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The Romanian Seismic Network consisting of 8 short-period stations (S13), 60 Altus — K2 and Q330 seismic stations, is primarily designed to survey the Vrancea seismic region (strong and moderate Vrancea earthquakes). Since July 2002, a new seismic monitoring system, Bucovina Seismic Array (BURAR) has been operating. BURAR consists of 12 seismic stations distributed on a 5 km × 5 km area. 9 stations are equipped with short-period (SP) vertical sensors (GS-21 res) and one station is equipped with broad-band (BB) three component sensor (KS 54000). Broad-band sensors GMG40T (1000V/cm/s) were installed at 5 of the short-period stations, at the beginning of 2008. Recently, NIEP has developed its real-time digital seismic network. This network consists of 21 broad band stations and one seismic array. In the next year NIEP will install additional broad band stations in the central part of Romanian territory and other 40 strong motions stations in Bucharest.At the National Data Centre (NDC) runs BRTT’s Antelope™ 4.9 data acquisition and processing software on two HP workstations for real-time and post processing. The Antelope Real-Time System is also providing automatic event detection, arrival picking, event location and magnitude calculation.The Romanian Seismic Network is already linked with IRIS and ORFEUS organizations and other European countries via Internet and is contributing in near real time with waveform data from 5 broadband stations.The seismotectonic characteristics of the Vrancea region offer the opportunity to create and develop a rapid seismic warning system. This system allows warning in an approximately 25 seconds time window for Bucharest.

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Application of local conditions in earthquake engineering is interconnected with the achievements in natural sciences like geology, seismology and geotechnics. Due to variation of soil conditions on the territory of Slovakia, the properties of response spectra and/or simulated or adapted recorded accelerograms should take these phenomena into account. The paper discusses the approaches to the determination of shear wave velocities and soil-structure interaction. Possible application of latest records from new Slovak seismic station network is discussed, too.

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The paper presents information on the seismic observation network of Belarus and describes in detail the development of instrumental observations in the region. The seismicity of the territory of Belarus has been thoroughly studied in recent years. The data available on earthquakes in the Belarussian territory were refined from literature and archive evidences, historical earthquakes near Mogilev were revealed. The Catalogue includes the results of continuous instrumental observations for 1965–2009 described in bulletins of seismic stations. An analysis of the location of earthquake epicenters suggests their uneven distribution over the area. Epicenters of low-magnitude earthquakes are abundant in the southern regions of Belarus and are confined to a zone of junction of the Pripyat Trough northwestern part and the Belarussian Anteclise. The induced seismicity of the Soligorsk mining region has been investigated. The investigation involved an analysis of dynamics of the annual space and time migration of epicenter grouping zones, which depends on the pattern of the induced changes of the present crust dynamic stress field. Seismic events are mainly confined to recent active fault zones.

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We present a short review of the most recent results coming from the numerical modeling of seismic hazard and interpretation of the new observations provided by the recently installed seismic stations in Romania. There are still controversial questions related to the asymmetric distribution of the ground motion radiated by the Vrancea intermediate-depth earthquakes and which is the main factor responsible for this particular distribution: seismic source, structural model, site effects or vulnerability. Our main goal is to provide a solution to this key problem, with direct implications upon the seismic hazard assessment. NE-SW elongation of the isoseismals and the maximum values in the Romanian Plain are well explained by the source radiation pattern and the average structural model. The attenuation toward NW is shown to be a frequency-dependent effect, much more important in the high frequency range (≯1 Hz). We conclude that the present seismic hazard of Romania, computed by the deterministic approach, fits well, as a first approximation, the ground motion distribution for the low-frequency band, and the apparent contradiction with the historically-based intensity maps arises mainly from a systematic difference in the vulnerability of the buildings in the intra- and extra-Carpathians regions.

