REPORT OF THE EXTERNAL REVIEW COMMITTEE
ON THE STATISTICAL SEISMOLOGY RESEARCH
PROJECT.
August 2006
Contents
1 Forward
1.1
External Review Committee
1.2
Statistical Seismology Research Group
1.3 Terms
of Reference
Introduction
Quality and
impact of academic activities
Statistical
theory and methodology
1.4
Seismological theory and methodology
2 Cooperative research activities and contribution to the
public good
2.1
Interinstitute activities
2.2 Contributions
to the public good
3 Bringing up the next generation
4 Comments and suggestions for the future work plan
5 Overall conclusions and recommendations
References
Appendix 1: Schedule of External Review
Appendix 2: Summary of materials presented the Review
Committee
Appendix 3: Programme of the 4th International Workshop on
Statistical Seismology
1 Forward
1.1 External Review
Committee
The
members of the committee and their home institutions are as follows.
Massimo
Cocco Instituto
Nazionale di Geofisica e
William
L. Ellsworth
Manabu
Hashimoto
Disaster
Prevention Research Institute,
Kunihiko
Shimazaki The
Earthquake Research Institute, The
David
Vere-Jones
and Statistical Research
Associates, Ltd.,
1.2 Statistical
Seismology Research Group
List
of members including postdocs and graduate students is as follows
Yosihiko
Ogata The
Institute of Statistical Mathematics (ISM)
(Leader)
Shinji Toda Visiting
Prof. of the ISM (2005--)
and
Geological Survey of
Yasuaki MURATA Visiting
Assoc. Prof. of the ISM (2003--2004)
and
Geological Survey of
Jiancang Zhuang Research
Fellow upon JSPS program (2001 -- 2005)
Kazuyoshi Nanjo Research
Fellow upon JSPS program (2003 --)
Takaki Iwata Research
Fellow of ISM (2005 --)
Masatsugu Wakaura Graduate
Student, The
Ushio Tanaka Graduate
Student, The
Akiko Kutsuna part-time
assistant
1.3 Terms of Reference
(1) Academic Contribution in terms of
(a) Statistical methods: Outcome and
Impact
(b) Seismology: Outcome and Impact
(c) Cooperative Research Activities
(2)
Contribution to the Society
(3)
Bring up Next Generation
(4)
Prospect of Future Development and Suggestions
Introduction
1.
The Review Committee visited the
The
main body of the Report is divided into sections following broadly the sequence
set out in the terms of reference.
2.
Members of the Committee would like to express their appreciation to Professor
Kitagawa for the opportunity to participate in the Review, and to Professor
Kitagawa, to members of the Institute's administrative staff, and to members of
the Statistical Seismology Research Group, for the many courtesies extended to
them during their visit. They would also like to express their appreciation of
the care and thoroughness with which the review materials had been prepared for
them before the Review took place.
Quality and impact of
academic activities
3.
The work the Review Committee was asked to consider comprised papers published
in the period 2003-2005, or in publication; contributions to conference
proceedings over a similar period; and material presented to the Committee at
the time of the Review. The material is summarized in Appendix 2. We consider
the work separately from statistical and seismological viewpoints, with a short
overview at the end of the section.
Statistical theory and
methodology
4.
The work of the Statistical Seismology Group is highly regarded within the
statistical community, especially within the areas of spatial statistics and
point processes. Their work provides a vivid illustration of how the demands of
a particular field can trigger the development of new statistical approaches.
In seismology, the extensive, high-quality earthquake catalogues which started
to become available two or three decades ago in Japan and elsewhere,
characterized as they are by high-dimensionality, power law dependencies,
extensive clustering, and near self-similarity, raise problems which lie
outside the framework of conventional statistical techniques, and require the
development of new models and new methods for their effective analysis.
Professor Ogata and his colleagues have made, and are making, fundamental
contributions towards overcoming these problems. As similar data become
available in other fields -
finance, medicine, population studies, and many others - the importance of the
Group's work may increase, provided it can be communicated effectively to
workers in these fields. Their work is also an outstanding demonstration of the
value statistical methods can have in assisting the development of an
observational discipline, and a tribute to the Group's ability to work
alongside their seismologist colleagues.
5.
Professor Ogata's papers have appeared in major general journals such as the
Journal of the American Statistical Association, Biometrika and the Journal of
the Royal Statistical Society, as well as in specialist journals and conference
proceedings in point processes and spatial statistics. The extensive series of
invitations he receives to international statistics meetings provide further
evidence of his personal high standing. During the last few years he has been
ably supported by Dr. Zhuang, but the more recent members of the Group
strengthen the seismological rather than the statistical side of the work.
Overall, and as the work of the Group expands, there is some danger of putting
an over large burden on Professor Ogata's shoulders, requiring him to develop
new, cutting edge ideas in statistics, to illustrate the effectiveness of these
ideas within seismology and elsewhere, and to maintain the general oversight
and management of the Group. In this respect the Group's overall position would
be strengthened by the addition of a senior colleague on the statistical as
well as on the seismological side.
6.
Three aspects of the work under review may be singled out as topics to which
the Group has made especially important contributions: the development of
procedures for estimating the parameters of non-homogenous, rapidly evolving,
space-time point processes ([2],[3]); the development of stochastic
declustering algorithms for
separating clustered point
data into clustering and background components ([4],[5]); and the development
of residual analysis methods for investigating discrepancies in the fit of time
and space-time point process models ([1],[2],[5]). The methods were developed
in the first instance around versions of the ETAS (epidemic type aftershock
sequence) models, but they are capable of extension to wider classes of models
and many different contexts. For example, the stochastic declustering approach
has potential value in many situations where spatial clusters are developed
over time, while the Group's work on residual methods includes both pioneering
contributions and important recent contributions to a major focus of current
interest in spatial statistics.
7.
In all three aspects mentioned the work of the group is outstanding and
establishes it as one of the leading groups worldwide developing practical
statistical methods for handling higher dimensional point process problems.
They have produced useful results also in other directions, for example in
handling renewal models with errors in variables, and in point process data
controlled by a combination of endogenous (clustering) and exogeneous (external
predictor) variables. A second round
of challenges from seismology may
be expected in the near future, as the extensive data on earth deformation from
GPS and other satellite measurements builds up, and invites analysis both in
its own right, and in conjunction with the seismicity data. The Institute, and
the Statistical Seismology Group in particular, is strategically placed to play
a prominent role in tackling these challenges.
1.4 Seismological theory
and methodology
8.
The ISM Statistical Seismology Group is recognized worldwide as one of the most
active, productive and innovative research groups in modelling the evolution of
seismicity in space and time.
Despite the small number of researchers, the number of research
publications from the Group is rather high. The publication list of the four
core members of the group contains more than 32 publications in the period
2003-2005, even though some of the postdocs joined the group only in 2004 or
late 2005. Continuation of the present high quality level of the activity is
attested by the number of papers submitted or in press. The journals where
research papers from the group are usually published are of high international
standing, suitable for the research tasks, and effective in publicizing their
scientific results and promoting collaboration with other research groups in
geophysics.
9.
From the seismological point of view, the topics listed as goals or motivations
in the Group's report are extremely important and focus on high priority topics
that attract the attention and the research of many groups within the
international seismological community. The goals are also robust, and of
relevance for promoting advanced studies in related fields; they can be shared
by many investigators in geophysics.
10.
In particular, their contributions to the analysis of the space-time evolution
of seismicity are excellent. This group has developed efficient models and
numerical tools that allow remarkably important practical applications to
analyze seismic activity both retrospectively and in real time. Among them the
most important is the ETAS model, which represents a powerful tool for
investigating the seismicity pattern, identifying the background seismicity and
its spatial distribution, determining the rate of production of aftershocks and
foreshocks, and modelling seismicity rate changes in space and time. The ETAS
model is now used in different regions of the world (
11.
One important outcome emerging from these studies is the use of statistical
models as diagnostic tools to identify anomalous trends and other features of
the seismicity pattern. The ETAS model itself is an extremely useful tool in
detecting anomalous features in seismic activity, including aftershock
activity, and in identifying and defining seismic quiescence. The results of
comparing the actual seismicity rates with the rates predicted by the ETAS
model have very interesting implications for the physical interpretation of the
processes controlling the evolution of seismicity. The connections between
seismicity rate changes and coseismic stress changes have been emphasized by
the ISM group and discussed in several important recent publications. In
particular, it is worth noting that the relative quiescence defined in relation
to the ETAS model represents the best currently available definition and
physical interpretation of the “stress shadow”. In other words, this represents
the most robust definition the stress shadow and the proposed numerical
approach is the best solution to identify seismicity rate reductions. This has been
recognized by the scientific community.
12.
The Group has a good record in opening up new ideas. For instance, the physical
interpretation of their results on the seismicity evolution in terms of stress
perturbations caused by earthquakes is extremely important and of relevance for
many researchers in seismology and geophysics. The Review Committee also
appreciates the value of linking Toda to the Group, where he has already
contributed significantly through his expertise on Coulomb stress modelling and
the theoretical predictions of seismicity rate changes with physical models
based on laboratory derived friction laws. For instance, the possibility now
being explored by the Group of selecting target areas for statistical analysis
by reference to the pattern of Coulomb stress changes is very interesting.
13.
The success of the Group and the recognition of its work by leading members in
the international community are quite evident, as was effectively demonstrated by
the successful STATSEI-4 workshop recently organized by Ogata. All members of
the Review Committee participated in the workshop and had a useful opportunity
to gauge the impressions of participants, as well as to see presentations by
the younger researchers in the group. It is the Committee's view that the Group
has a large impact within the scientific community, and is leading the field into new
directions.
14.
The work done by the younger researchers is good and promises well for the
future. Zhuang in particular has contributed significantly to the development
of new approaches and is well integrated into the Group's research work. The
most recent postdocs are promising, enthusiastic and well-motivated. They come to the Group with their own
fields of research, which then have to be integrated within the Group's
strategic working plans. For instance, Iwata's studies on tidal triggering
appear robust statistically, but problems remain with the physical
interpretation. At present the studies seem somewhat academic, although the
study of triggering mechanisms is extremely important; a promising direction
for further work might be to join the ETAS model with the Dieterich model with
arbitrary stressing rates. Nanjo's
work on earthquake prediction seems to lie a little outside the main strategic
working plan of the Group, although it might be interesting to perform a
systematic comparison between the PI and the ETAS approaches. Overall, the
Review Committee hopes that further new students and postdocs can join the
Group and contribute to the opening up of new ideas and horizons
(time-dependent seismic hazard, for instance).
15.
The Group's participation in and collaboration with the Earth Simulator was
outlined by R. Matsu’ura in a presentation to the Committee. It is interesting,
stimulating, and should be further implemented and maintained in the
future. It raises the wider issues,
taken up in more detail later in the Report, of how the ISM Group can most usefully
collaborate with other groups in
2 Cooperative research
activities and contributions to the public good.
16.
The Group enjoys productive collaborations with leading statisticians and
seismologists both within
2.1 Interinstitute
activities
17.
The Group has been collaborating for many years with leading statisticians and
seismologists internationally, such as Professor Vere-Jones (
18.
The Fourth Statistical Seismology Workshop preceding the Review provided
extremely valuable opportunities for interinstitute collaborations. The Group
invited Prof. Dieterich for tutorial presentations on the fault constitutive
law, implying forthcoming very fruitful collaboration of the Group with him and
colleagues on modeling seismicity on the basis of the fault behavior. More than
65 researchers from various organizations in many regions and countries, such
as China, France, Germany, Italy, Mexico, New Zealand, Switzerland, Taiwan, UK,
and USA as well as Japan attended the three-full-day meeting and one-day
excursion. Talks presented at the meeting invited the Group to collaborate with
on-going or planned real-time testing of various seismicity models. Dr. Wiemer
introduced a European framework for testing earthquake forecast models and Dr.
