' . • -
conventional engineering methods, proper design and construe*
tion procedures. The remainder of the study area consists
^ A-27
of areas with moderate to major geotechnical hazards. In •
these areas, costly detailed geotechnical investigations
would have to be conducted, and expensive, specialized
engineering techniques employed to achieve safe development.
b. Design and Code requirements - Current regulations
concerning seismic design are summarized in the 1973 edition
of the Uniform Building Code, primarily Chapters 23 and 29.
Recent earthquakes have demonstrated that these regulations
may not be totally adequate with respect to the seismic
conditions in Southern California and numerous revisions
have, for that reason, been proposed. The most activity
has been in the field of seismic consideration for structural
design for buildings. The City of Carlsbad should encourage
the International Conference of Building Officials to make
changes in the UBC that will recognize the Structural Engineers
Association of California Seismology Committee recommendations
and other new technology.
c. . Land Use Feasibility - Refer to Land Use Feasibility
Map, Appendix D
The study area can be divided into four areas on
the basis of land use feasibility. Each area has a parti-
cular combination of geologic conditions and seismic hazards
which would require that certain types of geotechnical
investigations be performed in order to achieve safe develop-
ment and minimize risk to life and property. (Refer to
Geotechnical Hazards Map, Appendix D)
,*<»%,
A-28
the type and depth of investigation depends in part-
on the type of proposed land use. The Land Use Feasibility
Table indicates the type and depth of investigation suggested
for the five basic types of land use considered to be rea-
sonably representative of all potential development. The
basic types of land use are: high rise (over four stories),
residential, heavy industry, light industry'or commercial,
and critical structures. Critical structures are defined
as those which ordinarily have high occupancy, such as
schools and stadiums, and those which must remain in opera-
tion during any emergency, such as hospitals and police
facilities.
The type and depth of investigation also depends on
the need to determine the precise nature and severity of
geologic and seismic hazards. Geologic conditions can vary
considerably from one site to another within an apparently
homogeneous area. Recommendations for geotechnical inves-
tigations can only be made on the basis of individual
professional determination at individual sites.
Table III, following, gives examples of routine and
detailed investigation procedures in relation to particular
geotechnical problems as they may occur at individual sites.
It is not complete, and is intended to serve only as a
guideline.
TAr.i.K in- .SIH:CKSTI:I) > WKSTI CATION n;n(:i:oin;i:s KOI;.._ .iNi CAI. .ruont.r-MS A-29
S1TK
FKOU1.KM
SltCCKSTEl) INVEST] CATION
DKTAll.KD
Erosion Control
erosion
siilation
drain.ij'.c control
landscaping
In addition to items under routine:
erosion rates of rocks or soils
siltation control
Engineering
faults
landslides
slope
stability
grading
excavation
drainage
grounu-'ater
reconnaissance of site
review literature and maps
prepare generalized geologic
map
drainage control
review grading plans
inspect during grading
prepare "«s built" geologic
nap
in addition to items under routine:
photogeologic study
prepare detailed geologic map
determine subsurface structure
analyze - fault potential, ground-
water conditions, slope stability
flood
Flooding Potential
U.S.G.S. Water Resources
Division, flood maps
determine flood potential based on
100 year or 1000 year storms
analyze drainage basin characteristics
hard rock
excavation
Geophysical Investigation
seismic surveys to determine
applicable excavation
techniques
same as routine
Occanographi c
beach and
sea cliff
erosion
tsunami
U.S. Corps of Engineers'; beach
and sea cliff erosion data
U.S. Coast and Geodetic Survey,
tide, current and storm data
California Division of Mines,
tsunami hazard maps
in addition to items under routine;
determine - longshore'currents,
maximum storm conditions, sand
supply and movement, maximum
wave heights, bottom topography,
evaluate all control measures
as to effects north and south of
area, analyze tsunami hazard
Seismic Hazard
earthquake
effects
generalized evaluation of
potential primary and
secondary earthquake
effects
research earthquake records includingsite strong motion data
establish maximum credible and design
earthquakes
geophysical investigation for microtremor data and primary and shear
wave velocities
dynamic soil response tests
computer analysis of dynamic response
of soil's and rocks
Soil and Foundation
soils and
foundations
obtain soil samples from
various depths test
samples for - cxpansivcness,
Strength and bearing data,
"R" values where needed,
others as required
determine groundwater levels,
drainage, slope conditions
in addition to items under routine:
specialized sampling
specialized testing and analysis of
soils - consolidation, triaxial
testing, permeability, dynamic
response
recommend specialized foundationdesigns
slope
stability
Slope
generalized Analysis ofStability based on geologic,
soil, and grounclwater data
in addition to items under routine:determine subsurface structure
geologic analysis oC rock structure
and proposed slopes
analysis of soil data for proposedslopes
analyze potential seismic'effects OB
slopes
B-l
Alluvium
Bedrock
APPENDIX B •
GLOSSARY
A general term for all sediment such as
sand and gravel deposited by streams;
(adjective, alluvial).
