Seismic Hazard, Vulnerability and Risk for Vrancea Events

International Symposium on Strong Vrancea Earthquakes and Risk Mitigation Oct. 4-6, 2007, Bucharest, Romania

SEISMIC HAZARD, VULNERABILITY AND RISK FOR VRANCEA EVENTS

Dan Lungu 1, Cristian Arion 1, Alexandru Aldea 1, Radu Vacareanu 1

ABSTRACT The paper presents the probabilistic seismic hazard analysis used for constructing the actual seismic hazard map of Romania. The new edition of the code for design of earthquake-resistant buildings and structures in Romania P100 was just issued in 2006 and follows the format and contents of Eurocode 8. Based on the available data obtained from more than 400 boreholes and using the GIS techniques, significant soil parameters were mapped for the territory of city of Bucharest and will allow seismic microzonation of Bucharest to be used as a tool for urban planning and earthquake risk reduction. The paper also explains the synergy between national programs and international projects as: JICA Project “Seismic Risk Reduction for Building and Structures in Romania” (2002-2008), World Bank Hazard Risk Mitigation and Emergency Preparedness Project in Romania (2004-2009) - Component B: Earthquake Risk Reduction, RISK-UE Project “An advanced approach to earthquake risk scenarios with application to 7 European towns” (2001-2004) and European Project PROHITECH “Earthquake Protection of Historical Buildings by Reversible Mixed Technologies” (2004 -2008).

INTRODUCTION

With about 2 millions inhabitants and 110,000 buildings Bucharest can be ranked as the megacity having the highest seismic risk in Europe due to (i) soft soil condition in Bucharest characterized by long predominant period (1.4 ÷ 1.6s) of ground vibration during strong Vrancea earthquakes and (ii) high fragility of tall reinforced concrete buildings built in Bucharest before 1940 and even before the 1977 big Vrancea earthquake. The city is located in the alluvial Romanian Plain, between the Danube and the Carpathian Mountains. Bucharest city is built in the meadow area of two rivers, Colentina and Dambovita, that cross the region from NW to SE., Fig. 1.

VRANCEA EARTHQUAKES CATALOGUES AND BUCHAREST EARTHQUAKE RECORDS

Seismic hazard in Romania is due to the Vrancea subcustral source located at depths between 60 and 180km where the Carpathians Mountains Arch bends, Fig.2. Vrancea subcrustral source affects more than 2/3 of the territory of Romania and an important part of the territories of Republic of Moldova, Bulgaria and Ukraine. According to the 20th century seismicity, the epicentral Vrancea area is confined to a rectangle of 40 x 80 km 2, having the long axis oriented NE-SW and being centred at about 45.6 o Lat N and 26.6 o Long E (i.e. about 130 km NE from Bucharest) Fig. 2.

1 Technical University of Civil Engineering, 124 Lacul Tei Blvd., Bucharest 020396, Romania Email: [email protected], [email protected], [email protected], [email protected] 292 D. Lungu et al.

Altitude, m

Colentina River 80

75 City Centre 70 Dambovita River 65

Figure 1) Topography of Bucharest Figure 2) Vrancea seismic zone in Carpathians Mountains of Romania

Vrancea earthquakes prove a significant mobility of their epicenters: 1940 and the 1990 events epicenters were located towards NE, while the 1977 event epicenter was located towards SW (i.e. Bucharest), and in 15 seconds during the 1977 event, that epicenter moved about 65 km from NW to SE.

It is emphasized that the damage of Vrancea subcrustal earthquakes is the combined result of both magnitude and depth: evidence shows that in Bucharest, the 1977 earthquake

(moment magnitude M W ≅ 7.5 at depth h=109 km) produced much greater damage and losses than the 1940 earthquake (M W ≅ 7.7 at h = 150 km). Two catalogues of the earthquakes that occurred on the territory of Romania were compiled, more or less independently, by Radu (1974, 1980, 1995) and by Constantinescu & Marza (1980, 1995), Table 1. The Radu’s catalogue is more complete, while the majority of significant events are also included in the Constantinescu & Marza catalogue. The magnitude in Radu catalogue is the Gutenberg-Richter magnitude, M GR . The magnitude in Constantinescu & Marza catalogue is the surface magnitude, M S, later tacitly assimilated as M GR (Marza, 1995). The Constantinescu & Marza catalogue has been converted in terms of moment magnitude, M W, into infp.ro catalogue. Even the 1802 (M GR =7.5) event is generally considered the largest Vrancea earthquake ever occurred, the largest seismic losses ever experienced were during the 1977 event (M GR =7.2), Figs.3, 4 and 5.

Table 1. Catalogue of 20th century subcrustal Vrancea earthquakes ( Mw ≥ 6.3 ) Date Lat. N 0 Long. E ° Radu Marza www.infp.ro Catalogue, 1994 Catalogue, 1980 Catalogue, 1998 1) h, km I0 MGR Mw I0 Ms Mw 1903 Sept 13 45.7 26.6 >60 7 6.3 - 6.5 5.7 6.3 1904 Feb 6 45.7 26.6 75 6 5.7 - 6 6.3 6.6 1908 Oct 6 45.7 26.5 150 8 6.8 - 8 6.8 7.1 1912 May 25 45.7 27.2 80 7 6.0 - 7 6.4 6.7 1934 March 29 45.8 26.5 90 7 6.3 - 8 6.3 6.6 1940 Oct 22 45.8 26.4 122 7 / 8 6.5 - 7 6.2 6.5 1940 Nov 10 45.8 26.7 150 9 7.4 - 9 7.4 7.7 1945 Sept 7 45.9 26.5 75 7 / 8 6.5 - 7.5 6.5 6.8 1945 Dec 9 45.7 26.8 80 7 6.0 - 7 6.2 6.5 1948 May 29 45.8 26.5 130 6 / 7 5.8 - 6.5 6.0 6.3 1977 March 4 2) 45.34 26.30 109 8 / 9 7.2 7.5 9 7.2 7.4 1986 Aug 30 45.53 26.47 133 8 7.0 7.2 - - 7.1 1990 May 30 45.82 26.90 91 8 6.7 7.0 - - 6.9 1990 May 31 45.83 26.89 79 7 6.1 6.4 - - 6.4 1) Maximum seismic intensity 2) Main shock International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 293

