Properties of the Aftershock Sequences of the 2003 Bingöl, M D = 6.4, (Turkey) Earthquake     

S. Öztürk  H. Çinar  Y. Bayrak  H. Karsli  G. Daniel 《Pure and Applied Geophysics》2008,165(2):349-371

Aftershock sequences of the magnitude M _{W =}6.4 Bingöl earthquake of 1 May, 2003 (Turkey) are studied to analyze the spatial and temporal variability of seismicity parameters of the b value of the frequency-magnitude distribution and the p value describing the temporal decay rate of aftershocks. The catalog taken from the KOERI contains 516 events and one month’s time interval. The b value is found as 1.49 ± 0.07 with Mc =3.2. Considering the error limits, b value is very close to the maximum b value stated in the literature. This larger value may be caused by the paucity of the larger aftershocks with magnitude M _D ≥ 5.0. Also, the aftershock area is divided into four parts in order to detect the differences in b value and the changes illustrate the heterogeneity of the aftershock region. The p value is calculated as 0.86 ± 0.11, relatively small. This small p value may be a result of the slow decay rate of the aftershock activity and the small number of aftershocks. For the fitting of a suitable model and estimation of correct values of decay parameters, the sequence is also modeled as a background seismicty rate model. Constant background activity does not appear to be important during the first month of the Bingöl aftershock sequences and this result is coherent with an average estimation of pre-existing seismicity. The results show that usage of simple modified Omori law is reasonable for the analysis. The spatial variability in b value is between 1.2 and 1.8 and p value varies from 0.6 to 1.2. Although the physical interpretation of the spatial variability of these seismicity parameters is not straightforward, the variation of b and p values can be related to the stress and slip distribution after the mainshock, respectively. The lower b values are observed in the high stress regions and to a certain extent, the largest b values are related to Holocene alluvium. The larger p values are found in some part of the aftershock area although no slip occurred after the main shock and it is interpreted that this situation may be caused by the alluvium structure of the region. These results indicate that the spatial distribution in b and p values are generally related to the rupture mechanism and material properties of an aftershock area.  相似文献   

Simulation of 3-D Teleseismic SV-waves Accelerated by the Multilevel Fast Multipole Method     

Özcan Çakir 《Pure and Applied Geophysics》2008,165(9-10):1707-1732

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On the nature of the FBS blue stellar objects and the completeness of the Bright Quasar Survey     

A. M. Mickaelian  A. C. GonÇales  M. P. Véron-Cetty  P. Véron 《Astrophysics》1999,42(1):1-14

The second part of the First Byurakan Survey is aimed at detecting all bright (B < 16.5) UV-excess starlike objects in a large area of the sky. By comparison with other major surveys such as the ROSA T All Sky Survey, the ROSAT WGACAT catalogue of point sources, the IRAS survey, the 6cm Green Bank, the 1.4GHz NRAO VLA, and the 92cm Westerbork Northern sky surveys and with the catalogue of mean UBVdata on stars, we estimate the number of AGNs present in the FBS survey and its completeness. We have made spectroscopic observations of nine of the most promising FBS candidates. We have found six new QSOs, bringing the total number of known QSOs in this survey to 42. By comparison with the Bright Quasar Survey, we found that the completeness of this last survey is of the order of 70% rather than 30–50% as suggested by several authors. Based party on observations collected at the Observatorie de Haute-Provence (CNRS, France). The APS databases are supported by the National Foundation, the National Aeronautics and Space Administration, and the University of Minnesota, and are available at hup:// aps.umn.edu. The Digitized Sky Survey was produced at the Space Telescope Science Institute (STScI) under U.S. Government Grant NAG W-2166. Published in Astrofizika, Vol. 42, No. 1, pp. 5–22, January–March, 1999.  相似文献   

Reliability of Lifeline Networks with Multiple Sources under Seismic Hazard   总被引：2，自引：0，他引：2  

A. Sevtap SelÇuk  M. Semih Yücemen 《Natural Hazards》2000,21(1):1-18

Lifelines are networks extending spatiallyover large areas. Transportation systems, pipelines,communication and power transmission systems areexamples of lifelines. The performance of a lifelineafter a major earthquake is particularly vital for acommunity because of the emergency services that areusually required after such events. Performancemeasures are usually expressed in terms of quantitiesthat are assessed based on statistical andprobabilistic methodologies. The major performancemeasure is the probability of reaching from aspecified point to another one successfully after acatastrophic event, such as an earthquake. Evaluationof this performance measure requires a seismic hazardmethodology, capacity determination techniques andnetwork reliability assessment methods. By combiningthese three aspects in one model, it is possible tocalculate the reliability of any lifeline system underseismic danger. The aim of this paper is to present aprobabilistic model for the evaluation of the seismicreliability of lifeline networks having multiplesources. The seismic reliability of a waterdistribution system located in Bursa, Turkey isassessed in order to show the implementation of theproposed model. The numerical calculations are carriedout by the LIFEPACK software, which is developed forthis purpose.  相似文献   

