Harmonization of Seismic Hazard in Vrancea Zone

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Harmonization of Seismic Hazard in Vrancea Zone

Anton ZaicencoInstitute of Geology and SeismologyAcademy of SciencesChisinau, Moldova

Iolanda CraifaleanuNational Institute for Building ResearchBucharest, Romania

Bulgarian Academy of Sciences

with Special Emphasis on Seismic Risk Reduction

Ivanka PaskalevaSofia, Bulgaria

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Proceedings of the NATO Science for Peace Project on

Influenced by Vrancea EarthquakesChisinau, Moldova20 May 2008

ISBN 978-1-4020-9242 -8 (e-book)

Harmonization of Seismic Hazard and Risk Reduction in Countries

ISBN 978-1-4020-9241-1 (PB)ISBN 978-1-4020-9240-4 (HB)

Library of Congress Control Number: 2008937478

PREFACE

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The NATO Science for Peace Project SfP-980468 Harmonization of Seismic Hazard and Risk Reduction in Countries Influenced by Vrancea Earthquakes was an ambitious attempt to harmonize the seismic-hazard assessment in Bulgaria, Moldova and Romania, and provide the guidelines for seismic risk reduction in the target countries. Related to the study of intermediate-depth Vrancea earthquakes, it became operational in 2005.

The project co-coordinators were as follows: • Prof. Güney Özcebe, Ankara, Turkey; • Dr. Anton Zaicenco, Chisinau, Moldova; • Dr. Iolanda Craifaleanu, Bucharest, Romania; • Prof. Ivanka Paskaleva, Sofia, Bulgaria.

The project has brought together leading research personalities in the area of earthquake engineering, seismology and earth physics from several countries for brainstorming sessions, informal discussions, and exchanges of ideas. One of its key components was an upgrade of the strong-motion seismic networks of the countries-participants, which created a foundation for a long-term collaboration. A number of papers have been published as a result of the work conducted under this project.

The present book contains the Proceedings of the Closing Workshop for Project SfP-980468, which was organized in Chisinau, Moldova on May 20, 2008.

From hazard analyses to protection of the historical buildings, from study of the dynamic properties of the soft soils to paleoseismology, there are few areas of interest that remain untouched. Research from the NATO members and partner countries in South-Eastern Europe that forms the components of NATO Project SfP-980468 has made solid contributions to the Workshop theme.

Lungu and Craifaleanu provide an extensive study involving the mapping of key ground motion characteristics and of linear/nonlinear spectral ordinates for all strong Vrancea earthquakes that occurred in the last three decades. The second paper by these authors presents an evaluation of the damage potential of Vrancea earthquakes based on the use of damage spectra.

Bonjer, Ionescu, Sokolov, Radulian, Grecu, Popa, and Popescu present the ground motion patterns of the October 27, 2004 Vrancea earthquake. Ground motion maps for the main shock are presented using the recordings of the accelerometer networks installed in Romania and the macroseismic intensities

PREFACE vi

as observed by the Internet community provided by the United States Geological Survey.

In her paper Craifaleanu gives comprehensive material on the required overstrength, expressed by the ratio between the demands imposed by Vrancea earthquakes and those imposed by the Romanian seismic design codes.

Borcia interprets instrumental data obtained in the Republic of Moldova (Chisinau and Cahul) and Romania (Vaslui and Birlad) during the 1986 and 1990 Vrancea earthquakes. The response spectra of strong-motion records, the global parameters that characterize an individual component of a record and instrumental intensity are the main numerical results obtained for the seismic records.

Alkaz, Zaicenco, and Isiciko investigate the dynamic properties of soft soils in Chişinău City. Authors propose a methodology for seismic microzonation based on a complex study of soil dynamic properties, structural damage observations, and numerical methods in seismic wave propagation.

A combination of different methods in the assessments of recurrence and probability of Vrancea intermediate-depth earthquakes is offered by Ginsari. She performs an analysis of recurrence relationships for two types of magnitudes, for different time intervals and by assigning alternative values of maximum possible earthquake magnitude.

Grecu, Radulian, Mandrescu, and Panza investigate the validity and relevance of the H/V spectral ratio technique in the particular case of Bucharest City, which was strongly affected by the 4 March 1977 (Mw=7.4) damaging earthquake.

