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8th Congress of the Balkan Geophysical Society
- Conference date: October 5-8, 2015
- Location: Chania, Greece
- Published: 05 October 2015
61 - 80 of 124 results
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Consideration about Deep Structure in Vrancea Zone from Gravity Data
More LessSummaryThe paper objective is to contribute to the clarification of the deep structure of the curvature Carpathians Vrancea by gravimetric and geodetic data interpretation in plate tectonics concept, conceptual models of the lithosphere, able to explain the increased seismicity in this area. Developing models that help explain the lithosphere geological structure of the upper crust, helping to elucidate the causes which contribute to the production of intermediate earthquakes in the Vrancea area.
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The Impact of Geomagnetic Storms for the Energy Sector
Authors L. Asimopolos and N.S. AsimopolosSummaryThe growth in intensity of induced geomagnetic current scan affect terrestrial infrastructures such as power electric networks, oil and gas pipes, telecommunications cables and railway circuits. The practical importance of this subject consists of the fact that the networks of transport of electric energy are the most important ones from the point of view of the destructive effects of induced geomagnetic currents. Their effect increases with the extension of electric networks, including continental interconnections.
The intensity of the induced currents depends by the characteristics of geomagnetic field, the soil resistance in the area in which is carried out the coupling field with the power system components, the spatial extension of the coupling area, the treatment of neutral network in which occurs the phenomenon. The circulation of CGI in the system components produces abnormal operating regimes resulted, in most cases, with the disconnection of an important part of the network affected.
The larger and larger dependence of society on the availability, reliability and security of the energetic system is uncontested.
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An Amplitude/Phase approach to the Interpretation of Magnetic Anomalies
More LessSummaryAeromagnetic data is widely used to prospect for many different minerals. A first step in many exploration projects is the use of a semi-automatic interpretation method that provides initial estimates of source parameters that can be refined by later modelling and inversion. Many such techniques exist, such as Euler deconvolution ( Thompson, 1982 ) and the Tilt-Depth method ( Salem et al, 2007 ). This abstract shows that by separating the magnetic anomalies of dykes and contacts into amplitude and phase portions their dip can be obtained.
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Nonlinear Inverse Modeling of Magnetic Anomalies due to Thin Sheets and Cylinders Using Occam’s Method
Authors R. Ghanati, H.A. Ghari, M. Mirzaei and M.K. HafiziSummaryThis paper is focused on inverting geophysical magnetic data due to simple shape anomalies including thin sheet and cylinder using Occam’s inversion scheme. A significant aspect of using Occam’s inversion is the choice of the regularization parameter controlling the trade-off between the data fidelity and regularization term in the cost function of optimization problem, and consequently, reliable estimation of subsurface models. Two criteria L-curve and weighted generalized cross validation (W-GCV) are considered in order to choose an optimum value of the regularization parameter. The proposed strategy was first tested on two theoretical synthetic models for each of the magnetic simple-shaped structures with different random errors, where a considerable agreement was obtained between the assumed and calculated models. The validity of the technique was also applied to one real data set from Morvarid iron-apatite deposit, in Northwest Iran. The correlation between the results derived by the proposed algorithm and corresponding known geologic features was reasonable.
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Gravity and Magnetic Potential Fields for the Western Black Sea Region - Marine and on Land Maps with High Resolution
Authors B.K. Ranguelov, M.S. Bayraktutan, R.S. Radichev and A. S. KisyovSummaryDuring the sea and on land expedition campaigns (2011–2012–2013), complex geophysical measurements have been performed on the board of the specialised geophysical vessel “Mare Nigrum” – Romania. Then, after the data processing, several maps have been produced. The onboard measurements included high resolution bathymetry by multiple beam equipment, total magnetic field vector measurements by a marine magnetometer with high sensitivity, gravimetric on board measurements and salinity deep profiling from time to time. The marine complex geophysical measurement profiles have been separated by a distance of 1 km and covered the deep sea waters, limited to the coast by the waterline of the ship.
Two years later, on land measurements of the gravity field (Bouguer anomaly), total vector of the magnetic field and gamma radioactivity background, have been performed on surface elongated S-N single profile with a measurement step from 200–300 meters.
The purpose of these measurements was to support the creation of unified on land and marine maps.
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Determination of Discontinuities Using Bouguer Gravity Map of Hatay (Turkey) and Its Surroundings
By F. DogruSummaryEdge detection and edge enhancement techniques play an important role in interpreting potential field data. There have been various edge detection applications to gravity data in order to determine the edges of subsurface structures in geophysics. The edge detection methods comprise analytic signal, total horizontal derivative (THDR), theta angle, tilt angle, hyperbolic of tilt angle (HTA), normalised total horizontal gradient (TDX) and normalised horizontal derivative (NTHD). In this study, wavelet transform method and boundary analysis techniques are applied both synthetic models and field data. A Bouguer gravity data set from city of Hatay (Turkey) and its surroundings is used for field data and results are compared.