Current velocity forecasting in straits with artificial neural networks,a case study: Strait of Istanbul     

Burak Aydog˘an  Berna Ayat  Mehmet N. Öztürk  Esin Özkan Çevik  Yalçın Yüksel 《Ocean Engineering》2010,37(5-6):443-453

Owing to their complex character, modeling flow patterns of narrow straits has always been a challenge, even with the numerical techniques of today. This study was aimed at predicting vertical current profiles of a given point in a narrow strait, the Strait of Istanbul. On account of the speed and simplicity it offers, and of its remarkable success in solving complex problems, the feed forward back propagation (FFBP) artificial neural network (ANN) technique was chosen for this study. The model was built on 7039 hours of concurrent measurements of current profiles, meteorological conditions, and surface elevations. The model predicted 12 outputs of East and North velocity components at different depths in a given location. Various alternative models with different inputs and neuron numbers were evaluated attaining the best model by trial and error. Predictions from proposed ANN model were in accordance with the observations with average root mean square error of 0.16 m/s. The same input parameters were then used to build models that predicted current velocities 1–12 h into the future. Results of these predictions show good overall agreement with observations and that FFBP ANN can be used as a reliable tool for forecasting current profiles in straits.  相似文献   

CCD <Emphasis Type="Italic">UBV</Emphasis> photometric study of five open clusters—Dolidze 36, NGC 6728, NGC 6800, NGC 7209, and Platais 1     

Z. F. Bostancı  T. Yontan  S. Bilir  T. Ak  T. Güver  S. Ak  E. Paunzen  Ç. S. Başaran  E. Vurgun  B. A. Akti  M. Çelebi  H. Ürgüp 《Astrophysics and Space Science》2018,363(7):143

In this study, we present CCD UBV photometry of poorly studied open star clusters, Dolidze 36, NGC 6728, NGC 6800, NGC 7209, and Platais 1, located in the first and second Galactic quadrants. Observations were obtained with T100, the 1-m telescope of the TÜB?TAK National Observatory. Using photometric data, we determined several astrophysical parameters such as reddening, distance, metallicity and ages and from them, initial mass functions, integrated magnitudes and colours. We took into account the proper motions of the observed stars to calculate the membership probabilities. The colour excesses and metallicities were determined independently using two-colour diagrams. After obtaining the colour excesses of the clusters Dolidze 36, NGC 6728, NGC 6800, NGC 7209, and Platais 1 as \(0.19\pm0.06\), \(0.15\pm0.05\), \(0.32\pm0.05\), \(0.12\pm 0.04\), and \(0.43\pm0.06\) mag, respectively, the metallicities are found to be \(0.00\pm0.09\), \(0.02\pm0.11\), \(0.03\pm0.07\), \(0.01\pm0.08\), and \(0.01\pm0.08\) dex, respectively. Furthermore, using these parameters, distance moduli and age of the clusters were also calculated from colour-magnitude diagrams simultaneously using PARSEC theoretical models. The distances to the clusters Dolidze 36, NGC 6728, NGC 6800, NGC 7209, and Platais 1 are \(1050\pm90\), \(1610\pm190\), \(1210\pm150\), \(1060\pm90\), and \(1710\pm250\) pc, respectively, while corresponding ages are \(400\pm100\), \(750\pm150\), \(400\pm100\), \(600\pm100\), and \(175\pm50\) Myr, respectively. Our results are compatible with those found in previous studies. The mass function of each cluster is derived. The slopes of the mass functions of the open clusters range from 1.31 to 1.58, which are in agreement with Salpeter’s initial mass function. We also found integrated absolute magnitudes varying from ?4.08 to ?3.40 for the clusters.  相似文献   

Period studies of five neglected Algol-type binaries: RW Cet,BO Gem,DG Lac,SW Oph and WY Per     

A. Erdem  S.S. Doğru  F. Soydugan  C. Çiçek  O. Demircan 《New Astronomy》2010,15(7):628-636

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Observations of faint eclipsing cataclysmic variables     

D. Zengin Çamurdan  C. İbanogˇlu  C.M. Çamurdan 《New Astronomy》2010,15(5):476-482

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Is NP Aqr a new near-contact binary?     

C. İbanogˇlu  Ö. Çakırlı  A. Dervişogˇlu 《New Astronomy》2010,15(4):373-379

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The effects of urbanization on water vapour pressure in a semi-arid climate     

İ. Çiçek  N. Türkoğlu 《Theoretical and Applied Climatology》2009,95(1-2):125-134

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