$ 29

$32 $33

$1 $ Collapsed building $31 8 2 Land use 9 $ 17 $ 3 16 18 Street $ $ $ $ $ 4 19 Urban built zone $ 27 $ 24 $ $ Rural built zone 5 Lake, river, canal 20 21 10 $ $$ 28 Park $ 22 $ $ 6 7 Forest 25 $ 12 11 $$ 26 $ $ 23 13 $ Garden $$ Cemetery Economic zone Agricultural zone 15 $ $14 N

W E

1 0 1 2 Kilometers S ArcView GIS 3.2 - ESRI California Figure 3) Collapsed buildings during the 1977 Vrancea earthquake in central Bucharest

Figure 4) 1977 earthquake: Dunarea Figure 5) Partial collapse of Faculty of building collapse (pre-war RC structure) Chemistry on Dambovita river

The first strong ground motion recorded in Romania was the 1977 record in Eastern Bucharest, at seismic station of INCERC, National Institute for Building Research, on a Japanese SMAC - B instrument. The ground motion was digitized and analysed by Building Research Institute, Ministry of Construction , Japan, 1978. "Digitized data of strong-motion earthquake accelerograms in Romania (March 4, 1977)" by Observational Committee of Strong Motion Earthquake, Kenchiku Kenkyu Shiro No.20, January.1.4. The unusual 1977 record, characterized by a long predominant period of ground vibration , T p ≅ 1.6s, has been used for calibrating design response spectra in Romanian seismic code for the period 1977- 1992 when almost 40% in Bucharest buildings stock has been built. After the 1977 earthquake a significant ground motion database of about 40 records was collected in Bucharest during the 1986 & 1990 Vrancea earthquakes. Based on the very important conclusions from 1977, 1986 and 1990 earthquakes, the Seismic instrumentation of Bucharest has been recently extended and improved by various national and international efforts. Presently Romania has more than 100 digital K2 & ETNA, Kinemetrics instruments and only in the last 2 years Romania installed 50 digital K2 and ETNA , Kinemetrics instruments, more than half in Bucharest.

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ISC, State Inspectorate in Constructions, JICA, Japan International Cooperation Agency, Project Reduction of Seismic Risk for Buildings and Structures in Romania, SFB, German Research Foundation, Project 461 on Vrancea earthquakes. Figure 6) Seismic networks of Romania Figure 7) Seismic networks of Bucharest

BUCHAREST SEISMIC HAZARD Magnitude recurrence

From regression of recent events data, the moment magnitude and the Gutenberg-Richter magnitude can be related as:

Mw ≅ M GR + 0.3 6.0 < M GR < 7.7 (1)

th From 20 century catalogue of events having Mw > 6.3, the average number per year of Vrancea subcrustal earthquakes with magnitude equal to and greater than Mw is:

log n( ≥Mw) = 3.76 - 0.73 M w (2)

Since the source magnitude is limited by an upper bound magnitude Mw,max , the recurrence relationship can be modified (Elnashai and Lungu, 1995) as:

− .1 687 1.8( −M ) − 1− e w n()≥ M = e .8 654 .1 687 Mw (3) w − − 1− e .1 687 1.8( )3.6

were the threshold lower magnitude is Mw0 =6.3 and the maximum credible magnitude of the source has been considered: Mw,max = 8.1.

Attenuation relationships for Vrancea subcrustal source

The envelope of the peak ground acceleration recorded in Romania during the last 3 strongest Vrancea events are interpolated in Fig.8 and shows the NE directivity of the subcrustal Vrancea source.

The database of Vrancea strong ground motions contains records from 47 free-field stations in Romania distributed on networks and events. The free field accelerograms were obtained at the ground level or the basement of 1 - 2 storey buildings. The accelerograms recorded on instruments installed at the basement of mid-rise and tall buildings (3 ÷12 storeys) were not used for attenuation analysis. The database has been completed with 9 free-field accelerograms recorded in Republic of Moldova and Bulgaria. International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 295

ROMANIA. Maximum peak ground acceleration PGA, cm/s2 recorded during 1977, 1986 and 1990 VRANCEA earthquakes

