IC/2002/119

United Nations Educational Scientific and Cultural Organization and

International Atomic Energy Agency

THE ABDUS SALAM INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS

EARTH SCIENCES CONTRIBUTION TO THE SAFE

DEVELOPMENT OF GROUND TRANSPORTATION SYSTEMS IN CENTRAL EUROPE

Geodynamics of Central Europe and Transportation

G.F. Panza Department of Earth Sciences, University of Trieste, Via E. Weiss 4, 34127 Trieste, Italy

and The Abdus Salam International Centre of Theoretical Physics, SAND Group, Trieste, Italy

and

M. Kouteva

Department of Earth Sciences, University of Trieste, Via E. Weiss 4, 34127 Trieste, Italy and

CLSMEE , Bulgarian Academy of Sciences, 3 Acad. G. Bonchev str. 1113 Sofia, Bulgaria.

More effective prevention strategies would save not only tens of billions of dollars, but save tens of thousands of lives. Funds currently spent on intervention and relief could be devoted to enhancing equitable and sustainable development instead, which would further reduce the risk for war and disaster. Building a culture of prevention is not easy. While the costs of prevention have to be paid in the present, its benefits lie in a distant future. Moreover, the benefits are not tangible; they are the disasters that did NOT happen.

Kofi Annan, 1999 (Document A/54/1)

MIRAMARE – TRIESTE

August 2002

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1. Introduction Our society--our way of life--depends on a complex network of infrastructure systems. These systems are lifelines that provide transportation and communication services, a supply of energy and fresh water, and the disposal of wastewater and waste products. Among the oldest of these lifelines are our transportation systems--highways, railroads, mass transit, ports, waterways, and airports. The recent political changes and running processes of globalisation in Europe motivate the priority of the sustainable development, e.g. sustainable transport and its interaction with human activities. In the European Union, total spending in the transport sector now runs, according to current estimates, at some 11 000 billion, or 10% of gross domestic product [1]. The recent results, obtained from the European transport research programme, concern enforcement of traffic rules, driver behaviour, passive safety [2], but not preparedness to meet a natural disaster (e.g. earthquakes, landslides, floods). A key policy target is to implement a new road safety action programme improving road user and road infrastructure safety. Attention has been paid to safety during road design, construction and maintenance and urban safety management schemes as well, but not to the natural hazards.

A major objective of the European transport networks is to upgrade the existing networks and to make better use of the existing capacity. Today’s European priorities are multi-modal corridors for freight, a rapid passenger network and traffic management plans for the major roads. These include a limited number of wide-scale projects strategic for the Community like the Alps and Pyrenees crossing or the rail corridor from Paris to Vienna and then to Budapest [3]. In this respect two recent major forecasts concerning the sustainable surface transport caught our attention:

(A) The White paper “European transport policy for 2010: time to decide” forecast a demand growth, by 2010, in the European Union of 38% for freight and 24% for passenger transport (base year 1998), [1]. A general trend in transportation systems is the dual mode system and non-stop guideways operation at full speed (up to 320 km/h) [4]. Thus crucial problems become the proper tracing of the guidelines and the reliable automatic control and also the possibility for warning in real time, with respect to sudden hazard, e.g. earthquake, landslides, avalanches.

(B) During the last century 929 major cities or urban agglomeration with more than 100 000 inhabitants have been counted in Europe [5]: a list of the main cities in Central Europe, containing urban agglomeration figures regarding populations and area, is shown in Table 1. Accordingly to the United Nation Population Division, the world population will undergo a major transition by about 2005 when the majority of humans will be in cities; in 1950 30% of the world’s population lived in cities and towns, and such percentage increased to 45% in 1995 [6].

Considering these forecasts and the running urbanisation processes, a major aspect of the challenge of the Sustainable Development in Europe is to bring the Preparedness to Meet Natural Disasters (PMND) to a common base. Such a task requires a large-scale research effort to encourage the deployment of procedures already under development and to help to promote innovative integrated techniques, based on large-scale common base, and able to handle the physical processes for the purpose of risk reduction and management. Thus a global geodynamic model of the Central European Initiative (CEI) Region becomes a crucial necessity.

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TABLE 1. List of the main cities in Central Europe containing urban agglomeration figures regarding populations and area [5].

