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Earthquake Quarterly - Summer
1997
This newsletter is a production of the
Western States Seismic Policy Council
121 Second Street, 4th Floor
San Francisco, California 94105
415/974-6422 fax 415/974-1747
e-mail: wsspc@wsspc.org
web address: http://www.wsspc.org
Steven Ganz, Executive Director
Andrea James, Administrative Assistant
Putting the "Policy" into WSSPC
WSSPC has turned a corner in its development and has begun the process of making policy
recommendations. As part of a comprehensive plan, WSSPC has implemented a procedure which
will allow thoughtful and practical policy recommendations to be developed. Members of
WSSPC can forward policy motions to the Board of Directors. These motions should be well
supported with background materials in order for the Board to have an educated discussion.
The Board will decide to forward the motion, with or without amendments, to the full
membership for adoption as a WSSPC Policy Recommendation. Ample time will be allowed for
the WSSPC membership to discuss the recommendations.
An integral part of the WSSPC Basin and Range Province Seismic Hazards Summit (see related
article on page 3) was developing policy. As a result of the policy plenary sessions, six
motions were forwarded to the WSSPC Board of Directors for action. Four of these motions
were approved, with amendments, to be forwarded to the WSSPC Membership. One motion was
adopted as internal WSSPC policy and no action was taken on the remaining motion.
The following are WSSPC Policy Recommendations which have been forwarded to the WSSPC
Membership. These recommendations have not been formally adopted by WSSPC. A vote on each
recommendation will take place at the WSSPC Annual Conference in November. Public comments
are welcome on these recommendations. On-going discussions are taking place on the WSSPC
internet discussion group (see page 5 for information on how to join).
WSSPC PR97-1: Active Fault Definition for the Basin and Range Province
WSSPC recommends that the following guidelines be used in defining active faults in the
Basin and Range physiographic province. Active faults can be categorized as follows,
recognizing that all degrees of fault activity exist and that it is the prerogative of the
user to decide the degree of anticipated risk and what degree of fault activity is
considered "dangerous":
Holocene Active Fault - a fault that has moved within the last 10,000 years.
Late Quaternary Active Fault - a fault that has moved within the last 130,000 years.
Quaternary Active Fault - a fault that has moved within the last 1,600,000 years.
It should be emphasized that more than half of the historic magnitude 6.5 or greater
earthquakes in the Basin and Range province have occurred on faults that did not have
Holocene activity, furthermore earthquakes in the province will occur on faults in all
three categories.
WSSPC PR97-2: Developing Guideline for Fault Trace Setbacks
WSSPC encourages individual state workshops to develop guidelines for local jurisdictions
to establish consistent criteria for setbacks from active faults. In several western
states, policy for the regulation of setbacks from active surface fault traces is
established at the local level. This results in considerable inconsistency even in
juxtaposed locales along the same fault zone.
WSSPC PR97-3: National Earthquake Risk Assessment and Allocation of Resources
WSSPC supports a national earthquake risk assessment and an allocation of resources based
on this assessment. WSSPC offers to take the initiative to coordinate a process with the
federal NEHRP agencies and regional earthquake consortia to establish national earthquake
hazard risk mitigation priorities through a forum providing state perspectives.
WSSPC PR97-4: Seismic Monitoring Networks
Because seismic monitoring networks are vital for earthquake hazard characterization and
because there is an insufficiency in available data, WSSPC encourages the continuation and
expansion of seismic monitoring networks, including strong motion instruments.
Back to Table of Contents
CALL FOR EXHIBITORS -
WSSPC Annual Conference 1997
On behalf of the Western States Seismic Policy Council (WSSPC), we are extending the
invitation for organizations to set up an exhibit at our Annual Conference to be held
November 4-7. We are confident that this year's conference will be our best ever and the
exhibit fair will be a huge success.
In addition to displays you may also sponsor an event such as meals, the conference
banquet and the socials. Sponsorship of these events will contribute to your
organization's exposure at this conference.