N 28 29 Ukraine 26 27 W E 25 23 24 21 22 S 48 Botosani # P r Hungary 11.5 u Republic of # t Satu-Mare Moldova PGA, cm/s2 Moldova Krasnogorka 0 - 75 Iasi & # Chisinau 82.0 75 - 150 146.4 & 150 - 200 212.8 47 Dochia 200 - 300 # % Cris Oradea 50.9 Cluj-Napoca # Bacau Seismic stations with % free-field records: 132.0 Barlad Onesti # # INCERC network # Transilvania 232.1 Adjud 168.6 % INFP network # 86.6 $ GEOTEC network Banat &Cahul Vrancioaia & R. of Moldova network % 1990 136.6 Mures 157.2 #· 46 Olt #· Focsani & Bulgaria network Surduc % Timisoara $ 1940 # 97.2 297.1 March 4, 1977 Muntele Rosu #· % 1986 Ramnicu Sarat Vidra Lotru # 164.0 Mw=7.5 $ Vidraru Arges 79.1 158.6 Tulcea $ #·1977 Carcaliu # h=109 km Valenii de Munte % 93.6 14.3 26.1 186.9 # # % Campina Istrita Aug.30, 1986 61.5 # 109.4 Baia Mw=7.2 # 45 Pitesti # Ploiesti Valahia 90.8 h=133 km 45.8 Peris# Dobrogea 223.8 #Otopeni219.8 Bolintin Vale Fetesti Cernavoda May 30, 1990 # # Branesti # # 208.6# 150.8 100.4 107.1 Bucuresti Calarasi Mw=7.0 Craiova # # h=91 km # 194.9 Constanta Black Sea Mw - moment magnitude Yugoslavia 114.1 h - focus depth Giurgiu # 44 Danube Turnu Magurele & Ruse112.4 Shabla32.9 #· Epicenters of strong # 112.2 & Vrancea events Kavarna 36.2& (Mw > 6.9) Bulgaria Varna 33.6 Provadia48.2 & 100 0 100 200 Kilometers & Lungu, Aldea, 1999 ArcView GIS version 3.1, ESRI Inc. CA Figure 8) Maximum recorded peak ground acceleration during the last Vrancea strong events

The following model has been selected for the analysis of attenuation:

ln PGA = c 0 + c 1 M w + c 2 lnR +c 3R +c 4 h + ε (4)

where: PGA is peak ground acceleration at the site, Mw- moment magnitude, R - hypocentral distance to the site, h - focal depth, c0, c 1, c 2, c 3, c 4 - data dependent coefficients and ε - random variable with zero mean and standard deviation σε = σln PGA . The extrapolation of data in the range of large magnitudes ( Mw≥7.5 ) is entirely based on the peak ground acceleration recorded in Bucharest during 1977 event. The coefficients obtained from the regression are given in Table 2, [Lungu, Demetriu et al ., 1998].

Table 2. Regression coefficients for horizontal peak ground acceleration

Sector c0 c1 c2 c3 c4 σlnPGA All data 3.098 1.053 -1.000 -0.0005 -0.006 0.502 Bucharest sector 1.685 1.181 -1.000 0.002 -0.005 0.461

The Romanian attenuation law for Vrancea earthquakes (Lungu et. Al.2000) fits in the value range given by international attenuation relations (Crouse, Youngs, Drake) developed for subcrustal regions in the last decades, Fig. 9.

350 Youngs et al., 1997 300 Lungu et al., 2000 Drake, 2001 250 Crouse, 1991 2 200 , cm/s , 150 PGA 100

50 MW =7.5 h=109 km 0 0 50 100 150 200 250 Epicentral distance ∆, km

Figure 9) PGA attenuation for subcrustal seismic sources [Aldea, 2002] 296 D. Lungu et al.

Based on the results of probabilistic seismic hazard assessment for Vrancea source (Lungu et al., 1994...2000), Fig. 10 presents the new hazard map in the new code for earthquake resistance of buildings in Romania, P100-2004 . The map gives the peak ground acceleration for design, ag (EC 8 notation) having mean recurrence interval, MRI =100 yr .

MRI=475yr PGA = 0,35 g Tp=1.6 s

Figure 10) Romania. Probabilistic zonation of peak ground acceleration for design in P100- 2006 code, MRI = 100yr

Soil parameters for seismic microzonation analysis The boreholes performed in Bucharest for soil investigation and seismic microzonation studies were carried out by the UTCB - Technical University of Civil Engineering, INCERC - National Institute for Building Research, NCSRR - National Center for Seismic Risk Reduction and ISPIF. By using data obtained from other existing boreholes made by all those institutes, it was possible to clarify the surface geology of Bucharest. Several deep boreholes were realized in Bucharest related to international cooperation projects of the Technical University of Civil Engineering and Japanese International Cooperation Agency with National Center for Seismic Risk Reduction, INCERC, Karlsruhe University, Germany.

The soil investigations performed in Bucharest and its metropolitan area showed, for the Northern area of the city, mostly sandy soil profiles and, for the Eastern (INCERC seismic station), Southern and Central areas of the city, mostly clayed soil types. Based on lithological data obtained from ISPIF, Metroul SA, INCERC, UTCB and CNRRS boreholes and taking into account the soil stratification in Bucharest made by Liteanu, maps of the superficial geological complex in Bucharest were developed using GIS technologies. The thickness of the soil layers distributed in the first 60 meters of the soil profile were mapped. Figs. 11 and 12 illustrates the maps obtained for the sandy-clay superior complex, and “Mostistea” thick bank of sands. It should be observed that the greatest thickness of „Mostistea” thick banks of sands in the first 60 meters is present in the northern part of Bucharest area (EREN seismic station), while the greatest thickness of the lacustral complex in the first 60 meters is present in the eastern (INCERC seismic station), southern and central part of the city. International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 297

Figure 11) Thickness distribution of lacustral Figure12) Thickness distribution of “Mostistea” (marled) deposits in the first 60 m sand banks in the first 60 m

