Université Tunis El Manar L Ecole Nationale d Ingénieurs de Tunis et BG Tunisia

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1 ENIT Université Tunis El Manar L Ecole Nationale d Ingénieurs de Tunis et BG Tunisia BG Tunisia Atelier International sur L Analyse du Risque et la Gestion des Catastrophes à l ENIT, novembre 2005 International Workshop on Risk Assessment and Disaster Management November 28-29, ENIT Contact et Informations Program Committee : [email protected] - Tel : Fax : BG Tunisia - External Affairs Department - Tel : Fax : Avec le concours de in Cooperation with : North African Seismological Group (NASG) - L Unité de Recherche «Ingénierie Géotechnique» L Association Scientifique de l ENIT (ASENIT) - L Association Tunisienne de Mécanique des Sols (ATMS)

2 Atelier sur L ANALYSE DU RISQUE et la GESTION des CATASTROPHES, Tunis, 28 & 29 novembre 2005 La gestion du risque quel qu il soit implique son analyse et le développement de plans d actions visant à le réduire. Ces plans d actions intègrent, outre la mise en place de procédures de renforcement d infrastructures, de planification urbaine et de réaction à un état de crise, (1) la sensibilisation des populations et institutions à la culture de la sécurité, (2) la consolidation des connaissances techniques et scientifiques en la matière et, (3) l acquisition des outils d analyse et de gestion ad-hoc. Cet atelier s inscrit dans le cadre d un projet global sponsorisé par BG-Tunisia visant à consolider la culture du risque (analyse et gestion de crise) auprès des élèves ingénieurs et étudiants chercheurs de l ENIT toutes spécialités confondues. Il est dédié à l analyse du risque naturel et urbain et à la gestion des crises; il donnera les concepts de base pour analyser le risque à toutes ses étapes, de l aléa à la vulnérabilité, jusqu à sa gestion, s appuyant pour cela sur les méthodologies les plus récentes développées dans l analyse et la gestion du risque sismique que viendront exposer des spécialistes et chercheurs méditerranéens impliqués dans la thématique à l échelle internationale. Il sera également l occasion d une réflexion partagée sur la stratégie à développer pour le renforcement de la culture du risque auprès des ingénieurs et formateurs de demain. 1 Workshop on RISK ASSESSMENT and DISASTER MANAGEMENT, November 28-29, 2005 Management of risk involves first the assessment of risk, and thereof the development of plans to reduce the risk potential. These plans include Preparedness, Mitigation, Response and recovery as well as Knowledge acquisition actions. Knowledge acquisition actions are aimed at acquiring the technical and scientific knowledge as well as the tools required for disaster assessment and management. This workshop is part of a global project sponsored by BG-Tunisia which contributes to strengthening the culture of risk amongst engineering and research students of ENIT. This workshop will review the methodologies for risk assessment including deterministic and probabilistic approaches, risk mapping and other techniques used for assessing major risk. The basic concepts of major risk assessment should be explained and examples, based mainly on the seismic risk, will be provided to illustrate the methodologies for risk assessment and their applications. It will also offer the opportunity to think on the strategy to be developed to reinforce the risk culture among the engineers and trainers.

3 Workshop on RISK ASSESSMENT and DISASTER MANAGEMENT, November 28-29, Program Sunday, November 27 09:00 15:00 Registration 12:00 14:00 Lunch 14:00 18:00 Tours: Bardo Museum, Carthage Museum, Tunis Medina. 19:30 Welcome Diner, Sidi Bou Saîd. Monday, November 28 08:00 09:00 Registration 09:00 09:30 Opening Ceremony 09:30 09:45 Group Photo & Coffee Break 09:45 13:00 Session 1. Risk Assessment and Disaster Management in Urban Areas, Chairmen: P-Y. BARD & G.F.PANZA 09:45 10:30 Management of Major Hazards in the Oil and Gas Industry, N.YOUNES 10:30 11 :15 Risque Environnemental, Prise de Décision Collective et Principe de Précaution, E.JOUINI 11:15 12:00 Aménagement de l Espace et Sécurité Civile, P.TRONCHON 12:00 12:45 The Istanbul Metropolitan Municipality Earthquake Master Plan Project, A. ANSAL 12:45 13:00 Questions 13:00 14:15 Lunch. 14:15 18:15 Session 2. Seismic Risk Assessment and Disaster Management, Case Studies. Chairmen: D.BENOUAR & A.ANSAL 14:15 15:05 Un Exemple d Etude Intégrée de Risque Sismique sur la Ville de Nice, P-Y. BARD 15:05 16:00 Seismic Hazard Assessment: Scenario-based deterministic approach at national and urban scale in Italy, G.F.PANZA 16:00 16:15 Coffee Break 16:15 17:15 Seismic Microzonation for Urban Planning and Vulnerability Assessment, A. ANSAL

4 17:15 17:45 Overviews of Seismic Hazard and Vulnerability Studies in Tunis City, N.B.ROMDHANE 17:45 18:15 Questions 18:30 20:00 IGCP & NASG working groups meeting. Tuesday, November :45 13:00 Session 3. Recent advances in Seismic Hazard Assessment and Vulnerability studies. Chairmen: G.F.PANZA & P.TRONCHON 08:45 09:45 Uncertainties in the Maghreb Countries Tunisia, Algeria, Morocco- Earthquake Catalogue and their Influence on Seismic Hazard Assessment, D.BENOUAR 09:45 10:45 Effects of Local Site Conditions on Strong Ground Motion: Physical Phenomena, Estimation Techniques Illustrated on Two Examples: (1) Site Effects in Alpine Valleys: The Grenoble Case & (2) Geotechnical Conditions and Local Seismic Hazard in Tehran, P-Y.BARD 10:45 11:00 Coffee Break 11:00 11:30 Seismic Evaluation and Innovative Retrofit of a Historical Building in Tunisia, S.El BORGI 11:30 12:30 Liquefaction Susceptibility and Microzonation, A.ANSAL 12:30 13:00 Questions 13:00 14:15 Lunch. 14:15 17:15 Session 4. Recent advances in Seismic Risk Assessment. Chairman: A.ANSAL 14:15 15:00 Pattern Recognition Methodologies for the Space-Time Identification of Strong Earthquakes: The Case of Italy, A.PERESAN 15:00 15:45 Synthetic Seismograms for Deterministic Seismic Zoning and Microzoning: Input Data Preparation and Modelling, F.VACCARI 15:45 16:00 Questions 16:00 16:15 Coffee Break 16:15-17:30 Session 5. Preparedness and Knowledge Acquisitions in High Educational Institutions. Chairmen: P.ZIMBARDO & N.B.ROMDHANE InCrisis, «Risques & Crises» pour un développement durable à IDEAMED, Co-construire des projets de coopération en Méditerranée, P.ZIMBARDO Discussions & Recommendations. 17:30 17:45 Closing Ceremony.