Country City Year Population Latitude Longitude Austria Vienna 1991 1806737 48.12 16.37 Bulgaria Sofia 1993 1188563 42.67 23.30 Croatia Zagreb 1991 867717 45.80 15.97 Czech republic Prague 1994 1216568 50.10 14.43 Hungary Budapest 1994 1962855 47.50 19.08 Italy Rome 1991 2693383 41.88 12.50 Poland Warsaw 1993 1643203 52.25 21.00 Republic of Romania Bucharest 1994 2060551 44.45 26.17 Slovakia Bratislava 1995 451272 48.17 17.17 Slovenia Ljubljana 1994 280146 46.07 14350 The Former Yugoslav Republic of Macedonia

Skopje 1992 448229 42.00 21.47

Yugoslavia Beograd 1991 1136786 44.83 20.50 The increasing convergence of different infrastructure elements makes the society more vulnerable to natural and man-made disasters as well as poor long-term planning decisions. The short-term interplay between the natural disasters, e.g. earthquakes, concerns the bearing capacity of the environment elements. The long-term solutions are based on the results and suggestions coming from the earthquake risk assessment and management. Therefore two topics are of major importance and concern both short and long-term final results:

! Mitigating natural disasters via hazard mapping, nature phenomena modelling and “immediate” scan of the earthquake resistance of the long-period communication facilities currently used in the CEI Region performing different scenarios.

! Long-range transnational planning based on a common framework, which can be provided by the global geodynamic model of the Region.

2. The earthquake lesson Earthquakes are both an international and a societal problem that is clearly growing worse with time. Earthquakes are a difficult societal problem, because they have a low annual probability of occurrence, but a high probability of causing considerable damage as a result of ground shaking, surface fault rupture, regional tectonic deformation, liquefaction, landslides and, at coastal locations, tsunami wave run-up. Since 1900 eight strong earthquakes with magnitude M > 6 have occur in Central Europe, each of which causing 1000 or more deaths [7] Table 2. According to the available historical earthquake data, 453 earthquakes with epicentral intensity I = IX - XII occur in the rectangular area limited by 38o -53o N and 5o - 30o E in the period 2100 B.C. - 1994 A.D. The epicentral map of these events, which is shown in figure 1, is based on the information provided by the Earthquake Database of the U.S. Geological survey [7]. The macroseismic intensity, considered to construct the map, which is shown in figure 1, corresponds to the Modified Mercalli Intensity scale, IMM. According to this scale IMM = IX corresponds to considerable damage in specially designed structures, etc.; IMM = X means that rails bent; IMM = XI correspond to the case when few, if any (masonry) structures remain standing; bridges are destroyed and rails bent greatly, and IMM = XII is total damage.

From the map shown in figure 1, one can see that the earthquakes are located mostly in the Southern part of Central Europe. It has been recently recognised that urban areas rather distant from earthquake sources may be prone to a seismic disaster, e.g. the earthquakes in Michoacan, Mexico 1985 (Mw = 8.0), Chilly 1997 (Mw = 7.1), Assisi, Italy 1998 (Mw = 5.2) were significantly felt within several hundred kilometres from their hypocenter. Typical examples of long period, i.e. far-reaching, seismic effects are the ones connected with Vrancea intermediate-

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depth earthquakes. For example, the quake of March 4, 1977 (Mw = 7.5), caused significant damage in Bulgaria and was felt up to Central Europe (at distances of about 1000 km). The USA statistics says that there are about 575,000 bridges in the United States. About 60 percent of these were constructed before 1970 with little or no consideration given to seismic resistance. Historically, bridges have been vulnerable to earthquakes, sustaining damage to substructures and foundations and, in some cases, being completely destroyed. In 1964, nearly

Figure 1. Location of earthquakes with epicentral intensity IX < IMM < XII, which occurred in the rectangular area limited by 38o-53o N and 5o - 30o E, in the time period 2100 B.C. - 1994 A.D. The map is constructed using the data and tools provided by the National Earthquake Information Centre, NEIC, World Data centre for Seismology, Denver, available via Internet (www.usgs.gov/neis/epc/epc_rect.html). Catalogue Used: NOAA; Data Selection: Significant Earthquakes World Wide (NOAA).