Firm or coherent rock material that
underlies the soil or overburden;
divided geologically into three classes
igneous, sedimentary, metamorphic.
Compressible
soil
A soil susceptible to
weight or pressure.
compaction under
Critical Structure - A high occupancy structure or a structure
which must remain in operation during
emergencies.
Earthquake
Epicenter
Erosion
Expansive
soil
Fault•\
Fault, active
Fault, inactive
Fault, potentially
active
Perceptible trembling to violent shaking
of the ground, produced by sudden dis-
placement of rocks below and at the
earth's surface.
The point on the earth's surface directly
over the focus or point of origin of an
earthquake.
The process whereby earth materials are
loosened, worn.away, decomposed, dissolved,
and transported from one place to another.
A soil which has the capability of large
volume changes reflecting an increase or
decrease in moisture content.
A fracture or fracture zone along which
there has been movement of the two sidas
relative to one another and parti lei to
the fracture.
A fault along which there
placement during the 1ast
has been dis*
11,000 years.
A fault along which there has been no
displacement for at least 3 million years.
A fault along which there has been dis-
placement during the last 3 million years,
but not during the last 11,000 years, and
along which there might be displacement
in the future.
B-2
Flood
Flood plain
Floodway
Friable
Geotechnical
Ground motion
Ground response
Ground rupture
*
Hard rock
High occupancy
Igneous rock
Intensity
Any temporary rise in stream flow or
water surface level that results in
adverse effects within the flood plain,
including but not limited to damages
from overflow of land, temporary back-
water in local drainage channels, storm
drains or sewers, bank erosion or channel
diversions, unsanitary conditions, or
other conditions of nuisance resulting
from deposition of materials within or
adjacent to watercourses, rise of ground-
water coincident with the rise in stream
flow, and the disruption of traffic cir-
culation resulting from stream or water-
course overflow.
The land area adjacent to a watercourse
which is subject to the overflow of
flood waters.
The channel of a stream or other water-
course and that part of the flood plain
reasonably required for passage of a
flood of given magnitude.
Easily crumbled, said of rock that is
poorly cemented.
Pertaining to geologic-soils-engineering
studies, features, conditions or events
Shaking motions of the soil or rock
during an earthquake
The reaction of the ground to bedrock
shaking
A break or fracture of the earth's surface
in a fault zone; the primary effect of
an earthquake.
Rock with a strong bonded structure, not
readily eroded; usually requires ripping
or blasting for excavation
An occupant load (capacity) of 300 persons
or more
The class of rocks formed by cooling and
crystallization from a molten state
A qualitative- measure of an earthquake's
destructiveness, based on observed damage
or effects; measured by modified Mercilft
Scale .»• - .
B-3
Landslide
Lateral spreading
•»;
Liquefaction
Local subsidence
Lurch cracking
Magnitude
Major structure
Metamorphic rock
Mud volcano
Project
The movement of a mass of-earth materials
down a hillside or steep slope
The movement of loose soils over low-
angle slopes into open areas; caused
by ground shaking during an earthquake
A "quick" condition generally produced-
in soft saturated soils by earthquake
shaking.
Downward movement of
caused by compaction
shaking drives water
saturated soils,
when earthquake
out of them.
The development of all sizes and types
of fissures in the ground due to ground
motion during an earthquake.
