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5th Congress of Balkan Geophysical Society
- Conference date: 10 May 2009 - 16 May 2009
- Location: Belgrade, Serbia
- Published: 10 May 2009
61 - 80 of 134 results
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Sensing the Earth's low ionosphere during solar flares, using VLF signals and GOES solar X-ray data
By A. KolarskiSimultaneous analysis of the effects of M2.5-class solar flare event on VLF signal amplitude and phase delay variations for the GQD/22.1 kHz and NAA/24.0 kHz signal traces was carried out. Solar flare data were taken from GOES12 satellite one-minute listings. The VLF data recordings were performed at the Institute of Physics, Belgrade, Serbia, by the AbsPAL system. It was found that a single solar flare event changes the lower ionosphere electron density height profile, in dependence of the Earth-ionosphere waveguide characteristics. The values of the parameters sharpness and reflection height during flare conditions have been evaluated for two traces considered.
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Common Reflection Angle Migration for improved prediction of structure and reservoir in structurally complexe regime
Authors R. Oezsen and C. GregoryWe present a new seismic subsurface imaging technology for generating high-resolution, amplitude preserved angle dependent reflectivity gathers and image volumes in the local angle domain. Such local angle domain common image gathers can be obtained from a multi arrival, ray based Common Reflection Angle Migration (CRAM) creating a uniform illumination at the image points from all directions. In order to improve initial velocity models, residual move-outs associated with CRAM gathers on the subsurface image points are measured by automatic picking of horizontal or vertical semblances along the geological horizons, smoothed and used in vertical and/or tomographic update. Anisotropy parameters are successfully tested using CRAM on land and transition zone data sets, examples of isotropic and anisotropic CRAM imaging results are shown in comparison with conventional Kirchhoff Migration.
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Some New Results of the Analysis of the Lanzarote (Canary Islands) Magnetic Anomaly with Elementary Sources-Final Dipols
Authors Zh. P. Zhelev, T. Petrova, F. Montesinos, R. Vieira, J. Arnoso and A. CamachoObtaining the main parameters (location and magnetudes) of the sources of the Lanzarote (Canary Islands) Geomagnetic anomaly with elementary sources through optimization. Interesting results are obtained.
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Use of Multichannel Analysis of Surface Waves in Near Surface Investigations for Housing Purposes
Authors A.E. Babacan and K. GelisliIn the last few years, many soil investigations have been carried out to determine the response of the subsurface structure to dynamic strengths in areas where multi-storey buildings are thought to be constructed. The calculation of the shear wave velocity, the information about the dynamic elastic properties of the underground layers obtained from these velocities and soil response are fundamental in these studies. Although the shear wave velocity is found by using different methods, the difficulties which appear during these applications have prompted scientists to search for alternative methods. One of these methods is the multi-channel analysis surface wave. Surface wave measurements were taken to calculate shear wave velocities using the seismic refraction method along three profiles in Trabzon where a housing project has been planned. Since Sera Lake Landslide has already occurred near the study area, geophysical investigation is necessary in this potentially dangerous area. Dispersion curves were obtained from f-k transformation applied to shot gathers. 1-D Shear wave velocity was determined by performing the non-linear least square method on these curves. Interpretation of the resulting data will help the geophysicist to conclude whether the area is building land or not.