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Western Boundary of East European Platform in Romania as Interpreted on Gravity and Magnetic Data
Authors D. Ioane and I. CarageaSummaryThe geophysical detection of the western EEP boundary at crustal depths, south of the junction with the Carpathian Mts, represents an important geotectonic information when improving regional crustal models. Such geophysical and tectonic models are of great value in SE Europe, where the Vrancea seismogenic zone is generating high magnitude earthquakes at crustal and intermediate depths.
Satellite and ground Gravity and Magnetic regional data are integrated and interpreted in view of a better understanding of the TESZ southern continuation and location of the western EEP boundary.
The integrated interpretation of both satellite and ground Gravity and Magnetic data offers detailed information on the western boundary of the East European Platform at continental or regional scales.
The interpretation of gravity stripped map of Romania illustrated the EEP western boundary at crystalline basement depth and at lithospheric depth, respectively.
Based on the satellite magnetic and the gravity stripped maps, the eastern part of the Moesian Platform is interpreted to have geophysical EEP affinities (high magnetic properties and higher density) than its western part, the Intramoesian Fault being considered as a regional tectonic contact.
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Depth Determination of Simple Shaped Bodies from Gravity and Magnetic Anomalies by Using Walsh Transforms
Authors C. Sari, M.A. Gungor and F. UzunSummaryWithin the scope of this paper, Walsh transform was applied to the total magnetic field and gravity anomalies obtained from the ideal subsurface structures and the field studies and the possibility of this method for the calculation of the depths to the source structures was investigated. This method is based on the Walsh transformation which can be applied to the total magnetic field and gravity anomalies. In this method, initially normalized energy density (NED) spectrum, then the differential energy density (DED) spectrum would be obtained. DED spectrum is the difference between two successive sequency numbers of the NED. The maximum value of sequency numbers (Imax) on DED spectrum is determined and, the depth of the subsurface structure that caused the anomaly can be computed by using of this value in the proper equation. The monopole, line of monopoles, dipole and line of dipoles models were chosen as the ideal subsurface sources for magnetic and sphere, infinite extend horizontal cylinder and semi infinite vertical cylinder for gravity in the theoretical studies and and the anomalies of these structures can be calculated. The depths of the subsurface structures were estimated by using Walsh transform method to the field data and the obtained results were compared with the previously calculated depth with the various other methods. Furthermore, the theoretical and the field magnetic and gravity anomaly data were evaluated with using Fourier-Power Spectrum method.
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Investigation of Sultana and Sultan Hamam Walls at Topkapı Palace with Non-destructive GPR-CX Method
Authors C. Yalciner, Y.C. Kurban, E. Altunel, A. Buyuksarac, M.I. Topcu and E. BelceSummaryHamam structures, which hold an important place in the Ottoman İmperial and public, are notable for its architecture as well as durability. Sultana and Sultan Hamam at Topkapı Palace is one of the most important Hamam in Ottoman History, which constructed centuries ago. To investigate the robustness of this Hamam by non-destructive examination with the GPR-CX (Ground Penetrating Radar — Concrete Exploration) method was carried out.
Mainly GPR-CX method was improved for investigate modern concrete walls and systems, as well as the high resolution and speed with non-destructivity made the system suitable for ancient buildings. In this study 2.3 GHz HF antenna was conducted with a 100×100 cm grid area to all the walls of Hamam and the Tubulis (heat duct), lead water pipes etc. were discovered. In addition the metal clamps of wall connections were also found and contributed to the static studies.
By courtesy of non-destructive GPR-CX method, many unknown data were put forward about Hamam, which were constructed at 1460 AD.
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Investigation of Disturbance on Gallery Floor of Hagia Sophia Museum with GPR Method
Authors Y.C. Kurban, C.C. Yalciner, E. Altunel, A. Buyuksarac, M.I. Topcu and E. BelceSummaryThe Hagia Sophia Museum has an important place in both Byzantine and Turkish history, which was constructed by Emperor Justinian in 532 – 537 AD. After get over many large earthquakes and disasters, the Hagia Sophia Museum has maintained its existence until nowadays with repairs and renovations at various times.
In this study, the crack in the Gallery floor ground and the condition of the vaults, which are located between Gallery floor and the main hall of the Hagia Sophia Museum were investigated by GPR (Ground Penetrating Radar) method with 1 GHz HF (High Frequency) antenna.