every bridge along the partially completed Cooper River Highway in Alaska was seriously damaged or destroyed. Seven years later, the San Fernando earthquake damaged more than 60 bridges on the Golden State Freeway in California. This earthquake cost the state approximately $100 million in bridge repairs. In 1989, the Loma Prieta earthquake in California damaged more than 80 bridges and caused more than 40 deaths in bridge-related collapses alone. The cost of the earthquake to transportation was $l.8 billion, of which the damage to state-owned bridges was about $300 million [8]. We doubt that similar statistics is available for the CEI Region. In Europe there are road and pedestrian bridges of different ages, products of ancient or modern construction technologies. Only over the Danube, the longest river road in the CEI Region, there are more than 20 bridges (e.g. 4 in Bratislava (Slovakia), 5 in Budapest (Hungary), the bridge connection Russe (Bulgaria) - Girgiu (Romania), 6 in Vienna (Austria), 8 in Serbia). Illustrations of destroyed bridges due to earthquakes, which occurred in USA [8] and Taiwan [9], are shown in figure 2. A and B. An example of destroyed bridge over the Danube that is a connection of crucial importance for the CEI Region is shown in figure 2. C [The photo has been found via Internet, at www.matf.bg.ac.yu/ rat/mostovi1.html]. Even, if this damage is not a disaster consequence, it emphases the importance of the dynamic capacity of such special structures.

Figure 2.A. Nortridge, Jan 17, 1994, M = 6.7

Figure 2.B. Taiwan, Sept. 21, 1999, M = 7.6

Figure 2.C. Novi Sad, 1998

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TABLE 2. Earthquakes, which occurred in the past century and causing 1,000 or more deaths

Date UT

C Location Deaths Magnitud

e Comments

1905 Sept. 8

Italy Calabria 39.4 N 16.4 E

2 500 7.9

1908 Dec. 28

Italy Messina 38.0N 15.5E

70 000-100 000

7.5 Earthquake and Tsunami

1930 July 23

Italy 41.1N 15.4E

1 430 6.5

1940 Nov 10

Romania 45.8N 26.8E

1 000 6.0

1963 July 26

Yugoslavia Skopje 42.1N 21.4E

1 100 6.0 Shallow, just under the city

1976 May 6

Italy NE 46.4N 13.3E

1 000 6.5

1977 March 4

Romania 45.8N 26.8E

1 500 7.2 *NB

1980 Nov. 23

Italy SE 40.9N 15.3E

3 000 7.2

*NB. In Romania, in 1977, 11 320 were injured, 32 high-rise buildings in Bucharest collapsed and two towns (Guirgu and Zimnicea) on the Danube were destroyed [10]. Due to the same event in Svishtov, NE Bulgaria, a high-rise residential building collapsed, and about 160 residences in NE Bulgaria were heavily damaged. During the Vrancea earthquakes a large number of long free period elements of the built environment in Romania (Bucharest and vicinity) and NE Bulgaria suffered significant damage [11]. 3. The problem 3.1. WHY Stability of the CEI region is vital for many aspects. The stability of transportation routes (international and domestic trade) and lifelines, like oil and gas pipelines, electric power, and telecommunication networks at regional and transnational scale is crucial for its sustainable development. Highway transportation systems contain many elements--pavements, tunnels, slopes, embankments, retaining walls, etc.; however, the most vulnerable element in the highway system appears to be bridges. A high standard of PMND through Central Europe, currently crippled by the different national levels of PMND, is essential to reduce the vulnerability of the lifelines and communication systems. The experience of interrupted communications, coming from the earthquakes’ lesson worldwide or man-made collapses, has been measured in high numbers of both human victims and significant financial losses. In Central Europe large destructive earthquakes are not unexpected. A paradigm being, the 1117 earthquake caused severe structural damage all over the Po valley in Italy, figure 3. Similarly a scenario earthquake representative of the Pannonian region and neighbouring areas could affect an area as large as the one encircled by the large ellipse in figure 4. 3.2. HOW Much has been learned from the failures due to earthquakes that strike in different regions. Currently, two approaches are being taken to improve the PMND. The first approach requires considerable time, but is economically reasonable. Design guidelines are upgraded as more knowledge is gained about the response of specialised transportation structures to seismic activity. These new design guidelines can be applied to new constructions as older structures, bridges in particular that are either structurally unsound or functionally obsolete. The second approach requires to identify those existing ground transportation systems that are important to the network and are susceptible to significant damage or collapse in the event of an earthquake, and to strengthen or retrofit them, and to enhance their response to seismic activity. This second approach thus requires significant expenditure. A minor fraction of the cost is represented by a