Schorlemmer summarized the initial effort of the Regional Earthquake Likelihood
Models (RELM) project for testing various earthquake potential models in
19.
The Group as such is not connected through
formal collaborative
agreements with other research groups, although in the past the Institute
as a whole has had formal collaborative agreements which promoted the work in statistical
seismology, for example with
Victoria University in New Zealand. At present the Group rather
informally collaborates with key and influential international research groups
as was exemplified by the successful Statsei Workshop. If any formal research
agreement is considered, the Institute should provide strong administrative
support.
2.2 Contributions to the
public good
20.
Prof. Ogata is an active member of the Coordinating Committee for Earthquake
Prediction, which meets every three months for discussion and exchange of ideas
and information on the latest seismic and crustal activity in
21.
The
22.
Probabilistic forecasts of aftershocks are issued by JMA and ERC after an
occurrence of large earthquakes. Although the forecast is based on the
Omori-Utsu formula and not on the ETAS model, both JMA and ERC adopt the
maximum likelihood estimation of parameters developed by Prof. Ogata. ERC
(2005) made public the 'Generalized National Seismic Hazard Maps' and plans to
revise it in five years. The maps utilize probabilistic estimates of an
occurrence of large earthquakes, which are mainly based on a renewal model of
earthquake recurrence. For the revision, the uncertainty in the probabilistic
estimates will be discussed and Prof. Ogata's statistical work on processing
paleoearthquake data will be a useful guide to future directions.
23.
It is clear that members of the Group would be welcome as participants in
international projects involving real time tests and validation tests such as
RELM in
3 Bringing up the next
generation
24.
The Review Committee is satisfied that a high quality of training is being offered
to the graduate students and post-docs associated with the Group, but
disappointed that the numbers are still small. It appears to the Committee that
there is only a limited number of young researchers in statistical seismology,
especially in
25.
The Committee notes that the ISM provides an annual open seminar to the public
or young scientists. Any such seminar needs to be considered an important
opportunity to publicize the activity of this Group. Coordination among the research groups
in ISM is necessary, but in general the Committee recommends that the ISM, and
the Statistical Seismology Group in particular, take every opportunity to
impress on young scientists the Group's achievements and their significance in
earthquake science.
26.
Every spring and autumn, the Seismological Society of Japan (hereafter SSJ)
holds its annual meetings. On
average more than 500 papers on several aspects of earthquake science will be
presented. Therefore it is not so easy for statistical seismology to be
highlighted in the meeting. However
the group can use other mechanisms provided by SSJ for this purpose. In
particular, SSJ holds a Summer School on Seismology every summer, which is
aimed exclusively at young students such as undergraduate students or master
course students in graduate school. The theme of the summer school is selected
from proposals or requests of SSJ members.
Other societies may also have similar seminars. The Statistical
Seismology Group could ask SSJ and other societies to periodically choose
statistical seismology as the theme of the seminar. The participation of the
Group in such activities would need to be supported by the Institute.
27.
The credit exchange program with the Soken-dai and other universities could be
used to attract the interests of young students. The best way might be to run
lecture series for the students from other universities which have credit
exchange programs. ISM is a part of
the Soken-dai and they have a course of statistics including statistical
seismology. Unfortunately there are
very few lecture series on statistical seismology in Japanese universities at
the present time. The main reason
is the lack of experts in this field. University visiting professor or
temporary lecturer positions can also offer useful opportunities to have
lectures in other universities. The
Group should consider the use of such programs.
4 Comments and
suggestions for the future work plan
28.
The Statistical Seismology Group within the ISM occupies a unique position, not
only in
29.
The goals of seismological research are as varied as the reasons society is
willing to invest in them, ranging from the purely academic to the highly
applied. The questions that society
commonly asks earthquake professionals are typically something like "when
will the next earthquake strike?", "how severe will it be?" or
"what can be done to lessen its impact?" Precise answers to these questions are
currently beyond our grasp, and may always be so. Within the seismological, earthquake
engineering and emergency management communities, however, the value of even
approximate answers to such questions is widely recognized. The new long-term earthquake forecast
for
30.
Within the framework of the Group's current research program, the Review
Committee particularly encourages the development of collaborative work with
researchers in other fields to incorporate deeper physical modeling into the
statistical analysis. As a primary example, it is important to deepen the
understanding of the statistical characteristics of seismicity in relation to
the physical processes taking place in the earth. Statistical seismology tends to treat
earthquakes as just a sample from a random process, while observational
seismology tends to focus on the characteristics of individual
earthquakes. Both approaches are
important, but statistical seismology has not won major popularity in
earthquake science, especially in
31.
The Review Committee also strongly encourages further development of the
program to rigorously evaluate models and forecasts. The hierarchical space-time modeling of
seismicity (HIST) holds great promise, and clearly represents frontier research
at the leading edge of the field. As one example, the Coulomb failure stress
model appears to be ripe for a carefully designed validation experiment, given
the new information--rich earthquake catalogs available in
32.
Beyond this, the
33.
Statistical models of seismicity are already being applied in public policy
decision analysis in
34.
To highlight one particular example where the ISM might be able to contribute,
for society, it is the shaking of the ground that matters far more than the
rupture of the fault. The predicted
intensity of ground motion controls the seismic design requirements for
structures of all kinds. Trillions
of Yen are invested every year in
5 Overall conclusions
and recommendations
35.
The Review Committee has no doubts about the high academic quality and scientific
value of the work being done by the Statistical Seismology Group. The Group has initiated and carried
through important developments as much from the seismological as from the
statistical side. Its members, and Professor Ogata in particular, are highly
respected in both communities for their innovative approach to problems of
modelling and analysis of seismological data, their insights, and their ability
to develop their work in collaboration with professional scientists in both
fields. Their work should continue to be strongly supported and promoted.
36.
The Committee was also very interested to learn about the scope of the work
undertaken by the Institute, and impressed by both its breadth and depth. Many problems of critical importance to
society are being investigated in partnership with leading experts from allied
fields. The Committee was
particularly interested to learn of the programs in risk evaluation and risk
management. The work in financial
and environmental risk represents important contributions to informed decision
making in an increasingly complex and interconnected global economy. It seems only natural that a
complementary program of research on earthquake risk would also pay a high
return on investment to society. No
country has a larger percentage of its population or national wealth at risk
from earthquakes than
37.
Greater difficulties present themselves in regard to the expansion of the Group
and its ability to attract and train top quality graduate students. The Review
Committee sees good work being done by students and post-docs, but the Group is
not training sufficient numbers in this increasingly important area. At the
same time there is a need for a senior staff member, particularly now on the
statistical side, to assist Professor Ogata in the development of new
statistical modelling and methodology and in further development of the program
to rigorously evaluate models.
38.
The Review Committee recommends that these issues be given serious
consideration by the ISM management, not just in the context of the Statistical
Seismology Group itself, but also in the wider context of the ISM's involvement
with engineering, insurance, and risk management.
References
[1]
Ogata, Y.(1988) Statistical Models for earthquake occurrence and residual
analysis for point processes. Journal of the American Statistical Association. 83, 9-27.
[2]
Ogata Y., Katsura, K., and Tanemura, M (2003) Modelling of heterogeneous
space-time seismic activity and its residual analysis Appl. Stat (Journal
of the Royal Statistical Society Series C). 52, 499-509.
[3]
Ogata, Y. and Zhuang, J. (2006) Space-time ETAS models and an improved
extension. Tectonophysics 413,
13-23.
[4]
Zhuang, J., Ogata, Y. and Vere-Jones, D. (2004) Stochastic declustering of
space-time earthquake occurrences.
Journal of the American Statistical Association 97, 369-380.
[5]
Zhuang, J. (2006) Second-order residual analysis of spatiotemporal point
processes and applications in model evaluation, Journal of the Royal Statistical
Society, Series B, 67, 68, Part4, 635-653
Appendix 1: Schedule of
External Review
Place:
Meeting Room of the Institute of statistical Mathematics
Date:
January 16, 2006
10:00 – 10:10 Introduction by Genshiro
Kitagawa (Director General)
* Objective of evaluation
* Terms of reference
10:10 – 10:20 Preliminary meeting
*
Selection of chairperson
*
Schedule and method
10:20 – 10:40 Hearing from Dr. Matsu’ura
10:40 – 11:40 Report by Prof. Ogata
11:40 – 12:20 Report by group members
13:30 – 13:50 Report by group members
13:50 – 15:00 Questions and discussion
15:30 – 17:10 Meeting
*
Evaluation
*
Arrangement for making review report
17:10 – 17:30 Comments by review
committee
Date:
January 17, 2006
10:00 – 12:00 Meeting
*
Evaluation
*
Arrangement for making review report
*
Discussion
Appendix 2: Summary of
materials presented to the Review Committee
(Notes:
Page numbers of the table of contents are those paginated for original report
presented to the Committee)
Progress Report on the
ISM Project 2003-2007
Statistical Seismology
Research Group
Prediction and Knowledge Discovery
Research Center
The Institute of Statistical Mathematics
Research Organization of Information and Systems
Table of Contents
Motivations behind this project
……………………………………………………………… 2
(1)
Hypocenter data ………………………………………………………………………………………… 2
(2)
Other geophysical datasets …………………………………………………………………... ……… 2
(3)
Point-process models ………………………………………………………………………………… 2
(4)
Earthquake / Aftershock forecasting ………………………………………………………………… 3
(5)
Exploration and modeling of the interface between physical and stochastic
processes …..……… 4
(6)
Space-time point-process modeling ………………………………………………………….……… 5
References
………………………………………………………………………………….…………… 5
Objectives of the
project ……………………………………………………………………… 7
Work Plan 2003 – 2007
…………………………………………………………….. ………… 8
Project Members ………………………………………………………………………………………… 8
Research Accomplishments 2003 – 2005 …………………………………………………..… 9
Principal works during 2003 – 2005
……………………………………………………………… 9
(1)
Coseismic activation / quiescence triggered by a large earthquake and Coulomb
stress changes …………… 9
(2) Relative quiescence in aftershock sequences and its mechanism
…………………………………………… 10
(3) Seismicity anomalies preceding large earthquakes and crustal stress
changes ……………………………… 11
(4) Space-time ETAS modeling ……………………………………………………………………..…. ……… 13
(5) Modeling the interface between physical and stochastic process ………………………………………...
15
(6) Simultaneous estimation of b-values
and detection rates of earthquakes for the application to aftershock
probability
forecasting
…………………………………………………………………..…………………. 16
Published
papers 2003 – 2005 ……………………………………………………….….…….……… 16
Refereed Journals ……………………………………………………………………………..………….
16
Main Proceedings
………………………………………………………………………………………… 18
Future plans for the
project ………………………………………………………………..
20
(1) Examination of scenarios for predicting asperity-slip based on the
seismicity anomalies …….. ……….. 20
(2) Effective space-time modeling of seismic activity and detection of
seismicity anomalies …………….….. 21
(3) Predictive space-time-magnitude
characterization of foreshocks ………………………………………..… 21
(4) Prediction and inversion problem between
seismicity changes and stress-changes ………………….……. 22
(5) Bayesian Probability assessments for Long-term prediction ………………………….………………… 22
(6) Statistical
modeling for more effective use and quality improvements of datasets
……………………... 23
References
…………………………………………………………………………………………………… 23
Motivations behind this
project
(1) Hypocenter data
The Hypocenter catalog
of the Japan
Meteorological Agency (JMA) is one of the most valuable
databases for earthquake prediction. This is because it contains records of a
large number of earthquakes dating back to 1925. The catalog covers the whole
of
(2) Other geophysical datasets
There are many precise geophysical records that are
useful in discussing the relationship with seismicity such as records of
extensometers, tiltmeters, volmetric strainmeters and the GPS. However, these
records are usually affected by various noises or ancillary geophysical signals
caused by the earthtides, and in particular, by meteorological factors
such as barometric pressure, precipitation, temperature and humidity.
