Table Of ContentPREFACE
Great loss of human life, structural damage, and social and economic upheaval have occurred
repeatedly in recent history due to such natural hazards as earthquakes, hurricanes, landslides,
floods and tsunamis. Both the US and Taiwan are threatened by such occurences and thus share a
common concern to mitigate these hazards. Recent disasters of particular interest in the US are the
1989 Loma Prieta and 1994 Northridge earthquakes as well as the 1993 Midwest flood.
Several decades ago, the US embarked on natural and manmade hazards mitigation research. In the
early 1980s, Taiwan launched a multiple hazards mitigation program with a sequence of five-year
plans. Since then, the US and Taiwan joined together in three symposia/workshops on research and
its application in multiple hazard mitigation. A fourth joint symposium workshop, Urban Disaster
Mitigation and the Role of Engineering and Technology, was held in Chicago, July 1994. Its
objectives were:
eto discuss the lessons learned from recent natural disasters
e to assess the current state of knowledge and practice in various natural hazard areas and to identify
frontal joint research opportunities for advancing this knowledge
(cid:12)9 to stimulate future cooperative research on and development of subjects of common need and
importance
eto evaluate the results of Taiwan's multiple hazards research program and its practical implications
for mitigation of such hazards in the US
(cid:12)9 to continue to build the long-term bilateral scientific relationship existing between academic and
practicing communities
This volume of proceedings contains state-of-the-art reports by world-renown researchers in their
respective disciplines. Speakers were selected through careful screening by the Steering Committee
to serve as delegates from their nation.
Sponsors of the joint symposium/workshop were National Science Foundation (NSF) in the US,
under program directors Dr. Eleonora Sabadell and Dr. S.C. Liu, and National Science Council
(NSC) in Taiwan. Their support is gratefully acknowledged.
Instrumental in the success of this event were a number of individuals serving on committees or with
organizations.
US STEERING COMMITTEE
Franklin Y. Cheng (Chair), University of Missouri-Rolla
James E. Beavers, Martin Marietta Energy Systems Inc.
Riley M. Chung, National Institute for Standards & Technology (NIST)
Anne S. Kirmidjian, Stanford University
George C. Lee, National Center for Earthquake Engineering Research (NCEER)
State University of New York (SUNY)-Buffalo
Joanne M. Nigg, Disaster Research Center, University of Delaware
Ben Yen, University of Illinois at Urbana-Champaign
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SYMPOSIUM/WORKSHOP ACTIVITIES
pohskroW/muisopmyS Group erutciP
x pohskroW/muisopmyS seitivitcA
Welcome Remarks at Opening Ceremony by Dr .F .Y Cheng,
SU Delegation Chair
Welcome Remarks at Opening Ceremony by Dr M. -S. Sheu,
Taiwan Delegation Chair
Symposium/Workshop Activities i x
Welcome Remarks at Opening Ceremony by Dr .S .C Liu, Program Director,
SU National Science Foundation
Banquet
RESOLUTIONS
Overall Recommendations
.1 Participants unanimously recognize the importance of mitigating the potential damage resulting
from natural hazards and support the continuation of cooperative research in areas of mutual
concern. Research on such topics as seismology, earthquake engineering, flood control, slope
stability and emergency management is considered as most urgently needed and being most likely to
produce mutually beneficial results.
2. In Taiwan the ongoing program of the National Science Council on multiple hazard mitigation is
well-planned and executed. Projects conducted under this program are beginning to produce useful
information. Continuing support of this program should be provided until its successful completion.
It is suggested, however, that demonstration projects be enhanced to ensure full interaction among
investigators and users. Relevant results should also be made available to the American research
community through an appropriate US-Taiwan joint research mechanism. Cooperation between
National Center for Earthquake Engineering Research (NCEER) at SUNY-Buffalo and National
Center for Research on Earthquake Engineering (NCREE) in Taiwan should be continued and
enhanced.
Acknowledging the success of this symposium/workshop, participants suggest that a similar
symposium/workshop be continued at intervals of two or three years.
