Workshop on the Evaluation of Probabilistic Seismic Hazard Analysis on the Basis of Observations

Workshop on the Evaluation of Probabilistic Seismic Hazard Analysis on the Basis of Observations

Hosted by the Government of France

Électricité de France (EDF)

Saclay, France

3–5 December 2018

Ref. No.: EVT1702159




In IAEA Safety Standards Series No. SSG-9, Seismic Hazards in Site Evaluation for Nuclear Installations, it is recommended that Probabilistic Seismic Hazard Analysis (PSHA) should be applied in site evaluation. In order to integrate multiple expert opinions, the logic tree approach is commonly applied, and branches are weighted by the consensus of experts. Such a procedure is described, for example, in the Senior Seismic Hazard Analysis Committee (SSHAC) approach in the United States of America. The advantage of that approach is the integration of different expert opinions, taking epistemic uncertainties into consideration.

However, as some discrepancies have been observed recently in some PSHA results, it has been recognized that further evaluations are needed for results derived by forward integration of the PSHA process (SSG-9, para 6.6), which consists of seismic source modelling, ground motion characterization and logic tree approach.

In parallel, a great effort has been made to accumulate data from observation records of earthquakes in the framework of seismology. Such data can be used to perform evaluations of PSHA results or can be used to rank (i.e. to assess the likelihood of) any branch of the logic tree, using, for example, Bayesian approaches.

It is particularly important that efforts are made to verify every elementary and integral step of the PSHA, taking actual observation into consideration. Such approaches are discussed and encouraged in seismological, geological and earthquake engineering scientific societies. Although these approaches are not new, they have not yet been implemented in many PSHA studies, owing to the lack of formal procedures and guidelines.

This workshop will discuss schemes of evaluation for PSHA based on actual observations and will clarify what kind of observations can be used in that context. It will also provide practical guidance on how to develop such approaches and how to use observations consistently with PSHA assumptions.

It will in addition contribute to reducing epistemic uncertainties and to improving seismic hazard assessments of nuclear installations in Member States.


Objectives of the Workshop

The objective of the workshop is to discuss information on the state-of-the-art practices and detailed technical elements related to the evaluation of PSHA based on observations, so that Member States can improve seismic hazard assessment of their nuclear installations using probabilistic methods to follow the recommendations of SSG-9.

Particular attention is devoted to covering diverse evaluation schemes to reflect the accumulated knowledge and information. The different types of observations to be used (including instrumental seismicity, historical seismicity and palaeoseismicity) and the way to process these consistently with the prior PSHA assumptions will also be discussed in the workshop.


Topics to be presented and discussed

The topics to be presented and discussed may cover any research work or practical case studies that used actual observation in order to rank, score or rate (i.e. to assess the likelihood of) any elementary assumption, models or branch of a PSHA (such as seismotectonic models, earthquake occurrence models, vibratory ground motion models …) or the integral PSHA results (such as weighting branches related to their likelihood based on observation), using, for example, Bayesian approaches or any other relevant approach.
The main topics that are covered are the following:

General framework of evaluating PSHA results based on observations

Contributions may include the description of approaches, methodologies, tools that are related to the evaluation of PSHA results based on observations. This may include any procedure or formal practice that have been implemented and published, or that are under preparation.

Evaluation of PSHA elementary steps based on observations

Contributions may cover the evaluation of any elementary step of a PSHA that could be either a physical model, an assumption or an input data, based on observations, such as:

  • Selection of earthquake databases and catalogues (including type of magnitude, completude periods, etc.)
  • Identification of seismotectonic models (including seismogenic structures, zones of diffuse seismicity, etc.)
  • Definition and selection of earthquake occurrence models (including models parameters, maximum magnitudes, etc.)
  • Selection of vibratory ground motion parameters (including GMPEs, aleatory and epistemic uncertainties propagation, etc.)

Evaluation of PSHA integral steps based on observations

Contributions may cover the evaluation of the overall results of the PSHA (that combine together many data, models, assumptions and epistemic branches, etc.) based on observations. This would typically include:

  • The evaluation of the centre, body and range of the prior PSHA based on observation
  • Any or some of the following types of observations, such as instrumental seismicity, historical seismicity and palaeoseismicity
  • Any or some geographical scales such as the site area and the regional scale around the site

Expected contributions

Contributions from other speakers on the topics mentioned above are also welcome. Therefore, any participant willing to present his/her work orally should submit an extended abstract (min. 400 words), including a list of associated published references together with the attached Form for Submission of a Paper (Form B), in which the author(s) will need to agree with one of the assignments of the rights.


Participation and Registration

The workshop is targeted at experts from regulatory bodies, utilities, technical support organizations, vendors and research and development organizations, who are working in the areas covered by the workshop.

All participants who pre-registered for the IAEA workshop on this website have to be also nominated by their competent national authority. IAEA workshop invitation will preferably be given to participants from IAEA Member States with a certain capacity of nuclear programme (e.g. having a nuclear power plant or a research reactor of high capacity and feasible embarking level).

The competent national authority (e.g. Ministry of Foreign Affairs or National Regulatory Authority of the individual Member State, where your institution is located) will be informed by the IAEA through the diplomatic channel on relevant information for the workshop. Each pre-registered participant will be requested to contact the competent national authority for the formal registration by filling a specific IAEA Participation Form A that will be provided by the national authority. The decision of each nomination will be subject by the national authority of the individual Member State. The IAEA will support participants with obtaining their nomination by the authorities through the diplomatic channel.

VERY IMPORTANT: After the nomination, pre-registered participants will be informed on the invitation status by the IAEA.

As first step please fill in the online pre-registration below.

Submission of abstracts

Participants willing to present their work must submit an extended abstract (minimum 400 words), including a list of associated published references. Please include this information when filling in the IAEA participation Form.

Important dates to remember

  • Deadline for online pre-registration : 30 September 2018
  • IAEA registration deadline : 15 October 2018
  • Extended abstract submission deadline: 30 October 2018
  • Workshop: 3–5 December 2018




Scientific Secretary

Mr Yoshimitsu Fukushima
Division of Nuclear Installation Safety
Department of Nuclear Safety and Security
International Atomic Energy Agency
Vienna International Centre
PO Box 100

Tel.: +43 1 2600 22064
Fax: +43 1 26007

Administrative Secretary

Ms Nadia Nammari
Division of Nuclear Installation Safety
Department of Nuclear Safety and Security
International Atomic Energy Agency
Vienna International Centre
PO Box 100

Tel.: +43 1 2600 22518
Fax: +43 1 26007


Subsequent correspondence on scientific matters should be sent to the Scientific Secretary and correspondence on other matters related to the workshop to the Administrative Secretary.


Scientific Organizing Committee

Mr Emmanuel Viallet (Chair)
EDF, France

Mr Jon Ake
Nuclear Regulatory Commission, USA

Ms Gloria Senfaute
EDF, France

Mr Dario Albarello
University of Siena, Italy

Mr Ramon Secanell
GEOTER-SAS (Fugro Group), Spain

Mr Masato Nakajima



Participants who require a visa to enter France should submit the necessary application to the nearest diplomatic or consular representative of France at least four weeks before they travel to France. Since France is a Schengen State, persons requiring a visa will have to apply for a Schengen visa. In States where France has no diplomatic mission, visas can be obtained from the consular authority of a Schengen Partner State representing France in the country in question.



No registration fee is charged to participants. The IAEA is not in a position to bear the travel and other costs of participants in the workshop.


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