Dineva, Paskaleva, La Mura, and Panza present and solve the 2-D elastodynamic model for seismic in-plane wave propagation in laterally inhomogeneous geological profiles embedded in a vertically inhomogeneous half-space in which an earthquake source is buried. The model and hybrid computational tool developed are applied in order to contribute to the seismic risk analysis of the Bulgarian capital Sofia.

An upper limit for horizontal peak ground acceleration generated by Paleolithic earthquakes is investigated by Gribovszki, Paskaleva, Kostov, Varga, and Nikolov. To pursue their goals authors examine broken and slim intact speleothems in Snezanka and Eminova caves in southwestern Bulgaria in the Rhodope Massif.

An acceleration data logger incorporating MEMS sensor for seismic arrays and structural health monitoring is presented by Mohniuc, Zaicenco, Kuendig, and Kurmann. This low-power class C device resolves accelerations at sub milli-g level on a bandwidth of 100 Hz, incorporates 16-bit ADC and has a GPS sensor.

PREFACE vii

Analysis of focal mechanisms of Vrancea earthquakes is provided by Sandu and Zaicenco. Seismic events with magnitude Mw>3.0 were studied for the time span 1967-2006. Ten independent catalogues were examined by the authors. They recomputed about 250 focal mechanism solutions from ISC database containing information on P-wave polarities, and made thorough comparative analyses.

In their paper, Zaicenco and Alkaz discuss numerical solutions of an elastic wave equation using spectral method based on Chebyshev grids.

Koleva, Ilie, and Akkar investigate maximum interstory drift ratio for shear-wall systems with fundamental periods ranging from 0.5 seconds to 1.25 seconds. Predictive equations, derived from a recently compiled ground-motion dataset, include focal mechanism and site class as explanatory variables.

A snapshot of the development of a strong motion registration system in Russe, Bulgaria is offered by Kouteva and Paskaleva, and the benefits of seismic monitoring in the region are discussed.

A parametric model for the August 30, 1986 Vrancea earthquake is offered by Zaicenco, Gavin, and Dickinson. They use Gabor wavelet to capture the coherent component of ground motion, and describe the high-frequency part by a stochastic method.

Paskaleva, Simeonov, Koleva, Kouteva, and Hadjiiski present results of applying a seismic microzonation procedure for designing and constructing a 34-storey administrative building in Sofia.

Paskaleva, Koleva, Vaccari, Zuccolo, and Panza describe an advanced modeling technique that allows computation of realistic synthetic seismograms in a set of selected sites in the Sofia urban area. Afterwards, they use a 3-D finite element modeling to assess a building structural performance.

A comprehensive study that includes catalogues of Vrancea earthquakes, earthquake records in Romania, the evolution of seismic zonation and seismic design codes, a seismic hazard map of Romania and design spectra in the new seismic design code P100-1/2006 following the Eurocode 8 format is proposed by Lungu, Aldea, and Arion. Another paper authored by this team tackles current challenges involved in conserving historical buildings in the center of Bucharest. The study includes historical earthquake damage and lessons learned, strengthening procedures for tall reinforced concrete fragile buildings in central Bucharest, and international projects for seismic risk reduction in Romania.

The authors of the papers comprised in the present volume express deep gratitude to John Ebel, John Evans, Klaus Hinzen, Luis Esteva Maraboto, Dieter Mayer-Rosa, Imtiyaz Parvez, Peter Rangelow, Yevgeny Rogozhin, Joachim Ritter, and Wolfgang Wirth for reviewing the articles.

The assistance of Judith Goldman in editing and proofreading the papers for this volume is highly appreciated.

The success of the project would not be possible without continuous support

Dr. Susanne Michaelis.

PREFACE

August 2008 Guney Ozcebe Anton Zaicenco

of the NATO Science Committee, and particularly Dr. Chris De Wispelaere and

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LIST OF CONTRIBUTORS WITH COMPLETE ADDRESSES

Akkar Sinan Middle East Technical University Department of Civil Engineering 06531 Ankara Turkey Aldea Alexandru Technical University of Civil Engineering Bucharest, 124 Lacul Tei RO-020396 Romania Alkaz Vasile Institute of Geology and Seismology Academy of Sciences of Moldova str. Academiei 3, MD-2028 Chisinau Moldova Arion Cristian Technical University of Civil Engineering Bucharest, 124 Lacul Tei RO-020396 Romania Bonjer Klaus-Peter Geophysical Institute University of Karlsruhe Hertzstr. 16 D 76187 Karlsruhe Germany Borcia Ioan Sorin National Institute for Building Research, INCERC Earthquake Engineering Division 266 Pantelimon St., Sector 2, RO-021652, Bucharest, Romania