GROUP I SEISMOLOGY
lareneG_ Recommendations
The risk that earthquakes pose to society in both the US and Taiwan is growing due to increased
urbanization within earthquake-affected regions of each country. Our common experience in recent
damaging earthquakes underscores the need to continue basic and applied research into the causes
and effects of earthquakes. Over the past several years, significant steps have been taken to
modernize seismological data collections in both countries. The challenge in the coming years will
be to apply these new data to the reduction of earthquake risk. Seismological research can be an
effective means of achieving this goal through bilateral cooperation between researchers in our two
countries to:
.1 Improve our understanding of the physics of the earthquake source.
2. Make more accurate predictions of strong ground motion.
3. Develop near real-time capabilities for locating earthquakes and estimating areas of
probable damage.
4. Explore the feasibility of seismic early warning systems.
Specific Cooperative Projects
.1 Continued cooperation between the Central Weather Bureau and the US Geological
Survey (USGS) for the development of the Taiwan Strong Motion Instrument Program
(TSMIP).
2. Continued cooperation in the analysis of strong ground motion data from the SMART-1
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array and SMART-2 array operated by the Institute of Earth Sciences, Academia Sinica,
and expansion of activities to analyze data collected by TSMIP.
3. Creation of a working group on rapid analysis and reporting of strong earthquakes.
a. Workshop to be held in Taiwan on rapid notification and seismic early warning
systems.
b. Creation of a seismological data exchange agreement to foster and assist joint research
projects that utilize information from the new instrument capabilities of each country.
These proposed programs can be most effectively achieved through direct researcher-to-researcher
contacts, including working visits to research centers, creation of task-oriented working groups, and
topical workshops. We also recognize that the changing research environment, particularly the
growing use of computer networks, provides new ways for researchers to collaborate, and these
means should also be employed to develop and assist the creation of bilateral projects.
List of Participants
_
Y.T. Yeh (co-chair), National Chung Cheng University
W.L. Ellsworth (co-chair), USGS, California
H. Hwang, University of Memphis
K.W. Kuo, Central Weather Bureau
Y.B. Tsai, Pacific Gas & Electric Co.
GROUP II EARTHQUAKE ENGINEERING
Gcnr Recommendations
.1 Cooperative research and scientific exchanges between NCEER in the US and NCREE in
Taiwan should be continued and expanded.
2. This type of joint US-Taiwan symposium/workshop to exchange research results should
be held once every two or three years.
Soecific Recommendations
.1 Development of site modeling using TSMIP free field data.
2. Study of structural identification/structural responses using TSMIP monitoring data from
actual structures.
3. Instrumentation and analysis of real lifeline systems within TSMIP.
4. Research on structural control technology, including active, passive and hybrid systems.
5. Development of performance-based seismic design codes for buildings.
6. Study of steel building frame design practice from Northridge earthquake experience.
7. Study of residual life/strength of existing structures, due to aging, and/or after fires,
earthquakes, strong winds and floods.
8. Development of non-destructive testing techniques, new materials and methodologies for
repair and rehabilitation of civil infrastructures.
Note that the above recommended list of cooperative research topics is not inclusive or exhaustive.
Additional topics may be developed as appropriate between the two countries from time to time.
List of Participants
L.R.L. Wang (co-chair), Old Dominion University
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C.S. Yeh (co-chair), NCREE
A.H-S. Ang, University of California at Irvine
W.F. Chen, Purdue University
F.Y. Cheng, University of Missouri-Rolla
R.M. Chung, National Institute of Standards and Technology
W.M. Dong, Risk Management Solutions Inc.
H.M. Hwang, Memphis State University
S.C. Liu, National Science Foundation
S.T. Mau, University of Houston
L.H. Sheng, California Department of Transportation
M.S. Sheu, National Cheng-Kung University
P.S-L. Shu, Sargent & Lundy
Y.B. Tsai, Pacific Gas & Electric Co.