A quantitative measure of the total
energy release of an earthquake measured
by Richter Scale
A major structure is defined as any
structure having-a capacity of 3QO persons
or more, a police or fire station* a
school, a hospital or rest home, or any
facility having the capacity to severely
damage the environment if destroyed such
as: dams and reservoirs, and'petroleum
storage facilities
Those rocks which have been transformed
from their previous state by heat, pres*
sure or both
A mound of mud ejected by the eruption of
groundwater during lurch cracking
Project means the whole of an action,
resulting in physical impact on the
environment, directly or ultimately,
that is any of the following:
(a) an activity directly undertaken by
any public agency including, but not
limited to, public works construction
and related activities, clearing or
grading of land, improvements to existing
pub!ic structures, enactment and amendment
of zoning ordinances, and the adoption
of local General Plans or elements thereof
pursuant to Government Code Sections
65100 - 65700*, (b) an activity undertaken
B-4
Sand boil
Sedimentary rock
Seiche
Seismic
Seismic effects,
primary
Seismic effects,
secondary
Settlement
Siltation
Slope stability
Soft rock
by a
or in
tract
other
more
i n v o ]
a lea
or ot
more
Envi-
Secti
person which is supported in whole,
part, through public agency con-
s, grants, subsidies, loans, or
forms of assistance
public agencies; (c)
ving the issuance to
se, permit, license,
her entitlement for
public agencies
onmental Impact
on 15037).
from one or
an activity
a person of
certificate,
use by one or
(from California
Report guidelines
A mo-nd of liquified sand ejected by
the eruption of groundwater during
cracking
- The rlass of rocks formed by the hardening
of accumulated layers of sediments such
as sinds and clays
- An earthquake-generated wave within an
enclrsed or restricted body of water
such as a lake, reservoir or lagoon
- Pertiining to earthquakes
- Groi-Td rupture; breaks or fractures in
the -arth's surface caused by displacement
in E fault zone
- Earthquake effects other than ground
ruptire; includes earthquake-induced
lancirTides, liquefaction, lurch cracking,
and "jteral spreading of soils and
strurtural damage due to ground vibration
- The rownward movement of a soil resulting
f roir s reduction in the voids in the
underlying soil
-The reposition of sediments in w.ater,
USUE Ty following a period of suspension
- The snility of a slope of soil or rock
material to resist moving downhill
- Roc: vith a loosely cemented structure,
gene-illy readily eroded; can usually
be ecavated with conventional earth
raovrg equipment
r B-5
Soil creep
Surface faulting
Terrace
Tsunami
Vibrational damage
Weathering
- A slow movement, also of rock fragments,
down an even, gentle slope
- same as ground rupture
- A step-like landscape form created by
an earlier period of erosion. Terrace
deposits generally are found on the
flat treads
- A high ocean wave generated by a submarine
earthquake or volcanic eruption
- Damage to a structure caused by the
transmission of earthquake vibrations
from the qround into the structure
- Disintegration, dissolving, and decora-
position of earth materials at or near
the surface
u-»
- • . .*«%
(W - - ^ • •
APPENDIX C
Index to State Laws Relating to Seismic Safety
Public Resources Code '
Section 660-662 and 2621-2625: These sections require the State
Geologist to delineate special studies zones encompassing potentially
and recently active fault traces. It requires cities and counties
to exercise specified approval authority with respect to real estate
developments or structures for human occupancy within such delineated
zones. Alquist-Priolo Geologic Hazard Zones.
Section 2700-2708: These sections require the Division of Mines and
Geology to purchase and install strong-lootion instruments (to measure
the effects of future earthquakes) in representative structure and
geologic environments throughout the state.
- Section 2750: Establishes a state raining and minerals policy, which
among other things, encourages wise use of mineral resources.
Education Code
Section 1502.1: This section requires that geologic and soils engi-
neering studies be conducted on all new school sites and on existing
sites where deemed necessary by the Department of General Services.
Section 15451-15466: These sections constitute the Field Act and
require that public schools be designed for the protection of life
and property. These sections, enacted in 1933 after the Long Beach
earthquake, are enforced by the State Office of Architecture and-
Construction in accordance with regulations contained in Title 21
of the California Administrative Code.
Health and Safety Code
Sections ISOOO.et seq: These sections require that geological and
engineering studies be conducted on each new hospital or additions
affecting the structure of an existing hospital, excepting therefrom
any story Type V buildings 4,000 sq. ft. or less in area.
Sections 19100-19150: These sections constitute the Riley Act and
require certain buildings, to be constructed to resist lateral force*
specified in Title 24 California Administrative Code.
Source: San Diego County Preliminary Seismic Safety Element
C-2
Section 17922, 17951-1793.5: These sections require cities and
counties to adopt and enforce the- Uniform Building Code, including
a grading section (Chap. 70), a minimum protection against some
geologic hazards.
Business and Professions Code
Section 7SOO-7S87: These sections provide for the registration of
'i geologists and geophysicists, and the certification of certain
• geologists in the specialty of engineering geology. .
Section 11010: This section requires that a statement of the soil
conditions be prepared, and needed modification carried out in
accordance with the recommendations of a civil engineer.