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sound definition of a geodynamic model of the CEI region, focussed on the safe development of ground transportation systems. Basic ingredients for this endeavour are maps of geological hazards, active crust deformations and structural velocity models of the Earth Crust, combined with the procedures for intermediate-earthquake prediction [12], used as a basis for multi-fold earthquake scenarios and seismic zoning maps.

To build up a global geodynamical model of the CEI region requires multidisciplinary investigations of the structure and the dynamics of the lithosphere (in the region) based on advanced geophysical methods (seismic, gravimetric, magnetotelluric, etc.), laboratory investigations and theoretical modelling of the rupturing process in rocks. The analysis of the seismicity record combined with the application of existing, successful, intermediate-term medium-range earthquake predictions have to be used to supply credible earthquake scenarios [13]. Advanced methods, analytical and hybrid, for computing synthetic seismic signals generated by complex seismic sources in laterally heterogeneous media have been already successfully proved their efficiency [14]. Starting from the information, provided by the existing databases, broad band ground motion, which is relevant to the seismic input definition for long free-period element of the build environment (e.g. long-span transportation systems, lifelines) can be generated. Thus it will be possible to make use of both recorded and theoretically simulated seismic excitations to estimate the current earthquake resistance of the ground transportation systems, to predict their dynamic behaviour during an earthquake and thus to prescribe preventive or retrofitting measures for their safe long-term exploitation.

Figure 3. The intensity IX isoseismal for the 1117 earthquake in the Po valley [15]

Figure 4. Schematic representation of the area that could be affected by a scenario earthquake representative of Vrancea (Romania) events (large ellipse), compared with the area damaged by the 1117 event (small ellipse). The CEI member countries are represented by their boundaries and capitals.

3.2. COST BENEFIT A timely investment made by the stakeholders or insurers, dealing with the built environment, can gain first less human losses and second much less expenses for recovering, restoration, rehabilitation, etc. of the built environment. A realistic preventive hazard assessment can increase or decrease the prescribed seismic loading and thus change the construction costs. The cost benefit has to be measured also in terms of operating transportation and communication systems during and after an earthquake strike.

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4. Gained experience and open problems 4.1. VELOCITY MODELS OF THE EARTH'S CRUST AND OF THE UPPERMOST MANTLE Different regional interdisciplinary studies in Europe have been carried out with the overall objective to understand the geodynamic processes that shaped its lithosphere and the attendant patterns of distribution of geological resources and dangers. Recently, from surface waves analysis, some shear wave velocity models of the Earth lithosphere, particularly relevant for ground motion simulation, have been obtained by Pontevivo and Panza [16] in Italy and bordering areas and in the Balkan Peninsula and the adjacent areas by Raykova and Nikolova [17]. The surface wave studies of the Balkan Peninsula and adjacent areas start with Papazachos et al. [18], Papazachos [19], Rizhikova and Petkov [20]. Later, Calcagnile, Panza, et al., [21, 22, 23] studied Southern-eastern Europe and Mediterranean Europe, and Yanovskaya and Nikolova [24] and Gobarenko et al [25] have investigated southern-eastern Europe and Asia Minor. From the rather complete compilation of the existing models made by Du et al., [26] it is evident the necessity to perform further studies in several CEI countries. 4.2. DETERMINISTIC SEISMIC HAZARD IN THE MEDITERRANEAN Seismic zoning is crucial in order to obtain the quantitative information needed for the design, construction and retrofitting of the built environment. A collection of papers, most of which have been motivated by the EC-COPERNICUS project "Quantitative Seismic Zoning of the Circum Pannonian Region" (QSEZ-CIPAR), centred at the Abdus Salam International Centre for Theoretical Physics (Trieste), the NATO Linkage grants "Earthquake hazard associated to the Vrancea region seismicity", and "Microzonation of Bucharest, Russe and Varna cities in connection with Vrancea Earthquakes" has been recently published. It provides information that is necessary for harmonising Eastern and Western Europe in terms of seismic safety compliance [13]. These studies involve a high degree of innovation because state-of-the-art techniques, which have been developed in the recent years, have been used throughout to get reliable estimates of ground motion in combination with effective methods for the assessment of seismic hazard. The complex logistic problem connected with this kind of activity has greatly benefited of the organisational network established in the framework of the Earth Sciences Committee of CEI. The primary result in this volume is a quantitative seismic zoning. Maps of various seismic hazard parameters numerically modelled, and whenever possible tested against observations, such as peak ground displacement, velocity and acceleration, of practical use for the design of earthquake-safe structures, have been produced. The synoptic analysis of the seismicity pattern, of the main geologic structures and of the geodynamic models, provided the starting point for the characterisation of the seismogenic areas and the means to define the seismogenically homogeneous provinces. With the key contribution of local experts a regional seismic catalogue has been compiled, merging national catalogues, and a representative earthquake mechanism and size has been assigned to each seismogenic area. The simultaneous involvement of scientists from different countries allows a minimisation of the effects of political boundaries quite often hampering such kinds of studies.