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Turkey's Disaster Archive System
By D. AkinTurkey, due to its geological, topographical and meteorological conditions, is often faced with major natural disasters. In those regions which experience natural disasters, losses are increasing more and more because of population density and extent of economical activities. In order to create a more resistant society against natural disasters, it is necessary to be successful in every phase of the disaster management. Therefore the importance of knowledge about the previous disaster events, which researchers and decision-makers should have, is increasing. In developing countries which have poor social memory such as Turkey, this issue is very significant. In order to awaken the social memory, these events should be archived. In the global world, an archive is a very important knowledge base which sheds light on the future from a record of the past. Decision-makers, researchers and executives should build their policies and strategies on this knowledge. In recent years, public archives have been opened to researchers in the internet. Therefore, the General Directorate of Disaster Affairs (GDDA) is aiming at contributing to this process by developing a National Disaster Archive System. This project was given priority to earthquakes, landslides, floods, avalanches, rock falls, which affect Turkey most. The GDDA archive contains more than 18.000 disaster files that have been scanned, and nearly 4500 files which meet these archive’s criteria have been transferred to the system. In the next phase, we will be in contact with other institutions; and natural and technological disaster data, which are in the archives of these institutions, will be entered into the system as well. In conclusion, an archive system, which could be accessible by researchers from at home and abroad, developed. In this paper, information about the aim, scope, targets, types of the archives, archives criteria of the Turkish National Disaster Archive System (TNDAS) were presented.
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The Relationship between Magnetic Susceptibility and Element Ratios of Clay Samples Collected Different Sites of Turkey
Authors A. Aydin, I. Cobanoglu and S.B. CelikIn this study, the measurements of magnetic susceptibility are taken on the clay samples at the laboratory and the results were correlated with oxide element ratios. The clay samples were collected from 21 different sites of Turkey. The chemical analyses were done using the XRF analysis equipment. High correlation coefficient between magnetic susceptibility measurements and some element ratios are observed. Especially FeOt, SiO2 and Al2O3 gave very good correlation coefficient; that are 0.76, 0.81 and 0.61 respectively. Good correlation between magnetic susceptibility and pH values which is 0.70 is also obtained. Data of MS and its frequency dependence are also presented, and their relation with the chemical analyses results is discussed.
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Pollution Analysis with Magnetic Susceptibility Measurements in Denizli, Turkey
By A. AydinIt was showed the relation between the contents of heavy metals and the magnetic susceptibility and the distributions of the pollutions in the surface soil in part of Denizli, Turkey. We saw the pollution sources and distributions dimensions which are one of the most important environmental threats. Distributions of heavy metal pollution in the area were tried to show by using 111 field measurements, 111 field samples and 50 near road samples. It was used showing the distribution of heavy metallic elements deposited from exhaust gases and fumes chimney in area near the high way and around. Figure1 shows that the dot shows the position of magnetic susceptibility samples points, the contour maps of low and high magnetic susceptibility and frequency dependent and it is given that the contour maps of Cr and Pb, the dots shows the position of samples in Figure 2. It was showed the pollutant distributions after mapping the data of magnetic susceptibility and showed their sources to assess environmental threats. Magnetic susceptibility method is cheaper and less time-consuming against chemical methods. We showed that it is enough only using magnetic susceptibility measurements could provide heavy metal pollution distribution in residential areas.
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Geophysics...........Earth & Ocean Sciences
By A.E. AdebayoGeneric Mapping Tools (GMT) version 3 has been released and is available free of charge via Internet. The package contains all software source codes, manual pages, and documentation as well as the new shoreline databases. Over the last 4 years we have received many helpful suggestions and bug reports from GMT users. For Version 3 these bugs have been fixed, and some of the easier suggestions for improving version 2.1.4 have been incorporated. In compiling GMT version 3, we have leaped several difficult hurdles to make three major improvements.
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Feasibility of Underground Stress Estimation by Combined Use of Time-Lapse P-P and P-S Seismic Data
More LessIn the following discussion a new methodology is developed which relates seismic travel time changes to subsurface stress variation. Rock saturation state which has a combined effect with pressure on seismic data is assumed to be irrelevant since time lapse seismic here is not intended for oil reservoir monitoring but to examine if it can be used as a tool to monitor subsurface stress variation around seismically active faults. This technique is based on empirical relationship between rock stress and velocity that is derived during laboratory ultrasound core measurements. The relationship is then theoretically connected to seismic P-P and P-S travel times to develop a relationship between seismic travel time variation and changes in stress magnitude. When common values of stresses are applied in the equation, promising seismic P-P and P-S travel time sensitivity is observed. This strong sensitivity of time-lapse seismic travel times to stress variation can be used to monitor stress condition at hazardous area around faults.