Therefore, it is important to model the causal relationships and response
functions of these effects in order to calibrate the records for genuine
quantities of interest. For example, the computer program BAYTAP-G [Ishiguro
et al., 1984] used to implement the Bayesian deconvolution procedure for removing
tidal effects has been used with much
frequency by many researchers in seismology and geodesy in
(3) point-process models
Point processes. A point-process is a mathematical model of the stochastic occurrence of a series of events. The modeling of point-processes became a powerful tool in the field of applied statistics in the 1980’s, for three reasons. Firstly, the concept of the conditional intensity function provided us with an extensive free hand with which to produce models describing the detailed interface between the physical mechanism of occurrences and some stochastic factors. This is the predictive occurrence rate function (roughly, the differential of the occurrence conditional probability) of the present time, the occurrence times of the past events and other relevant time series data such as magnitudes and other available geophysical records. Use of this function also made available a general effective simulation method using the thinning operation [Ogata, 1983]. Secondly, it became possible to write the likelihood function directly in terms of the conditional intensity function. The third reason was due to the availability of practical algorithms for optimizing non-linear functions using a computer, enabling us to obtain the maximum likelihood estimate (MLE), their error estimates, and the likelihood-ratio or the AIC to examine the goodness-of-fit of models. Together with these revolutionary bases, a diagnostic analysis of the model and data became available with the time-transformation using the integral of the conditional intensity function [Ogata, 1983, 1988; Ogata and Shimazaki, 1984; Ogata, 1999]. Benefiting from these, a substantial number of applications became available, including the program packages TIMSAC84 [Akaike et al., 1985] and SASeis [Utsu and Ogata, 1997] in the IASPEI Software Library.
The ETAS model. The epidemic type aftershock sequence (ETAS) model [Ogata, 1986, 1988, 1989] is one such model. It is generally accepted that each earthquake changes the probability of successive earthquakes in a region, the size of which scales with its magnitude, and by an amount that can be estimated using the Gutenberg-Richter magnitude distribution and the Omori-Utsu law for the rate of aftershocks, where aftershocks are allowed to be larger than the mainshock. The ETAS model forms the basis of many current probabilistic earthquake prediction schemes. Inherent in these models is the assumption that the probability of a large earthquake is completely determined by the sum of stresses transferred by prior earthquakes within a considered region. By a set of parameter values the ETAS model is well adapted to various seismicity patterns including the mainshock-aftershock type and swarm type.
Diagnostic analysis using the ETAS model. Since a sequence of aftershocks is triggered by complex mechanisms under fractal random media, it is difficult to calculate the transferred stresses within and near the rupture fault. That is, triggering mechanics within an aftershock sequence are too complex for us to calculate the effect of stress changes. Therefore, the statistical empirical laws of aftershocks are useful as a practical representation of the outcome due to the complex interaction of the self- or proximate triggering. On the other hand, the ETAS model is a statistical model constructed based on the empirical laws of aftershocks. Therefore, the model itself hardly describes the mechanism of affecting stress changes behind the seismicity changes. Diagnostic analyses of the model can reveal such new knowledge included in the data. That is to say, the activation and quiescence relative to the model’s prediction could suggest exogenous stress-changes in the regions.
(4) Earthquake / Aftershock forecasting
Primary models for aftershock forecasting. It has been about a decade since aftershock probability forecasting
[Reasenberg and Jones, 1989] was
implemented to inform the public in
Anomalous aftershock activity. Precursory seismic quiescence as a predictor of large earthquakes has attracted much attention amongst seismologists in the last several decades, ever since Inouye [1965] first proposed the concept. This suggests that we need much more research into the relation between the quiescence and subsequent earthquake activity in order to obtain an effective prediction. We should also explain how quiescence can take place in a much wider area than the rupture source [Inouye, 1965; Ogata, 1992]. Studying many aftershock sequences should provide us with a better understanding of the physical mechanism of the precursory utility. For predicting large aftershock, Matsu’ura [1986] noted the utility of the quiescence in aftershock occurrences relative to the Omori-Utsu decaying formula.
Using the ETAS model and on
the basis of the proposed procedure, 259 aftershock sequences of various
threshold magnitudes are investigated for the 76 main shocks of M6 class or
over that occurred in and around Japan during the last three-quarters of the
last century [Ogata, 2001]. Relative
quiescence is revealed in ~40% of the aftershock sequences, and almost all of
the others are developed normally; relative activation is rarely found. We have
seen that the aftershock activity provides useful information for assessing the
probability of a following large event (M6 class or over) in the neighbourhood.
Namely, if the aftershock activity from the first event becomes relatively
quiet compared to the expected normal decay, the occurrence rate of a larger
event in the neighbourhood (within a distance of 3o) is a few times
higher during the first decade after the main shock than would be the case for
normal aftershock activity. However, it is not yet clearly understood the
physical mechanism of the causal relationship between the relative quiescence
and the forthcoming occurrences of large aftershocks or even large earthquakes
of the similar size to the mainshock. The recently accumulated earthquake
mechanism data may help better our understanding.
Seismicity rate change and Coulomb’s failure stress change. We are concerned with the precise prediction of time- and history-dependent occurrence rates of an earthquake sequence, particularly, aftershock sequences, in order to test the hypothesis that abrupt stress-change due to a seismic or an aseismic slip triggers a seismicity-rate-change in the surrounding area. This is because stress changes in a region are very frequently affected by nearby events, which trigger further aftershock clusters. In principle, seismic activity should be enhanced in the zones where an increment of Coulomb’s failure stress (CFS) is positive, and also activity should be reduced (seismic quiescence) in the stress-shadow zones. For example, some retrospective case studies have shown the stress shadow [e.g., Harris, 1998; Toda and Stein, 2002] due to large earthquakes to coseismically inhibit the activity in some neighboring seismic regions in California, in addition to many cases of activated seismicity triggered by an large event [e.g., Toda et al., 1998]. A similar phenomena can be expected by the activation and quiescence relative to the predicted seismicity by the ETAS model.
(5) Exploration and modeling of the interface between physical and stochastic processes
External stress changes and swarms. It is well known that volcanic swarms and other swarms are affected by magma intrusion [Dieterich et al., 2000; Toda et al., 2002] and water migration [Matsu’ura and Karakama, 2005]. According to the Coulomb failure criterion, the variation of both, stress and pore pressure, can result in earthquake rupture. Aftershock sequences characterized by the Omori-Utsu law are often assumed to be the consequence of varying stress, whereas earthquake swarms are supposed to be triggered by fluid intrusions. Statistical models for describing the relationship are desired. Also, there are some papers reporting that occurrence rates of some swarms and aftershocks are correlated to certain components of earth-tide’s time series [e.g., Iwata, 2002]. It is desirable to have models examining the causal relationship between mechanisms of earthquakes and stress tensors of stresses due to earth-tide.
Inversion. On the other hand, it will be informative to produce an image of the geophysical quantities in time and space, by making an inversion of the parameters of the statistical models of earthquake occurrences. Such examples include b-values of the G-R magnitude frequency [Ogata et al. 1993a and b], and p-values of the Omori-Utsu model for the aftershock decay [Mogi, 1967]. More examples should also be considered, making use of models such as the extended space-time ETAS model, making use of a Bayesian framework. The geophysical quantities could include the stress distribution and temperatures of the crust, and the friction coefficients of the fault interface (asperities) etc.
Quiescence and activation relative to the ETAS prediction and crustal stress
changes. Seismic
quiescence and activation have attracted much attention amongst seismologists as the
precursors to a large earthquake. Of particular interest is that the
stress-changes transferred from a far-field rupture or silent slip can cause
seismic changes in a region. On the other hand, since a sequence of aftershocks
is triggered by complex mechanisms under heterogeneous fractal media, it is
difficult to precisely describe the transfer of stresses both within and near
to the field. In other words, triggering mechanics within an aftershock
sequence are too complex to calculate the effect of stress changes.
Nevertheless, we can use statistical empirical laws as a practical solution to
aftershock triggering. That is to say, fitting and extrapolating a suitable
statistical model for normal seismic activity in a situation without exogenous
stress changes provides us with an alternative method through which to see the
seismicity changes explicitly. Thus, our motivation is to show the possibility
that the diagnostic analysis based on fitting the ETAS model, and its
space-time extension, fitting to regional seismicity can be helpful in
detecting small exogenous stress changes. Indeed, these changes are so slight
that the geodetic records from the GPS network can barely recognize systematic
anomalies in the time series of displacement records.
(6) Space-time point-process modeling
The relative
quiescence before great earthquakes is discussed in wide seismic regions in Ogata [1992] for high threshold
magnitudes of more than M5. However, these are too high to discuss intermediate
strong earthquakes. The locations of earthquakes from hypocenter catalogs are
now accurate enough to discuss the spatial aspect of seismicity, such as the
clustering of aftershocks and seismicity gaps. Ogata [1998] considers several possible extensions of the ETAS
model to space-time data, based on classical empirical studies of aftershocks,
and also on a number of contrasting speculative hypotheses about the physical
nature of the space-time clustering. Their goodness-of-fit is compared by the
aid of the AIC for two data sets from tectonically distinctive areas in and
around
However, as the data size increases, spatial heterogeneity of the seismic activity becomes conspicuous. For example, shape of the anistropic clustering becomes more complex, differing from place to place. Even cluster sizes are significantly different from one another, especially between those in offshore and inland area [Utsu, 1969; Ogata, 2001].
Furthermore, according to the restricted trigger model [Ogata, 2001], secondary aftershocks of large cluster sizes are
located around the boundary of the main rupture zone of the 1995
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Objectives of the project
were as follows:
(1)
To develop practical space-time models that are sufficiently close to the real
seismic activity. Specifically, the model must elaborate enough to spatially
adapt to various different clustering patterns. In order to represent various
seismicity patterns, we will adopt a hierarchical space-time point-process
model, in which the parameter values are dependent on the location of the
earthquakes.
(2)
To detect and evaluate anomalous features of general seismicity and aftershock
activity relative to the modeled rate by the ETAS model, to explore its
space-time features using statistical diagnostic methods and to make modeling
of seismicity anomalies.
(3)
To explore the relation between the seismicity-rate-change in a region and the
stress-change in the crust, which varies due to the fault mechanisms of
earthquakes.
(4)
To statistically model the relationship between the occurrence time series of
focal earthquakes in a region and the time series records of anomaly events, in
order to enhance the performance of probability forecasting.
(5)
To model the heterogeneity of various datasets which are affected by some
instrumental and geophysical factors, such as various noises, missing events or
values, and detection rate changes of earthquakes in time and space.
Work Plan
2003 - 2007
We will undertake as many of the followings as early as possible:
(1) We will apply the ETAS model to a number
of sequences of earthquakes from various regions over a recent period to examine
any significant deviation of the activity from the rate predicted by the model.
We will explore matching such an anomaly and a crustal stress-change due to a
co-seismic and a pre-seismic slip somewhere in order to examine whether such a
seismic anomaly can be a sensitive sensor of stress change.
(2) We will particularly be concerned with the anomalously quiet aftershock activity preceding a large aftershock.
(3) We will make use of fault mechanism data of earthquakes to calculate the Coulomb-stress-change estimation transferred from a pre-slip or a slow slip in order to discuss the significance of the causal relation between stress change and seismicity anomalies.