Soil investigation in existing boreholes In Bucharest area, the velocity propagation of shear wave in the ground was measured by the seismic reflection method at the beginning of 70’s. Starting with 1990, based on wave velocity values, predominant periods for different sites were calculated in order to correlate them with spectral composition of recorded seismic motions. Several measurements of wave velocities were performed in Bucharest area using a relatively new technique: the suspension PS logging method, Fig 13. The equipment used for the measurement of compression (P) and shear wave (S) velocities versus depth is a donation from Japan International Cooperation Agency (JICA) to NCSSR. The analysis of travel-time data coordinated with the site stratigraphy revealed the seismic velocity profiles and other related

parameters as Young’s modulus (E din ), shear modulus (G din ) and Poisson’s ratio ( νdin ). The measurement of wave velocities on various sites as INCERC, UTCB, City Hall, Victory Square sites indicates higher values of Vs at the UTCB Tei and North sites, which suggest the presence of a soil stratification characterized by short central period of response spectra. Collecting and interpreting the soil data, the shear wave velocities values in the first 30 meters of soil profiles, obtained by averaging the values, are presented in Fig.14.

Generation of P-waves Generation of S-waves Downhole sensor Figure 13) Down-hole measurements in central part of Bucharest 298 D. Lungu et al.

Figure 14) Bucharest. Microzonation map for shear wave velocity (m/s) averaged on 30m Long Predominant Period of Soil Vibration in Bucharest Versus Surface Geology Based on the analysis of frequency contents of recorded ground motions in 12 location in Bucharest during the 1977, 1986 and 1990 Vrancea earthquakes versus soil profiles at recording sites (stations) the following conclusion has been established [Lungu, 1999, Aldea et al., 2002]: The short control period TC ≤ 0.8s corresponds to the soil profiles, mainly located in the Northern part of Bucharest (EREN seismic station) and the long control period

TC ≥ 1.0s of soil vibration during the 1977 and 1986 events corresponds to soil profiles, mainly located in the Eastern (INCERC seismic station), Southern and Central parts of Bucharest. The mapping of recent borehole data using GIS technology has confirmed the conclusions of the above study. Microzonation maps for peak ground acceleration and control period of response spectra TC for 1986 earthquake are presented in Figs. 15, 16, [Lungu et al., 1999]. As it can be noticed, there is a clear difference between the Eastern, Central and Southern Bucharest and the rest of the city. In this side of Bucharest the peak ground acceleration has lower values and the control period has higher values in comparison with north and western side where peak ground acceleration reaches the highest values and the control period is lower. A similar pattern was noticed on the microzonation maps for May 30, 1990 event.

Microzonation of Ground Motion Parameters The acceleration response spectrum is of major engineering interest and seismic hazard assessment is often made in terms of spectral values. Attenuation relationships and seismic macrozonation and microzonation maps in terms of spectral values can be developed for estimating the earthquake demand for design purposes. The city of Bucharest has a specificity in terms of acceleration response spectra SA due to it’s soil condition characterized by a long control period of response spectra. This long control period appears just in case of moderate and strong Vrancea earthquakes, [Lungu et al. , 1998, 2001]. The quite large spectral values at long periods are not just a local phenomenon in some parts of the city, the microzonation of SA for 1986 event, Fig. 18, showing a practically uniform distribution of spectral values at the level of about 200cm/s 2 at T=1.5s . In comparison in Fig. 17 presents the microzonation of SA for 1986 at T=0.5s [Aldea et al., 2002, Arion, 2003]. International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 299

BUCHAREST, Aug. 30, 1986 Vrancea earthquake: peak ground acceleration PGA, cm/s2 BUCHAREST. Aug. 30, 1986 Vrancea earthquake: control period of response spectra Tc, s B BU UC C #Y U #Y UR RE 219.8 ES 0.67 ST TI I - - T T TI T I R R G Otopeni U V G Otopeni U O I O V N ILO VI N IS S T A R TE A E R

I I AI DA D O O

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FUNDENI O U R E O IR S R I S R B V C C B V C C L U ER L U ERN I NICA I ICA C D PANTE C D ISPH/ARM PANTE I ISPH/ARM LIMON I LIMON I IN UI I IN UI Militari CUL A Militari CUL A U IC IAN U IC IAN V I $Z R V I $Z R E N U E N U R CE U R CE 86.8 #Y U #Y T O 1.26 #Y #Y T O U 1.07 TR T U TR T R O R O PAC I C N PAC I 96.2 C N II 0.90 I II 100.6 I E L E L INCERC Panduri A INCERC C Panduri A C B B E CHISINAU E CHISINAU 95.3 #Y P C #Y P EC A UNIRII E 1.43 AN UNIRII N D D D D U I Colentina River OARA Drumul Sarii U TI Colentina river IMISOARA R ST TIMIS R ES T Drumul Sarii I SE R I AS RE RA ES AR SS A SU #Y M U U #Y M U C V CA V A A M A M IL A R IL ENCEA R HENCE B GH I B G I A A IH IH M I M I R I R I A

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L L O A L L T I R A I R A A S V S V E E L L E E R R U U G G A A M M - - I I T O T O S L S L T T M E E M E E A R N R N I A I R U T R U T A E A E S C I S C I T Metalurgiei T Metalurgiei I U I U C C B E B E NT #Y NT #Y UR B UR 71.7 B A E A E R 1.51 A R R RA C U C U T T E EN E N C CE N N I 135.4 I Bucuresti-Magurele Bucuresti-Magurele %[ Lungu, Aldea, 1999 %[ 1.05 Lungu, Aldea, 1999