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Evaluation of ambient noise levels at selected digital stations of the Bulgarian National Seismological Network (BNSN)
Authors L.D. Dimitrova and S.B. NikolovaAn evaluation of the ambient seismic noise for five digital broadband BNSN (Bulgarian National Seismological Network) stations is presented. The Power Spectral Density (PSD) and Probability Density Function (PDF) are calculated using data from winter month (February 2006) when high noise level is observed. The method applied allows using data contaminated with earthquakes and other “disturbing” signals due to their low-level probability of occurrence. Selection of seismic stations was done in order to comprise different site conditions, which highly influence the ambient seismic noise. The results obtained are of substantial importance for evaluation of the existing seismic broadband station performance as well as for the site selection for new stations.
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Bati Raman Oilfield, PNN™ Tool Application Cased Study
Authors M.J. Jakelic and A.P. PreglejBatı Raman field is the largest oilfield in Turkey, having an estimated 1.85 billion barrels of heavy oil reserves. It contains low-pressure, low gravity (10-13° API) oil at an average depth of 1300 m (4300 ft). The field was first put into production in 1961 and had produced 1.5 % of its reserves by 1986, when Production Company began immiscible CO2 gas injection. Since year 2000 production rate is drastically declining and the company seeks the ways to increase CO2 sweep efficiency. The expectation from the analysis done with PNN™ Tool was to locate CO2, estimate water saturation, detect unswept zones, and determine contribution of the perforations to the production. Logging task was to locate CO2, estimate water saturation, detect unswept zones, and determine contribution of the perforations to the production. Using processing and presentation of data it was possible to evaluate PNN water saturation (SWPNN), PNN porosity water (PORWPNN) and oil reserves. Measured intervals cover predominantly limestone and dolomitic limestone reservoirs, both containing some shale. Comparing saturations from the Open Hole and PNN measurements, it is notable that more producible oil is still present in the formation.
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Active and passive seismic integration by 3D tomography
Authors A.L. Vesnaver and L. LovisaMicroseismicity is better observed when receivers are located in wells, because the ambient noise is much lower. On the other hand, the standard Wadati’s method is not reliable for estimating the time origin in that case, as the Vp/Vs ratio can not be assumed to be constant for all events. This problem can be fixed adding further receivers at the Earth surface for the time origin estimation. Finally, using jointly surface and borehole receivers, we can better locate the hypocentres, illuminate the reservoir by seismic tomography and highlight possible fluid pathways. The enhanced Earth’s images so obtained can enhance processes as hydrocarbon production, gas storage and CO2 sequestration.
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The Period and Amplification Map of Bartin by Means Ambient Noise Measurements
Authors M. Mirzaoglu and D.P. SahinbazThis paper describes the results of the study of ambient noise measurements at Bartın, which is located in Northwestern part of Turkey. Seismic noise measurements were carried out in the interested area at 200 sites. Short periods (less than 1 second) were taken into account at the main peak in the spectral ratio between the horizontal and the vertical components. Two maps showing the spatial variations of the predominant periods and seismic amplification according to Nakamura technique in the investigated area were drawn. The analysis results show that within the investigated area, Northern part of East-west trending Bartın creek and in additions to that Western and Eastern part of North-west trending Bartın creek have shown relatively high predominant periods and high seismic amplification. This result is well-adjusted with the geological effect on seismic amplification.
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National Strong Motion Network of Turkey
Authors M. Akif Alkan, T. Kuru, S. Karakisa, A. Apak, D. Kokbudak, E. Cakir, S. Altiok, H. Albayrak, Y. Iravul and B. TuzelStrong Motion Network of Turkey was established in 1973 at Earthquake Research Department under the Ministry of Public Works and Settlement General Directorate of Disaster Affairs.The first strong ground motion had been recorded in 1976 and all the earthquakes of the year 1976 have been recorded by our network.