(4) We will try to make a statistical point process model to explain the causality between geodetic anomalies and seismicity anomalies in the same field.
(5) We will publish a software package to make programs available such as the estimation and diagnostic procedure of the ETAS model for the seismologists, after testing the stability of such programs.
(6) We will make a practical model to enable real-time probability forecasting of aftershocks immediately after a large earthquake (say, within 24hours), when the detection rate of aftershocks is extremely low, due to contamination of arriving seismic waves. This is urgent since the majority of large aftershocks are most likely to occur during this period, and hence forecasting during this time is most critical for public in the affected area.
(7) We will develop methods of diagnostic analysis for space-time seismicity data by introducing a space-time seismicity-ratio of real seismicity to the predicted by the space-time ETAS model, and modeling it in Bayesian framework.
(8) We will prepare a software package to publish the MLE and Bayesian procedure of the space-time ETAS model, and test the stability of such programs with many datasets.
Project Members:
Statistical Seismology Research Group, Prediction and
Yosihiko
OGATA, Prof. of the Institute of Statistical Mathematics (ISM)
Shinji TODA, Visiting Prof. of the ISM and Geological Survey of Japan, AIST,
2005 -
Yasuaki MURATA, Geological Survey of Japan, AIST , Visiting Assoc. Prof. of the
ISM 2003 - 2004
Jiancang ZHUANG, Research Fellow upon JSPS program, 2001 - 2005
Kazuyoshi NANJO, Research Fellow upon JSPS program, 2003 -
Takaki IWATA, Research Fellow of ISM,
2005 -
Masatsugu WAKAURA, Graduate Student, The
Ushio TANAKA, Graduate Student, The
Akiko KUTSUNA, part-time assistant
Research Accomplishments 2003 - 2005
Principal works during 2003 - 2005
(1) Coseismic activation / quiescence triggered by a large earthquake and Coulomb stress changes
It is clearly seen that after a large
earthquake, many off-fault activities with positive Coulomb stress increments
are enhanced, while negative ones (stress shadow) are inhibited, in regions
that include many earthquakes of similar fault-mechanisms detected down to
small magnitudes. Such various examples are shown in western Japan, which was
affected by the two great earthquakes of 1944 and 1946 in the Nankai trough,
with other various ones being seen in Hokkaido inland and the southern offshore
of Hokkaido which was affected by the 2003 Tokacho-Oki great earthquake. See
also the published referred papers [4] , [23], [32], [A8], and the main reported manuscript [A15], [A16], [A23] and [A24] for
further examples of coseismic triggering. These papers and reports
are listed in the end of this section under Research Accomplishments.
Seismicity changes in western
Seismicity-changes
and
stress-changes triggered by the 2003 Tokachi earthquake [A21, A33]. Coseismic activation and quiescence are
conspicuous in the eastern inland region of Hokkaido after the 2003 great
earthquake of M8.0 in the space-time occurrence of microearthquakes detected
from 2001 through 2003 (depth 
25km).
The DCFF for the receiver faults
with N75oE right lateral strike-slip at the depth of 10km and the
Tokachi-Oki event’s slip model takes positive and negative values in the
western and eastern part, respectively, which is corresponds well to the
regions of activation and quiescence in microseismicity. The exception is that
the very active spot in the western region suddenly stopped the activity after
the great event, but this is also well explained by the different alignment of
the receiver fault from the rest of the western part of the
microseismicity. We found another
triggered activation and quiescence in a complicated manner within the 3D
volume down to 100km depth beneath the southern inland region of
Coseismic activation and quiescence
relative to the ETAS model [22, A19].
Fitting and extrapolating the ETAS model for normal seismic activity in a
situation without exogenous stress changes provides us with an alternative
method through which we can detect the relative changes of seismicity
sensitively. Thus, the diagnostic analysis based on fitting the ETAS model is
helpful in detecting small exogenous stress changes. For example, shallow
earthquakes (M >=1.5) in the Tohoku inland region of largest DCFF values (ranging +5~+50 millibars) due
to the 2003 May 26 Miyagi-Ken-Oki earthquake of M7.1 is seen to be activated
relative to the predicted occurrence rate by the ETAS model. The foreshock
activity during the first event of M5.5 and the mainshock of M6.2 (the both
occurred at
(2) Relative quiescence in aftershock sequences and its mechanism
In order to extract regional stress-changes transferred from
the slip of a far-field fault, we have to remove the effect of the complex,
proximate triggering mechanics occurring within
aftershock clusters. As a practical solution, the ETAS model is
fitted to the sequence of events from the region in order to precisely mimic the normal activity there. We
are primarily concerned with seismicity-rate-changes (enhancement and reduction)
relative to the rate predicted by the ETAS model, and explore matching them to
the pattern of Coulomb's stress-changes that occur due to a rupture or a
suspected silent slip. We have shown a number of such examples from recent
seismic activities in
Aftershock activity of large earthquakes in Southern
California [2].
The Hector Mine aftershock activity has been normal, relative to the decay predicted
by the ETAS model during the 14 months of available data and no further large
event has taken place in the vicinity up until now. In contrast, although the
aftershock sequence of the 1992 Landers earthquake (M=7.3), including the 1992
Big Bear earthquake (M=6.4) and its aftershocks, fits very well to the ETAS up
until about 6 months after the mainshock, the activity showed clear lowering
relative to the modeled rate (relative quiescence) and the anomaly lasted
nearly 7 years, leading up to the Hector Mine earthquake (M=7.1) in 1999.
Specifically, the relative quiescence occurred only in the shallow aftershock
activity, down to depths of 5 - 6 km. The sequence of deeper events showed
clear, normal aftershock activity that fitted well to the ETAS throughout the
whole period. We argue several physical explanations for these results. Among
them, we strongly suspect aseismic slips within the Hector Mine rupture source
that could inhibit the crustal relaxation process within “shadow zones” of the
Coulomb’s failure stress change.
Furthermore, the aftershock activity of the 1992 Joshua Tree earthquake
(M=6.1) sharply lowered in the same day of the mainshock, which can be
explained by a similar scenario due to aseismic slip.
Consecutive earthquakes in Miyagi
Prefecture and its offshore [22,
A19]. Anomalous seismicity such as quiescence and activation is
defined by a systematic deviation of seismic activity from the predicted rate
by the ETAS model that represents the normal occurrence-rate
of earthquakes in
a region indicating the empirical triggering effect by
the previous events.
The model is fitted to a dataset of origin-times and magnitudes of earthquakes or aftershocks
during May-August 2003 in and around northern
Anomalous
aftershock activity of the 2004 Niigata-Ken-Chuetsu earthquake of M6.8 [A30].
We are
concerned with the drastic shift of the depth distribution of aftershocks
against time, around 0.5 days after the mainshock when we have no major
aftershock. The cross-section of DCFF
diagram for the aftershocks of similar mechanisms to the mainshock’s on the
plane of fault’s strike direction of the mainshock (reverse faulting) against
depth shows positive and negative values in shallow and deep parts of the
aftershock volume, respectively, by the assumed precursory slip of the large
M6.1 event that occurred 3.7 days after the mainshock. The precursory slip can
be triggered by the mainshock rupture with a large positive DCFF.
Relative quiescence reported before the
occurrence of the largest aftershock (M5.8) with likely scenarios of precursory
slips considered for the stress-shadow covering the aftershock area [30, A27, A35]. Monitoring of aftershock
sequences to detect lowering activity, relative to the modeled rate (the
relative quiescence), becomes realistic and practical in predicting the
enhancement of the likelihood of having a substantially large aftershock, or
even another earthquake of similar size to the mainshock or larger. A
significant relative quiescence in the aftershock sequence of the 2005 March
earthquake of M7.0 off the western coast of
(3) Seismicity anomalies preceding large earthquakes and
crustal stress changes
An
earthquake prediction scenario from the implication of the relative quiescence
can be based on the asperity hypothesis in the sense that precursory slip
around asperities applies more shear stress to the asperities which promotes
the rupture of the main fault. On the other hand, aseismic slips in a
particular region are not necessarily a precursor to the large event but may be
aseismic slips that are repeated in the same region with no subsequent large
events. Therefore, identification of an aseismic slip leading to the rupture of
an asperity remains a further difficult research theme in earthquake
prediction. At present, this issue should be considered in terms of
probabilistic prediction proactively making likely scenarios of precursory
slips.
Intermediate-term
seismicity anomalies preceding the rupture around the focal region of the 2004
Niigata-Ken-Chuetsu earthquake of M6.8
[A27, 29]. The
ETAS model is applied to four sequences of earthquakes (M>=2), which
occurred from 1997 through to October 2004 in four respective regions divided
around the source of the 2004 Niigata-Ken Chuetsu earthquake. The four regions
are divided North, East, South and East around the source by the boundaries of
positive and negative CFS increments (i.e., the counters of neutral CFS
increment) for the receiver faults (10km depth) of dominating angles in this
region. The actual cumulative number of events deviates upward in region North
and South, but downward in East and West, from the predicted cumulative curve
after the change-point, consistently with the regions of the Coulomb
increments. These show that precursory slip may have taken place in the Chuetsu
mainshock fault plane.
Synchronous seismicity changes in and around the northern
Features of seismic activities in and around Tohoku District, northern
Japan, prior to the large interplate earthquakes off the coast of Miyagi
Prefecture [29, A20]. This paper is
concerned with the intermediate-term prediction of the forthcoming M7.4 ~ 8.2
earthquake on the plate boundary, off the east coast of Miyagi Prefecture,
northern Japan, which has the highest occurrence probability among the
long-term forecasted events announced to the public. Seismicity and aftershocks
in the regions of stress-shadow show significantly lower activity than the rate
predicted by the ETAS model (the relative quiescence) during some years
preceding each of the previous ruptures in 1936 and 1978, whereas the
seismicity is normal or even activated in the regions of neutral or increasing
Coulomb failure stress (CFS), which leads to the scenario based on the likely
precursory slip within or near to the source.
Assuming
such a scenario, a number of sequences of earthquakes or
aftershocks during 1979-2004 from various regions in northern
Anomalies in
the aftershock sequences of the 2003 Tokachi-Oki earthquake of M8.0 and the
2004 Kushiro-Oki earthquake of M7.1, and seismicity changes in the eastern 
2.5) of the 2003 Tokachi-Oki earthquake of M8.0 become quiet
relative to the ETAS five months after the mainshock. Latitude coordinates of
the aftershock epicenters against the transformed time by the ETAS model show
that the quiescence took place in the southern part of the aftershock area
whereas the northern part was normal. This is explained by the shadowing of the
DCFS
assuming slips in or near the source of the 2004 Kushiro-Oki earthquake of
M7.1. At the same time, this slip should affect contrasting DCFS
pattern in eastern
Seismicity in and around the Kyushu
District, preceding the 2005 earthquake of M7.0 at the western offshore region
of Fukuoka Prefecture [A34]. The ETAS model is applied to the sequences of events with M1.5
during the 10 year period from1995 to
On distributions of focal mechanisms [12,
A11, A22, A25, A29].
We
see a change of the normalized frequency distribution of DCFS values before
and after 1995, calculated at the hypocenter of all earthquakes listed in the
JMA earthquake mechanisms catalog in a wide area of northern
Next,
we discussed the
likelihood of three rupture models of the 2005 earthquake of M7.4 off the coast
of the
(4) Space-time ETAS
modeling.
Stochastc
clustering / declustering by the space-time ETAS model [13, 25, 33, A17, A18, A27]. On the basis of the space-time ETAS model
and the thinning procedure, this paper gives the method of how to classify the
earthquakes in a given catalogue into different clusters stochastically. The
key points of this method are the probabilities of one event being triggered by
another previous event and of it being a background event. Making use of these
probabilities, we can reconstruct the functions associated with the
characteristics of earthquake clusters to test a number of important hypotheses
about the earthquake clustering phenomena.