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LIST OF CONTRIBUTORS

Craifaleanu Iolanda-Gabriela Technical University of Civil Engineering Bucharest Faculty of Civil, Industrial and Agricultural Buildings Department of Reinforced Concrete Structures 124 Lacul Tei Blvd., Sector 2, RO-020396 Bucharest, Romania National Institute for Building Research, INCERC Earthquake Engineering Division 266 Pantelimon St., Sector 2, RO-021652, Bucharest, Romania Dickinson Bruce Department of Civil and Environmental Engineering Edmund T. Pratt School of Engineering Duke University Durham, NC USA Dineva Petia Institute of Mechanics Bulgarian Academy of Sciences (BAS) Acad. G. Bonchev block 4, 1113 Sofia Bulgaria Gavin Henri Department of Civil and Environmental Engineering Edmund T. Pratt School of Engineering Duke University Durham, NC USA Ginsari Victoria Institute of Geology and Seismology Academy of Sciences of Moldova str. Academiei 3, MD-2028 Chisinau Moldova Grecu Bogdan National Institute of Research and Development for Earth Physics (NIEP)

12 Calugareni st., Ilfov Romania

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Bucharest-Magurele (PO Box: MG-2)

LIST OF CONTRIBUTORS

Gribovszki Katalin Hungarian Academy of Sciences Geodetic and Geophysical Research Institute MTA-ELTE Geological, Geophysical and Space Science Research Group Hungary Hadjiiski Kiril Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Ionescu Constantin National Institute of Research and Development for Earth Physics (NIEP)

12 Calugareni st., Ilfov Romania

Institute of Geology and Seismology Academy of Sciences of Moldova str. Academiei 3, MD-2028 Chisinau Moldova Koleva Gergana Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Koleva Nikolina Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Kostov Marin Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria

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Bucharest-Magurele (PO Box: MG-2)

Isiciko Evgheniy

LIST OF CONTRIBUTORS

Kouteva – Guentcheva Mihaela Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Kuendig Christoph GeoSIG Ltd. Europastrasse 11 8152 Glattbrugg Switzerland Kurmann Thomas GeoSIG Ltd. Europastrasse 11 8152 Glattbrugg Switzerland La Mura Cristina DST– Department of Earth Sciences University of Trieste Via E. Weiss 4, I-34142 Trieste Italy Lungu Dan Technical University of Civil Engineering Bucharest, 124 Lacul Tei RO-020396 Romania Mandrescu Neculai National Institute of Research and Development for Earth Physics (NIEP) Magurele-Bucharest (PO Box: MG-2) 12 Calugareni st., Ilfov Romania Mohniuc Ruslan Institute of Geology and Seismology Academy of Sciences of Moldova Str. Academiei 3, MD-2028 Chisinau Moldova

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LIST OF CONTRIBUTORS

Nikolov Gabriel Geological Institute Sofia 1113 Acad. G. Bonchev, str. block 4 Bulgaria Panza Giuliano DST – Department of Earth Sciences University of Trieste Via E. Weiss 4, I-34142 Trieste Italy and The ICTP – Abdus Salam International Centre for Theoretical Physics Strada Costiera 11, I-34100 Trieste Italy Paskaleva Ivanka Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Popa Mihaela National Institute of Research and Development for Earth Physics (NIEP)

12 Calugareni st., Ilfov Romania Popescu Emilia National Institute of Research and Development for Earth Physics (NIEP)

12 Calugareni st., Ilfov Romania Radulian Mircea National Institute of Research and Development for Earth Physics (NIEP)

12 Calugareni st., Ilfov Romania

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Bucharest-Magurele (PO Box: MG-2)

Bucharest-Magurele (PO Box: MG-2)

Bucharest-Magurele (PO Box: MG-2)