Time: 21:28:37 GMT PGA, cm/s2 Free-field seismic stations: N Time: 21:28:37 GMT Tc, s Free-field seismic stations: N 0.4 - 0.7 #Y INCERC stations Epicenter: 45.53 Lat.N 50 - 100 #Y INCERC stations W E Epicenter: 45.53 Lat.N W E 26.47 Long.E 26.47 Long.E 100 - 150 $Z GEOTEC station 0.7 - 1.0 $Z GEOTEC station S S 1.0 - 1.3 Moment magnitude: Mw=7.2 150 - 200 %[ INFP station Moment magnitude: Mw=7.2 %[ INFP station 200 - 250 1.3 - 1.6 Focus depth: h=133 km Focus depth: h=133 km Average epicentral distance to Bucharest: d=125 km ArcView GIS version 3.1, ESRI Inc., CA. Average epicentral distance to Bucharest: d=125 km ArcView GIS version 3.1, ESRI Inc., CA. Figure 15) Bucharest - Aug.30, 1986 Figure 16) Bucharest - Aug.30, 1986 earthquake: microzonation of PGA event: microzonation TC

Figure 17) Bucharest - Aug.30, 1986 event: Figure 18) Bucharest - Aug.30, 1986 event: microzonation of SA values at T=0.5s microzonation of SA values at T=1.5s NATIONAL PROGRAMS FOR SEISMIC RISK REDUCTION The national programs for seismic risk reduction in Romania are focusing the following three objectives: (i) Strengthening of fragile buildings in Bucharest, (ii) Upgrading the code for seismic design of buildings and structures and (iii) Seismic instrumentation of Romania. Strengthening of Fragile Buildings in Bucharest The governmental action of identification of dangerous buildings in Romania started in 1994. In 2001, a new Government Ordinance stated that the Government will 100% advance the necessary funds for strengthening of the buildings to the private owners of apartments in “seismic risk class 1” buildings (more than 95% of housing units in Romania are private!). If 300 D. Lungu et al.

the owner salary is less then national average, he have to pay back (to the state) nothing. If it is not, he has to pay the money back in 25 years, with 0% interest. Anyway, the owner has to agree on the strengthening of its apartment, in case he has to leave the housing unit during the construction work. Of course, the owners do not like leaving and the necessary buildings for temporary housing during strengthening are not yet available. Moreover, if one apartment owner does not like/agree on strengthening of its apartment, the strengthening of the whole building cannot be done! Ministry of Transport, Construction and Tourism, MTCT promoted a new official act that make compulsory the strengthening of the building structure if the majority of private owners accepts the strengthening (in spite of several owners who would not like to allow strengthening of their apartments). According to the data (Aug 2005) of MTCT, 2720 vulnerable residential buildings (having 79100 housing units) have been identified in Bucharest. From these 2720, 350 residential buildings were recognized as "seismic risk class 1", i.e. as very vulnerable buildings. At the top of the list of 350 buildings there are 123 tall reinforced concrete buildings built in central Bucharest prior to World War II, 20 out of 123 buildings are located on the main central boulevards of Bucharest: Calea Victoriei & Magheru/Balcescu, Fig. 19. In addition to the pre - war buildings, more than 50 pre- 1977 buildings built during the time interval 1945 - 1977 have been included into the most dangerous "seismic risk class 1" buildings in Bucharest. They are tall flexible RC buildings with soft and weak groundfloor (for shops) located on the soft soil condition of Bucharest.

1977 earthquake in Bucharest 1977 earthquake in Bucharest

Collapse of the ground floor Faculty of Medicine of Bucharest . a. ’60 building b. ’40 building Damage of the masonry building built in 19th century

Balcescu 25 (Wilson) Balcescu 30 Magheru 20 Magheru 27

Calea Victoriei 2-4 Calea Victoriei 25 Calea Victoriei 101 A-B Calea Victoriei 124 Figure 19) Seismic vulnerability class 1 buildings in central Bucharest International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 301

Seismic risk class Matrix

Vulnerability Importance and exposure class class I II III IV i 1 1 2 3 ii 1 2 3 3 iii 3

“Seismic risk class 1 building to be immediately retrofitted! buildings”

Strengthening of 9 storey residential building in central Bucharest, 2003

Aug. 2005: March 2007:

7 buildings are fully retrofitted 10 buildings are fully retrofitted 118 buildings buildings are are under under retrofitting retrofitting 1142 buildings buildings have in retrofitting retrofitting projects design ready 14 buildingsstage or are under on the contracting waiting list thefor design retrofitting project

According to Romania Census at the end of 2004 year, the total number of housing units in Romania was 8,176,487 (4,406,508 urban – 53.9% and 3,769,979 rural – 46.1%) and the total living floor area (without corridors, stairs, kitchen, bathrooms, and others annexes) was 309.937.818m 2 i.e about 38 m 2/ housing unit.

Bucharest

Source data: UTCB & Geosystems Romania Source data: UTCB & Geosystems Romania (1996) (1996) Created in ArcGIS 8 using ArcMap Created in ArcGIS 8 using ArcMap

Housing units built before 1944 Housing units in buildings having more than 7 storey built before 1944

302 D. Lungu et al.

The 1977 earthquake total losses were 2.05 billion US$ (at that time) according to the World Bank report in 1978. About half of those losses came from damage of buildings, i.e. about 1 billion US$. The projection of 1 billion US$ (at 1977 time) to 2007 time, based on inflation rate [S. Williamson, 2006] and using various economical international indicators as Consumer Price Index - CPI, GDP per capita, GDP, lead to 3.5 ÷ 7.0 billion Euros.