Sponsorship fees include breakfast and lunch on Wednesday, November 5, for two of your
organization's representatives. Additional day rate passes for the conference will be
available at $65 per day. Hotel rooms are available at the WSSPC conference rate of
$105.00 (Canadian Currency plus tax) per night for single occupancy. For more information
call the Ocean Pointe Resort Hotel (1-250/360-5860).
Over 100 registrants are expected to attend this conference including state directors and
geologist as well as the people on the front line of earthquake mitigation and education.
The conference will provide you with an excellent opportunity to display your products to
those directly involved in the field as well as key decision makers.
Conference Sponsorship Opportunities
Exhibitor Display Booths
WSSPC will host a exhibitor fair from 7:00 p.m. - 10:00 p.m. on November 4, 1997 and from
10:00 a.m. to 5:30 p.m. and 7:00p.m. to 10:00p.m. on November 5, 1997. The buffet luncheon
on Wednesday November 5, will have the displays as the primary focus. There are two booth
sizes from which to choose. The basic display area will be 6' x 6'. Included in the
display area will be a 6' x 18" table, two chairs and an area behind the table for
self-supporting displays. Additionally, a very limited number of 12' x 8' booths will be
available for self-supporting displays. (Tables can be made available for the larger
display areas.)
Meal and Social Activity Sponsorships
WSSPC is offering an opportunity for organizations to sponsor conference meals and
receptions. Organizations will be included in the conference program as the sponsor of the
given activity, and conference organizers will announce the support of the sponsoring
organization at the respective meal or event. At each of the breakfasts, lunches, socials
and the conference banquet sponsors are welcome to display a sign with the sponsor name.
In addition, an area at the each event will be made available for sponsors to display
information.
Back to Table of Contents
1997 Uniform Building Code Ground Shaking Criteria
Robert E. Bachman, Fluor Daniel, Inc.
The recently published 1997 Uniform Building Code (UBC) incorporates two significant
changes to the ground shaking criteria which apply to all structures. The first change is
a revision to soil types and soil amplification factors. The second change is the
incorporation of near source factors in UBC seismic Zone 4. Together these changes result
in the largest increases in code ground shaking criteria which has occurred in the past 30
years. Records obtained from the Strong Motion Instrumentation Program (SMIP) along with
USGS records were the primary sources of data used to justify these code changes.
Soil Types and Soil Amplification Factors
The ground shaking basis for code design is reflected in the 5% damped elastic response
spectra . The response spectra is defined in terms of two site seismic coefficients Ca and
Cv. The site seismic coefficients are determined as a function seismic zone, soil type,
and in Zone 4 near source factors. The soil profiles are subdivided into six types based
on the average soil properties in the top 100 feet of the soil profile. The types are
identified as SA through SF. The types are based on consensus deliberations from the
USGS/NCEER/SEAOC workshop held at USC in 1992. These are identical to soil profile types
that are found in 1994 NEHRP Provisions.
The site seismic coefficients Ca and Cv are determined from Tables 1 and 2 based upon the
soil profile type, seismic zone and in UBC Zone 4 the near source factors Na and Nv. It
should be noted that the value of the soil factors depart significantly from previous
codes in that both short period and long period structures are effected by soil effects
and that the amplifications increase significantly at lower ground acceleration levels. In
previous codes soil effects were only considered for long period structures. The
amplification factors are consistent with the consensus from the previously referenced USC
workshop and are identical to those found in the 1994 NEHRP provisions. These effects are
consistent with observations in the Mexico City and the Loma Prieta earthquakes
Near Source Factors
The near source factors were developed by Ground Motion-Ad-Hoc-Committee of the SEAOC
Seismology Committee to account for the effects of ground motions near the source of
seismic events. The factors are a refinement of what was developed for seismically
isolated structures included initially in the 1991 UBC. Near source ground motion records
and observed damage from Northridge and Kobe have provided convincing evidence of
significantly more intense ground shaking near the fault rupture then had been previously
accounted for.