LIST OF CONTRIBUTORS

Sandu Ilie Institute of Geology and Seismology Academy of Sciences of Moldova Str. Academiei 3, MD-2028 Chisinau Moldova Simeonov Svetoslav Central Laboratory Seismic Mechanics and Earthquake Engineering Bulgarian Academy of Science (BAS) Acad. G. Bonchev block 3, 1113 Sofia Bulgaria Sokolov Vladimir Geophysical Institute University of Karlsruhe Hertzstr. 16 D 76187 Karlsruhe Germany Vaccari Franco DST – Department of Earth Sciences University of Trieste Via E. Weiss 4, I-34142 Trieste Italy Varga Peter Geodetic and Geophysical Research Institute of Hungarian Academy of Sciences (HAS) 6-8 Csatkai 6-8, 9400 Sopron Hungary Zaicenco Anton Institute of Geology and Seismology Academy of Sciences of Moldova str. Academiei 3, MD-2028 Chisinau Moldova Zuccolo Elisa DST – Department of Earth Sciences University of Trieste Via E. Weiss 4, I-34142 Trieste Italy

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CONTENTS

Romania’s Seismicity and Seismic Hazard: From Historical Records to Design Codes .................................................................................... 1 D. Lungu, A. Aldea, C. Arion Focal Mechanism Solutions for Vrancea Seismic Area.................................... 17 I. Sandu, A. Zaicenco Ground Motion Patterns of Intermediate-Depth Vrancea Earthquakes: The October 27, 2004 Event........................................................ 47 K.-P. Bonjer, C. Ionescu, V. Sokolov, M. Radulian, B. Grecu, M. Popa, E. Popescu A Parametric Model Combining Gabor Wavelet and Stochastic Component for the August 30, 1986 Vrancea Earthquake................................ 63 A. Zaicenco, H.P. Gavin, B.W. Dickinson Estimation of the Recurrence and Probability of Vrancea Intermediate Depth Earthquakes ....................................................................... 85 V. Ginsari Seismic Protection and Protection Against Demolition of Bucharest’s Historical Buildings ................................................................ 101 D. Lungu, C. Arion, A. Aldea Seismic Microzonation of Chişinău: A Tool for Reducing Seismic Risk....... 117 V. Alkaz, A. Zaicenco, E. Isiciko Relevance of H/V Spectral Ratio Technique for Bucharest City .................... 133 B. Grecu, M. Radulian, N. Mandrescu, G. Panza A Contribution to the Assessment of the Seismic Vulnerability of Large Structures in Sofia City..................................................................... 151 I. Paskaleva, G. Koleva, F. Vaccari, E. Zuccolo, G. Panza Hybrid MS-BIEM for Seismic Site-Response Phenomena: A Case Study of Sofia ..................................................................................... 163 P. Dineva, I. Paskaleva, C. La Mura, G. Panza

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CONTENTS

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of the Russe Region of BulgariaSeismic Monitoring: A Contribution to the Sustainable Development

..................................................................... 183 M. Kouteva, I. Paskaleva An Assessment of the Parameters Controlling Seismic Input for the Design and Construction of a High-Rise Building: A Case Study for the City of Sofia.................................................................. 197 I. Paskaleva, Sv. Simeonov, N. Koleva, M. Kouteva, K. Hadjiiski An Estimation of the Maximum Interstory Drift Ratio for Shear-Wall Type Structures....................................................................... 225 G. Koleva, I. Sandu, S. Akkar Shake Maps of Strength and Displacement Demands for Romanian Vrancea Earthquakes................................................................ 241 D. Lungu, I. Craifaleanu A Comparative Analysis of Accelerographic Records Obtained in the Republic of Moldova and Romania During the 1986 and 1990 Vrancea Earthquakes ....................................................................... 263 I.S. Borcia An Assessment of Damage Potential and Building Performance Demands for Romanian Vrancea Earthquakes................................................ 275

Estimating an Upper Limit on Prehistoric Peak Ground Acceleration Using the Parameters of Intact Speleothems in Caves in Southwestern Bulgaria ................................................................. 287 K. Gribovszki, I. Paskaleva, K. Kostov, P. Varga, G. Nikolov MEMS-Based Data Logger for Seismic Arrays and Structural Health Monitoring........................................................................................... 309

Numerical Solution of an Elastic Wave Equation Using the Spectral Method ........................................................................................ 319 A. Zaicenco, V. Alkaz A Comparison Between the Provisions of Present and Past Romanian Seismic Design Codes Based on Required Structural Overstrength ............... 329 I. Craifaleanu

I. Craifaleanu, D. Lungu

R. Mohniuc, A. Zaicenco, C. Kuendig, T. Kurmann