Upgrading the Code for Seismic Design of Buildings and Structures Based on the results of probabilistic seismic hazard assessment for Vrancea source [Lungu et al., 1995...2002] and taking into account the contributions from the crustal seismic sources around Romania, Fig. 10 presents the hazard map for the new code for design of earthquake resistant buildings in Romania, P100-1/2006. The map give the design peak ground acceleration, ag for the MRI =100 yr seismic event. The P100-1/2006 code was developed at Technical University of Civil Engineering, Bucharest in 2004 within a contract with the Ministry of Transports, Constructions and Tourism, and it has been published in the Oficial Gazette of Romania no. 462/2005. The new P100 Code follows the format and contents of Eurocode 8. The draft of the code for earthquake resistance of existing buildings and structures should be prepared in 2007 with the consultancy of the World Bank Project "Hazard Risk Mitigation and Emergency Preparedness"-Component B.

INTERNATIONAL PROJECTS FOR SEISMIC RISK REDUCTION IN ROMANIA JICA Project Japan International Cooperation Agency (JICA) Technical Cooperation Project on Reduction of Seismic Risk for Buildings and Structures started in Romania on October 1 st , 2002. The project has been signed in 2002, when 100 years of diplomatic relations between Japan and Romania were celebrated . The scope of the Project is to strengthen the capacity of earthquake related disasters prevention activities in Romania. The duration of the Project is five years and half . The implementing agency of the Project is the National Center for Seismic Risk Reduction (NCSRR), a public institution of national interest subordinated to the Ministry of Transports, Constructions and Tourism of Romania. The activities are carried out by NCSRR in partnership with UTCB and INCERC Bucharest. During the Project period, 29 young Romanian engineers were trained in Japan, 7 Japanese long-term experts and 37 Japanese short-term experts worked in Romania. Equipments for seismic instrumentation, dynamic characterization of soil and structural testing rising up approximately to 260 million yens (i.e. 2.17 million USD) were donated by JICA to Romania, through NCSRR. The total cost of the Project is roughly 7 million USD.

NCSRR received from JICA seismic instrumentation equipments ( Kinemetrics ). OYO Seismic Instrumentation Corp . and NCSRR installed the equipments in 2003. In 2005-2006 the NCSRR network was enlarged with Romanian investment (within the budget ensured by MTCT ), other sites being instrumented with Geosig equipments and technical support. NCSRR network [Aldea et al. , 2007] contains 3 types of instrumentation: free-field stations (outside Bucharest), instrumented buildings and stations with ground surface and boreholes sensors (in Bucharest).

Six (6) Kinemetrics ETNA stations were installed in 2003 on the SW direction starting from Vrancea epicentral area toward Bucharest, for ground motion attenuation analysis. All of them are in buildings with 1 or 2 storeys, which can be considered as a free field condition. Two Geosig IA-1 accelerometers were installed in 2006 and 2007, on a perpendicular axis to the SW. Since its installation in 2003, the NCSRR network recorded more than 170 seismic motions from 26 earthquakes with moment magnitudes ranging from MW=3.2 to 6.0 . Between the earthquakes recorded by NCSRR network, 21 are from Vrancea subcrustal source, 2 from Vrancea crustal source, 2 from shallow sources in Bulgaria and 1 from North- Dobrogea shallow source. The Vrancea earthquake of October 27, 2004 ( Mw=6 ) is the largest event recorded by NCSRR seismic network. International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 303

Table 3. NCSRR Bucharest seismic stations with sensors at ground-surface and in boreholes Surface Depth of sensor Depth of No. Site Station ID sensor in shallow sensor in deep Equipment location borehole, m borehole, m 1 UTCB Tei UTC1 free field -28 -78 1 storey 2 UTCB Pache UTC2 -28 -66 building

1 storey 3 NCSRR/INCERC INC -24 -153 building K2 + 1 storey 4 Civil Protection Hdq. PRC -28 -68 FBA-23DH building (Kinemetrics) 5 Piata Victoriei VIC free field -28 -151 6 City Hall PRI free field -28 -52 7 Municipal Hospital SMU free field -30 -70 GSR24+AC23 DH 8 UTCB Plevnei UTC3 free field -30 (Geosig)

Table 4. Description of the NCSRR seismic instrumentation of buildings Location of Station Location of Structure No. Site Station & Equipment ID Sensor 1 Sensor 2 Sensor 3 Sensor 4 1 Stefan cel Mare (1) BLD1 11 th floor 12 th floor 5th floor 1st floor RC frame '80s K2 + 2 Stefan cel Mare (2) BLD2 Basement 7th floor 4th floor Free field RC frame '60s Episensor 3 National Television TVR 14 th floor 15 th half-floor basement - RC frame '60s ES-T roof rd (Kine- 4 BRD-SG Tower BRD th 3 basement - - RC dual 2003 (19 floor) metrics) roof IA-1 5 UTCB Lacul Tei UTC5 th basement - - RC frame '60s (4 floor) (Geosig)

The structural testing equipment consists of a steel reaction frame, loading control device, data acquisition and processing systems. The following load combinations are possible with the provided equipment: (i) bending with shear force for beam testing, (ii) bending with shear and axial force for column, shear wall and portal frame. The maximum weight of tested specimens is 70kN and the maximum dimensions of the specimens are 2.5m by 3 m.