In order to establish, the near source factors, the first step is to identify and locate
known active faults in UBC Zone 4 and classify them into one of three source type based on
maximum moment magnitude and slip rate. Faults are classified based on their maximum
magnitude M and slip rate R. Type A sources are faults that have a moment magnitude
potential of M > 7.0 and a slip rate SR equal to or greater than 5 mm/year. These types
of faults are considered to be active and capable of producing large magnitude events.
Most segments of the San Andreas Fault would be classified as a Type A fault. Type C
sources are faults that have a moment magnitude potential of M less than 6.5 and a slip
rate of SR less than or equal to 2 mm/year. Type C faults are considered to be
sufficiently inactive and not capable of producing large magnitude events such that
potential near-source ground shaking effects can be ignored. Most faults outside of
California are Type C. Type B sources are all faults that are not either Type A or Type C
and include most of the active faults in California. The 1997 UBC requires that the
locations and characteristics of these faults be established based on approved
geotechnical data from reputable sources such as the California Division of Mines and
Geology and the USGS.
Once faults are located relative to a site and the source type is established, the near
source factors Na and Nv are determined. These factors were established by the Ad Hoc
Ground Motion Committee and are based on the average increase, measured in the near field
from Northridge and other earthquakes. The near source factors apply to both strike-slip
and reverse-slip (thrust) fault mechanism although reverse-slip faults produce about 20%
greater shaking on the average. The short period (acceleration domain) near source factor
(Na) is based on response at 0.3 seconds and long-period (velocity-domain) near source
factor (Nv) based on 1.0 second response. Values of Nv are bumped upward by about 20% to
account for the increase in average response in the fault-normal direction above that
predicted by the attenuation function for the random component of horizontal ground
shaking (ref. Somerville, 1996 7th US/Japan Workshop, Lessons learned from Kobe and
Northridge). The commentary to the SEAOC bluebook notes ground shaking at "forward
directivity" sites is likely to be 1.25 times the Cv and Ca coefficients based on
average fault normal response.
Distance from Faults and Fault Maps
The rules for measuring distance from a fault were also established by the Ad Hoc ground
motion committee and are found in the code. It is interesting to note that for
non-vertical faults a zero distance fault zone has been established as illustrated. The
distance from a fault is measure from this zero distance fault zone.
Active faults near field maps are currently being developed for California Zone 4 for
California Mines and Geology. The form of the maps will be like a Thomas Guide and will be
at a scale of 1:150,000. The background will include street maps and freeways. An
individual will be able to find their house on the maps. The USGS is providing fault
information developed for Project 97 for maps outside of California and the maps will be
developed by donated private sources. The maps will be published for sale by ICBO in fall
of this year.
In conclusion, the inclusion of soil and near field effects in the 1997 UBC represent one
of the most state-of-the-art, meaningful, and impactive changes in the code by the
geoscience community in the history of seismic codes. The effects will continue to be
improved in the new International Building Code which replaces the UBC beginning in the
year 2000.
Back to Table of Contents
WSSPC Basin and Range Province Seismic Hazards Summit: A
Summary
The Western States Seismic Policy Council (WSSPC) hosted the Basin and Range Province
(BRP) Seismic Hazards Summit in Reno, Nevada, May 13-15, 1997. The purpose of the summit
was to review important technical issues in characterizing seismic hazards in the BRP and
consider their public-policy implications. The purpose of the summit, and of the Western
States Seismic Policy Council Basin and Range Province committee, is to accurately and
effectively characterize seismic hazards in the province and to identify policies and
means of communication that will effectively reduce the loss of life and property.
Participants included a broad range of researchers and scientists, as well as users. A
conference-long poster session presented seismic-hazards maps of each of the WSSPC BRP
states and results of recent scientific research. Each day of the summit ended with a
discussion that helped develop policy recommendations that were presented to the WSSPC
Board of Directors for consideration for formal adoption as WSSPC policy. A technical
proceedings volume will be published.
The opening session of the summit highlighted user's perspectives on information needs and
how seismic-hazards information is being put to practical use. One example is the new
seismic provisions in the 1997 Uniform Building Code, which now includes factors to
address near-source effects and a new method to address site effects. Speakers addressed
issues related to the trend toward performance-based building codes and problems caused by
making changes to the codes, particularly seismic-zone boundary changes. Loss estimation
is becoming increasingly important, and issues related to characterizing seismic sources
and information needs for the new FEMA HAZUS loss-estimation software were highlighted.