We applied this reconstruction method to
the shallow seismic data in
Hierarchical
Space-Time Model for Regional Seismicity [1, A2, A5, A6, A9]. A space-time
point-process model is specified in which earthquake intensity is modelled as a
function of previous earthquakes’ occurrence times, locations, and magnitudes.
Specific forms of the function of locations and times are based on the
established empirical laws, such as the modified Omori formula and the
Utsu-Seki scaling law of aftershock area against magnitude, but their parameter
values are known to be different from place to place. Thus the parameters are
further considered to be functions of spatial locations (but not time)
represented by linear interpolation over a tessellation based on observed
locations of earthquakes. Using the smooth representation for each parameter
function in the model, a penalized log-likelihood method is used for the
fitting, where the optimal weights of the penalties are objectively tuned by an
empirical Bayesian method. Having done that, our final goal is to detect the
temporal deviation of the actual seismicity rate from that of the modeled
occurrence rate. For this procedure we estimate the space-time residual function
represented by linear interpolation over a 3-dimensional tessellation based on
observed times and locations of earthquakes, carrying out the similar penalized
log-likelihood method. According to the estimated residual function, there are
a number of zones where temporal deviation from the fitted model, with quiet
periods, occurred before large earthquakes.
Hierarchical
Space-Time Model for characterizing regional seismicity and anomaly detection [11, A2, A5, A6,
A9]. The
regional earthquake
occurrence rate is modeled as a function of previous activity for which the
specific form is based on empirical laws, such as the modified Omori formula
and the Utsu-Seki scaling law of aftershock area against magnitude. Its
parameters, including the p-value of
the aftershock decay rate, can vary from place to place, showing some geophysical feature appearing
correlated with the crustal temperature. This model is used to
visualize features of the regional seismic activities in and around
Furthermore,
this space-time model enables us to magnify anomalous periods and regions where
the actual occurrence rates deviate systematically from the modeled one. Thus,
the activation and quiescence relative to the model’s prediction could provide
sensitive detection of stress-changes in the regions. We are concerned with
relative activation and lowering of the seismicity to explore the regions
matching the pattern of Coulomb’s stress changes due to a rupture or silent
slip elsewhere. For example, such anomalies as those seen in the seismic
activity in most central
(5) Modeling the interface
between physical and stochastic process
Detecting fluid signals in seismicity
data through statistical earthquake modeling [14]. According to the Coulomb failure criterion,
the variation of both stress and pore pressure can result in earthquake
rupture. Aftershock sequences characterized by the Omori-Utsu law are often
assumed to be the consequence of varying stress, whereas earthquake swarms are
supposed to be triggered by fluid intrusions. The role of stress triggering can
be analyzed by modeling the 3D elastic stress changes in the crust. However,
fluid flows initiating seismicity cannot be identified without dealing with
both pore pressure variations and earthquake connected stress field changes
resulting in complex seismicity patterns.
We show that the ETAS model is an
appropriate tool to extract the primary fluid signal from such complex
seismicity patterns. We analyze a large earthquake swarm that occurred in the
year 2000 in Vogtland/NW-Bohemia,
Model simulations are
performed in which earthquakes are triggered by fluid intrusion as well as
coseismic and postseismic stress changes on a fault plane embedded in a 3D
elastic half-space. They reproduce the observed swarm characteristics including
the temporal power-law increase of the seismic moment release. Analyzing these
simulations, we find that the proposed deconvolution procedure is able to
reveal the underlying pore pressure variations. This model may be applied to
the swarm owing to magma intrusion [e.g.,
A7].
Analysis of observations on the ultra-low frequency electric field in the
Beijing Region [24]. This paper presents a
preliminary analysis of observations on ultra-low frequency ground electric
signals from stations operated by the China Seismological Bureau over the last
20 years. The data analyzed consists of estimates of the total strengths
(cumulated amplitudes) of the electric signals during 24-hour periods. The
thresholds are set low enough so that on most days a zero observation is
returned. Non-zero observations are related to electric and magnetic storms,
occasional man-made electrical effects, and, apparently, some pre-, co-, or
postseismic signals.
To investigate the
extent that the electric signals can be considered as preseismic in character,
the electric signals from each of five stations are jointly analyzed with the
catalogue of local earthquakes within circular regions around the selected
stations. A version of Ogata’s Lin-Lin algorithm is used to estimate and test
the existence of a pre-seismic signal. This model allows the effect of the
electric signals to be tested, even after allowing for the effects of
earthquake clustering. It is found that, although the largest single effect
influencing earthquake occurrence is the clustering tendency, there remains a
significant preseismic component from the electrical signals. Additional tests
show that the apparent effect is not postseismic in character, and persists
even under variations of the model and the time periods used in the analysis.
Samples of the data are presented and the full data sets have been made
available on local websites.
Microseismicity and Earthtide [15, A1]. This paper analyzes the microseismicity
in the Tanba region during the two year period following the 1995
(6) Simultaneous estimation of b-values
and detection rates of earthquakes for the application to aftershock
probability forecasting [A31,
A32].
It is known that the detection rate of aftershocks is extremely low during the period
immediately following a large earthquake due to the contamination of arriving
seismic waves. This has resulted in considerable difficulty in obtaining an
estimate of the empirical laws of aftershock decay and the magnitude frequency
immediately after the main shock. This paper presents an estimation method for
predicting the underlying occurrence rate of aftershocks of any magnitude
range, based on the magnitude frequency model that combines Gutenberg-Richter’s
law with the detection rate function. This procedure enables us to announce
real-time probability forecasting of aftershocks immediately after the
mainshock, when the majority of large aftershocks is likely to occur.
Published papers 2003 – 2005
Refereed
Journals:
2003:
[1] Ogata, Y., Katsura, K. and Tanemura, M. (2003) Modelling of heterogeneous space-time occurrences of earthquakes and its residual analysis, Applied Statistics (J. Roy. Stat. Soc. Ser. C.), Vol. 52, Part 4, pp. 499-509 (2003).
[2] Ogata, Y., Jones, L. and Toda, S. (2003) When and
where the aftershock activity was depressed: Contrasting decay patterns of the
proximate large earthquakes in southern
[3] Ogata, Y. (2003) Examples of statistical models and
methods applied to seismology and related earth physics, International
Handbook of Earthquake and Engineering Seismology, International
Association of Seismology and Physics of Earth's Interior, Vol. 81B,
HandbookCD#2, Chapter 82.
[4] Toda, S. and Stein, R.S. (2003) Toggling
of seismicity by the 1997
[5] Vere-Jones, D. and Ogata, Y. (2003) Statistical
principles for seismologists, International Handbook of Earthquake and
Engineering Seismology, International Association of Seismology and Physics
of Earth's Interior, Vol. 81B, pp. 1573-1586.
2004:
[6] Cho,
[7] Iwata, T., and Nakanishi, I. (2004) Hastening of occurrences of
earthquakes due to dynamic triggering: The observation at Matsushiro, central
[8] Nanjo, K., Nagahama, H. and Yodogawa, E.. (2004) Symmetry in the
Self-organized Criticality, The Journal of the International Society for the
Interdisciplinary Study of Symmetry (ISIS-Symmetry) Symmetry: Art and Science
2004 (Editors D. Nagy and G. Lugosi) ISIS-Symmetry,
[9] Nanjo, K. and Nagahama H. (2004) Fractal Properties of Spatial
Distributions of Aftershocks and Active Faults, Chaos, Solitons and Fractals,
19, pp. 387-397, doi: 10.1016/S0960-0779(03)00051-1.
[10] Nanjo,
K. and
Nagahama, H. (2004) Discussions on Fractals, Aftershocks and Active Faults:
Diffusion and Seismo-electromagnetism, The Arabian Journal for Science and
Engineering, 2004, 29, 2C, pp. 147-167.
[11] Ogata, Y. (2004) Space-time model for regional seismicity and detection of crustal stress changes, J. Geophys. Res., Vol. 109, No. B3, B03308, doi:10.1029/2003JB002621.
[12] Ogata, Y. (2004) Seismicity quiescence and activation in
western
[13] Zhuang, J., Ogata, Y. and Vere-Jones, D. (2004) Analyzing earthquake clustering features by using stochastic reconstruction Journal of Geophysical Research, 109, B5, B05301, doi:10.1029/2003JB002879.
2005:
[14] Hainzl, S. and Ogata, Y.
(2005) Detecting fluid signals in seismicity data through statistical earthquake
modeling, J. Geophys. Res., Vol.110,
No.B5, B05S07, doi:10.1029/2004JB003247 (2005).
[15] Iwata, T. and Young, P. (2005) Tidal stress/strain and the
b-value of acoustic emissions at the
Underground Research Laboratory, Canada, Pure and Applied Geophysics, 162, pp. 1291-1308.
[16] Iwata,
T., M. Imoto, and S. Horiuchi (2005) Probabilistic
estimation of an earthquake growth to a catastorophic one, Geophys. Res. Let., 32.
L19307, 10.1029/2005GL023928.
[17] Nanjo,
K.Z., Nagahama, H. and
Yodogawa, E. (2005) Symmetropy of fault patterns: Quantitative measurement of
anisotropy and entropic heterogeneity, Mathematical
Geology, 37, 3, pp. 277-293,
doi: 10.1007/s11004-005-1559-z.
[18] Nanjo, K.Z., Turcotte, D.L. and
Shcherbakov, R. (2005) A model of damage mechanics for the deformation of the continental
crust, J. Geophys. Res., 110, B7, B07403, DOI:
10.1029/2004JB003438.
[19] Nanjo, K.Z. and Turcotte, D.L. (2005)
Damage and rheology in a fiber-bundle Model, Geophys. J. Int., 2005, 162, pp. 859-866,
doi:10.1111/j.1365-246X.2005.02683.x.
[20] Holliday, J.R., Nanjo, K.Z., Tiampo, K.F., Rundle, J.B.
and Turcotte, D.L. (2005) Earthquake forecasting and its verification, Nonlinear Processes in Geophysics, 12, pp. 965-977, doi:
1607-7946/npg/2005-12-965.
[21] Ogata, Y. (2005)
Synchronous seismicity changes in and around the
northern
[22] Ogata, Y. (2005) Detection of
anomalous seismicity as a stress change sensor, J. Geophys. Res., Vol.110, No.B5, B05S06, doi:10.1029/2004JB003245.
[23] Toda, S., Stein, R.S., Richards-Dinger, K. and Bozkurt,
S. (2005) Forecasting the evolution of seismicity in
southern
[24] Zhuang, J., Vere-Jones, D.,
Guan, H., Ogata, Y. and Ma, Li (2005) Preliminary analysis of
observations on the ultra-low frequency electric field in the Beijing region, Pure
and Applied Geophysics, 162, pp.
1367-1396.
[25] Zhuang, J. Chang, C., Ogata, Y. Chen, Y. (2005) A study on the
background and clustering seismicity in the Taiwan region by using point
process models, J. Geophys. Res., 110, B5, B05S18, doi:10.1029/ 2004JB003157.
In press or accepted:
[26] Nanjo, K.Z., Nagahama, H. and Yodogawa, E., Symmetropy of earthquake patterns:
asymmetry and rotation in a disordered seismic source, Acta Geophysica Polonica, in press, Volume 54.