5 Organization Committees 4 Program & Advisory Committee Members: A. ANSAL (Turkey) D. BENOUAR (Algeria) G. F. PANZA (Italy) P-Y. BARD (France) N. B. ROMDHANE (Tunisia) P. TRONCHON (France) Facilities & Finance Committee Members F. PEARSON (BG Tunisia) M. BEN ABDALLAH (BG Tunisia) N. B. ROMDHANE (ENIT) Student Arrangements Committee Student Committee Chair: Amin DHMAIED Registration Committee: Nedra FASSATOUI, Imen BEL HAJ ALI, Hela BEN AIDA, Ones ZEMNI, Sihem LOUATI, Soumaya SAIDANE Publicity Committee: Zied DAGHMOURI, Ramzi BEN MANAA, Ghassen ELLOUZE, Tarek CHTIOUI, Mohamed ISSAOUI Transport Committee: Mohamed Amine LOUKIL, Chokri CHANGUEL, Amine DHMAIED Time Keeper: Jihed BEN HAMOUDA.

6 Abstracts Management of Major Hazards in the Oil and Gas Industry N.Younes* 5 The presentation aims at introducing the topic of major hazards (MH) management. It will flag the importance of MH management for providing a safer workplace for the workforce and the public in the areas surrounding oil and gas facilities. Key concepts will be defined and hazard identification and mitigation techniques will be described including their effectiveness and relevance depending on the lifecycle stage of the facility. Practical examples will be used to understand major hazards and to explain the main mitigation techniques. Finally, specific aspects of risk perception and human factors linked to MH management will be explored. * After graduate studies in the USA leading to a Master of Science in Mechanical Engineering, Nebil Younes returned back to Tunisia in 1985 and held several Project Engineering positions with ETAP and later with Marathon Oil. He joined BG Tunisia Loss Prevention team in Some of his key achievements included tunisification of the Loss Prevention Department, adoption of a risk-based approach to major hazards management, embedding of a positive safety culture and introduction of international environmental standards to E&P activities. In 1999, the Miskar offshore facilities became the Group's first overseas platform to be certified ISO Starting March 2000, Nebil undertook a challenging assignment in Cairo as BG Egypt- Vice President, Loss Prevention helping the local management team and workforce achieve exceptional HSE performance. In parallel, He also managed the Asset's ground breaking Corporate Governance Improvement Project. Since August 2002, Nebil is BG Group's Head of Safety based at the Group's headquarters in Reading, UK. The role includes developing the Group-wide safety strategy and monitoring the overall safety performance. He is also the custodian of BG Group's HSSE Management System and is currently driving implementation of behavioural change processes across all the Group's Assets. One of his main challenges is to transfer safety culture development and behaviour-based safety techniques and processes to more general business applications.

7 Risque Environnemental, Prise de Décision Collective et Principe de Précaution E.Jouini* 6 Notre gestion de l'environnement notamment à travers son impact sur l'évolution du climat est la source de nouveaux risques d'une ampleur sans précédent. Face à ces derniers, l'approche statistique traditionnelle est inadaptée et seuls les avis d'experts peuvent permettre d'appréhender le futur. Que faire alors lorsque ces expertises sont divergentes? Quelles règles de consensus retenir? Quelles procédures de décision, de suivi et de gestion mettre en place? Quel coût la société est elle prête à payer pour limiter ces risques et quelle part de ces derniers est-elle prête à assumer? Quelle évaluation financière pour des risques dont l'horizon dépasse de très loin celui que les approches actuarielles classiques ont l'habitude de prendre en compte (la durée de vie de déchets nucléaires est de plusieurs centaines d'années)? * Mathématicien, ancien élève de l'école normale supérieure (Paris), membre de l'institut universitaire de France et vice-président de l'université Paris-Dauphine chargé de la recherche. Les travaux d'elyès Jouini sont à l'interface des mathématiques, de l'économie et de la finance. Il est d'ailleurs à signaler que bien que mathématicien, il a reçu le prix du meilleur jeune économiste en 2005 et a été professeur de finance à la Stern School of Business, New-York University. Elyès Jouini, actuaire agréé par le ministère des finances, a créé en Tunisie le cabinet de conseil Actuaria spécialisé en contrôle, évaluation et suivi des risques financiers (retraites, assurances, crédit,...). Il est également administrateur indépendant de la Banque de Tunisie et membre de nombreux conseils scientifiques (Fondation Banque de France, Fondation Europlace de Finance, Conseil des Indices, Institut des Actuaires,...). Aménagement de l Espace et Sécurité Civile P.Tronchon* L'activité humaine est souvent à l'origine de modifications et même de transformations du milieu naturel qui peuvent avoir des conséquences dangereuses pour l'homme. De plus, aménageurs et constructeurs ne prennent pas toujours suffisamment en compte les problèmes techniques induits par l'urbanisation pour des raisons financières. Les risques naturels et les pollutions peuvent donc être aggravés par l'activité humaine inconsciente et parfois «affairiste». L'évolution quant à la détermination des responsabilités en matière de sécurité civile depuis la décentralisation aurait du avoir pour effet de renforcer la protection des citoyens contre les dangers de toutes sortes provoqués par l'homme. Malheureusement, force est de constater que le transfert de compétences en matière d'utilisation des sols cumulé avec la crise économique ont plutôt conduit les décideurs locaux et nationaux à rechercher des compromis parfois incompatibles avec la sécurité des citoyens. Force est de constater également que le développement économique dont la traduction sur le terrain se concrétise très souvent par une urbanisation

8 insuffisamment programmée et réfléchie, a pour conséquence une très forte aggravation des risques naturels. Il est temps que nos politiciens assistés de leurs experts cessent de considérer les catastrophes naturelles comme un signe des temps irrémédiable, dues exclusivement à des dérèglements climatiques (pluies plus abondantes, réchauffement de la planète). En d'autres termes, à quoi peut-il être utile d'étudier le phénomène des risques majeurs si nous devons conclure après chaque catastrophe naturelle qu'il s'agit alors d'un cas de force majeure? En France, la décentralisation des autorisations d'occuper le sol a probablement aussi produit des effets pervers non attendus par le législateur. Alors que les lois de 1981 et 1995 avaient créé des plans d'exposition aux risques et des plans de prévention des risques majeurs, on peut s'étonner que si peu de tels documents, plus de 20 ans après leur création, ont été approuvés. Ce n'est pas un problème financier et encore moins une pénurie de compétence en la matière. Pourtant, un risque naturel majeur a été identifié dans près de communes sur les que compte la France. Au moment où l'on entend parler de toutes parts de la rareté du foncier et de son coût, il est permis de douter de la détermination des pouvoirs publics à vouloir empêcher l'urbanisation des zones dangereuses pour l'homme. 7 * Docteur en Droit (mention Droit Public Aménagement de l Espace et Sécurité Civile) et habilité à diriger les recherches en géographie & aménagement, Pierre Tronchon a été directeur de l école d architecture de Montpellier (1991 à 1999). Actuellement, il est Conseiller d Administration de l Équipement, chargé de mission d inspection générale chargé des secteurs : espaces protégés, architecture, ingénierie publique, bâtiment et constructions publiques. Il professe également à l université de Perpignan et à l université de Montpellier I. Dans le cadre de ces fonctions actuelles, et plus spécialement en tant qu inspecteur sur le thème «ingénierie publique», il est familiarisé et habitué au système et procédures des marchés publics. InCrisis, «Risques & Crises» pour un développement durable à IDEAMED, Co-construire des projets de coopération en Méditerranée, P.Zimbardo* C est dans un contexte de complexité croissante et généralisée que cette communication propose d apporter une mise en perspective sur les liens entre environnement, développement durable, technologie, risques, crises et vulnérabilités des territoires, pour introduire la problématique de l'éducation des citoyens dans l enseignement de la technologie et des sciences de l ingénieur. Cette approche introduira le débat sur la nécessité de mettre en réseau les acteurs de la Méditerranée et de créer un environnement capable de permettre l émergence de projet co-construit au bénéfice des territoires. * Après un parcours d une dizaine d année comme Ingénieur d affaires dans le domaine de la haute technologie, Patrick a développé depuis 1990 des méthodes et outils dédiés aux Systèmes d Informations Projets en environnement complexe. Expert international auprès de la division industrielle de l ONU et du PNUD, il accompagne le redéploiement des filières et le développement des