W.H. Tang, University of Illinois at Urbana-Champaign
Y.K. Wen, University of Illinois at Urbana-Champaign
G.C. Yao, National Cheng-Kung University
GROUP III FLOOD ENGINEERING, LANDSLIDES AND ROCKSLIDES
General Re.commendations
There has been very limited joint research between the US and Taiwan on floods and landslides,
mostl), on an individual exchange basis, due more to lack of funds than to communication. In view
of Ta~wan's special geophysical characteristics of intense rain, seismicity, steep slopes and tropical
weather, there is an opportunity for effective cooperation that will benefit both countries
economically, socially and environmentally. This is evidenced by the substantial annual damage
cost (multi-billion dollars) of floods and landslides.
Consequently, there are possible joint research areas too numerous to list. Some general research
areas of common interest are as follows:
.1 Forecasting and prediction of floods and landslides.
2. Effectiveness of structures and techniques for landslide and flood mitigation.
3. Data acquisition and management, including the use of GIS.
4. Multiple-hazard induced floods and landslides, such as rain-and-earthquake-induced
landslides, landslide-induced floods, and flood-and-earthquake-induced dam failures.
5. Demonstration and experimental sites for the above.
6. Coastal flood and surge mitigation.
Soecific Coooerative Proiects
_ _ _
.1 Research on floods:
a. Evaluation of reliability (in both magnitude and time) of existing real-time flood
forecasting methods and possible improvement in forecasting techniques.
b. Risk of failure of flood control structures.
c. Improved flood prediction methods for flood engineering design.
d. Study of rainfall for improved forecasting and prediction of floods.
e. Safety of dams.
f. Selection and comparison of demonstration sites in Taiwan and the US.
g. Coastal flooding due to land subsidence.
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2. Research on landslides (multiple-hazards approach to landslide tasks):
a. Prediction/hazard mapping/zone of influence of hazard, e.g. debris flow, avalanche,
landslide.
b. Study of rainfall as a cause of landslides.
c. Geographic information systems to combine effects of multiple hazards.
d. Static and dynamic stability of soil and rock slopes.
e. Seismic displacement of soil and rock slopes.
f. Ground motion amplification of soil and rock slopes.
List of Particioants
B.C. Yen (co-chair), University of Illinois at Urbana-Champaign
S.T. Chen (co-chair), National Cheng Kung University
R.H. Chen, National Taiwan University
Frederick N-F. Chou, National Cheng Kung University
M.H. Hsu, National Taiwan University
R.L. Schuster, USGS, Colorado
T.D. Stark, University of Illinois at Urbana-Champaign
W.H. Tang, University of Illinois at Urbana-Champaign
GROUP IV SOCIO-ECONOMIC IMPACT
General Recommendations
It was recognized that the cross-national analysis of multi-hazard mitigation programs--used in
Taiwan and the US--would be beneficial to both countries in their efforts to reduce the vulnerability
of urban areas to natural hazard impact. Academic scholars in both countries have continuing
research interests in social, economic, and policy issues that would be involved in studies on this
general topic.
Research in this area would have four general purposes"
.1 To understand the different strategies, policies and programs that are used by all levels of
government to reduce natural hazard threats and vulnerability.
2. To identify the factors that influence the adoption and implementation of these policies,
procedures and programs.
3. To identify the factors that lead to successful reduction in vulnerability of the urban social
and built environments to natural hazard threats.
4. To investigate the costs and benefits--soci~ and economic--of the various hazard
reduction approaches used in both countries.
Specific Cooperative ProjectS
Three specific projects in the socio-economic and policy area are being recommended. While these
projects are discrete and could be conducted independently, there would be great benefit in
completing them sequentially, with each project building on the results of the previous effort. All
three projects would provide a comprehensive analysis of the policy environment and the factors
which influence it, with respect to mitigating natural hazards in major urban areas in Taiwan and the
US.
.1 Identification of governmental--national, state, county, municipal--policies used to reduce
natural hazard threats and vulnerability in urban areas.
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a. This would require the identification of a common set of natural hazards in a
comparable set of urban areas to provide the basis for a cross-national study.
b. Economic and policy data would be collected on efforts undertaken or considered to
make the urban environment safer.
2. Assessment of policies' effectiveness in reducing threat and vulnerability.
a. For each hazard identified in the cities selected, responsible government departments
would be identified.
b. Semi-structured face-to-face interviews would be used to gather data from
governmental decisionmakers with respect to specific mitigation efforts.