Traditional methods for seismic zoning use either a deterministic or a probabilistic approach and base their analysis on empirically derived laws for ground motion attenuation. However, the current rapid advances in computer technology allowed for increasing refinement in the numerical simulation of seismic ground motion, which is a key element for ground motion predictions. The zoning results given are based both upon probabilistic seismic hazard assessment with state-of-the-art techniques, and deterministic seismic hazard assessment using realistic modelling of ground motion. The applied deterministic approach defines the hazard from the envelope of the values of ground motion parameters (like acceleration, velocity or displacement) determined considering scenario earthquakes consistent with seismic history and seismotectonics, and using the knowledge about litospheric physical properties. The predictive

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capabilities of the deterministic modelling [13, 14], systematically verified since 1996, indicate that future events may generate seismic load even larger than that observed so far. In the Pannonian region and neighbouring areas, the possible ground displacement can exceed 60 cm, with obvious catastrophic consequences on bridge bearings and lifelines. In figs. 5 - 8 maps of the maximum expected magnitudes, peak values of the horizontal ground motion (displacement, velocity) and design ground acceleration are shown for the European/Mediterranean countries that up to now have been involved in this major effort for mitigating seismic hazard.

The deterministic approach followed to compute ground motion, seismic hazard and for microzonation, is completely different and complementary to the probabilistic approach as in general proposed. It addresses some issues largely overlooked in the probabilistic approach:

1. the effect of crust properties on attenuation are not neglected; 2. the ground motion parameters are derived from synthetic time histories and not from

overly simplified attenuation "functions"; 3. the resulting maps are in terms of design parameters directly, and do not require the

adaptation of probabilistic maps to design ground motions; 4. such maps address the issue of the deterministic definition of ground motion in a way

which permits the generalization to locations in which there is little seismic history; 5. the synthetic data set is formed by complete time series that can be directly used for the

non-linear dynamic analysis of structures and for the estimation of the damaging potential in energetic terms [27, 28]

The results contained in [13] offer information necessary to greatly reduce the number of human casualties and the amount of property loss at the occurrence of a big earthquake in a large part of South East Europe and North Africa. Given the number of nuclear power plants located in the studied region (one in Bulgaria, one in Romania, one in Hungary, one in Slovenia), the results of the present study should be used as a starting point for successive more detailed investigations aimed at the retrofitting of the existing plants. This may be a necessary action in order to reduce the environmental hazard associated with such plants. It is a good background also for tracing some studies related to the ground transportation systems. Last but not least, the major results obtained in terms of response spectra form working hypotheses for possible integration-revision of the European seismic code EUROCODE8 (EC8) that, indeed, has suffered in the aspects of generality from the past political situation in Europe. Particularly important is the contribution to the definition of the suitable response spectra to be used with the intermediate-depth earthquakes in Vrancea (Romania). 4.3. SEISMIC MICROZONATION Another very important gained experience is the beginning of microzoning actions in large cities, with particular attention to Bucharest, Debrecen, Ljubljana, Naples, Rome, Russe, Sofia and Zagreb. The Realistic Modelling of Seismic Input for Megacities and Large Urban Areas has been a major commitment of UNESCO-IUGS-IGCP, under its project 414 and it is now focussed on the Mediterranean basin (UNESCO-IUGS-IGCP project 457). Some results regarding Bucharest (Romania), Debrecen (Hungary), Naples and Rome (Italy), Russe and Sofia (Bulgaria) and Zagreb (Croatia) are shown in figs. 9 - 15 [29].

