| 书目名称 | Vrancea Earthquakes: Tectonics, Hazard and Risk Mitigation | | 副标题 | Contributions from t | | 编辑 | F. Wenzel,D. Lungu,O. Novak | | 视频video | http://file.papertrans.cn/986/985096/985096.mp4 | | 丛书名称 | Advances in Natural and Technological Hazards Research | | 图书封面 |  | | 描述 | This volume contains the most relevant peer-reviewed paperspresented at The First International Workshop on Vrancea Earthquakes,held in Bucharest on November 1-4, 1997. Strong earthquakes inthe Romanian Vrancea area have caused a high toll of casualties andextensive damage over the last several centuries. With a momentmagnitude of 7.4, the 1977 earthquake caused more than 1500casualties, the majority of them in Bucharest. The contributionsaddress key problems of seismotectonics of the Vrancea area andrelated strong ground motion, hazard assessment, site effects andmicrozonation, structural damage and earthquake resistant design, riskassessment and disaster management from an international and regionalperspective. This list of topics shows the diverse contributions fromthe multidisciplinary fields of geosciences, geophysics, seismology,geology, civil engineering, city planning, and emergency reliefpractices. This book is of value for scientists interested inearthquake hazard and seismic risk research as well as forseismologists, geophysicists and Earth scientists. It is also usefulfor authorities responsible for public safety and natural hazardmitigation plans and for insurance comp | | 出版日期 | Book 1999 | | 关键词 | Geoinformationssysteme; civil engineering; concrete; earthquake; geophysics; seismic; seismology; hydrogeol | | 版次 | 1 | | doi | https://doi.org/10.1007/978-94-011-4748-4 | | isbn_softcover | 978-94-010-5994-7 | | isbn_ebook | 978-94-011-4748-4Series ISSN 1878-9897 Series E-ISSN 2213-6959 | | issn_series | 1878-9897 | | copyright | Springer Science+Business Media Dordrecht 1999 |
| 1 |
Modern Recording of Seismic Strong Motion for Hazard Reduction |
Bruce A. Bolt |
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Abstract
Striking progress has occurred in recording strong shaking from damaging earthquakes since the 4 March 1977 Vrancea, Romania, earthquake (.. = 7.4). Free-field accelerometers in seismic regions have significantly increased in number, geographical distribution, and dynamic range. Many digital instruments are now operational. In Europe and the Middle East alone, the number of individual triaxial recordings during the last 30 years exceeds 2500. Of particular importance, the 1989 Loma Prieta, 1992 Landers, 1994 Northridge (all in California), and the 1995 Hyogo-ken Nanbu, (Kobe) Japan, earthquakes have provided not only hundreds of key free-field accelerograms but many instrumental records of building response..In Romania there are now over 70 strong motion accelerometer stations and an important data base of seismic ground motion records is accumulating, including records from the intermediate depth Vrancea earthquakes of 1977, 1986, and 1990. The Bucharest accelerograms of the 1977 earthquake are of the greatest value in predicting future strong ground motions in Bucharest. The 1 to 2 sec velocity pulse in the horizontal components (repeated in the 1986 earthquake) is generated by d
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| 2 |
Seismotectonics of the Romanian Vrancea Area |
F. Wenzel,F. P. Lorenz,B. Sperner,M. C. Oncescu |
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Abstract
The seismicity of the Romanian Vrancea area has peculiar features: (1) strong earthquakes occur at intermediate depths in a very narrow source volume; (2) the seismogenic zone is situated beneath continental crust, at the SE corner of the highly arcuate Carpathian arc; (3) no evidence for active ongoing subduction is found today. Several geophysical models were developed that tried to provide an explanation for the localization of seismicity at depth (Fuchs ., 1979; Oncescu, 1984; Tavera, 1991). They contain ideas on interaction of a paleo-subduction zone with more recent subduction and include initial concepts of slab break-off. In recent years new facts and concepts came up that merit a re-evaluation of the tectonic scenarios related to Vrancea seismicity.