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Seismic coda Qattenuation (Q c) in the frequency range from 6 to 20 Hz of two distinct Scoda windows (early and later portions) are compared to analyse the effects of both coda windows on crustal seismic attenuation estimates around Samambaia fault (João CâmaraNortheastern Brazil). Q cvalues associated with the later portion are systematically higher than those related to the early portion. These values follow a frequency (f) function given by Q c(f) = Q 0 f , where Q 0= 11739 and= 1.000.06. In general, Q 0estimate is less sensitive to site effects and stabler than that obtained from the early portion of S coda waves, while its corresponding frequency dependence is similar to that obtained from the early portion of S coda waves. It suggests thatparameter does not depend on coda window's location along the seismic signal. A comparative analysis of both Q 0andvalues with those found recently shows that there is no difference in using early or later portion of S coda waves in the stations located on Pre-Cambrian basement in the João Câmara area. This comparison also shows that the major variations in Q 0values were observed at seismic stations installed on sedimentary terrain. Differences in the seismic attenuation, in both sides of the Samambaia fault, were also observed in this study, and it is in agreement with the hypothesis that Samambaia fault is a kind of boundary between two seismic attenuation zones.

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Abstract  

Due to the subcrustal earthquakes located at the sharp bend of the Southeast Carpathians, Vrancea zone in Romania has a high potential seismic hazard in Europe. Among several seismic precursors, radon anomalies in air, ground, and groundwater in the epicentral areas can be associated with the strain stress changes that occurred before and after earthquakes. In order to support this theoretical view, the main aim of this paper was to investigate temporal variations of radon concentration levels in air near the ground and in ground air by the use of solid state nuclear track detectors CR-39 and LR-115 in relation with some seismic events at two seismic stations Vrancioaia and Plostina, located in Vrancea active region. This paper reports essentially the observation of radon concentration levels in the air near the ground at 1 m height for the earthquakes that occurred during the period of November 2010–October 2011 and moment magnitudes M w in the range of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$2.0 \le M_{\text{w}} \le 4.9$$ \end{document}
. The average radon concentration in air above the ground measured with CR-39 detectors recorded for 1 year period in Vrancea area was 1,094.58 ± 150.3 Bq/m3 and 10 days fluctuations were placed in the range of 129 ± 40 Bq/m3 and 5,888 ± 700 Bq/m3. Also have been reported measurements of in soil radon concentrations in drill holes at 0.5 m depths during period of March 1977–October 1980, just after 4 March 1977, M w 7.4 Vrancea earthquake. The knowledge of air–ground–gas 222Rn anomalies is very important for earthquake pre-signals assessment as well as for precisely location of geologic active faults.
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Abstract  

South-Eastern part of Romania has a highest potential seismic risk in Europe due to the earthquake-prone Vrancea zone placed at conjunction of four tectonic blocks in the South-Eastern part of Carpathian Arc. This paper is an attempt to analyze the development of radon pre-earthquake anomaly in relation with moderate seismic events in Vrancea area through permanent monitoring with solid state nuclear track detectors CR-39 detectors. Radon in air above the ground was measured during 1 year period (November 2010–October 2011) in four selected test sites: Vrancioaia (VRI) and Plostina (PLOR) located in Vrancea zone, and Muntele Rosu-Cheia and Bucharest. During sampling period recorded earthquakes that occurred mostly in Vrancea epicentral region were minor-moderate of moment magnitudes in range of
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. The average radon concentration in air above the ground measured with CR-39 detectors and 10 days period recorded simultaneously at all test sites, registered the following values: (1) in Vrancea area (similar in VRI and PLOR) was 1094.58 
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 150.3 Bq/m3; (2) at Muntele Rosu-Cheia seismic station measured in a mountain tunnel laboratory was 3695.91 ± 440 Bq/m3; (3) at Bucharest station was 380.53 
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 69.17 Bq/m3, and 10 days CRn fluctuations in the range of (88 
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 40 to 912
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 130 Bq/m3). Clear radon anomalies, mostly at VRI and PLOR in Vrancea epicentral area as well as at Muntele Rosu-Cheia have been measured before seven minor earthquakes which were recorded in the range of moment magnitude
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in Vrancea area. Temporal variation of radon in air near the ground have been examined in relation with meteorological parameters like as air temperature, relative humidity, air pressure and wind velocity. Permanent monitoring of radon concentration anomalies in seismic area Vrancea is an important issue as surveillance tool in the field of earthquake hazard for Romania.
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