[27] Nanjo, K.Z., Rundle, J.B., Holliday, J.R. and Turcotte, D.L., Pattern informatics and its
application for optimal forecasting of large earthquakes in
[28] Chen, C.C., Rundle, J.B., Holliday, J.R., Nanjo, K.Z., Turcotte, D.L., Li, S.C. and
Tiampo, K.F., The 1999 Chi-Chi, Taiwan, earthquake as a typical example of
seismic activation and quiescence, Geophys.
Res. Let., 2005 accepted.
[29] Ogata, Y., Seismicity anomaly scenario prior to the major recurrent earthquakes off the east coast of Miyagi Prefecture, northern Japan, and its implication for the intermediate-term prediction, Special Issue on Dynamics of Seismicity Patterns and Earthquake Triggering, eds. S. Hainzl, G. Zoler and I. Main, Tectonophysics, in press.
[30] Ogata, Y., Anomaly monitoring
of aftershock sequence by a reference model: A case study of the 2005
earthquake of M7.0 at the western
[31] Ogata, Y. and Zhuang, J., Space-time ETAS models and an improved extension, Special Issue on Critical Point Theory and Space-Time Pattern Formation in Precursory Seismicity, eds. K. Tiampo and M. Anghel, Tectonophysics, in press.
[32] Toda, S. and Matsumura, S., Spatio-temporal stress states estimated from seismicity rate changes in the Tokai region, central Japan, Tectonophysics, in press.
[33] Zhuang J., Ogata Y. and Vere-Jones D., Diagnostic analysis of space-time branching
processes for earthquakes. Chapter 15 of Case Studies in Spatial Point
Process Models, Eds. Baddeley A., Gregori P., Mateu J., Stoica R.
and Stoyan D. Springer-Verlag, New York, in press.
Main
Proceedings:
2003:
[A1] Iwata,
T. and Katao, H.
(2003) Analysis of
a correlation between the phase of the moon and the occurrences of
microearthquakes in the Tanba plateau through the point-process modeling, Programme and Abstracts of the 2003, Fall
Meeting of the Seismol. Soc.
[A2] Ogata,
Y. (2003) A practival space-time model for regional seismicity (invited), EGS-AGU-EUG Joint Assembly,Nice,
France, Geophysical Research
Abstract , Volume 5, 2003, CD-ROM,
ISSN: 1029-7006
[A3] Ogata,
Y. (2003) Sesimicity-change-analysis by a space-time point-process model
(invited) The 3rd Statistical Seismology Workshop,
[A4] Ogata,
Y. (2003) Seismicity quiescence and activation in western
[A5] Ogata,
Y. (2003) Seismicity changes in western
[A6] Ogata, Y. (2003) A
space-time model for regional seismicity
and detection of seismicity changes (in Japanese), Chikyu Monthly, 25, 10, pp. 783-787.
[A7] Toda, S. and Stein, R.S. (2003) Earthquake triggering by volcano-tectonic events: An example
from the 2000 Izu Islands swarm (invited talk), XXIII Ceneral Assembly of the
International Union of Geodesy and Geophysics, 2003.
[A8] Toda, S.
(2003) A Fresh Look at the Triggering of Earthquake Pairs, Such
as the Landers-Big Bear, Landers-Hector Mine, Izmit-Duzce, and Nenana-Denali,
and March-May 1997 Kagoshima Events (invited talk), American Geophysical Union 2004 fall meeting.
2004:
[A9] Ogata, Y. (2004) The 6th World Congress of the Bernoulli Society for Mathematical Statistics and Probability, and 67th Annual Meeting of the Institute of Mathematical Statistics, “Space-time model for regional seismicity and detection of crustal stress changes”, July 25-29, 2004, Barcelona, Spain, (invited lecture)
[A10] Ogata,
Y. (2004) Statistical models of point processes and prediction and
discovery in seismic activity (in Japanese), Spring Meeting of the Mathematical
Society of Japan,
[A11] Ogata,
Y. (2004) Static triggering and statistical modeling (in
Japanese), The 156-th Meeting of
Coordinating Committee for Earthquake Prediction , Geographical Survey
Institute, Kudan, Tokyo, February 16, 2004, Japan (topics invited lecture)
[A12] Ogata,
Y. (2004) Synchronous seismicity changes in and around the
northern
[A13] Ogata,
Y. (2004) Stress changes, seismicity changes and statistical models,
Workshop on Seismic Activity and Probabilities of Major Earthquakes in the
Kanto and Tokai Area , Central Japan, Wadati Memorial Hall, Institute for Earth
Science and Disaster Prevention, Tsukuba, Japan (invited presentation), http://kt-jisin.bosai.go.jp/WS/Program/index.html,
(invited talk)
[A14] Nanjo, K.Z., Rundle, J.B. and Hollidy, J.R. (2004) Pattern Informatics and Its Application to Forecasting Large Earthquakes in Japan, Abstract for AGU 2004 Fall Meeting, Eos Trans. AGU, 85(47), Fall Meet. Suppl., Abstract NG22A-07 (invited talk).
[A15] Toda, S. (2004) Recent progress in earthquake triggering
study and possible applications to earthquake prediction (in Japanese), The
156-th Meeting of Coordinating
Committee for Earthquake Prediction , Geographical Survey Institute, Kudan,
Tokyo, February 16, 2004, Japan (topics invited lecture)
[A16] Toda, S., and Matsumura, S. (2004) Spato-temporal stress
states estimated from seismicity rate changes in the Tokai region, central
Japan (invited talk), American Geophysical Union 2004 fall meeting.
[A17] Zhuang, J., Ogata, Y. and Vere-Jones, D. (2004) Diagnostic analysis of space-time branching
processes for earthquakes, Spatial Point Process Modeling and its Applications,
Benicassim, Castellon, Spain, Spatial Point Process Modelling and Its
Applications, Col-Lecco Treballis D'Infomatica/Tecnologia, Num. 20, ISBN
84-8021-475-9 Publication de la Universitat Jaume-I, Castello de la Plana,
Spain, pp. 273-292.
[A18] Zhuang, J., Ogata, Y. and Vere-Jones, D. (2004) Visualizing goodness-of-fit of point-process
models for earthquake clusters., Analysis of Natural and Social
Phenomena: Data Science and System Reduction; an international workshop of the
21st Century COE program at Keio University, http://coe.math.keio.ac.jp/english/event/cherry_bud/index.html, (invited talk).
[A19] Ogata, Y. (2004) Quiescence of the 2003 foreshock/aftershock activities in and
off the coast of Miyagi Prefecture, northern Japan, and their correlation to
the triggered stress-changes (in Japanese), Report of the Coordinating
Committee for Earthquake Prediction, 71,
pp. 260-267, Geographical Survey Institute of Japan.
[A20] Ogata, Y. (2004) Statistical analysis of seismic activities in and around
Tohoku District, northern Japan, prior to the large interplate earthquakes off
the coast of
[A21] Ogata, Y. (2004) Seismicity changes and stress
changes in and around the northern
[A22] Ogata, Y. (2004) Static triggering and statistical modeling (in Japanese),
Report of the Coordinating Committee for
Earthquake Prediction, Vol. 72, pp. 631-637, Geographical Survey Institute
of Japan.
[A23] Toda, S. (2004) Recent progress in
earthquake triggering study and possible applications to earthquake prediction
(in Japanese), Report of the Coordinating Committee for Earthquake
Prediction, 72, pp.
624-626, Geographical Survey Institute of Japan.
[A24] Toda, S. (2004) Seismicity
changes in inland activity before and after the 2003 Miyagi-Ken-Oki earthquake
and its implications (in Japanese), Chikyu Monthly, 27, 1, 56-61.
[A25] Ogata, Y. (2004) On changes of statistical distribution of focal
mechanisms of events prior to the main ruptures, Programme
and Abstracts of the 2005 Fall Meeting of
the Seismol. Soc.
2005:
[A26] Murata, Y. and Ogata, Y. (2005) Surficial density
estimation from gravity data using Delaunay triangular network, Joint meeting
for Earth and Planetary Science, J031-004, Makuhari, Chiba Prefecture, Japan,
May 2005.
[A27] Ogata, Y.(2005) Seismicity anomalies
measured by the ETAS model and stress changes (solicited), The General Assembly
2005 of the European Geosciences Union (EGU), , April 24-29, 2005, the Austria
Center Vienna (ACV), Vienna, Austria (invited lecture).
[A28] Ogata, Y. (2005) Seismicity changes in western
[A29] Ogata, Y. (2005) On the aftershock activity of the 2004 earthquake of M7.4
at the southeast off the coast of the Kii Peninsula, and constraints on the
fault rupture models by the mechanisms and space-time pattern of the
aftershocks (in Japanese), Report of the Coordinating Committee for Earthquake
Prediction, 73, pp. 495-498
Geographical Survey Institute of Japan.
[A30] Ogata, Y. (2005) On an
anomalous aftershock activity of
the 2004 Niigata-Ken-Chuetsu earthquake of M6.8, and intermediate-term
seismicity anomalies preceding the rupture around the focal region (in
Japanese), Report of the Coordinating Committee for Earthquake Prediction,
73, pp. 327-331, Geographical Survey
Institute of Japan.
[A31] Ogata, Y. (2005) Simultaneous estimation of b-values and detection rates of
earthquakes for the application to aftershock probability forecasting (in
Japanese), Report of the Coordinating Committee for Earthquake Prediction,
Vol. 73, pp. 666-669, Geographical Survey Institute of Japan.
[A32] Ogata, Y. (2005) Toward urgent forecasting of aftershock hazard - Simultaneous estimation of b-value of the Gutenberg-Richter’s law of the magnitude frequency and changing detection rates of aftershocks immediately after the mainshock, preprint.
[A33] Ogata, Y. (2005) Anomalies
in the aftershock sequences of the 2003 Tokachi-Oki earthquake of M8.0 and the
2004 Kushiro-Oki earthquake of M7.1 and seismicity changes in the eastern
Hokkaido inland (in Japanese), Report of the Coordinating Committee for
Earthquake Prediction, 74, pp.
83-88, Geographical Survey Institute of Japan.
[A34] Ogata, Y. (2005)
Seismicity changes in and around Kyushu District before the 2005 earthquake of
M7.0 in the western offshore of Fukuoka Prefecture (in Japanese), Report of
the Coordinating Committee for Earthquake Prediction, 74, pp. 523-528, Geographical Survey Institute of Japan.
[A35] Ogata, Y. (2005)
Relative quiescence reported before the occurrence of the largest aftershock
(M5.8) in the aftershocks of the 2005 earthquake of M7.0 at the western
Fukuoka, Kyushu, and possible scenarios of precursory slips considered for the
stress-shadow covering the aftershock area (in Japanese), Report of the
Coordinating Committee for Earthquake Prediction, 74, pp. 529-535, Geographical Survey Institute of Japan.
[A36] Ogata, Y. (2005) Anomalies in the aftershock sequences of the 2003 Tokachi-Oki earthquake of M8.0
and the 2004 Kushiro-Oki earthquake of M7.1 and seismicity changes in the
eastern Hokkaido inland, Programme and
Abstracts of the 2005 Fall Meeting of
the Seismol. Soc.
[A37] Toda, S.
(2005) Style of stress accumulation and release in northern Honshu
Future plan for the project
(1) Examination of scenarios
for predicting asperity-slip based on the seismicity anomalies
Anomaly monitoring of aftershock sequences
to detect lowering activity, relative to the modelled rate (the relative
quiescence), is now becoming realistic and practical in predicting the
enhancement of the likelihood of having a significantly large aftershock, or
even another earthquake of similar size or larger occurring. In order to
predict the location of a large aftershock or another proximate large
earthquake, we have to assume that a significant slip may have
occurred within and near to the source of the suspected earthquake due to the acceleration
of quasi-static (slow) slips on the fault as the time of rupture of the major
asperity approached. This is indicated, for example, by the analysis of small
repeating earthquake data. Thus, we should look carefully at the activity in
the stress-shadow, transferred from the slip. Such scenarios for the prediction
should be useful for examining and explaining any such anomalous features.