It is well accepted that one of the most important factors influencing the space variability of the ground motion is the site response. The local amplification, or de- amplification, effects can dominate the ground shaking response whenever lateral heterogeneity, such as topographical features or soft-sedimentary basins are present in a site.

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Figure 5. Maximum observed magnitudes (smoothed) in the Mediterranean region. For more details see [14].

In presence of lateral heterogeneity, the insurgence of local surface waves and local resonance can give rise to a complicated pattern in the spatial ground shaking scenario, up to a length scale comparable with the smallest wavelength contained in the seismic wavetrain. A better understanding of the ground motion spatial variability can be obtained installing local, dense, seismic arrays at different sites. This implies the recording, with a network of instruments, of multiple seismic sources. The cost of such an operation is evident. For this reason in the UNESCO-IUGS-IGCP projects a theoretical approach based on the computation of synthetic seismograms for the estimation of the site responses has been used. The method relies upon computer codes, developed from a detailed knowledge of the seismic source process and of the propagation of seismic waves, that can simulate the ground motion associated with the given earthquake scenario.

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Figure 6. Maximum ground displacements in the Mediterranean region due to earthquake hazard.

Whenever possible the theoretical signals have been compared quite successfully with relevant observations. In such a way, synthetic signals, to be used as seismic input in a subsequent engineering analysis, e.g. for the design of earthquake-resistant structures or for the estimation of differential motion, can be produced at a very low cost/benefit ratio. The ground motion modelling technique applied in these projects proves that it is possible to investigate the local effects even at large epicentral distances, taking into account both the seismic source and the propagation path effects. The computation of realistic seismic input, taking source and propagation effects into account, utilising the huge amount of geological, geophysical and geotechnical data, already available, goes well beyond the conventional deterministic approach and gives a very powerful and economically valid scientific tool for seismic microzonation.

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Figure 7. Design ground accelerations, DGA, in the Mediterranean region due to earthquake hazard.

Because of its flexibility, the method is suitable for inclusion in new integrated procedures, a kind of compromise between probabilistic and deterministic approaches. The ability to estimate realistic seismic hazard at very low probability of exceedance may be important in protecting against rare earthquakes. The deterministic approach, based upon the assumption that several earthquakes can occur within a predefined seismic zone, represents a conservative definition of seismic hazard for pre-event localised planning for disaster mitigation. Numerical simulations of the seismic source and of the wave path are a more adequate technique than making estimates based on recorded accelerograms (empirical Green functions), since such records are always influenced by the local soil condition of the recording site. With realistic numerical simulations it is possible to obtain, at low cost and exploiting large quantities of already available data, the definition of realistic seismic input for the existing or planned built environment, including special objects.

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Figure 8. Maximum ground velocities in the Mediterranean region due to earthquake hazard.

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. A large set of strong ground motions, either recorded or theoretically simulated, is a necessary database for the civil engineering design, regarding both new seismo-resistant construction and the re-evaluation of existing built environment. In this sense it supplies also a particularly powerful tool for the prevention aspects of Civil Defence. This procedure for seismic hazard mitigation is scientifically and economically valid for the immediate (no need to wait for a strong earthquake to occur) estimate of the seismic input and seismic zonation of different scale areas, where the geotechnical data are available.

Figure 9. A. Preliminary seismic zonation map of Bucharest.

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Figure 9. B. Response spectra, SA (g), (0% damping – solid line; 5% damping – dashed line) - The zones correspond to fig. 9.A

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 01 . 02 . 03 . 04 . 05 . 0T (s)

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 01 . 02 . 03 . 04 . 05 . 0T (s)

Zone 4 Zone 5

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 01 . 02 . 03 . 04 . 05 . 0T (s)

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 01 . 02 . 03 . 04 . 05 . 0T (s)

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 01 . 02 . 03 . 04 . 05T (s)

Zone 3Zone 1 Zone 2

?