Finally, to set the stage for subsequent technical discussions, Clarence Allen highlighted
the uniqueness of the BRP and the challenges in characterizing its earthquake hazards.
The initial technical discussion centered on difficulties in characterizing
"active" faults and the issue of defining which faults should be considered
active for what purposes in seismic-hazards assessments. Typical BRP faults have
relatively low slip rates and long, irregular recurrence intervals, although faults
covering a wide range of activity levels are found in the BRP. Talks centered on whether a
Holocene or late Pleistocene definition of active faults is more appropriate in the BRP,
how to characterize the hazard from BRP faults, what types of recurrence models should be
used, and how the actual hazard of surface faulting is handled in various BRP states.
The second day of the summit concentrated on characterizing strong ground motions in BRP
normal-faulting earthquakes, given the current lack of strong-motion data for such
earthquakes. Some data indicate that ground motions in extensional regimes are somewhat
less than those of similar-magnitude earthquakes in compressional regimes, and this is
supported by new field evidence documenting the preservation of semi-precarious rocks near
BRP normal faults. New BRP attenuation relations are being developed, chiefly as a result
of work for the Yucca Mountain Nuclear Waste Repository in Nevada. Researchers noted
spacial variations in shaking intensity in a normal-faulting earthquake in Turkey, where
damage statistics indicated larger ground motions on the downthrown block. Near-fault
rupture pulses are well-documented in strike-slip and reverse-faulting earthquakes, but
laboratory models indicate that such pulses may not be as important in normal-faulting
earthquakes. Computer modeling and instrumental monitoring of seismic-wave amplification
in deep BRP basins indicate that the basins significantly amplify and increase the
duration of longer-period ground motions, particularly in deeper parts of the basins.
The final day of the summit addressed probabilistic seismic hazards analyses (PSHAs) and
their application in the BRP. One theme of the session was the need to standardize
historical earthquake catalogs and collect additional fault slip-rate data. Because of the
irregularities in earthquake recurrence and uncertainties in BRP recurrence models, PSHAs
are particularly well-suited for assessing seismic hazards in the BRP. PSHAs can be
improved as more becomes known about: 1) modern strain rates from GPS measurements, 2)
distributed faulting (displacement on multiple faults in one earthquake), 3) earthquakes
on one fault causing seismic "loading" on adjacent faults, 4)
magnitude-frequency distribution of earthquakes regionally and on individual faults, and
5) causes and likelihood of temporal clustering of earthquakes.
Conference attendees unanimously passed six motions. (See Putting the "Policy"
into WSSPC") Before these become WSSPC recommendations, resolutions, or positions,
they must be approved by the WSSPC Board of Directors, then by the full membership of
WSSPC. Four of the motions were amended and approved by the Board of Directors to present
at the next WSSPC Business Meeting, November 7, 1997, during the Annual Conference in
Victoria, British Columbia.
The WSSPC BRP Committee, which organized the summit under the leadership of Craig dePolo
(Nevada Bureau of Mines and Geology), will remain as a WSSPC committee to follow-up on
these summit recommendations. It is likely that another BRP Seismic Hazards Summit will be
held in coming years. Contact WSSPC office (415-974-6435, or by e-mail: wsspc@wsspc.org),
to be notified when the proceedings volume is available.
Back to Table of Contents
WSSPC AWARDS IN EXCELLENCE
The Western States Seismic Policy Council Awards in Excellence recognizes achievement in
different areas of earthquake mitigation, preparedness and response. This program is both
an effective method to share model programs throughout our region, as well as to recognize
the hard-working, creative and innovative efforts within the earthquake hazard reduction
community.
It is the hope of WSSPC to bring greater visibility to exemplary state, county and local
programs and policies and to facilitate the transfer of those successful experiences to
other states.