Section 11100-11629: These sections require studies in subdi visions
to evaluate the possibilities qf flooding and unfavorable soils »
Government Code: ...
Section 8589.5: This section requires that inundation saps -and
emergency evacuation plans be coinpleted for areas subject to inunda*
tion by dam failure.
Section 65300-6S302.1: These sections require that each city and
county shall adopt the following elements;
Seismic safety element consisting of the identification and
appraisal of seismic hazards including an appraisal of land-
sliding due to seismic events.
Conservation element, including the conservation, development
and utilization of minerals.
Safety element including protection, of -the community from
geologic hazards including mapping of known geologic hazards.
C-3
Summary of State Legislation on Seismic Safety
The Field Act
The Long Beach earthquake of March 10, 1933, (Richter nagnitude 6.3),
occurred at 5:54 p.m. on a Friday evening and destroyed or seriously damaged
iTiany buildings in that area, including alsost all of the public school
buildings. If the shocks had occurred during school hours, the probable
loss of life sr.ong school children would have been horrifying. Raalizing
that inuch of the loss and damage could have been avoided if the school
builldings had been properly designed and constructed, the stats legisla-
ture adopted the Field Act, Assembly Bill 2342, which was patterned soare-
vhat after the Stats Dam Act of 1929. This bill because Chapter 59 of the
1933 Statutes, and became effective as an emergency measure upon the signa-
ture of the Governor on April 10, 1933, a month after the earthquake. The
Field Act was made applicable only to public school buildings and docs not
apply to the State colleges or universities, or to private schools.,
The Field Act (Education Code Sections 1S4S1 through 15465) assigned
to the Division of Architecture in the State Department of Public Works
the authority and responsibility, under police power of the State, to pass
upon and approve or reject plans and specifications, and to supervise the
construction of all public school buildings. It requires that an archi-
tect or structural engineer prepare the building plans and supervise the
construction, and it requires continual inspection of the construction
by an officially approved inspector employed by the school district. The
act further provided that the division adopt building regulations as it
deemed necessary and proper; it also contains provisions for the enforce-
ment of the act. School buildings constructed under the Field Act provi-
sions have shown consistently high performance in all earthquakes to which
they have been exposed.
The Riley Act
After the Long Beach earthquake of 1933, the Riley Act, Assembly Bill
2391 (Health and Safety Code Sections 19100 to 19170), was adopted by the
California Legislature; it applied to buildings constructed after May 26,
1933. This legislation required that all buildings, except certain types
of dwellings and farm buildings, be designed for a lateral force of not
less than 2% of the total vertical design load.
In 1953 the lateral force requirements was revised to 3% of this load
for buildings less than 40 ft. high and 2% for those over 40 ft. high. In
1965, the required lateral force design values were again revised by the
legislature to reflect, by reference, those of Article 23, Part IV, Title
24 of the CAC in effect at that time. These values were essentially the
same as the ones specified in the 1961 Uniform Building Code and, in general,
followed most of the recommendations of the SEAOC.
C-4
State BuiltiinjT Standards Commission
In 1953, the State Building Standards Law was enacted (Section 18900-
1S917 of the Health and Safety Code) to establish the State Building Stand-
ards Commission and to adopt a single State building code compiled from
regulations adopted by the various State agencies. Its purpose was to v
eliminate conflict, duplication, and overlap in State building regulations.
The adopted State Code is published in Title 24 of the California
Administrative Code (CAC). In 1963, the lateral-force requirements of
the IPS I Uniform Building Code, and the recoinr.endations of ths SHAOC were
adopted and published in Title 24, CAC. In December, 1971, following^ a
mandate by the legislature to adopt model codes by reference, the 1970
Uniform Building Code was adopted by reference as the basic regulations
ir Part 2 of Title 24, CAC. Exceptions to these basic regulations for
public school buildings and other State building occupancies are published
in Part 6 of Title 24,. CAC.
Recent Legislation
The Joint Committee on Seismic Safety has influenced the activities
of many disaster-related organisations through public hearings and investi-
gations into earthquake safety programs. Although the primary effort has
been directed toward preparing ths final statewide seismic safety plan, a
number of items of legislation-considered too important to be delayed-have
also been presented. Among the urgent items of legislation, 14 out of 26
introduced by Senator Alquist to date have been adopted into law. Of
special interest are major bills covering hospital construction, strong
motion instrumentation, faultline zoning, seismic safety element and
emergency service structures. Outlined below is a brief synopsis of the
various earthquake-related measures introduced since the committee's
inception.