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| 3 |
Weak and Strong Ground Motion of Intermediate Depth Earthquakes from the Vrancea Region |
Mihnea-Corneliu Oncescu,Klaus-Peter Bonjer,Mihaela Rizescu |
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Abstract
On March 4, 1977, at 19:21 UT, a destructive earthquake with M.= 7.4 hit the Vrancea region in the Eastern Carpathians. The 100 km deep event was felt at distances greater than 2000 km and produced extensive damage in the epicentral area as well in Bucharest. Ambraseys (1977) and Hartzell (1979) were the firsts to note the particular shape of the (single) strong motion record available, recorded by a Japanese SMAC accelerograph: a low frequency pulse-like signal with a peak value close to 210 cm/s. at the INC site in Bucharest (see Figures 1 and 2). The complex character of the rupture and the focal mechanisms of the individual events have been widely studied by Müller et al. (1978), Fuchs et al. (1979), Räkers and Müller (1982) and Iosif et al. (1983).
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| 4 |
The Romanian Earthquake Catalogue Between 984 – 1997 |
Mihnea C. Oncescu,Vasile I. Marza,Mihaela Rizescu,Mihaela Popa |
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Abstract
Earthquake catalogues are the primary input data for seismic hazard computations. An earthquake catalogue should be up-to-date, complete, homogeneous and accessible. There are several earthquake catalogues for the Romanian earthquakes published until now (e.g. Purcaru, 1979; Radu, 1979; Constantinescu and Marza, 1980; Radu, 1991; Trifu and Radulian, 1991), but none of them fulfil . above-mentioned criteria.
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| 5 |
Twenty Years Recording of Albanian Seismological Network: A Catalogue and Distribution of Seismic En |
B. Muço |
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Abstract
Analyzing twenty years recording of Albanian Seismological Network (ASN), in this paper are given some characteristics of recent seismicity of the country. The construction of the catalogue of earthquakes of Albania with M.≥3.0 for the period 1976–1995 is also described here. On the basis of this catalogue, calculating the seismic energy released for 220 cells covering all the Albanian territory, a panorama of distribution of seismic energy and cumulative magnitudes is provided which gives insight to a better understanding of seismicity of the country and helps on its hazard assessment.
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| 6 |
Studies Concerning Directionality of Seismic Action for Vrancea Earthquakes |
M. Stancu,I. S. Borcia |
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Abstract
The accelerograph network of Building Research Institute INCERC Bucharest consists of 71 SMA-1 accelerographs located in all seismic zones of Romania. A number of 51 accelerographs are mounted at ground level in low-rise buildings. The INCERC network furnished more then 110 useful records obtained during the Vrancea earthquakes of March 4, 1977 (Richter magnitude M = 7.2), August 31, 1986 (M = 7.0), May 30, 1990 (M = 6.7) and May 31, 1990 (M = 6.1), codified in the following as events 771, 861, 901 and 902.
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| 7 |
Classification and Evaluation of Vrancea Earthquake Records from Republic of Moldova |
A. Zaicenco,D. Lungu,V. Alkaz,T. Cornea |
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Abstract
The free-field accelerograms from Republic of Moldova come from four seismic stations in Kishinev, capital of Republic of Moldova, as well as from other two stations: Kahul, near the Romanian border (≈46° lat.N), and Krasnogorka, 60 km from Kishinev.
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| 8 |
Seismic Microzonation of Site Effects |
Jean-Pierre Meneroud |
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Abstract
We have been developing in France a specific methodology which takes community vulnerability into account. Those microzonings are normally presented as a map at scale 1: 5,000 or 1: 10,000 of the particular effects that are due to site effects, which concern the modification of the seismic signal; taking them into account leads us to the identification of homogeneous zones from a ground shaking view point. In order to determine site effects we use different methodologies: a numerical one of course but above all an experimental one. We use two kinds of experimental methods: the one uses micro earthquakes to establish transfer functions (comparing record at studied site and substratum), the other uses microtremor (H/V process). We translate the result into French regulation by drawing up a map with homogeneous areas where transfer function is the same. It is then possible to attribute to each of these areas a coefficient t’(T) that should be applied to the So(T) regulation spectrum. We also can draw a map: giving the equal amplitude curves or the equal frequency curves. These maps render not only the seismic response of the site but also the shape aspect of alluvium basins and in par
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| 9 |
Modelling, for Microzonation Purposes, of the Seismic Ground Motion in Bucharest, Due to the Vrancea |
C. L. Moldoveanu,G. F. Panza |