9 8 territoires en Afrique particulièrement dans le cadre de programmes de bonne gouvernance, de renforcement des capacités institutionnelles & structurelles du secteur public et des partenariats technologiques & industriels du secteur privé. Il intervient dans les processus de communication et de coordination par émergence de communauté collaborative sur des projets sensibles. Expert en Ingénierie d enseignement à l ex-groupe des Ecoles Supérieures d Ingénieurs de Marseille en cours de devenir la 5ème École Centrale en France, il assure la responsabilité opérationnel de la filière «Risques et Crises» (formations de 3ème cycle en Mastère Spécialisé ; parcours qualifiants ; actions collectives ; animation de e-communautés) au Centre d Innovation et de Management Euro méditerranéen pour le Développement de la Chambre de Commerce et d Industries de Marseille Provence pour laquelle il intervient dans les projets internationaux dédiés à l innovation pour le développement durable sur le bassin Méditerranéen. Spécialiste sur les logiques d Intelligence Collective, il se consacre au déploiement de «passerelles & dispositifs géo territoriaux» entre espaces économiques dans le cadre des accords avec l UE. [email protected] Site Web : Un Exemple d Etude Intégrée de Risque Sismique sur la Ville de Nice P-Y. Bard* Co-auteurs: Anne-Marie Duval, Patrice Foin, Philippe Guéguen, Etienne Bertrand, Jean-François Vassiliades, Sylvain Vidal, Christian Thibault, François Dunand. Comparés à d'autres aléas naturels (crues, mouvements de terrain), les séismes destructeurs ont la spécificité d'avoir une période de retour beaucoup plus longue, dépassant généralement largement la mémoire individuelle (et encore plus les mandats électifs), et ce même si des événements modérés mais suffisamment forts pour être ressentis surviennent assez régulièrement. La prévention se heurte donc souvent à un manque de prise de conscience, qui touche l'ensemble de la population, du propriétaire ou locataire aux décideurs locaux, en passant par les professionnels de la construction. La réduction du risque sismique est de fait une œuvre de longue haleine qui doit impliquer de multiples acteurs, et comporte nécessairement plusieurs facettes. Nombre de pays plus sismiques que la France (Japon, Californie, ) ont déjà fait face à cet écueil depuis longtemps, et ont appris qu'un moyen efficace pour favoriser une prise de conscience informée, sans dramatisation ni minimisation, était la réalisation d'études "de scénario", consistant à évaluer à l'avance, à l'échelle d'une agglomération, les dommages que pourrait occasionner un séisme "plausible", en communiquer les résultats à l'ensemble des acteurs de la construction et à la population, et élaborer sur cette base une politique concertée de prévention ciblée en priorité sur les points les plus vulnérables. A titre d'illustration de cette démarche, seront présentés et discutés les approches utilisées et les résultats obtenus dans le cadre d'une étude récemment finalisée sur la municipalité de Nice (France). Le projet "GEMGEP" a

10 été lancé à l'issue de la DIPCN sur l'initiative du Conseil Général des Ponts-et- Chaussées, avec les concours financiers de l'administration centrale du Ministère de l Equipement, du ministère de l Ecologie et de la municipalité niçoise. Les objectifs en étaient à la fois scientifiques et opérationnels, via la définition de "scénarios sismiques", essayant d'anticiper des crises sismiques sur Nice, par une estimation des dommages que pourraient causer aux principaux enjeux de la ville des séismes "plausibles", et la mise au point et/ou la transposition de méthodologies nouvelles, tant pour l'estimation de l'aléa local (effets de site) que pour l'analyse de la vulnérabilité du parc immobilier existant. 9 Seront présentés successivement les différents volets de cette étude très pluridisciplinaire, avec, à chaque fois les méthodes utilisées et les résultats particuliers obtenus sur le cas de Nice: identification, analyse et quantification de l'"aléa", ou actions susceptibles d être générées par des séismes probables et qui se trouveront imposées aux ouvrages: choix des événements de scénario, évaluation des mouvements produits sur le territoire concerné en fonction de la distance et de la nature du sous-sol, évaluation des effets induits (liquéfaction, mouvements de terrain). recensement des différents "enjeux", installations humaines dont les occupants et la fonction peuvent être affectés par l'occurrence d'un séisme, et détermination de leur "vulnérabilité", c'est-à-dire de la courbe liant leur endommagement à l'ampleur de la sollicitation imposée. synthèse par croisement entre l'aléa et la vulnérabilité, permettant d'évaluer le "risque" en gardant bien à l'esprit que les résultats finaux doivent être analysés avec un certain recul avant de prendre des décisions pour un plan d'action. Effects of Local Site Conditions on Strong Ground Motion: Physical Phenomena, Estimation Techniques illustrated on two examples P-Y.Bard* Surface geology very often exhibits strong vertical and lateral heterogeneities, which can heavily affect the propagation of seismic waves in their path to the Earth s surface. In some cases, they can induce significant and drastic modifications in the surface s ground motion. The presentation will first briefly recall the state-of-knowledge concerning wave propagation phenomena in typical near-surface geological configurations (surface and subsurface topography, soft alluvial cover, etc.), and then outline the main methods that may be used for their estimation (empirical, numerical, instrumental). The practical issues will be discussed on the example of two recent studies performed for a) a moderate-size, moderate-hazard, significant-risk city (Grenoble, France), and b) a large-size, largehazard, huge-risk area (Tehran, Iran). If there is some time left, and as many