In fact, given an anomaly of seismicity rate change,
the difficulty lies in identifying the slip location and its imminence to a
major rupture; most of them are unknown so far as no other data or constraints
are available. For probable predictions, Ogata [2005c]
explored and reported several scenarios of
stress transfers from some thinkable slips, such as that they could have been
triggered by the M7.0 rupture at 20th March 2005 off western Fukuoka
city and moreover that the stress-shadows due to the slips should, in turn,
have covered the majority of the aftershock region. These include a conjugate
fault of the main fault rupture and several known active faults near the
rupture fault. However, the largest aftershock that occurred two weeks later
was not included in the suspected scenarios. The only exception was the
predicted unlikely slip within the Kego Fault that runs through the urban area
in the city of
(2) Effective space-time modeling
of seismic activity and the detection of seismicity anomalies
In any application of the
(hierarchical) space-time ETAS model, the data has to be homogeneous in space
and time. The threshold magnitude of completely detected earthquakes throughout
a long period and wide region is high, and the number of earthquakes above such
a threshold magnitude is very limited compared to the number of listed
earthquakes in a catalog. This is because the detection rate of earthquakes for
each magnitude is dependent on time and location. Especially, the detection
rate of aftershocks is extremely low during the period immediately following
the main shock, due to contamination of arriving seismic waves.
For an estimation of the detection rate in time and
space, we propose utilizing the statistical model introduced by Ogata and Katsura [1993] for the
simultaneous estimation of the b-values
of Gutenberg-Richter law together with the detection-rate (probability) of
earthquakes of each magnitude-band from the provided data of all detected
events, where both parameters are allowed to change in time. Thus, by using all
the detected earthquakes in a given period and area, we can estimate the
underlying ETAS rate of both the detected and undetected events and their b-value changes, taking the time-varying
missing rates of events into account. It is our hope that it will become
possible to give details of seismicity patterns such as aftershock productivity
parameters to delineate asperities [Ogata,
2005a] over the period and region of the relative quiescence as given in Ogata et al. [2003].
As a
primary step toward achieving this objective, Ogata [2005b] presents an estimation method for predicting
underlying occurrence rate of aftershocks of any magnitude range. This
procedure enables real-time probability forecasting of aftershocks immediately
after the mainshock, when the majority of large aftershocks is likely to occur
and when the forecasting is most critical for public in the
affected area.
(3) Predictive space-time-magnitude characterization of foreshocks
Descrimination of foreshocks and
clustering / declustering algorithms as a short-term prediction.
Discrimination of foreshock sequences from other clustering activity is an
important problem in short term earthquake prediction. When sequential
earthquake activity starts somewhere, it can be a swarm, a foreshock sequence,
or simply a mainshock-aftershock sequence. Therefore, it is very desirable to
know whether the activity is a precursor to a forthcoming significantly larger
earthquake or not. Ogata et al.
[1995, 1996 and 1999] and [Ogata,
1999b] investigated data sets of earthquake clusters to discriminate features
of foreshocks from earthquakes of other cluster types in a statistical sense，and found several features of some predictive
value, including the fact that foreshocks were more closely-spaced in time than
either swarms or aftershocks, the fact that foreshocks were closer together in
space than other types of events, and that foreshocks' sizes were more likely
to increase chronologically than the other types. By modeling such
discriminating features they developed probability forecasts of an earthquake
cluster being of foreshock type.
However the primary difficulty of this procedure is to find a suitable declustering algorithm for real-time forecasting of probability. There are two contrasting typical clustering algorithms, that is, the magnitude-based clustering (MBC) and the single-link-clustering (SLC) ones. The MBC based forecast performs very well, but a MBC cluster cannot formed until the occurrence of the main shock. The SLC algorithm is better for the real-time recognition of a cluster, but does not perform objectively. Recently, based on the space-time ETAS model, Zhuang et al. [2002, 2005] proposed a stochastic clustering algorithm, which appears quite useful in such a forecasting. Because of its stochastic nature, a Baysian predictive procedure will be useful.
(4) Prediction and inversion problem between
seismicity changes and stress-changes
It is becoming important to study how to make predictions and how to solve inverse problems based on the quantitative relationships between seismicity rate changes (due to the ETAS) and stress-changes. In particular, we are concerned with the theory of rate/state-dependent friction and its application to the seismicity-rate-change equation of Dieterich [Dieterich, 1994; Dieterich et al., 2000; Toda and Stein, 2003].
(5) Bayesian Probability assessments for Long-term prediction
Inference of hazard of a fault rupture and its uncertainty from data
of a small number of events, possibly with uncertain occurrence times. Conventionally, a probability of the next rupture during a future period is
calculated by the predictive hazard function into which we plug the MLE values
of BPT model [Matthews et al., 2002]
estimated by the historical data of occurrence times. However, when the number
of events in the data is small, the predictive hazard function based on the MLE
usually causes a serious bias of hazard rates. Therefore, in order to see the uncertainty of estimated hazard functions, we use the Bayesian inference
introducing a set of appropriate prior distributions. Furthermore, if a record of the slip-sizes of the events is
available, Ogata [2001, 2002]
proposes an extended renewal process for a stochastic version of the
time-predictable model of Shimazaki and
Nakata [1980] by assuming the same distribution of the ratio of the time
interval of the successive pair of events to the slip size of the first event
of the pair. Thus, we can estimate more effectively not only the hazard
function of the next event but also its uncertainty
based on the occurrence time data of the events associated with the records of
corresponding slip sizes.
When paleoearthquake data is analyzed, our further concern is the raw data in which occurrence times of events themselves are uncertain and given by confidence intervals or some chronological likelihood function [e.g., Sieh et al., 1989] inferred from geological evidences based on trench studies. For such records, we consider another Bayesian inference in which each uncertainty of occurrence time is interpreted as a prior distribution associated with the likelihood of a renewal process model [Ogata, 1999]. Integration of the posterior function with respect to the uncertain occurrence times and also the parameters of the renewal process model is implemented in order to compare the goodness-of-fit of competing renewal processes (e.g., log-Normal, Weibull and BPT models). Thus, the corresponding marginal posteriors of the model provide both estimates of distributions of the uncertain occurrence times and also the predictive hazard rates associated with the selected renewal process model. Particularly, in the case where occurrence time of the last event is uncertain, a natural assessment of current and future hazard of the forthcoming rupture can be provided.
(6) Statistical modeling for more effective use and quality improvements of datasets
There are many precise measurements such as geodetic extensometers,
tiltmeters, volmetric strainmeters, GPS and so on. However, these records are
always affected by some noises and other signals of various kinds
caused by the motions of the sun, moon, and particularly meteorological factors
such as balometric pressure, precipitation, temperature and humidity.
Therefore, it is important to model the causality and response functions of
these effects in order to know the genuine records of interest. Special care
should be put to the GPS time series data to detect geodetic anomalies
sensitively, since this dataset is now playing an important role similar to the
earthquake catalog in the sense that the stations are very densely located
throughout
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Ogata, Y.
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Appendix 3: Programme of
the 4th International Workshop on Statistical Seismology
In order to
demonstrate work of the Group to the committee, STATSEI-4 workshop organized by
Professor Ogata was held at the campus of the
The 4th International Workshop on Statistical Seismology (Statsei4)
2006.01.09-2006.01.13
Introduction
and Aims
The international workshop on Statistical
Seismology (statsei) is hosted this time by the
This workshop has been held nearly biannually
since 1998 at
One of the main features of the workshop this
time would be exploring the quantitative relationships between the seismicity
rate changes and stress changes. In particular, we are concerned with the
theory of rate/state-dependent friction and its application to the
seismicity-rate-change equation of Dieterich. Therefore, we have invited Prof.
Jim Dieterich to give tutorial or keynote lectures to stimulate our
discussions.
More details other than described below, such
as abstract and power-point oral and poster presentations, statistical
soft-wares distributed at the workshop and photos, are given in the workshop
home page, http://www.ism.ac.jp/~ogata/Statsei4/index.html.
The
session structure consists of three themes:
Triggering; rate/state dependent friction law
in relation to seismicity rate changes
Seismicity studies including statistical
modeling
Predictions and evaluations including
real-time and long-term probability forecast
Dates:
The workshop was held from the 9th January to
the 13th January.
Jan 9:
Registration and ice breaking
Morning, Jan 10 -- 12 Jan: Oral and poster sessions
We had excursion during the workshop on 13th
January.
Workshop site:
The Workshop site was held at the campus of
the Graduate University for Advanced Studies, which is located on a hill top of
the
Organizing
Committee
Ogata, Yosihiko (Chair); Tanemura, Masaharu;
Tamura, Yoshiyasu; Higuchi, Tomoyuki; Iwata, Takaki; Jiancang Zhuang; Nanjo,
Kazuyoshi
Sponsors
and Collaborations:
Institute of Statistical Mathematics
Advisory Board:
Benzion, Yehuda (Los Angels); Chen, Yuh-Ing (
Dieterich, James (
Kitagawa, Genshiro (
Rhoades, David (
Wiemer, Stefan (
Participants:
Adelfio, Giada (
Beauval, Celine (IRD - Géosciences Azur,
Sophia Antipolis, France)
Bebbington, Mark (
Ben-Zion, Yehuda (USC,
Brownrigg, Ray (
Catalli, Flaminia (Istituto Nazionale di
Geofisica,
Chen, Yuh-Ing (
Chiodi, Marcello (
Christophersen, Annemarie (
Cocco, Massimo (Istituto Nazionale di
Geofisica,
Cochran, Elizabeth S. (UCLA,
Console, Rodolfo (Istituto Nazionale di
Geofisica,
D'Amico, Sebastiano (Istituto Nazionale di
Geofisica,
Dieterich, Jim (
Ellsworth, Bill (USGS,
Enescu, Bogdan (
Felzer, Karen (USGS,
Gomberg, Joan (USGS,
Gross, Susanna (
Hainzl, Sebastian (
Hashimoto, Manabu (
Hasumi, Tomohiro (
Helmstetter, Agnes (
Huang, Chi-Shen (
Imanishi, Kazutoshi (AIST, Tsukuba)
Imoto, Masajiro (NIED, Tsukuba)
Itaba, Satoshi (AIST, Tsukuba)
Iwata, Takaki (ISM,
Jiang, Minmin (
Johnston, Steven (
Kanao, Masaki (NIPR,
Katsumata, Kei (
Kawada, Yusuke (
Ma, Li (
Maeda, Kenji (MRI-JMA, Tsukuba)
Marsan, David (Université
de Savoie)
Matsu’ura, Ritsuko (ADEP,
Matsuzawa, Toru (
Miyazawa, Masatoshi (
Murakami, Junko (SRA,
Murru, Maura (Istituto
Nazionale di Geofisica, Rome)
Nalbant, Suleyman (
Nanjo, Kazuyoshi (ISM,
Neri, Giancarlo (
Ogata, Yosi (ISM,
Rhoades, David (GNS,
Rotondi, Renata (CNR
IMATI, Milano)
Schorlemmer, Danijel
(ETH, Zurich)
Scotti, Oona (IRSN,
Fontenay-aux-Roses, France)
Shi, Yaolin (GUCAS,
Beijing)
Shimazaki, Kunihiko (ERI,
Tokyo)
Tanaka, Sachiko (NIED, Tsukuba)
Tamura, Yoshiyasu (ISM,
Toda, Shinji (AIST, Tsukuba)
Tsuruoka, Hiroshi (ERI,
van Stiphout, Thomas (ETH,
Veen, Alejandro (UCLA,
Vere-Jones, David (SRA,
Wang, Ting (
Wiemer, Stefan (ETH,
Woessner, Jochen (California Institute of
Technology,
Yang, Wen-Hsi (
Yoshida, Akio (NIPR,
Zechar, Jeremy (USC,
Zhou, Shiyong (
Zhuang, Jiancang (ISM,
Zuniga, Ramon (Univ. Nacional Autonoma de Mexico,
Programme
- Tutorial, Utsu Memorial and Kenote lectures
(cf., the blue colored frame) are sponsored by
- We had two poster core sessions on Tuesday
and Thursday. The size of the poster is 120cm in WIDTH and 190cm in HEIGHT in
maximum.