Tiber edges

Central Tiberalluvial basin

Paleotiberbasin edges

N o n e a r - s u r f a c evolcanic rocks

Near-surfacevolcanic rocks

Near-surfacevolcanic rocks

5

4

3

2

1

5 ?

ZONE

Termini

Colosseum

SaintPeter

N0 1

km

Column ofTrajan

Column ofMarcus Aurelius

Figure 10. Microzonation map of Rome (top), based on the computation of realistic seismic ground motion due to three seismogenic zones around Rome: the Fucino area, the Alban Hills and the Carseolani Mountains. For the five zones identified in the map, the maximum absolute spectral acceleration (5% damping) is given (bottom).

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Figure 11. A. Map of the seismo-stratigraphic zones of Naples.

Figure 11. B. Average (left column) and maximum (right column) response spectra for the 1980 earthquake at the 6 zones in Naples, see Fig.11.A.

Figure 12. A. A generalised tectonic scheme of Sofia region, investigated profiles (AB, CD and EF) and location and focal mechanisms of the considered earthquakes.

Figure 12. B. Profile CD: RSR versus frequency and epicentral distance.

13. A

Figure 13. A. Scheme of the soil conditions at the site of Russe according to EUROCODE 8 crossed by the investigated profile a-a.

13. B

Figure 13. B. Validation of the theoretical results considering the recorded accelerations at Russe due to the Vrancea 1986 earthquake. Response spectra amplitude for 5 % damping for East-West (E) and for the vertical (U) components for both theoretical (solid line) and observed (dashed line) signals are shown.

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part (2-D) of the model along the profile as shown in Figure 14. (Left).

AB CB

DEF

GH

1

2

3

4

1

2

3

4

14 14.5 15 15.5 16 16.5 17 17.5

1

2

3

4

Epicentral distance (km)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.0 m

205.0 m

Vp[g/cm3] [km/s]

Figure 15. A. Map of the inner part of Debrecen, with the available intensity data.

Figure 15. B. Response Spectra Ratio, RSR, (5% damping) versus frequency (Epicenter Hosszúpályi)

4.4. GROUND TRANSPORTATION SYSTEMS A successful example that describes the attention that must be paid when dealing with the transportation systems in Europe is the recently completed project “Advanced methods for assessing the seismic vulnerability of existing motorway bridges” (EC – VAB), and particularly the Task: Effects On Bridge Seismic Response Of Asynchronous Motion At The Base Of Bridge Piers [30], figure 16. An extended structure that has dimensions greater than the characteristic wavelength of the ground motion, can have different parts of its foundations out of phase due to the non-synchronous seismic input and thus the structure is not moving in a coherent way with the surrounding ground, being differential motion relevant.

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Figure 16. A. Transverse acceleration time series corresponding to final source-section configuration, calculated at the 8 sites. The amplitude of the signals is normalized with respect to the maximum one.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

30.0 30.1 30.2 30.3 30.4 30.5 30.6 30.7Distance (km)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Figure 16. B. RSR versus epicentral distance and frequency for final source-section configuration.

For very extended-in-plan or very long span structures (e.g. pipelines, multi-span bridges) the differential motions play an important role even when no strong lateral heterogeneity is present in the vicinity. The reason is that the so-called wave-passage effect (i.e. the phase shift of the seismic arrivals at the different part of the structure) is sufficient to generate incoherent motion on a scale length of the order of one hundred meters. The lateral heterogeneity can produce strong spatial variations in the ground motion even at small length scales that can be hardly accounted for by stochastic models. In absolute terms, the differential motion amplitude is comparable with the input motion amplitude when displacement, velocity and acceleration domains are considered. The preliminary studies that are required for the construction at a given site have to assure that reliable data about the geometry and mechanical properties of the medium and about the seismic sources, necessary for the computation of realistic synthetic ground motion time histories are available. Thus it is possible to perform deterministic ground motion computations. 4.5. OPEN PROBLEMS The main challenge is to bring at the same level the PMND in all the Central European countries. Several problems oriented to both earthquake risk assessment and earthquake risk management, related to the transportation systems and the sustainable development of the CE region in general, are still open: ! The upgrade and unification of the existing seismic monitoring network and of the regional

databases containing tectonic, geological, seismological, geophysical and soil data could make available a unique data bank containing presently scattered and not easily accessible and therefore poorly exploited information.