11 developing and/or moderate hazard countries are tempted to use microtremors for estimates of site effects, the main learning of the recently finished "SESAME" European project will be outlined, with emphasis on the good outcomes of the noise-based techniques, and serious warnings on the danger of their misuse. 10 Site effects in alpine valleys: The Grenoble case Pierre-Yves Bard*, Emmanuel Chaljub, Cécile Cornou, Fabrice Cotton, Philippe Guéguen, Marc Kham. Besides high seismic risk areas like Taiwan, Japan, Mexico or California, specific sudies may be useful in some other areas characterized by only moderate regional hazard, but peculiar site conditions and significant exposure. The Grenoble area belongs to this latter category, because of its location in an embanked valley filled with thick and young quaternary (post-glacial) clayey sediments, and of its rapid economic development over the past century, involving both a steady population increase and some critical industrial facilities. The presentation will first outline a variety of experimental and theoretical investigations carried out over the past decade in the Grenoble area, in order to measure, understand, and as much as possible predict, the seismic ground motion. Various site response measurements with temporary and permanent seismological networks have consistently outlined very large amplification values (around 10) over a broad frequency range (from 0.3 Hz to 5 Hz), also associated with a large increase of ground motion duration. Dense array measurements unambiguously proved both the large importance of local surface waves diffracted on valley edges, which carry an apparent cumulative energy 4 times larger than the direct body waves, and the relative stability of the diffraction scheme, whatever the incident wavefield. Various geophysical and geotechnical techniques have been used in order to investigate the mechanical and geometrical characteristics of the deep sediments, including a deep borehole across the whole sedimentary column, which allowed a careful calibration of all the surface exploration techniques (gravimetry, active and passive seismic exploration). This has allowed to constrain a 3D model and to perform numerical simulations of the low frequency response of the basin. 2D (Aki-Larner) and 3D (Finite Difference, spectral elements) modelling indicate very strong diffraction phenomena as well as global resonance patterns, leading to large amplification values and duration increase. This is due to the hardness of the bedrock (Vs > 2000 m/s) compensating the relative stiffness of the sediments (S wave velocity values varying from 250 m/s at surface to 950 m/s at 500 m depth),, the steep edge slopes, and the very irregular geometry. The next issue is to predict how, and by how much, the basin response will be modified in case of moderate (M=5.5) local earthquakes, that could strain the soil strata outside its quasi-linear domain. While fully non-linear modelling has not yet been performed, a simplified, linear-equivalent 2D modelling suggests that the corresponding effects are small at low frequencies and become significant at

12 higher frequencies; they are, however, very sensitive to the NL characteristics of the deep soil, which is still completely unknown. This site will be used for an international benchmark testing of 3D wave propagation codes, the results of which will be presented during an international symposium to be held in Grenoble on August 30-September 1st, 2006 (ESG2006). Geotechnical Conditions and Local Seismic Hazard in Tehran 11 Pierre-Yves Bard*, Ebrahim Haghshenas. Tehran, capital of Iran, the economical and political centre of the country and one of the biggest and most populated cities in the world, is under the threat of large magnitude (above 7) earthquakes located on very near faults. This high seismic hazard and risk resulted in a French-Iranian cooperation program on the tectonics of central Alborz and the seismic hazard in Tehran. Within this framework, a PhD thesis was funded focusing on the analysis of geotechnical conditions and their influences on seismic ground motion Within the Tehran urban area. In this goal a seismological survey was conducted from February to June 2002, involving the installation of 13 temporary seismological stations on geotechnically representative sites: two on the rock in northern an southeastern parts, a few on consolidated coarse grained deposits in the northern part, and the most in the southern part with fine grained deposits. The main objective was the experimental estimation of the amplification effect of the soils. In addition the ambient noise was recorded at more than 60 locations within the city. These noise data plus the data of more than 130 other sites recorded during previous microzonation projects by IIEES were processed to help in the interpolation of experimental transfer functions obtained for the 13 seismological stations. The main part of the work consists in the analysis of these data in relation with the geotechnical conditions. Various experimental techniques were used to quantify amplification and prolongation of ground motion: standard site/reference spectral ratio, receiver function, H/V spectral ratio on noise, group delay method and at last sonogram. The results reveal a large site effect affecting both the amplitude and duration of ground motion on the majority of the studied sites: in particularly, the southwestern part of the city experiences an amplification level reaching 7-8, contrasting with the moderate values (factor 2 to 3) predicted in previous studies with a 1D approach. In addition, this amplification occurs on a very broad frequency band, starting at very low frequency ( Hz). The work also includes a systematic comparison of the information deduced from ambient noise and earthquake recordings, on the basis of a comprehensive data set coming from more than 150 European sites. While the H/V technique does predict the fundamental frequency for approximately 80% of the sites, it sometimes fails, especially for low frequency, continental, stiff sites such as Tehran, where H/V curves remain flat for the majority of the sites.

13 12 The last piece of work consists in the simulation of the strong motions with the empirical Green's function technique. Four different scenarios, corresponding to the occurrence of strong earthquakes (Mw from 7.1 to 7.6) on Mosha, North-Alborz and Garmsar faults, were considered. The resulting simulations indicate large peak acceleration values and the predicted response spectra sometimes exceed the design response spectra specified in the present Iranian Building Code. From ambient noise measurements to site effect assessment: Main results from the SESAME project. Pierre-Yves Bard* and SESAME participants 1 The presentation will outline the main accomplishments and findings of the SESAME European project, dedicated to assessing the actual reliability of techniques using ambient vibration measurements for characterizing seismic site effects. Two techniques - the very simple H/V ("Nakamura's") technique, and the more advanced array technique - have been thoroughly considered under different viewpoints, in order to a) better understand their physical basis, b) assess their actual meaning in view of site effect estimation, and c) propose user guidelines and processing software to ensure a correct use. Comparing the results of noise numerical simulation with actual observations allowed to draw some conclusions on the composition of the actual noise wavefield, and on the ability of H/V and array techniques to deal with 1D, 2D or 3D structures. Comprehensive tests and checks allowed to better assess the reliability and meaning of H/V measurements, especially as a standard processing software is now proposed together with user guidelines. A lot of theoretical and software development could also be achieved in relation with the array techniques, leading to a set of practical recommendations and analysis tools. This broad set of investigations indicates basically that ambient noise measurements, when performed, processed and analyzed "with caution", can provide useful, though limited, qualitative and quantitative information on site conditions and amplification effects: they can be recommended as an inexpensive and fast tool for microzonation and/or site/specific studies. The software, guidelines and recommendations available from the project web site through the SESAME web site which represent the consensus view of a rather large community of European scientists, are intended to explicit clearly and practically the fuzzy expression "with caution". Considering that a huge amount of work based on ambient vibration recordings is carried by many other teams throughout the world, it is hoped the outcomes of this project will be a significant milestone, providing opportunities for fruitful exchanges, and allowing in the long run to reach a worldwide consensus regarding the use of microtremor measurements for site effect assessment. 1 SESAME participants: C. Acerra, G. Alguacil, A. Anastasiadis, K. Atakan, R Azzara, R. Basili, E. Bertrand, B. Bettig, F. Blarel, S. Bonnefoy-Claudet, P. Bordoni, A. Borges, M. Bøttger-Sørensen, L. Bourjot, F. Cara, A.