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Abstract
The Vrancea seismoactive region, characterized by intermediate-depth earthquakes, is the quake source that has to be taken into account for microzonation purposes of Bucharest that could suffer serious damage also because of the severe local site effects. The strong seismic events originating in Vrancea have caused the most destructive damage experienced on the Romanian territory and may seriously affect vulnerable high risk constructions (such as nuclear power plants, chemical plants, large dams, pipelines etc.) located on a wide area, from Central Europe to Moscow..Realistic numerical simulation, describing the propagation of the seismic wavefield generated by a given quake in a complex geological structure, is a powerful tool, that may be efficiently used to estimate the ground motion for microzonation of the whole Bucharest area..The realistic modelling of ground motion is carried out by means of a sophisticated hybrid technique that combines modal summation (Panza, 1985; Vaccari et al, 1989; Florsch et al., 1991; Panza, 1993; Romanelli et al., 1996) and finite difference (Fäh 1991; Fäh and Panza, 1994; Fäh et al., 1994). The input data necessary for computations are the latera
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| 10 |
Reliability of Response Spectrum Curves at Low Frequency Region |
R. Blazquez |
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Abstract
The seismic design of low frequency systems differs considerably from the normal practical situation, in the sense that is based on spectral velocities and displacements rather than on spectral accelerations. This fact imposes some limitations on the standard spectral analysis that must be considered. First, the amount of processing spurious noise present in the strong motion records must be known and kept bounded at all times. The above is particularly true for analog accelerograms, for which the instrument characteristics and the procedures used to retrieve the original data affect significantly the reliability of the long period range of response spectra. Other sources of enor, however, are not man-induced and therefore escape human control. This is the case of uncertainties that emanate from geologic or geophysical phenomena, like anomalous attenuation laws (e.g., Vrancea earthquakes in Romania), fault directivity, site effects, and so on. Actually, all this factors decrease the reliability of the spectral ordinates at low frequencies and need to be carefully evaluated. Besides they are important in assessing the seismic performance of base-isolated structures at high risk cond
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| 11 |
Seismic Microzoning of Bucharest (Romania): A Critical Review |
N. Mândrescu,M. Radulian |
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Abstract
Bucharest suffered on repeated occasions strong damages as a result of the Vrancea intermediate-depth earthquakes, located in a confined isolated focal volume beneath the Eastern Carpathians Arc bend. The particular seismic energy radiation and the seismic cycle in Vrancea focus, characterized by 2–3 major shocks (.. > 7.0) per century, lead to a high level of the seismic risk in Bucharest.
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| 12 |
2-D Modeling of Site Response for Microzonation Purposes |
P. Suhadolc,F. Marrara |
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Abstract
The estimation of seismic site effects is becoming an important part of the scenario-like modelling approaches used to predict the seismic strong motion in vulnerable environments. We show how detailed numerical modeling can lead to estimates of the seismic amplification due to site effects that are consistent with observations..Such modeling allows for the full utilisation of both the seismological and the large amount of geological, geophysical and geotechnical data, already available. Therefore, detailed modelling of the ground motion for heterogeneous media (up to several Hz) can be used for immediate microzonation purposes, without the need to wait for the occurrence of the next big event in the not always densely instrumented area of interest.
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| 13 |
Near-Surface Geology and Dynamic Properties of Soil Layers in Bucharest |
D. Lungu,A. Aldea,T. Moldoveanu,V. Ciugudean,M. Stefanica |
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Abstract
The importance of site effects due to soil condition in Bucharest was firstly observed during the 1977 Vrancea earthquake. A substantial understanding of the effect of near-surface geology on the characteristics of the ground motion came later, from the analysis of the frequency content of the 1986 Bucharest accelerograms and of corresponding soil profiles at recording sites. The paper focuses on the correlation of the frequency content of the recorded accelerograms in Bucharest with the properties of the near-surface geology (stratigraphy, dynamic characteristics of the soil layers, etc.).To a great extent, the near-surface geology study for the city of Bucharest is based on laboratory tests made by ., during Bucharest subway construction works. Soil layers in thousands of meters of boreholes were analysed.