! The seismic hazard due to intermediate-depth events is not so well understood yet. For the Vrancea intermediate-depth events, on one hand side, the attenuation relations used in the probabilistic approach seems to underestimate the hazard, mainly at large distances; on the other hand side, the deterministic results are deliberately representative of the most conservative scenario.

! Different methodologies for 2D ground motion modelling have been developed worldwide, but very few studies deal with full 3D modelling, three-dimensional structural models and three-dimensional earthquake sources. The earthquake ground motion typically exhibits a degree of variability due to focusing and defocusing of the seismic waves, site resonance, basin edge induced waves, non-linear sediment amplification, etc. A fundamental question is to what degree the uncertainties in the predicted ground motion due to these effects can

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be reduced by further research. An important decision is the choice of the technique used for ground motion modelling.

! To provide standardised earthquake risk assessment and multipurpose seismic input at transnational scale requires the harmonisation of the procedures for seismic risk assessment used in the CE Region coupled with the Eurocodes implications. It is necessary to outline a strategic plan for the integration of the current knowledge made available by different scientific disciplines (seismology, geology and engineering) in order to make recommendations for mitigating the impact from earthquakes in the CE Region. Such integrated approach would provide a useful tool for decision-makers to increase earthquake preparedness and to reduce the effects of other consequent natural hazards (e.g. landslides, flooding) and hence it would permit significant reductions in casualties, damaged structures and infrastructure losses from earthquakes e.g. [31].

! A balance between both upgrading existing codes and retrofitting measures approaches is needed to strengthen the ground transportation system against a seismic attack. This balance can be accomplished by upgrading those elements that form vital links in the network and are vulnerable to damage, while at the same time impose new applicable, geographically appropriate, seismic design standards on new construction.

! Research in earthquake engineering is still needed. Research programs are expected to advance the state of the practice in PMND, and in particular the ground transportation systems. These programs will provide improved tools to assess the vulnerability of ground transportation systems and corresponding technologies to retrofit deficient systems in a cost-effective, timely, and efficient manner.

5. Conclusions Hyper-concentrations of population, as well as of infrastructures, critical facilities, production, goods and services, contribute to higher risks as natural disasters are being magnified when they strike a major city or major communication systems. To bring the lifelines and transportation systems in line with sustainability objectives is one of the main key challenges in Europe, since little attention is paid to the credible risks and to the possible disastrous consequences of the occurrence of different natural disasters (e.g. earthquakes, landslides, coseismic effects). A realistic geodynamic model is a necessary common base for the upgrading of the Preparedness to Meet Natural Disasters (earthquakes, landslides, soil liquefaction and floods) and for the assessment of the stability of the lifelines systems that cross the region. This model combined with credible hazard scenarios, and with seismic microzonation studies represent the base for the realistic definition, including the energetic aspects, of the peak perturbations that can be experienced by different transportation and lifeline systems. As any form of action in favour of protection, social and sustainable economic development, the prevention and attenuation of natural disasters should be based on research through an international strategy of management. It is well accepted today that advances in science and technology together with a clear social policy are able to mitigate considerably the negative effects of natural disasters [e.g. 14]. The quantitative evaluation of risk, by providing a rational basis for risk reduction, can be helpful in reorienting the current strategies. The focus must be shifted from the highly expensive post-disaster rescue and relief operations (prevalent in many countries) to cost effective advance actions aimed at creating knowledge based hazard resilient public assets. Preventive action is a prerequisite for saving a significant fraction of the Gross National Product of given countries in case of natural disaster. Euroscience and IUGG may play a key role in motivating the supportive action promoting projects on “Environment and Sustainable Development” (e.g. Bank Foundations call for proposals).

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Acknowledgements The authors would like to express their gratitude to all partners supporting the CEI -WGS&T and the Earth Science Committee from Austria, Bulgaria, Croatia, Czech Republic, Hungary, Italy, Poland, Republic of Romania, Slovakia, Slovenia, The Former Yugoslav Republic of Macedonia and Yugoslavia, and the Progetto Universita dell’Iniziativa Centroeuropea/INCE. References

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