14 Caserta, J.-L. Chatelain, C. Cornou, F. Cotton, G. Cultrera, R. Daminelli, P. Dimitriu, F. Dunand, A.-M. Duval, D. Fäh, L. Fojtikova, R. de Franco, G. di Giulio, M. Grandison, P. Guéguen, B. Guillier, E. Haghshenas, J. Havskov, D. Jongmans, F. Kind, J. Kirsch, A. Koehler, M. Koller, J. Kristek, M. Kristekova, C. Lacave, M. La Rocca, A. Marcellini, R. Maresca, B. Margaris, P. Moczo, B. Moreno, A. Morrone, J.A. Ojeda, M. Ohrnberger, I. Oprsal, M. Pagani, A. Panou, C. Paz, E. Querendez, S. Rao, J. Rey, G. Richter, J. Rippberger, P.Roquette, D. Roten, A. Rovelli, G. Saccoroti, A. Savvaidis, F. Scherbaum, E. Schisselé, E. Spühler-Lanz, A.Tento, P. Teves-Costa, N. Theodulidis, E. Tvedt, T. Utheim, J.-F. Vassiliadès, S. Vidal, G. Viegas, D. Vollmer, M. Wathelet, J. Woessner, K. Wolff, S. Zacharapoulos. 13 * Docteur ès Sciences Physiques, ancien de l Ecole Polytechnique (Paris) et de l Ecole Nationale des Ponts et Chaussées (Paris), Pierre-Yves est Ingénieur Général des Ponts-et-Chaussées, Chargé de mission Risque Sismique au LCPC/MSRGI (Laboratoire Central des Ponts-et-Chaussées, Division Mécanique des Sols, des Roches et Géologie de l'ingénieur), affecté au LGIT (Laboratoire de Géophysique Interne et Tectonophysique, UMR C5559, Observatoire de Grenoble). Il est chargé de cours dans les modules "Risque Sismique" de divers établissements: Ecole Nationale des Ponts-et-Chaussées, Ecole Centrale de Paris, Université Louis Pasteur (Strasbourg), Université Joseph Fourier (Grenoble). Il enseigne depuis 1993 aux sessions de l'international Training course on "Seismology and Seismic hazard Assessment" (GeoForschungZentrum Potsdam + UNESCO + IDNDR) - (Potsdam, Roorkee, Managua, Nairobi, Beijing, Concepcion/ Antofagasta, Pretoria). Il est également coordinateur du projet européen SESAME ( Vice-Président de l Association Française de Génie Parasismique : (depuis septembre 2004), responsable de la cellule "aléa sismique" du groupe de travail "Nouveau Zonage sismique" du GEPP/CGPC, membre du Bureau Editorial de différents journaux scientifiques: "Soil Dynamics and Earthquake Engineering", "Journal of Seismology and Earthquake Engineering", "Bulletin of Earthquake Engineering", membre du Comité d Evaluation du GNDT (Groupe National de Défense contre les Tremblements de Terre) mis en place par la Protection Civile Italienne ( ) et membre de la "CSS1" (Sciences physiques et chimiques de l environnement planétaire) de l'ird (Institut de Recherche pour le Développement). [email protected] Laboratoire Central des Ponts-et-Chaussées et Laboratoire de Géophysique Interne et Tectonophysique Observatoire de Grenoble, BP 53 X, Grenoble Cedex, France Seismic Microzonation for Urban Planning and Vulnerability Assessment. A.Ansal 1 *, K.Özaydın 2, M.Erdik 1, M.Yıldırım 2, H.Kılıç 2, S.Adatepe, 2, P.T.Özener 2, M.Tonaroglu 2, K.Sesetyan 1, M.Demircioglu 1 1 Bogazici University, Kandilli Observatory and Earthquake Research Institute, Istanbul, Turkey 2 Yıldız Technical University, Civil Engineering Faculty, Istanbul, Turkey ^ ^,, ^ A microzonation study has been conducted as a part of the Zeytinburnu Pilot Project within the scope of the Earthquake Master Plan for Istanbul [1]. The basic purpose was to produce input for urban planning and to supply site specific ground motion data to be used for the vulnerability assessment of the building stock. Very detailed geological and geotechnical studies were conducted to evaluate the variation of site characteristics within the town of Zeytinburnu. The pilot area was divided into cells by a grid system of 250 x 250 meters. This approach is adopted for estimating the effects of site conditions by assigning partly hypothetical boreholes at the centre of each cell. Representative soil profiles were classified according to

15 14 the Turkish Earthquake Code and NEHRP site classification, equivalent (average for the top 30m) shear wave velocities were calculated, and site response analyses were conducted for each cell. The final stage of the study involved interpretation and assessment of all the available data to finalise the microzonation maps in the selected area. The results obtained were mapped using GIS techniques by applying linear interpolation among the grid points, thus enabling a smooth transition of the selected parameters. Soft transition boundaries are preferred to show the variation of the mapped parameters. Better defined clear boundaries were not used to allow some flexibility to the city planners and to avoid misinterpretation by the end users that may consider the clear boundaries as accurate estimations of the different zones. The approach adopted in the assessment of the calculated zonation maps involves the division of the area into three zones as (A, B, and C) without presenting the numerical values for any parameter. The variations of the calculated parameters were considered separately and their frequency distributions were calculated. Thus, the zone A shows the most unsuitable 33 percentile, zone B the medium 34 percentile and zone C shows the most favourable 33 percentile. The basic intention of the site response analysis is to estimate the effect of local site conditions in assessing the site amplification with respect to ground shaking. It would be logical to base this decision on all the available results obtained from site identification based on equivalent shear wave velocity and site response analysis conducted in the region. In the case of site response analysis, a suitable parameter is considered to be the average spectral acceleration between 0.1 and 1.0 second periods. Thus, the variation of the average spectral accelerations was mapped in terms of three zones (A, B and C). The microzonation map with respect to ground shaking was based on average spectral accelerations and spectral amplifications obtained from equivalent shear wave velocities. The final stage involved the evaluation of ground motion characteristics to be used for the vulnerability assessment of the building stock. The acceleration response spectra calculated by site response analyzes for each cell were evaluated utilizing two best fitting algorithms to determine the parameters for the NEHRP design spectra. Effect of Ground Motion Scaling in Site Response Analyses Eser Durukal, Atilla Ansal* and Gökçe Tönük The aim of this study is to gain insight into the significance of ground motion scaling in site response analysis. Using 1D site response models at two sites with pre-determined levels of earthquake hazard, the resulting response variability is investigated for the selected series of ground motion records compatible with the site-specific earthquake hazard scaled to different intensity measures such as peak ground acceleration, peak ground velocity and Arias intensity. The uncertainty introduced by scaling and the effectiveness of different scaling methods are evaluated. This preliminary investigation is considered as a step towards understanding how ground motion scaling will affect the non-linear dynamic response of geotechnical structures.

16 Liquefaction Susceptibility and Microzonation A. Ansal* and G.Tönük Bogaziçi University, Kandilli Observatory and Earthquake Research Institute, Istanbul ^ Liquefaction of soil layers has been a major cause of damage to soil structures, lifeline facilities and building foundations in the past earthquakes and poses a significant hazard in future earthquakes. Significant efforts have been made to evaluate the mechanics of the soil behaviour during cyclic excitations and to determine the factors affecting liquefaction susceptibility based on laboratory and field tests. Laboratory studies conducted on silty and clayey sands indicate the importance of plasticity of the fines content. Various procedures developed to evaluate liquefaction susceptibility of soil layers were applied to analyze the liquefaction susceptibility in the field for implementing engineering remediation measures. One approach that has gained wide acceptance within the framework of urban planning is to establish microzonation maps with respect to liquefaction susceptibility to mitigate possible earthquake damage related to liquefaction. 15 Educational and Professional History Bogazici University, Kandilli Observatory and Earthquake Res. Ins. Professor of Earthquake Engineering August Tokyo University, Civil Engineering Dep., Tokyo Japan JICA Visitor, Nov.1994-Feb National Civil Engineering Laboratories, Lisbon, Portugal Visiting Prof., Jan.-March 1990 Istanbul Technical University, Faculty of Civil Engineering Professor of Geotechnical Engineering October 1988-August 2002 Norwegian Geotechnical Institute, Oslo, Norway Post Doc. Res., Aug 1982-Aug.1983 Istanbul Technical University, Faculty of Civil Engineering Associate Prof. of Geotechnical Engineering March 1982-Oct Northwestern University, Evanston, Illinois, USA Civil Engineering Department Ph.D. in Geotechnical Engineering Istanbul Technical University, Istanbul, Turkey Civil Engineering Faculty M.S. in Geotechnical Engineering Major Scientific, Research and Academic Activities: -Partner in EU Framework 6 Project titled Risk Mitigation for Earthquakes and Landslides, LESSLOSS, Editor in Chief for Book Series on Geotechnical, Geological and Earthquake Engineering, Kluwer Ac. Pub., Editor of International Journal Bulletin of Earthquake Engineering, Kluwer Academic Publishers, Secretary-General of European Association for Earthquake Engineering, Member of ISSMFE Technical Committee TC4 on Earthquake Geotechnical Engineering, 1985-

