On the selection of GMPEs for Vrancea subcrustal seismic source   总被引：2，自引：0，他引：2  

Radu Vacareanu  Florin Pavel  Alexandru Aldea 《Bulletin of Earthquake Engineering》2013,11(6):1867-1884

The Vrancea subcrustal seismic source is characterized by large magnitude ( $M_{W} \ge 7$ ) intermediate-depth earthquakes that occur two or three times during a century on average. In this study several procedures are used to grade four candidate ground motion prediction equations proposed for Vrancea source in the SHARE project. In the work of Delavaud et al. (J Seismol 16(3):451–473, 2012) four ground motion prediction models developed for subduction zones (Zhao et al. in Bull Seism Soc Am 96(3):898–913, 2006; Atkinson and Boore in Bull Seism Soc Am 93(4):1703–1729, 2003; Youngs et al. in Seism Res Lett 68(1):58–73, 1997; Lin and Lee in Bull Seism Soc Am 98(1):220–240, 2008) are suggested as suitable for Vrancea subcrustal seismic source. The paper presents the appropriateness analysis of the four suggested ground motion prediction equations done using a dataset of 109 triaxial accelerograms recorded during seven Vrancea seismic events with moment magnitude $M_{W}$ between 5.4 and 7.4, occurred in the past 35 years. The strong ground motions were recorded in Romania, as well as in Bulgaria, Republic of Moldova and Serbia. Based on the ground motion dataset several goodness-of-fit measures are used in order to quantify how well the selected models match with the recorded data. The compatibility of the four ground motion prediction models with respect to magnitude scaling and distance scaling implied by strong ground motion dataset is investigated as well. The analyses show that the Youngs et al. (Seism Res Lett 68(1):58–73, 1997) and Zhao et al. (Bull Seism Soc Am 96(3):898–913, 2006) ground motion prediction models have a better fit with the data and can be candidate models for Probabilistic Seismic Hazard Assessment.  相似文献   

Horseshoes and nonintegrability in the restricted case of a spinless axisymmetric rigid body in a central gravitational field     

Radu Balan 《Celestial Mechanics and Dynamical Astronomy》1995,63(1):59-79

The purpose of this paper is to study the motion of a spinless axisymmetric rigid body in a Newtonian field when we suppose the motion of the center of mass of the rigid body is on a Keplerian orbit. In this case the system can be reduced to a Hamiltonian system with configuration space of a two-dimensional sphere. We prove that the restricted planar motion is analytical nonintegrable and we find horseshoes due to the eccentricity of the orbit. In the caseI ₃/I ₁>4/3, we prove that the system on the sphere is also analytical nonintegrable.On leave from the Polytechnic Institute of Bucharest, Romania.  相似文献   

Attenuation in Southeastern Carpathians area: Result of upper mantle inhomogeneity   总被引：1，自引：0，他引：1  

M. Popa  M. Radulian  B. Grecu  E. Popescu  A.O. Placinta 《Tectonophysics》2005,410(1-4):235-249

The systematic analysis of seismograms recorded on the Romanian territory using Vrancea intermediate-depth earthquakes shows a strong asymmetric pattern relative to the epicentral area: on one side, in the Transylvanian Basin and the Eastern Carpathians (approximately along the inner volcanic chain), the amplitudes are reduced by a factor of 20 on average and the high frequencies are attenuated, in contrast with the other side, in the foreland platform. This pattern is explained by a significant attenuation increase caused by a strong lateral variation of the structure in the upper mantle, immediately towards NW of the Vrancea seismic active volume. This region corresponds to the most recent volcanic activity in the Persani Mountains and with the low-velocity body adjacent toward NW to the high-velocity body subducted beneath Vrancea area as indicated by seismic tomography and heat flow results. The CALIXTO'99 tomography experiment, deployed for 6 months in 1999, provides the largest number of observations for Vrancea earthquakes ever recorded on the Romanian territory. We select data from 8 earthquakes generated in this time interval in the Vrancea nest, which were recorded with signal / noise ratio greater than 5 by at least 25 stations. All of them are small- to moderate-magnitude events (3.6 ≤ M_w ≤ 4.2). The attenuation is much more important in the high-frequency range (> 1 Hz), than at low frequencies. Since the large Vrancea earthquakes can radiate significant energy in the low-frequency range (< 1 Hz), our results show that the seismic hazard level is much more uniform all over the Romanian territory in the low-frequency range than in the high-frequency range.  相似文献   

On the possibilities of using the power spectrum in some geological and geophysical problems     

Radu Botezatu 《Mathematical Geology》1970,2(3):303-305

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Engineering behaviour of rocks     

M.E. Popescu 《Engineering Geology》1983,19(4):293-294

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Geology for geotechnical engineers.     

M.E. Popescu 《Engineering Geology》1983,19(4):294-297

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C.R.I. Clayton and J. Milititsky, Earth Pressure and Earth-Retaining Structures, Surrèy University Press (1986), p. 300.     

M.E. Popescu 《Engineering Geology》1987,23(3-4):308-309

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Shallow vs. deep, old vs. recent tectonic movements at the Eastern Carpathians Arc Bend     

V. Lazarescu  M.N. Popescu 《Tectonophysics》1986,131(3-4)

The seismically most important region of Romania is the Vrancea epicentral area of the Eastern Carpathians Arc Bend (ECAB). The occurrence of earthquakes is here indisputably caused by subduction processes, either relict ones in connection with a “dead” slab, or directly produced by continuous underthrusting or by type A subduction, after a continent/continent collision.In order to investigate the type of subduction process, the authors used structural geological criteria i.e., features of local strike-slip faults and sigmoidal curves of fold axes or of overthrusting lines, already mapped across the area.By use of these criteria, it is concluded that there is an offset directed northwestwards, with an amplitude of 9–12 km, within the Cretaceous-Paleogene flysch and Neogene molasse deposits outcropping at ECAB.If the measured transcurrent movements reflected only the distortions of the sedimentary cover, the offset should be directed SE, because overthrusting processes are larger from SW to NE at ECAB. Instead, the northwestern direction disclosed by the offset vector suggests that the basement movement occurred when the formations were transversally dislocated, after the “charriage” structure at ECAB had been born.This conclusion is consistent with a hypothetical NW movement of the basement of the ECAB foreland.  相似文献   

Macroseismic field of the March 4, 1977 Vrancea earthquake     

C. Radu  G. Polonic  I. Apopei 《Tectonophysics》1979,53(3-4)

The macroseismic field of the Vrancea earthquake of March 4, 1977, characterized by the following parameters : H = 19h 21m 56s, ø = 45.8°N, γ = 26.8° E, h = 95 Km, M = 7.2, I = VIIIMSK has been analyzed. The following problems were studied : area and shape of the isoseismals of intensity III–VIII ; elongation of the isoseismal ellipses and decrease of intensity with distance. The results confirm our previous studies (Radu and Apopei, 1978) of strong intermediate earthquakes, but render evidence for some peculiarities in the seismic intensity attenuation as well.  相似文献   

Romanian industry in transition     

Claudia Popescu 《GeoJournal》1993,29(1):41-48

Restructuring of industry in Romania today is part of the transition from a centrally-planned to a free market economy. The paper deals with salient features of socialist industry and the trends which have occurred since 1989 in the context of greatly reduced state intervention. Current trends are identified as a key to further evolution in the future and some international comparisons are attempted now that industrial enterprises in all parts of Europe are developing new relationships with capital, labour and the state.  相似文献