The following were proposed during the 1971 session of the legislature:
1. Senate Bill 351-Seisroic Safety Element
Status enacted (Chapter 150) » ; -._".. ; t.
SB 351 requires that all general plans consider the following:
(a) A land use element, (b) a circulation element, (c) a housing element,
(d) a conservation element, (e) an open-space element, and (f) a seismic
safety element consisting of the identification and appraisal of.seismic
hazards. - .-..-•'.
C-5
2. Senate Bill 352-Hosnital Safety
Status: Died in Senate Committee on finance; vair.t reduced as
SB 519 and passed into law (Chapter 1130) in 1972,
SB 352 requires that plans for hospital construction or altera-
tion be rade by a structural engineer and a licensed architect, It estab-
lishes earthquake resistance for hospitals, and provides for approval of
the plans and inspection of hospital construction and operation by the
State Department of Public Health through^its contract with the Schoolhouse
Section of the Office of Architecture and Construction in tha Departstent
of General Services.
3. Senate Bill 479-Public School Siting
Status: enacted (Chapter 913).
/ •
SB 479 requires a geologic investigation of prospective sites for
new schools and for additions to existing schools. Sites investigated
within the last five years are exentpted.
4. Senate Bill 778-Local Building Department Records .
Status: Enacted (Giapter 616).
SB 778 requires that the building department of a city or county
maintain as public records plans of the buildings-for which that department
has issued permits. •
5. Senate Bill 1206-Active Faults
Status: Dropped in Senate Committee on Governmental Organization;
reintroduced and passed into law as SB 520 (Chapter 1354) in 1972,
SB 1206 directs the State Geologist to delineate a zone along
active faults and requires that all structures be constructed within that:
zone to be approved by the State Geologist on the basis o.f geologic and .
engineering reports.
6. Senate Bill 1374-^trong-M0tion Instrumentation Program
\ • . .'.......-.....:-.;'
Status: Enacted (Chapter 1152).
SB 1374 directs the California Division of Mines and Geology to
organize, purchase, install and monitor instruments in representative struc-
tures and geological environments in the State.
C-6
7. Senate Current Resolution S4-State Capitol Status . •
Status: Passed (Resolution Chapter 233).
SCR 84 requests that the State Architect evaluate the safety of
the V.'est Win;* of the Capitol Building and determine the costs of reconstruct
tion to :neet earthquake-resistant standards.
The following were introduced during the 1972 session:
1. Senate Bill 519/ Seismic Structural Safety of Hospitals .
Status: enacted (Chapter 1130). *
SB 519 requires that the State Department of Public Health,
through a contract with the Department of General Services, develop hospi-
tal construction standards and regulations, assume responsibility for over-
seeing construction, and perform structural plan-checking, and such periodic
review of operating hospitals as required to assure adequate resistance to
earthquake damage. It also calls for the creation of any advisory building
safety board.
2. Senate Bill 520-Alquist-Prioloa Geologic Hazard Zones Act
Status: enacted (Chapter 1354)*
SB 520 expands the membership of the State Mining and Geology
Board and instructs that body to prepare policies -and criteria for the
development of designated special studies zones encompassing major active
fault traces. Additional fees are charged to those applying for building
permits on sites within such zones and the revenues are split by the State
and local jurisdiction. The State Geologist shall prepare maps of those
zones for use by local and State government.
3. Senate Bill-689 Clarification of School Building Sites Bill
of
Status: enacted (Chapter 332} » '•.-..', .
SB 689 makes clarifying changes in the requirements established
by SB 479 (1971) concerning geologic and soils investigations for school
building sites. . . ..
4. Senate Bill 895-Clarification of Strong-Motion Progran Of 1971
Status Enacted (Chapter 664). . t-,
C-7('
38 895 makes' clarifying changes in the requirements established
by S3 1374 (1971) concerning the basis for fee collection and administration
by local jurisdictions of the strong-motion instrumentation program.
5. Senate Bill 396-Dam Safety
Status: enacted (Chapter 780).
SB 896 requires that owners of dams designated by the State
Office of Emergency Services (GES) prepare inundation maps and submit
thera to appropriate local public safety agencies and OES. Local juris-
dictions affected are required to prepare emergency evacuation procedures
based upon such information. .
6. Senate Bill 897-Assessment of Geologically Hazardous Lands
Status: Held in Senate Revenue and Taxation Committee for
Interim Study.
SB 897 would establish procedures whereby property owners could
obtain reduced property assessments based upon geologic reports submitted .
to the assessor, providing the owner agreed not. to develop such property
for tha areas determined to be unsafe.