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An Approach of Socio-Environmental-Economic Aspects towards Geothermal Sustainability
More LessSustainability is a slice of those three different aspects which have close relationship each other towards integrate of its essence. It might not the first study that is keenly focusing on the sustainability case, it also shows the specification of each aspect and the whole relationship as an integrating system. Each aspect then spread into social progress, environmental protection, and economic growth. Later, they will be sliced become eco-efficiency (economic-environmental), socio-economic, and socio-environmental. From its interaction, there will be a point as sustainability in geothermal system.
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Geothermal Potentials of the Banja Luka Region
Authors B. Ivankovic and P. BegovicIn the past decade, the demand for new energy sources is getting momentum, and many efforts are being made in an attempt to develop new sources of energy and their more efficient exploitation. Banja Luka is located in the west of Republika Srpska (B&H), and within a radius of 20 kilometres three zones of discharge of thermo mineral water have been detected. The aim of this paper is to point out to the geothermal potential of the Banja Luka region as well as to provide direction for further research and the possibilities of the multipurpose use of those waters.
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2D Inversion of Magnetotelluric Data by Sequential Use of Smoothing Regularized Inversion and Quasi-Newton Inversion
More LessMagnetotelluric (MT) method is one of the electromagnetic method with which the very deep underground structure can be investigated. Nowadays, MT data mostly collected each station along a profile and this data set interpreted by the help of two-dimensional inversion algorithm. In this study, to invert MT data sequentially, we suggested to use smoothing regularized inversion and Quasi-Newton inversion algorithm that is called hybrid solution. We compared smoothing regularized inversion, Quasi-Newton and hybrid inversion results for both synthetic data and real data collected for oil exploration in east part of Turkey.
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Tsunami investigations in the Black Sea (Bulgarian experience to the EU SCHEMA Project)
Authors B.K. Ranguelov and G.H. MardirosianSCHEMA is the acronym of the Scenarios for Hazard-induced Emergencies Management Contract No: 030963 with EC of the PF6 Priorities (Space). Duration – 36 months, 12 Partners organizations from France, Portugal, England, Italy, Greece, Morocco, Turkey and Bulgaria The Project is constructed by several working packages - Lessons learn by the previous experience - 5 test site areas are under investigation - Morocco: Rabat region; Bulgaria : Varna region on Black sea – Balchik town is a representative sample; France : Mandelieu , Cote D’Azur; Portugal : Setubal; Italy : Catania, Sicily. The main task of the Project is to satisfy the end-users requirements about the possible prevention and protection actions to the population of the threaten test sites.
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The most ancient salt production factory in Europe and the oldest seismic event documented to the region of Provadia
Authors B.K. Ranguelov and V. NikolovAbout 5400 BC, the Neolithic people started to produce salt to meet their needs, at a place called now Provadia. A large salt body served as a source of this prehistoric factory, that produced the most important and vital product of the early farmers. This unique site in Europe excavated by the team of Prof. Vassil Nikolov shows the history of this place. Huge industry was developed and functioned more then 1000 years. Thick walled pots and hearths for the brine evaporation have intensively been produced, and can be seen now. It is possible to consider the prehistoric earthquake that occurred about 7000 years ago and destroyed the Chalcolithic dry-stone fortifications as a natural hazard interrupting for some time the salt production. A lot of facts, evidences and a hypothesis about such an event are presented to support this conjecture.
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Classifications, Management and Aerospace Methods for Natural Hazards Studies
Authors B.K. Ranguelov, N. Marinova, G.H. Mardirosian and E.N. SpassovThe last year’s world hazardous events (tsunamis, earthquakes, hurricanes, floods, etc.), generated a lot of discussions about the effectiveness of the space research technologies. The introduction of the high technologies in the everyday practice, fast communication systems and recent hardware and software, allows considering that early warning systems can play an important role in the population protection and safety. The concept of the destructive potential is introduced and several classifications about the different natural hazards and their possible negative influences are constructed.
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