3. Assessment of public perception of hazards that threaten a given community and the
efficacy of governmental efforts to reduce vulnerability.
a. Structured questionnaires would be developed to collect data from a random sample of
the general public and from interest group (stakeholder) representatives.
b. Data would be analyzed and recommendations made.
List of Participants
C-Y.D. Chang (co-chair), National Taiwan University
J.M. Nigg (co-chair), University of Delaware
B.G. Jones, Cornell University
LOCAL ARRANGEMENTS AND HOSTS
Peter S.L. Chu, Sargent & Lundy, Chicago
Roy Wu, Director General of Coordination Council on North American Affairs (CCNAA)
Office in Chicago
John Wang, Director of Science Division, CCNAA Office ni Chicago
LIAISON COMMITTEE
Howard Hwang, Memphis State University
David C.C. Tung, North Carolina State University
INSTITUTIONAL SPONSORS
University of Missouri-Rolla; Rolla, MO 65401; USA
National Cheng Kung University; Tainan 70101; Taiwan
SESSION CHAIRS
Peter S.L. Chu, Sargent & Lundy, Chicago
Riley M. Chung, NIST
Weimin Dong, Risk Management Solutions Inc.
Ming-hsi Hsu, National Taiwan University
Howard Hwang, Memphis State University
C.H. Loh, National Taiwan University
Le-Wu Lu, Lehigh University
Wilson H. Tang, University of Illinois at Urbana-Champaign
John Wang, CCNAA Office in Chicago
Leon Wang, Old Dominion University
Yi-Kwei Wen, University of Illinois at Urbana-Champaign
DELEGATION CHAIRS
Franklin Y. Cheng, University of Missouri-Rolla
Maw-Shyong Sheu, National Cheng-Kung University
Editors
Franklin Y. Cheng
Maw-Shyong Sheu
CHARACTERISTIC EARTHQUAKES AND LONG-TERM
EARTHQUAKE FORECASTS: IMPLICATIONS OF CENTRAL
CALIFORNIA SEISMICITY
W. L. Ellsworth
U.S. Geological Survey, MS-977, Menlo Park,
AC 94025, U.S.A.
ABSTRACT
Waveform analysis of seismicity in central California reveals the routine occurrence of families of repeating
earthquakes, events that rupture the same fault area in events of similar magnitude. These repeating
earthquakes share many of the attributes proposed under the characteristic earthquake hypothesis for
recurrence of large earthquakes including: a probability distribution for recurrence intervals with a central
mean and long-tail; proportionality between length of recurrence interval and mean rate of strain accumulation;
and absence of evidence for repetition before the recovery of released elastic strain energy. Temporal
clustering, the principal non-Poisson component of seismicity, appears to involve successive failure of
adjoining or nearby parts of the fault, without re-rupture of the already broken fault areas.
KEYWORDS
Earthquake Probabilities; characteristic earthquakes; recurrence; clustering; prediction
INTRODUCTION
The elastic rebound theory of H.F. Reid (1910), and the seismic gap hypothesis originally proposed by S.A.
Fedotov (1965) and by K. Mogi (1968) form the cornerstones of long-term earthquake forecasting as it is has
been applied to plate boundaries around the world. In general, the likelihood of an earthquake is related to the
amount of elastic strain energy stored along the fault, with regions that have recently ruptured having low
probability of failure, while those that have been locked for long periods having higher probability of failure.
These ideas have been refined by numerous authors in applications on both fault-specific and global scales
over the past 20 years.
In the early 1980's, the possibility that individual fault segments produced essentially but one rupture pattern,
a characteristic earthquake, was proposed by several authors on the basis of both geological and
seismological evidence (Schwartz and Coppersmith, 1984; Bakun and McEvilly, 1984). Under this
hypothesis, the next earthquake on a particular fault segment will occur when the strain drop in the last has
recovered. If correct, this model has significant practical value as it provides a vehicle for moving the
estimation of seismic hazard from Poissonian probabilism into the realm of time-dependent hazard assessment
(Muir-Wood, 1993). This hypothesis has played a key role in, for example, the siting of the Parkfield