7. Senate Constitutional Amendment 42-Assessment Valuation
Status: held for interim study.
SCA. 42 is a companion bill to SB 897. It allows the legislation
to provide for reassessment of damaged property after the lien date for a
given tax year.
8. Senate Constitutional Amendment 76-Legislature*s Disaster Powers
Status: held in Assembly Rules Committee . ... '
SCA 76 extends to natural disasters the situations in which the
legislation can convene and fill the offices of deceased members.
9. Senate Concurrent Resolution 66-Capitol Visiting Restrictions
Status: held in Senate Rules Committee ,
SCR 66 prohibits guided tours of the West Wing of the Capitol,
prohibits entrance to the wing by persons under 18 without a waiver, and
requires posting of warning signs of structural danger at entrances*
e-8
-«v.
' ' S*^\ . _
The following were introduced in 1973:
1. Senate Bill 308-Update of Cross-References in Hospital Bill of 1972
Status: enacted (Chapter 189}.
x
S3 308 corrects code cross-references in SB 519 (1972) made
inapplicable by the passage of subsequent 1972 legislation reordering the
Health and Safety Code.
2. Senate Bill 424-Assessment Valuation . • • „, • • \.' • • .
Status: held by author in State Revenue and Taxation Committee.
SB 424 is similar to SB 897 of 1972 and provides for immediate
reassessment of damage property provided its use is appropriately revised»
3. Senate Bill 1266-Revision of Dam Safety Bill of 1972
Status: enacted (Chapter 762).
S3 1266 amends SB 896 of 1972, requiring only one inundation nap
at full capacity and stipulating that OES, rather than dart owners, will
distribute the maps to public safety officials.
4. Senate Bill 1372-Future Emergency Services Structures •
Status: will be heard in Senate Committee on Government Organi-
zations in January, 1974. •
SB 1372 provides for the development of construction regulations
for future emergency services structures by the State Office of Architecture
and Construction. Enforcement is at the local level. Appeals procedures
are also provided for. •
5. Senate Bill 1373-Mandate of Local Disaster Plans
Status: will be heard in Senate Committee on Government Organi-
zations in January, 1974. -
SB 1373 mandates local disaster plans which are now optional. OES
is charged with establishing criteria and checking local plans for coarpliancs
with the State Disaster Plan. OES would report yearly to the legislature on
the status of the plans.
• v - y . ;'
» 6. Ssnate Bill 074-Existing Emergency Servicel^tructures
Status: held by author in Senate Conanittee on Government Organi-
sation
SS 1374 provides for bringing existing emergency service structurs
up to code (S3 1372) when funds are available from State and local bonds.
7. Senate Bill 1575-New Equipment in Emergency Services Structures
*
Status: held by author in Senate Committee on Government Organi-
zation .
SB 1375, the final bill in the "Emergency Services Structures" series,
forbids the installation of new Federal or State-funded communications and/or
disaster equipment in any structures not meeting the standards established in
S3 1372. *
8. Senate Constitutional Amendment 13-Assessment Valuation
Status: held by author in Senate Revenue and Taxation Coaunittee
SCA 13, a companion bill to SB 424, permits the legislature to
establish regulations regarding assessment of damaged property.
9. Senate Joint Resolution 4-Federal Earthquake Research Funds
Status: passed (Resolution Chapter 94).
SJR 4 memorializes the President to assure Califomians that
Federal earthquake research funds will not be cut back due to any reorgani-
zation of Federal agencies. The bill calls for a 10 percent increase in
research funding. .
10. Senate Concurrent Resolution 77: Extend Life of Joint Committee
Status: passed (Resolution Chapter 190).
SCR 77 extends the life of the Joint Committee to run concurrently
with this legislative session (ending December, 1974).
The following were introduced during the 1974. session:
1. Senate- Bill 1729-Creates a Seismic Safety Commission.
Abolishes the Building Safety Board and Strong-Mbtion Instrumen-
tation Board. Reports annually to the Governor and Legislature. .
C-TQ
2. Senate Bill 2148- Emergency Services
Exempts licensed engineers, geologists, architects and building
officinls from liability for services rendered during an emergency situation
caused by an earthquake.
v3. Senate Bill 2365-Annual General Plan Review
', Requires cities and counties beginning October 1, 1975, to
annually submit their general plans to the Council on Intergovernmental
Relations and the Office of Planning and Research for review.
-»'•*' ""•• " * 4
\