17 Seismic hazard assessment: scenario-based deterministic approach at national and urban scale Giuliano F. Panza* 16 Dipartimento di Scienze della Terra - Università di Trieste and The Abdus Salam International Centre for Theoretical Physics Miramar, Trieste A proper evaluation of the seismic hazard, and of the seismic ground motion due to any earthquake, can be accomplished by following a scenario-based deterministic approach in view of the limited seismological data, with a complementary check based on both probabilistic and empirical procedures. The definition of realistic seismic input can be obtained from the computation of a wide set of time histories and spectral information, corresponding to possible seismotectonic scenarios for different source and structural models. The realistic modelling of the ground motion is a very important base of knowledge for the preparation of ground shaking scenarios that represent a valid and economic tool for the seismic microzonation. This knowledge can be very fruitfully used by civil engineers in the design of new earthquake-resistant constructions and in the reinforcement of the existing built environment, and, therefore, supply a particularly powerful tool for the prevention aspects of Civil Defense. Where the numerical modelling is successfully compared with records, the synthetic seismograms permit the microzoning, based upon a set of possible scenario earthquakes. Where no recordings are available the synthetic signals can be used to estimate the ground motion without having to wait for a strong earthquake to occur (pre-disaster microzonation). In both cases the use of modelling is necessary since the so-called local site effects can be strongly dependent upon the properties of the seismic source and can be properly defined only by means of envelopes. In fact, several techniques that have been proposed to empirically estimate the site effects using observations convolved with theoretically computed signals corresponding to simplified models, supply reliable information about the site response to non-interfering seismic phases, but they are not adequate in most of the real cases, when the seismic sequel is formed by several interfering waves. This is seen also in macroseismic data. The skill of seismology to estimate realistic ground motions at a particular site should be fully exploited by seismic engineers. In fact, even if recently strong motion records in near-fault, soft soil, or basin conditions have been obtained, their number is still very limited to be statistically significant for seismic engineering applications. The quantification of the critical ground motion expected at a particular site requires the identification of the parameters that characterize the severity and the damage potential. Such critical ground motion can be identified in terms of energy and displacement demands the latter particularly relevant for seismic isolation, which should be evaluated by considering the seismological, geological, and topographic factors affecting them.

18 The deterministic seismic hazard maps, constructed before the occurrence of two strong events in Europe (Assisi 1997; Bovec 1998), show the good predictive capabilities of the modelling approach used. They turn out to be in very good agreement with the Vrancea seismic records and, contrary to the results of probabilistic analyses, point out that the seismic hazard in Romania and NE Bulgaria is mainly due to the large Vrancea intermediate-depth earthquakes. Similar deterministic hazard maps have been compiled for India, China, Ethiopia, Cuba and many Mediterranean Countries. 17 To avoid possible severe underestimation of hazard, it is advisable to replace routinely the methods based on the convolution concept with the realistic estimation of the site effects, that can be done via waveform modelling. Such an approach differs significantly from the today s engineering design practice that relays upon rock - site hazard maps and applies the site correction at a later stage, by convolution. The approach illustrated in this study may be efficiently used to estimate the ground motion for the purposes of microzonation, urban planning, retrofitting or insurance of the built environment, etc. It makes it possible to obtain the definition of the seismic input at low cost and exploiting large quantities of existing data (e.g. geotechnical, geological, seismological). Research lines of the Seismology group at the Department of Earth Sciences University of Trieste The research activity of the Seismology group at the Department of Earth Sciences of the University of Trieste covers a wide variety of topics in seismology and earthquake engineering, spanning from earthquake prediction to seismic hazard assessment, from structural to seismic source studies, especially by means of the high-frequency modal summation method for the computation synthetic seismograms. The research is performed in the framework of numerous national and international projects. The Seismology group acts also at the Abdus Salam International Centre for Theoretical Physics (SAND Group), with the aim to develop a new theoretical and computational base for the understanding, modeling and prediction of seismicity and seismic risk, through the application of non-linear dynamics and accurate 3-D modeling of earth structure and earthquake sources. Seismic hazard and broad-band ground motion evaluation using deterministic and deterministicprobabilistic methods; site effects and microzonation studies in urban areas. Kinematic and dynamic modelling of extended seismic sources. Studies on the resolving power of data and the inversion problem and refining of the lithosphere-astenosphere model in the Europe area using tomography. Uncertainties in the Maghreb countries Algeria, Morocco, Tunisia earthquake catalogue and their influence on seismic hazard assessment. Djillali Benouar* The main purpose of this work is to establish a uniform catalogue of all earthquakes reported in the Maghreb region, which satisfies the conditions of homogeneity, and to derive from this basic data set the general laws governing the space and time distribution of earthquake occurrences in the seismic source zones, and to evaluate the seismic hazard, using past records. This research work shows