ELIGIBILITY
State, provincial, county, or city governmental agencies in WSSPC member states are
eligible for the WSSPC Awards in Excellence. Programs can be nominated by the originating
agency or by an outside agency.
CATEGORIES
Awards will be given in the following categories:
· Mitigation Efforts · Educational Outreach Programs
· Response Plans/Materials (three categories awarded)
· Use of New Technology · Outreach to Business/Government
· Research Projects · Outreach to Schools
· Innovations (i.e. Private/Public Partnership) · Outreach to the General Public
SCHEDULE
August 15, 1997 -- Deadline: Applications are due to WSSPC Office
-- WSSPC Awards Committee begins to review applications
September 15, 1997 -- Awards Committee selects awarded programs
October 1, 1997 -- Winners notified and encouraged to attend WSSPC Annual Conference
November 6, 1997 -- Awards ceremony at WSSPC Annual Conference
January 15, 1998 -- Publish a volume of award winning programs
SELECTION CRITERIA
At each stage of the award selection process, the following questions are employed to
determine whether the program or policy is eligible for further consideration:
· Is it a state/local/regional government sponsored program or product?
· Does it represent a new and creative approach to problem(s) or issue(s)?
· Does the program or product address significant problem(s) or issue(s) that are local,
regional or national in scope?
· Has the program been operational for at least one year (since August 30, 1996)?
· Has the program or product been effective in achieving its stated goals and purposes?
· Could the program or product be easily transferred to other states or regions?
AWARD
The Western States Seismic Policy Council will be awarding certificates of achievement to
finalists in the program categories. If funding is available, monetary awards will be made
to the winning agencies. A description of each awarded program will be included in a WSSPC
publication for wide distribution.
To receive a nomination application, please contact the Western States Seismic Policy
Council office at (415) 974-6435 or e-mail us at wsspc@wsspc.org.
Back to Table of Contents
SPOTLIGHT ON:
THE EARTHQUAKE ENGINEERING RESEARCH INSTITUTE (EERI)
The Earthquake Engineering Research Institute (EERI), founded in 1949, is an
international, nonprofit, professional association comprised of more than 2,500 engineers,
geoscientists, building officials, architects, planners, social scientists and others
actively working in the earthquake hazard reduction field.
The objectives of the Institute are the advancement of the science and practice of
earthquake engineering and the solution of earthquake engineering problems to protect
people and property from the effects of damaging earthquakes.
Today, as the field of earthquake hazard mitigation expands, EERI takes on tasks which
reflect its unique interdisciplinary membership: fostering communication between different
disciplines and bridging the gap between new knowledge, design practice, and hazards
reduction policy.
Among all the activities designed to improve the exchange and application of knowledge,
EERI is probably best known for its field investigations and reports of the effects of
destructive earthquakes. With National Science Foundation support, EERI has for many years
conducted a project to maximize learning from destructive earthquakes through planning and
coordination of post earthquake reconnaissance teams. Under this project, EERI has
established and published field guides and response plans for the conduct of earthquake
investigations.
Preliminary information on the effects of destructive events can be rapidly published in
the monthly Newsletter. For major earthquakes, EERI publishes reconnaissance reports and
sponsors briefings and conferences. EERI also publishes long-term findings based on
research about specific earthquakes in its quarterly journal, Earthquake Spectra.
Much of the work of EERI is conducted under the auspices of our two dozen technical
committees. Among the most active are the Public Policy Committee, the Publications
Committee, the Technical Seminars Committee, the Traditional Education Committee, the
Experimental Research Committee, and the US/Japan Committee on Urban Earthquake Hazard
Reduction
EERI has a tradition of sponsoring major technical conferences to provide a forum for the
exchange of information between researchers in diverse but related disciplines. In
addition, every four years EERI organizes the U.S. National Conference on Earthquake
Engineering. During the past several years, EERI has organized a series of public
briefings following major earthquakes. Throughout the U.S., briefings were held on the
Armenia, Loma Prieta, Northridge and Kobe earthquakes generally drawing over 1,000
participants to each series.