Number of tested Structural element specimens since 2004 RC columns 16 RC walls 5 Masonry walls 27 Steel braces 3 Energy dissipation device 1 RC slabs 14 Total number of tests 66

Figure 20) Equipments donated by JICA : reaction frame the tests performed with the equipments WORLD BANK Project The World Bank "Hazard Risk Mitigation and Emergency Preparedness" Project for Romania (HREM Project) has several components: (i) Component A: Strengthening of Disaster Management Capacity; (ii) Component B: Earthquake Risk Reduction - 71.2 million US$ (i.e. about 1/3 of total costs of the project) and (iii) Components C, D&E: Flood, Pollution & Project Management, respectively. The Component B has the following subcomponents: Strengthening of high priority buildings and lifelines; Design & supervision; Building code review and study of code enforcement; Professional training in cost effective retrofitting. The Project management unit (PMU) for Component B is located at MTCT, Ministry of Transports, Construction and Tourism. 304 D. Lungu et al.

Figure 21) CNRRS. Tests on walls (RC shear wall, masonry wall)

World Bank report entitled “Preventable Losses: Saving Lives and Property through Hazard Risk Management” Strategic Framework for reducing the Social and Economic Impact of Earthquake, Flood and Landslide Hazards in the Europe and Central Asia Region, published in Oct, 2004 concludes: (i) Romania is regarded as one the most seismically active countries in Europe; (ii) Bucharest is one of the 10 most vulnerable cities in the world. The following recommendations from the report concerns Romania: (i) Upgrade the legal framework for hazard specific management; (ii) Review the existing buildings code for the retrofitting of vulnerable buildings; (iii) Conduct a comprehensive public awareness campaign for the earthquake risk; (iv) Invest in hazard mitigation activities in order to reduce the risks caused by earthquakes; (v) Develop financing strategy for catastrophic events. RISK-UE Project RISK-UE Project entitled "An advanced approach to earthquake risk scenarios with applications to different European towns" had a budget of ~ 2.5 million €; (UE: 66 % and participants: 34 %). With the financial assistance from the European Commission within FP5, RISK-UE Project was launched in 2001. The RISK-UE project developed a general and modular methodology for creating earthquake-risk scenarios that concentrates on the distinctive features of European towns, including both current and historical buildings. It is based on seismic-hazard assessment, a systematic inventory and typology of the elements at risk and an analysis of their relative value and vulnerability, in order to identify the weak points of urban systems. The resulting scenarios will give concrete figures of direct possible earthquake damage and would lead to action plans at city level. There were 17 project participants from: Bulgaria, France, Greece, Italy, Macedonia, Romania, and Spain. UTCB, Technical University of Civil Engineering, Bucharest has been responsible for the Workpackage 1, European distinctive features, inventory database and typology and Workpackage 7, Seismic risk scenarios. The WP 1 had 2 objectives: Objective 1 - Distinctive features of European towns focusing on: Town identity; Population characteristics; Urbanised area and elements at risk; Impact of past earthquakes on elements at risk; Strong motion data in the city and seismic hazard; Geological, geophysical and geotechnical information; Evolution of earthquake resistant design codes; Earthquake risk management efforts; and Objective 2 - Europe inventory database and typology including an classification of buildings occupancy and the building typology matrix, BTM. WP 1 also contains a comparative study of seismic characteristics for the 7 European towns (Barcelona, Bitola, Bucharest, Catania, Nice, Sofia, Thessalonik). PROHITECH Project The Project is entitled "Earthquake Protection of Historical Buildings by Reversible Mixed Technologies" and has a 2.4 million € funding (U.E.: 88 %, participants: 12 %); starting date International Symposium on Strong Vrancea Earthquakes and Risk Mitigation 305

is 2004 and ending date is 2008. The research project PROHITECH is framed within the INCO thematic areas, devoted to “Protection and conservation of cultural heritage” in the Mediterranean area. The main subject of the research is the seismic protection of historical and monumental buildings, namely dating back from the ancient age up to the mid of the 20th Century. The main objective of the project consists in developing sustainable methodologies for the use of reversible mixed technologies in the seismic protection of the existing constructions. Such buildings cover a wide and diversified range of structural categories, including both masonry and reinforced concrete buildings and also some steel constructions, needing to be fitted with adequate anti-seismic provisions. Reversible mixed technologies exploit the peculiarities of innovative materials and special devices, allowing ease of removal when necessary. Furthermore , an optimization of the global behaviour under seismic actions is achieved by the combined use of different materials and techniques. The endpoint of the research is a proposal of codification for the use of such technologies in the seismic protection of existing constructions. SFB 461 Project The research Project is entitled "Strong Earthquakes: A Challenge for Geosciences and Civil Engineering" starting date is 1996 and ending date is 2007 (4 periods of 3 years each) and involves 7 institutes of Collaborative Research Center 461, University of Karlsruhe: Geodetic Institute; Geological Institute; Geophysical Institute; Institute for Technology and Management in Construction; Institute of Photogrammetry and Remote Sensing; Institute of Reinforced-Concrete Structures and Buildings Materials; Institute of Soil and Rock Mechanics . The Romanian participants are: Romanian Group for Strong Vrancea Earthquakes (RGVE), i.e: INFP, INCERC, UTCB, Faculty of Geology and Geophysics and GEOTEC. The Project Structure for 2005-2007 has the following components: A1: Deep Seismic Sounding of the Vrancea Zone ; A6: Stress Field and Geodynamics ; A7: Strong Ground Motion Assessment; B1: Three-Dimensional Plate Kinematics in Romania ; B3: Seismogenic Potential of the Vrancea Subduction Zone-Quantification of Source and Site Effects from Strong Earthquakes; B4: Nonlinear Wave Phenomena in Fine and Soft Soils; B6: Geothechnical and Seismic Microzonation in Bucharest ; B7: Hydrogeology and Site Effects by Earthquakes in Bucharest; C3: Disaster Management- Models and Simulation; C5: Image Analysis in Geosciences and CivilEngineering; C6: Knowledge Representation for Disasters with Technical Information Systems ; C7: Novel Rescue and Restoration Technologies; C9: Vulnerability Analysis of Existing Structures ; Z1: Central Geographical Information System (GIS) ; Z2: SFB Management . The benefits for Romania from SFB 461 project came from: a new country-wide free-field instrumentation of Romania, the first 100m borehole instrumented in Bucharest, the test building with seismic rubber bearing isolators, significant bilateral mobilities for Romanian and German scientists, interdisciplinary and multidisciplinary approach in earthquake engineering and engineering seismology and joint papers in various European and national seismic conferences.