19 18 example of seismic hazard mapping in the region under study as well as for the site of Algiers. For the Maghreb region, earthquake hazard constitutes a constant threat to human life and property, sometimes causing major economic losses and disruption. The rapid urbanisation, development of critical engineering works such as dams, nuclear power plants, and industrialisation of cities with modern types of buildings and the concentration of populations living or settling in hazardous areas are matters of growing concern, as they contribute to heavier loss of life and increase considerably the cost of disaster damage. The environment concerns and an increased official and public awareness of earthquake hazards have, in the last decade, led to a rapid rise of interest in seismicity and, seismic hazard and risk evaluations in the Maghreb countries. In order to assess the seismic hazard with a certain degree of reliability, an earthquake data of the region under survey which are as complete, homogeneous and accurate as possible are needed. For this purpose, and from the point of view of long term prediction and seismic hazard assessment, it is imperative that input data in the catalogues of the Maghreb countries be revised and homogenised using original past records. This remains a fundamental mean for an effective and reliable basis for seismic hazard analysis and thus risk assessment and naturally disaster management. It illustrates the uncertainties in the earthquake catalogue and their influence on the seismic hazard assessment and thus on the seismic risk. It discusses also the relationships between the earthquake catalogue and the seismic design loads and their effects on the behaviour of the structures during an earthquake. * Djillali Benouar is Professor in Earthquake Engineering (University of Science & Technology Houari Boumediene (USTHB) and Director of the Built Environment Res. Lab. (USTHB), BP 32 EL-ALIA, Bab Ezzouar, Alger, Algeria. Djillali maintains an active academic career. He started his career as a civil engineer (University of Algiers, Algeria); after graduate studies in USA (M. Sc. In Earthquake Engineering, Stanford University) and post graduate studies in U.K (Ph.D. degree in Engineering Seismology, Imperial College), he was a Post-Doctoral Fellow at the Institute of Industrial Science (University of Tokyo, Japan) He is Associate Member of the Third World Academy of Science (TWAS), Senior Associate to the International Centre for Theoretical Physics (ICTP) and consultant at the World Bank, UNESCO, IIED, UN/ISDR. He received the UNESCO-GADR-AWARD-2005 for Disaster Risk Reduction. Seismic Evaluation and INNOVATIVE Retrofit of a Historical Building in Tunisia S. El-Borgi 1 *, H. Smaoui 1, F. Casciati 2, K. Jerbi 1 and F. Kanoun 1 1. Applied Mechanics and Systems Research Laboratory, Tunisia Polytechnic School, B.P. 743, La Marsa 2078, Tunisia. 2. Department of Structural Mechanics, University of Pavia, via Ferrata 1, Pavia, Italy. This paper summarizes work conducted within the framework of a European Commission funded project on the use of appropriate modern seismic protective systems in the conservation of Mediterranean historical buildings in earthquakeprone areas. The case study is the one and a half century old Palace of Ksar Said, located near the Capital of Tunisia. At the center of the palace, a collection of

20 portraits and furniture are preserved in a room of great architectural and historical value which is the most precious part of the building to be protected. Ambient vibration tests were conducted to measure the acceleration at selected locations of the building. Output-only modal identification techniques were applied to extract the modal signature of the structure. A finite element model of the palace was elaborated based on the measured characteristics of stone and mortar and updated according to its measured vibratory response. Seismic vulnerability assessment of the building was carried out via three-dimensional time-history dynamic analyses of the structure. Results indicate a high vulnerability that confirms the need for intervention. A retrofit scheme is proposed that consists of a steel framing attached to the portraits room structure directly with added fluid viscous dampers. Vulnerability assessment of the retrofitted building reveals a substantial improvement especially in the vicinity of the portraits room. 19 * After graduate and post graduate studies in the USA leading to a Master of Science in Civil Engineering (Structural Engineering, Northwestern University, Evanston, Illinois) and to a Ph.D. in Civil Engineering (Structural Engineering and Applied Mechanics, Cornell University, Ithaca, New York), Sami El Borgi returned back to Tunisia and held academic positions with Tunisia Polytechnic School, La Marsa. Sami El Borgi is now full professor, chairman of the Mechanics Department, coordinator of the Computational Mechanics Master s Program and Applied Mechanics Doctoral Program. The Master s Program is developed in collaboration with the Department of Engineering Science and Mechanics of Virginia Tech and with funding from the U.S. State Department. His research interests are Fracture and Contact Mechanics of Functionally Graded Materials; Seismic protection of civil engineering structures using modern control techniques; Structural Health Evaluation through Ambient Vibration Testing, Output-only Modal Identification and Finite Element Updating; Confinement of vibration in flexible structures; Dynamic Modeling and Control of Micro-Electromechanical Systems (MEMS). [email protected] Synthetic Seismograms for deterministic seismic zoning and microzoning: Input data preparation and modelling. F. Vaccaria*, F. Romanelli a, G.F. Panza a,b a Department of Earth Sciences, University of Trieste, Trieste. Italy b The Abdus Salam ICTP, SAND Group, Miramare, Trieste. Italy Deterministic procedures for seismic zoning, based on the computation of synthetic seismograms, have been developed at the Dept. of Earth Sciences of the University of Trieste. In its probabilistic interpretation the scenario-based approach is in full compliance with the likelihood principle therefore meeting the requirements of modern risk analysis. Input data required are those describing the seismic sources that generate the wave motion, and the structural models travelled by the seismic waves. For regional studies, the level of knowledge does not allow for extremely detailed investigations. The studied territory is divided into an appropriate number of polygons, associated with average structural models made of flat, parallel layers. Each layer is described by its thickness, density, P and S wave velocities and Q, the

21 20 quality factor describing the anelasticity. The seismicity of the region is analyzed, and a set of seismic sources is distributed within the seismogenic zones. Scaled point sources are used to generate synthetic seismograms on a grid of sites covering the whole territory, and ground motion parameters, significant from the engineering point of view, are extracted from the seismograms and mapped. Typical problems encountered in data collection are: (1) incomplete earthquake catalogues, (2) limited knowledge of structural models and (3) spatially inhomogeneous distribution of knowledge. With such uncertainties, it is not meaningful to extend the computations to very high frequencies, so a cutoff frequency of 1 Hz is imposed in the generation of the synthetic seismograms, computed by the modal summation technique. Nevertheless, to overcome the lack of knowledge, with this deterministic approach it is easy enough to make parametric analyses in order to check the robustness of the computed hazard scenario, adopting different sets of input data and comparing the obtained results. For microzonation studies, a hybrid approach has been developed, that combines the modal summation technique, valid for laterally homogeneous anelastic media, with finite difference, and optimizes the advantages of both methods. Synthetic seismograms are generated with a cutoff frequency in the range 5-10 Hz along 2D profiles, considering topography and complicated subsoil geometries. Wave propagation is treated by means of the modal summation technique from the source to the vicinity of the local, heterogeneous anelastic structure that we may want to model in detail. A laterally homogeneous anelastic structural model is adopted, which represents the average crustal properties of the region. The generated wavefield is then introduced in the grid that defines the heterogeneous area and it is propagated according to the finite-differences scheme. With this approach, source, path, and site effects are all taken into account, and it is therefore possible to carry out a detailed study of the wavefield that propagates at large distances from the epicenter. As already mentioned for the regional studies, the methodology allows for the easy preparation of different scenarios, extremely important for the prediction of the ground motion amplification that can be expected during future earthquakes. The analysis of relative motion along a profile can also be done: it allows the study of the behavior of elongated structures (lifelines, bridges etc) during an earthquake. It has been demonstrated that the relative motion of adjacent bridge piers can be comparable with the input motion amplitude when displacement, velocity and acceleration are considered. A user friendly application has been developed that allows the quick preparation of the 2D profile, once its properties have been defined. Franco Vaccari is a contract researcher at the University of Trieste, Dip. di Scienze della Terra. He received his Ph.D. in Solid Earth Geophysics and Geodynamics at the Institute of Geodesy and Geophysics of the University of Trieste, with a thesis on the interpretation of accelerometric data in laterally heterogeneous media. His main research topics are: Seismic sources. Modelling of source rupturing process deduced from the analyses of strong motion data. Computation of synthetic seismograms in 2D media with the modal summation approach. Computation of synthetic isoseismals and their comparison with the macroseismic field. Seismic hazard assessment and seismic zoning.