EERI Annual Meetings provide both structured programs on current issues and informal
exchanges between researchers, practitioners, and government policy makers. Invited
speakers present research results, share their practical ideas and experiences, discuss
hazards reduction policy and assess the effects of recent earthquakes. The 1997 Annual
Meeting was held in Austin, Texas, and focused on "Challenges Associated with
Existing Facilities".
In 1984, the Institute introduced Earthquake Spectra, a quarterly journal devoted to
current research pertaining to earthquake hazard reduction, which is provided to members
and subscribers. Spectra is intended to serve the informational needs of many active
professions: engineers, code officials, geologists and seismologists, planners and public
officials.
Members also receive a monthly Newsletter containing information about the Institute's
activities, a calendar of meetings, publications, and relevant information from around the
world.
EERI produces many slide sets that illustrate subjects related to earthquake engineering
practice, including: typical construction errors, errors in detailing, damage caused by
the Mexico City, Whittier, Armenia, Loma Prieta, Northridge and Kobe earthquakes. In
addition, EERI has produced videotapes of its technical briefings of the Armenia, Loma
Prieta, Northridge and Kobe earthquakes.
Under the sponsorship of the Public Policy Committee, EERI has established a State and
Local Policy Action Program, designed to enhance interaction with state and local
government agencies concerning current earthquake policy issues.
The Traditional Education Committee has established eleven EERI Student Chapters
throughout the country to heighten the participation of college students in various EERI
activities.
The Publications Committee has created a new Design Series, illustrating the
decision-making process that goes into the design of an individual building. Meant to
serve as an educational tool in the classroom and for the practicing professional, the
Series is expected to generate one booklet each year.
Since 1991, EERI has offered two scholarship programs, supported by FEMA, each awarded to
encourage the transfer of research to practice according to the goals of the National
Earthquake Hazard Reduction Program. One is a graduate study fellowship and the other is a
professional fellowship. At each EERI Annual Meeting, the most recent graduate fellow
presents his or her final report. The professional fellows' final reports are available
free of charge and hundreds of copies have been disseminated throughout the country.
EERI created an Endowment Fund in the fall of 1993. The Fund is being used to stimulate
new and unique ventures, to identify gaps in research, to improve application and
practice, and facilitate public policy that leads to effective reduction of earthquake
risks. The first two in the series of Endowment Fund White Papers are, "Public Policy
and Building Safety" and, "Construction Quality, Education and Seismic
Safety."
For more information about EERI you can contact them at (510) 451-0905.
Back to Table of Contents
Magnitude 7.0 Earthquake on Hayward Fault: A Scenario
Reported by: Earthquake Engineering Research Institute with support from FEMA, November
1996
At the 1995 Annual Meeting of the Earthquake Engineering Research Institute, a special
day-long symposium was held on the multidisciplinary challenges of a major urban
earthquake, using the northern Hayward fault as an example. The presenters covered all
aspects, from the social and economical setting of the San Francisco Bay Area, through
geologic, seismologic, and engineering aspects, to the emergency response and recovery
issues that will challenge government and industry in the months and years after the
earthquake.
This publication provides a valuable tool for planners, design professionals, emergency
and risk managers, and public officials. By identifying the most vulnerable areas and
structures, it provides the information needed to develop programs that will reduce future
losses and speed recovery.
For those outside the San Francisco Bay Area, this fascinating document demonstrates how a
scientifically credible scenario can be used to create awareness of and gain support for
comprehensive programs to reduce earthquake losses.
Copies of Scenario for a Magnitude 7.0 Earthquake on the Hayward Fault can be purchased
for $15 prepaid plus $5 shipping/handling from the EERI. Order at 499 14th St., #320,
Oakland, CA 94612-1934 or fax to 510/451-5411 with your credit card number.
Back to Table of Contents
WSSPC On-Line Discussion Group
Now you can participate in seismic policy discussion, as well as find out the latest
information about the seismic hazards community. You only need e-mail to participate.
To sign up: send an e-mail to wsspc@wsspc.org
Include your name, organization, address, telephone number, and e-mail address.
Back to Table of Contents
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