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| 14 |
A Note on Empirical Site Responses in Bucharest, Romania |
Klaus-Peter Bonjer,Mihnea-Corneliu Oncescu,Lynda Driad,Mihaela Rizescu |
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Abstract
To quantify the variations of the site responses in downtown Bucharest the horizontal- to vertical-component spectral ratio method (H/V) on different kinds of seismic data was applied. Starting September through November 1997 we have recorded ambient seismic noise at 16 sites in Bucharest. In addition, we used ambient noise and small earthquake records from the instruments which had been deployed during an aftershock campaign in June/July 1990. Furthermore, we have examined S-waves of strong Vrancea earthquakes..The ambient noise ratios, determined on two profiles which cross in the center of Bucharest, show a remarkable constancy of the main resonance period. They range in a narrow band from 1.2 to about 1.6 seconds with an average value of T.=1.36±0.14 s. A second but small amplitude resonance at even greater periods is recognizable with T.=5.22±0.9 s..First recordings of Vrancea earthquakes by the new K2 network corroborate that the high frequency peak ground accelerations (PGA) may differ up to 2–3 times in downtown Bucharest. However, lowpass filtering with a corner frequency of 1Hz reduces these differences from several 100% to about ±15%, thus confirming the almost constant
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| 15 |
Macroseismic Field of the Romanian Intermediate-Depth Earthquakes |
N. Mândrescu,M. Radulian |
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Abstract
Romania is a country of moderate seismicity, with 2–3 major earthquakes (.. > 7) per century. These events occur at subcrustal depths (60 < . < 200 km), in a confined epicentral area (approximately 3,000 km.), located at the Eastern Carpathian Arc bend, in the Vrancea Mountains. There are only few seismic regions in the world with comparable focus isolation and persistence (e.g., Hindu Kush in Afganistan and Bucaramanga in Columbia). The large Vrancea earthquakes severely affect not only the Romanian territory, but also extended areas in the neighboring countries.
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| 16 |
The Seismic Earth Response by Considering Nonlinear Behavior of the Soils to Strong Vrancea Earthqua |
G. Marmureanu,C. Moldoveanu,C. Cioflan,B. Apostol |
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Abstract
The nonlinear effects in the ground motion during strong earthquakes are a controversial issue between seismologists and geotechnical engineers. The soil effect, is one of filtering the seismic motion, increasing the amplitude in some frequency ranges and decreasing it in others. The transverse body S waves induced by strong earthquakes, with possible shear strains γ≅10. (as it is the case of March 4, 1997, Vrancea event, M.=7.2) have the most distructive effect. The nonlinear viscoelastic behavior of the superficial soil deposits for such large deformations has an important influence on the propagation of the seismic waves in the hazard and microzonation studies.
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| 17 |
Influence of Local Soil Conditions on Earthquake Motion in the Territory of Moldova Republic |
V. Alkaz |
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Abstract
The present paper is the attempt to generalize the results of extensive study of local soil conditions influencing earthquake motion in the territory of the Republic of Moldova. It has been shown that for specific regional conditions such factors as thickness of soft soil, shear waves velocity, high impedance contrast between the clay-sandy layers and limestone basement play a decisive role in forming the amplitude level and spectral composition of motions occurring on surface. It has also been established that the influence of waterlogging, lithology is less than traditionally adopted..The unusually high level of damage to modern structures has been observed, resulting from resonance phenomena pertinent to soil-structure system..Regional methodology of seismic microzonation based on a complex study of soil dynamic properties is being advanced..The results obtained may be of use in solving problems of seismic microzonation and soil profile types classification.
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| 18 |
Seismic Retrofitting of Reinforced Concrete Buildings in Romania |
Liviu Crainic |
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Abstract
Romania is a country with severe seismic conditions: more than half of its territory is subjected, periodically, to earthquakes having intensities I = VII … IX MM. After the strong earthquake of November, 1940 (Richter M = 7.4), another severe seismic event occurred on March 4, 1977; it produced heavy damage: 32 high-rise buildings collapsed in Bucharest, two small towns - Zimnicea and Alexandria- were, practically, destroyed. About 3000 people were killed and 12,000 injured.
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| 19 |
Dynamic Behaviour of High Damping Rubber Bearings for Building Seismic Isolation |
Josef Eibl |
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Abstract
The conventional methods for earthquake-resistant structural design use high strength or high ductility concepts to mitigate damage from seismic effects. In the first case, corresponding to shear wall structures, generally the design is problematic in that their fundamental frequency of vibration is in the range of frequencies where earthquake energy is the strongest, resulting in a very high floor acceleration, which may cause damage to equipment or machinery. The second, the capacity design method, incorporates that a part of the energy transmitted into the structure by. an earthquake is dissipated by plastic deformations. The capacity method mostly used for flexible structures as frames, provided that plastic deformations occurred in structural elements, which are designed to undergo such large deformations. Therefore, the design of such yielding zones has to be planned carefully. However, this concept may lead to a very high interstory drift, causing P-Δ effects and damage to non-structural elements. Thus, the costs for retrofitting or strengthening after a strong earthquake can be very high. An alternative approach consists in isolating the structure base from the ground by us
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