NATO Project The NATO Project is entitled "Harmonization of Seismic Hazard Risk and Reduction in Countries Influenced by Vrancea Earthquakes. A Science for Peace Project". The 250 000 € project has as starting date: 2005 and as ending date: 2008. The participants are: National Institute for Building Research INCERC Bucharest, Romania; Moldavian Academy of 306 D. Lungu et al.

Sciences, Institute for Geophysics and Geology, Kishinev, Republic of Moldova (Project coordinator); Central Laboratory for Seismic Mechanics and Earthquake Engineering, Sofia, Bulgaria and Middle East Technical University Department of Civil Engineering, Ankara, Turkey. The Project aim is the harmonization of joint hazard map for Vrancea earthquakes in terms of contour lines for peak ground acceleration, mean recurrence interval of design events, data base of events, records etc., REFERENCES Aldea A., Poiata N., Kashima T., Albota E., Demetriu S. (2007) “NCSRR digital seismic network in Romania”, Proceedings of International Symposium on Seismic Risk Reduction. The JICA Cooperation Project in Romania Bucharest, April 2007, p.143 – 156. Aldea, A., (2002). “Vrancea source seismic hazard assessment and site effects”, PhD thesis Technical University of Civil Engineering Bucharest, Bucharest, 256p. Arion, C., 2003. “Seismic Zonation of Romania considering the soil condition and seismic sources”. PhD Thesis UTCB, Bucharest, 181p. Crouse, C.B., 1991. Ground-motion attenuation equations for earthquakes on the Cascadia subduction zone, Earthquake Spectra, Vol.7, No.2, p.201-236 Constantinescu, L., Marza, V.I., (1980) A computer-compiled and computer-oriented catalogue of Romania’s earthquakes during a millennium. Revue Roumaine de Géologie, Géophysique et Géographie. Tome 24, No2, Editura Academiei R.S.Romania, p.193-206. Drake, L., 2000. Estimation of depth and attenuation of earthquakes in Bolivia, Contract No.F49620-97-1-0214 at Observatorio San Calixto, Bolivia with U.S. Department of Defence, 10p. Lungu, D., Aldea, A., Arion C., (2002), GIS Mapping of Earthquake Risk and Buildings Retrofitting in Bucharest, 12 th European Conference on Earthquake Engineering Paper Reference 584 Published by Elsevier Science Ltd. Lungu, D., Arion, C.,Vacareanu, R., City of Bucharest: Buildings Vulnerability and Seismic Risk Reduction Actions, Proceeding of the Conference 250th Anniversary of the 1755 Lisbon earthquake, Lisabona, Portugalia, 1-4 Nov 2005 Lungu, D., Cornea, T., Craifaleanu, I., Aldea, A., 1995. Seismic zonation of Romania based on uniform hazard response ordinates. 5th International Conference on Seismic Zonation, Nice, France, Oct.16-19. Proceedings Vol.1, p.445-452, Quest Editions. Lungu, D., Cornea, T., Aldea, A., Zaicenco, A., (1997). Basic representation of seismic action. In: Design of structures in seismic zones: Eurocode 8 - Worked examples. TEMPUS PHARE CM Project 01198. Edited by D.Lungu, F.Mazzolani and S.Savidis. Bridgeman Ltd., Timisoara, p.1-60. Lungu, D., Arion, C., Aldea, A., Demetriu, S., (1999), “Assessment of seismic hazard in Romania based on 25 years of strong ground motion instrumentation”, NATO ARW Conference on strong motion instrumentation for civil engineering structures, Istanbul. Lungu, D., Aldea, A., Arion, C., Demetriu, S., Cornea, T., 2000. Microzonage Sismique de la ville de Bucarest - Roumanie, Cahier Technique de l’Association Française du Génie Parasismique, No.20, p.31-63 Youngs, R.R., Chiou, S.-J., Silva, W.J., Humphrey, J.R., 1997. Strong ground motion attenuation relationships for subduction zone earthquakes, Seismological Research Letters, Vol.68, No.1, p.58-73 Radu, C. manuscripts, (1994). Catalogues of earthquakes occurred on Romanian territory during the periods 984-1990 and 1901-1994. Williamson S.H., "Five Ways to Compute the Relative Value of a U.S. Dollar Amount, 1790 - 2005," MeasuringWorth.Com, 2006.) World Bank Report No. P-2240-RO (1978), Earthquake in Romania, March 4, 1977.