22 Pattern recognition methodologies for the space-time identification of strong earthquakes: the case of Italy. A. Peresan* a,b, L. Romashkov ac, G. Panza a,b, V. Kossobokov c,d, A. Gorshkov c a b c d Department of Earth Sciences, University of Trieste, Trieste. Italy The Abdus Salam ICTP, SAND Group, Miramare, Trieste. Italy International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of Sciences, Moscow, Russian Federation Institut de Physique du Globe de Paris, Paris, France 21 The process of preparation of a large earthquake usually involves a system of faults rather than a single fault; hence the seismic precursors have to be searched within regions of several hundred kilometres in linear dimensions. Even if, based on the observed precursors, we know that an earthquake is in preparation, it is not clear where and when it will occur inside the considered region. As the time approaches a catastrophic event, the precursory activation of smaller earthquakes tends to cluster around the impending source zone of a big one. At present, the most developed approach appears to be represented by the intermediate-term middlerange earthquake predictions (i.e. with a characteristic alarm-time from a few months to a few years and a space uncertainty of hundreds of kilometres), based on certain variations of the background seismic activity preceding large earthquakes. The algorithms M8 and CN belong to a family of formally defined procedures for intermediate-term middle-range earthquake prediction. They are structured according to a pattern recognition scheme to allow for a diagnosis of the periods of time (TIP: Time of Increased Probability for the occurrence of a strong earthquake), when a strong event is likely to occur inside a given region of investigation. Further algorithms (e.g., the MSc algorithm) have been developed that permit to reduce significantly the spatial uncertainty of predictions (although at the cost of additional failures to predict), making use of additional information carried by the lower magnitude seismic activity. Their applicability, however, is limited by the difficulty to keep a high level of detection, especially in areas of moderate seismic activity. A further reduction of space uncertainty is feasible through the combined use of seismological, geological and morphostructural information. In fact, the patternrecognition can be used as well as other techniques to identify the sites capable to generate the strong events inside the alerted areas, independently from any transient seismic information. The pattern recognition technique for the identification of earthquake prone areas is based on the assumption that nearly all strong events nucleate in correspondence with specific structures, the nodes. Nodes are formally determined by the Morphostructural Zonation (MSZ) method, using tectonic, geological and and geomorphological data, with special care to present day topography. The pattern recognition of earthquake-prone areas, in common sense, does not belong to the family of earthquake prediction algorithms since it does not provide any information about the time of occurrence of the

23 22 expected earthquakes. Nevertheless, it can be considered as the term-less zeroapproximation, which restrains the alerted areas (e.g. defined by CN or M8) to the more precise location of large events. An example of the multi-scale approach to earthquake predictions, where time and space are reduced in consecutive steps, is provided considering the application of the above mentioned methodologies to the Italian territory. Italy represents the only region of moderate seismic activity where the two different prediction algorithms CN and M8 are applied simultaneously for the routine monitoring of seismicity. Several experiments have been dedicated to assess the robustness of the methodology against the unavoidable uncertainties in the data and significant efforts have been made to minimize the intrinsic space uncertainty of predictions and the subjectivity of the definition of the areas where precursors should be identified. With these results acquired, an experiment has been launched in July 2003, aimed at a real-time test of M8 and CN prediction for earthquakes with magnitude larger than 5.4 in the Italian region. The results of the intermediateterm middle-range predictions in Italy are regularly updated every two months and are made accessible to a number of scientists (a complete archive of predictions is available on-line), hence allowing for a real-time testing of the predictive capability of the applied algorithms. The time information given by the intermediate-term middle-range earthquake prediction can be very useful for preparedness and rescue actions. Moreover, the space and time constraints provided by the different pattern recognition methodologies can be usefully integrated with the procedures for the deterministic assessment of seismic hazard, thus blending together the information from a wide seismological, geological and geomorphological dataset, into time-dependent realistic scenarios of ground motion at different scale. * Antonella Peresan, PostDoc at the Department of Earth Sciences University of Trieste. She received her PhD in geophysics, in 2000, and her laurea in physics, in 1996, from the University of Trieste. She is active member of the ICTP, SAND Group since Her research interests mainly concern the physics of earthquake prediction, involving the analysis of seismicity patterns in tectonic and volcanic areas, as well as in synthetic catalogues. Her research activities range from the application and testing of intermediateterm earthquake prediction algorithms, to their integration with the procedures for deterministic hazard assessment and to the numerical block structure simulation of the lithosphere dynamics.

24 Overview of seismic hazard and vulnerability studies for Tunis City. N. Bouden-Romdhane* 1 Co-authors: M.Aîdi 1, A.Ksentini 1, S.Dridi 1, A.Sassi 1, S.Anibi 1, M.Haffoudhi 1, A.Romdhane 1&2, F.Rejiba 2, P.Mechler 2, A.M.Duval 3, S.Vidal 3, M.Kham 4, J.F.Semblat 4, A.Khalfet 5, S.Ben Abdallah 6, N.Attafi : Ecole Nationale d Ingénieurs de Tunis, 2 : Département de Géophysique Appliquée, Paris 6, 3 : CETE Méditerranéen, Nice, 4 : Laboratoire Central des Ponts et Chaussées, Paris, 5 : Département de Géologie, Faculté des Sciences de Tunis, 6 : Institut National de Météorologie. The city of Tunis is located in a convergence zone of active faults and is classified among the most exposed areas to the seismic risk according to the Tunisian seismic code. Due to the socio-economic importance of the city, national research groups from ENIT (Ecole Nationale d Ingénieurs de Tunis), EPT (Ecole Polytechnique de Tunisie) initiated comprehensive seismic hazard and vulnerability studies in collaboration with INM (Institut National de la Météorologie), the department of applied geophysics of the UPMC (Paris 6), the CETE Méditerranéen (Nice) and the L.C.P.C (Paris). The work undertaken covers the main process of earthquake engineering and seismic micro zonation with special emphasis on site effects, liquefaction potential and vulnerability assessment of the downtown area. The seismic site response assessment was conducted by means of both experimental surveys and 1D&2D numerical modelling (specially the basin and topographic effects). The ongoing vulnerability assessing includes the classification of the pilot built area and the corresponding damage quantification. EMS98 and GNDT intensitybased procedures have been performed as well as the nonlinear static procedure also called pushover analysis. All data, collected and produced, are implemented in a GIS environment. This lecture presents a coverage of the main results and immediate perspectives. * Najla Bouden Romdhane is associate professor at ENIT and Ecole Polytechnique de Tunisie, co-director of the research group Ingénierie Géotechnique and Training & External Affairs Director of ENIT. She started her career as Civil Engineer (ESTP, Paris); she received her Ph.D. in Mining Engineering (Ecole des Mines de Paris) and her Thèse d Etat in Civil (Earthquake) Engineering (ENIT). She is involved in French and European projects and was visiting research professor at the Department of Applied Geophysics, Université Paris 6 (July-August 1999, April 2000, October 2001, September 2002). She is member of the European Society of Earthquake Engineering, member of the North African Seismological Group, board member of the MESF group (Middle East Seismological Forum, Vice Chairmen of the Academic Advisory Committee of NACETE (the North African Centre for Engineering Education, a satellite centre of the UICEE, UNESCO International Centre for Engineering Education) and General Secretary of ASENIT (Association Scientifique de l Ecole Nationale d Ingénieurs de Tunis). She received the National Education Merit Medal in November [email protected]

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