- 20 minutes for each oral talk, 10 minutes
for discussion.
Date Time
Jan. 9
(Mon)
Afternoon Registration
Evening Welcome Party
Jan. 10
(Tue)
09:45-10:00 Opening remarks
10:00-11:00 *Tutorial 1, D. Vere-Jones: Stochastic models for the analysis of
seismicity data
11:00-11:30 *Utsu Memorial 1, R. S. Matsu'ura: The
late Prof. Tokuji Utsu: His career with geophysics and seismology
11:30-12:00 *Utsu Memorial 2, Y. Ogata:
Contributions of Professor Tokuji Utsu to statistical seismology and recent
developments
12:00-13:30 Lunch
Statistical
Modeling and Forecasting of Earthquake 1
13:30-14:00 K. Shimazaki:
Long-term earthquake forecasts in
14:00-14:30 S. Wiemer, M.
Cocco, G. Gruenthal, I. Main, W. Marzocchi, M. Gerstenberger, D. Schorlemmer:
Towards an European framework for testing earthquake forecasts
14:30-15:00 M. Imoto:
Statistical models based on the Gutenberg-Richter a and b values for estimating
probabilities of moderate earthquakes in
15:00-15:30 S. Zhu, Y.
Shi: Improved stress release model and its application to earthquake prediction
in
15:30-15:45 Coffee break
15:45-16:15 D. A. Rhoades:
Seismogenesis, scaling and the EEPAS model
16:15-16:45 S. Hainzl, T.
Kraft: Analysis of complex seismicity pattern generated by fluid diffusion and
aftershock triggering
16:45-17:15 Y. I. Chen, C. S. Huang:
Time-dependent b value for aftershock sequences
17:15-17:45 K. Z. Nanjo,
B. Enescu, R. Shcherbakov, D. L. Turcotte, T. Iwata, Y. Ogata: Aftershock
relaxation for Japanese and Sumatra earthquakes
17:45-19:30 Dinner
19:30-22:00
Poster Session Core Time, Group A
G. Adelfio, M. Chiodi: Earthquakes
clustering based on maximum likelihood estimation of point process conditional
intensity function
R. Brownrigg: A statistical seismology
software suite
Y. I. Chen, C. S. Chen, W. H. Yang, K. F.
Ma The relationship between the earthquake rate change and the gradient of
stress change
Y. I. Chen, C. S. Huang Analysis of
aftershock hazard using power prior information
A. Christophersen, E. G. C. Smith Are
foreshocks really mainshocks with larger aftershocks?
B. Enescu, J. Mori, M. Miyazawa, T.
Shibutani,
K. Ito,
Y. Iio, T. Matsushima, K. Uehira Quantifying the early aftershock activity of
the 2004 Mid Niigata Prefecture Earthquake (Mw6.6)
K. Imanishi, W. L. Ellsworth Earthquake
source parameters of microearthquakes at
T. Iwata, H. Katao The correlation
between the phase of the moon and the occurrences of microearthquakes in the
Tamba region
M. Kanao, Y. Nogi, S. Tsuboi Spacial
distribution and time variation in seismicity around Antarctic Plate before and
after the M9.0 Sumatra Earthquake, 26 December 2004
M. Murru , R. Console, F. Catalli, G.
Falcone Application of physical and stochastic models of earthquake clustering
to regional catalogs
Y. Ogata Relative quiescence reported
before the occurrence of the largest aftershock (M5.8) with likely scenarios of
precursory slips considered for the stress-shadow covering the aftershock area
Y. Ogata Toward urgent forecasting of
aftershock hazard: Simultaneous estimation of b-value of the
Gutenberg-Richter's law of the magnitude frequency and changing detection rates
of aftershocks immediately after the mainshock
D. Schorlemmer, M. Gerstenberger, T.
Jordan,
E. Field,
S. Wiemer, L. Jones, D. D. Jackson From the testing center of regional
earthquake likelihood models to the collaboratory for the study of earthquake
predictability
S. Tanaka Tidal triggering of earthquakes
precursory to the 2004 Mw = 9.0 Off
A. Veen,
F. P. Schoenberg Estimation of spatial-temporal point process models using the
(stochastic) Expectation Maximization algorithm and its application to
T. Wang, L. Ma, Y. Li A study on the
limited power law model [abstract] [poster]
J. D. Zechar, T. H. Jordan Comparative
testing of alarm-based earthquake prediction strategies
F. R. Zuniga Interevent times within
aftershock sequences as a reflection of different processes
Jan. 11
(Wed)
09:15-09:45 L. Ma, T.
Wang, B. Yin, W. Wang, J. Huang, C. Zhang: Exploratory statistical analysis
with the data of various observations in Tangshan well
Statistical
Modeling and Forecasting of Earthquake 2
09:45-10:15 D. Marsan, G. Daniel, M.
Bouchon: Seismicity shadows: Observations and modelling
10:15-10:45 D.
Schorlemmer, M. Gerstenberger, T. Jordan, D. Jackson, S. Wiemer, Y. Kagan, L.
Jones, N. Field: From the testing center of regional earthquake likelihood
models (RELM) collaboratory for the study of earthquake prediction (CSEP)
experiment in intermediate-term earthquake prediction: Possibility of an M8
earthquake occurring off the coast of eastern Hokkaido in 2005
10:45-11:15 K. R. Felzer:
The snowball effect: Statistical evidence that big earthquakes are rapid
cascades of small aftershocks
11:15-11:30 Coffee break
11:30-12:30 *Tutorial 2 ,
J. Dieterich: Tutorial on stress- and state-dependent model of earthquake
occurrence: Part1-model and formulation
12:30-14:00 Lunch
14:00-15:00 *Tutorial 3,
J. Dieterich: Tutorial on stress- and state-dependent model of earthquake
occurrence: Part2-applications
15:00-15:30 M. Bebbington,
K. Borovkov: Producing Omori's law from stochastic stress transfer and
release
Earthquake
Triggering 1
15:30-15:45 Coffee break
15:45-16:15 R. Console, M.
Murru, F. Catalli: Applying the rate-and-state friction law to an epidemic
model of earthquake clustering
16:15-16:45 A. Helmstetter, B. E. Shaw:
Estimating stress heterogeneity from aftershock rate
16:45-17:15 S. Toda, R. S.
Stein, K. Richards-Dinger, S. Bozkurt: Forecasting the evolution of seismicity
in southern
17:15-17:45 K. Maeda:
Estimation of the fault constitutive parameter A$\sigma$ and stress
accumulation rate from seismicity response to a large earthquake
18:00-21:00 Party
Jan. 12 (Thr)
Breakfast
09:15-09:45 M. Jiang, S.
Zhou: A new multiple dimension stress release statistic model based on
co-seismic stress triggering
Earthquake
Triggering 2
09:45-10:15 M. Cocco, L.
Chiaraluce, Fl. Catalli: Seismicity migration and time-dependent stress
transfer: Supporting and conflicting evidence from the Umbria-Marche (
10:15-10:45 S. S. Nalbant,
S. Steacy, J. McCloskey: Real-time application of Coulomb stress modelling and
related issues
10:45-11:15 E. S. Cochran: Tidal
triggering of earthquakes: Response to fault compliance?
11:15-11:30
Coffee break
11:30-12:00 M. Miyazawa: Dynamic
triggering with no and/or little time-delay
12:00-12:30 S. Gross: Statistical
measures of dynamic triggering
12:30-14:00 Lunch
14:00-14:30 J. Gomberg, K.
Felzer, E. Brodsky Earthquake dynamic triggering and ground motion scaling
14:30-15:30 *Keynote Lecture , J. Dieterich:
Stress- and state-dependence of earthquake occurrence
15:30-15:45 Coffee break
15:45-16:15 J. Woessner,
S. Wiemer, S. Toda: Correlating properties of aftershock sequences with
earthquake physics
Phyisical
Modeling of Eearthquakes
16:15-16:45 T. Matsuzawa,
N. Uchida, T. Okada, K. Ariyoshi, T. Igarashi, A. Hasegawa Quasi-static slips
before and after large interplate earthquakes inferred from small repeating
earthquake data
16:45-17:15
Y. Ben-Zion, V. Lyakhovsky Analysis of aftershocks in a lithospheric model with
seismogenic zone governed by damage rheology
17:15-17:45 W. L.
Ellsworth, S. H. Hickman, M. D. Zoback: Seismology in the source: The
17:45-19:30 Dinner
19:30-22:00 Poster Session Core Time, Group B (see below)
C.
Beauval, S. Hainzl, F. Scherbaum: The impact of the spatial uniform
distribution of seismicity on probabilistic seismic hazard estimation
F.
Catalli, R. Console: An application of the Dieterich model for seismicity rate
change to the 1997 Umbria-Marhe, central
N.
Chopin, E. Varini: Particle filtering of a state-space model for seismic
sequences
S.
D'Amico, D. Caccamo, F. Parrillo, F. M. Barbieri, C. Lagana: Anomalies in the
temporal decay of seismic sequences
S. D'Amico, D. Caccamo, A. Zirilli, F.
Parrillo, S. M. I. D'Amico, A. Alibrandi: Some analysis of seismicity in the
T. Hasumi: Spatial-temporal statistics
between successive earthquakes on 2D Burridge-Knopoff model
S. Itaba, K. Watanabe: Seismicity cycle
and large earthquake
S. Zhou, R.Robinson, M. Jiang: The role
of fault interactions in the generation of the 1997 Jiashi strong earthquake
swarm,
Y. Kawada, H. Nagahama: Temporal
power-laws on preseismic activation and aftershock decay affected by transient
behavior of rocks
N. Kuehn, S. Hainzl: The effects of fault
zone coupling on seismic cycling and aftershock generation
G. Neri, B. Orecchio, D. Presti: Coulomb
stress changes from grouped magnitude 7+ earthquakes in south
R. Rotondi, G. Zonno: Bayesian analysis
of the local intensity attenuation
D. Gospodinov, R. Rotondi: RETAS: a
restricted ETAS model inspired by
O. Scotti, C. Clement, F. Bonilla:
Earthquake recurrence models for faults: The crucial role of intermediate
magnitude earthquakes in seismic hazard assessment
H. Tsuruoka: Development of seismicity
analysis software on Unix, Windows and Mac OS X
T. van Stiphout, S. Wiemer: Testing the
precursory seismic quiescence hypothesis
D. Vere-Jones, J. Murakami, A.
Christophersen: A further note on
A. Yoshida, G. Aoki: Enhancement and
diffusion of seismic activity around major intraplate earthquakes in
J. Zhuang, Y. Ogata: Properties of the
probability distribution associated with the largest event in an earthquake
cluster law
G. Zoller, Y. Ben-Zion, S. Hainzl, M.
Holschneider: Properties of seismicity and surface deformation generated by
earthquakes on a heterogeneous strike slip fault in elastic half space law
Jan. 13 (Fri)
08:30-17:00 Excursion
(JAMSTEC 1; JAMSTEC 2)
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on 1 November
2006