The obtained data revealed quite clearly, the deterioration in the vault structure located under the Gallery floor. In the same time it has also revealed the work to strengthen the reinforced metal system made at this level. GPR results showed that, the strengthening work larger than the strengthening work mentioned in many older sources at the Hagia Sophia Museum, and these new results contribute to the future static studies. After this successful GPR study, the new project on the walls and the basements of the Hagia Sophia Museum was started with GPR and GPR-CX (Ground Penetrating Radar — Concrete Exploration) methods.
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GPR Survey at the Venetian Fortification Walls of Chania
Authors N. Spanoudakis, A. Vafidis and C. BourbouSummaryIn this paper we present the results of a Ground Penetrating Radar (GPR) survey for the detection of a demolished part of the Venetian walls of Chania, Crete, Greece. It is part of the collaboration of the local Ephorate of Antiquities and the Laboratory o Applied Geophysics, Technical University of Crete, for the detection of buried antiquities, for the urban planning of the city. The GPR time slices, depict a linear anomaly in the west to east direction which is interpreted as the extension of preserved parts of the wall.
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Employing CEEMD for Improving GPR Images - A Case Study from a Neolithic Settlement in Thessaly, Greece
Authors M. Manataki, A. Sarris and A. VafidisSummaryIn this study we apply Complete Ensemble Empirical Mode Decomposition on several GPR lines derived from a survey at Magoula Almyriotiki, a Neolithic settlement in Thessaly, Greece where buried structures are identified but are obscured by noise. The workflow we followed consists of a preprocess step (time zero, dewow, gain and background removal) followed by decomposition with CEEMD. The modes that exhibit less noise and at the same time gather all the reflections from the buried houses, were the third and the fifth IMF. Their summation was then used to calculate instantaneous envelope and to extract slices. From the obtained results the images are significantly improved highlighting further details of the buried antiquities, suggesting that CEEMD is a promising tool for processing GPR data when combined with standard filters and corrections.
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Performance of a Ground Penetrating Radar Antenna in Heterogeneous Environments
Authors C. Warren, I. Giannakis and A. GiannopoulosSummaryUnderstanding how energy is transmitted and received by Ground Penetrating Radar antennas is crucial to many areas of the industry: antenna design, data processing and inversion algorithms, usage of antennas in GPR surveys, and interpretation of GPR responses. The radiation characteristics of antennas are usually investigated by studying the radiation patterns and directivity. For GPR antennas it is important to study these characteristics when the antenna is in environments that would typically be encountered in GPR surveys. Physically measuring antenna radiation patterns in such environments presents many practical difficulties, and there have been very limited numerical studies that combine real GPR antenna models with realistic environments. This paper presents a numerical investigation of the radiation characteristics of a high-frequency GPR antenna in a realistic environment. An advanced modelling toolset has been developed that enables detailed models of GPR antennas to be used with realistic heterogeneous soil models. In this initial investigation small differences in directivity have been observed between a lossless dielectric environment and a more realistic environment featuring a heterogeneous soil model. These findings are part of an on-going full parametric study incorporating a range of different soils, fractal weightings and also the inclusion of rough surface modelling.
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Mapping of the Bauxite Ore Surface Using 3D Ground Penetrating Radar Data
More LessSummaryThe major goal of the study is test the ability of Ground Penetrating Radar (GPR) to determine the depth and thickness of bauxite layer at Az Zabirah town, north-central of Saudi Arabia. Bauxite is the most important aluminum ore. the 25 MHz frequency antenna has been used in this study insure better resolution of the subsurface and to get more penetration to image the Bauxite layer. (GPR) survey was conducted above 28 borehole, Where was taken seven profiles. Results showed the calculated total volume of bauxite in the survey area based on the GPR data is about 34696 m3 while that based on the borehole data is about 34101 m3. The minor difference in the calculated volumes (about 1%) indicates that the GPR data is more readable and could replace the borehole data or reduce the number of drilled holes.
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Investigating the Geophysical Characteristics of Gypsum through GPR
Authors M.S. Sari and Ö.B. BektaşSummaryGypsum crops out widely in the areas where the urbanization is intense in Sivas city center. In this study, in an appropriate selected area, geophysical characteristics and structure of gypsum have been investigated by applying geophysical methods of GPR (Ground Penetrating Radar). GPR measurements have been taken as 11 profiles with a Ramac GPR device by using 250 MHz shield-antenna. The distance between each profile has been taken as 2m and the length of each profile has been taken as 50m. All the area has been surveyed and ground radar sections have been obtained by GPR method. Gathering all the data, it has been found out that the areas with strong reflections (for the first 5m. depth) revealed in ground radar sections are not homogeneous massive gypsum bodies as presented in geological studies and contain different size and position fill material (clastic material). In addition, investigating such areas through GPR method has enabled to reveal the geophysical characteristics of the region as gypsum contains fractures-cracks, fillings and dissolution spaces.
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A GPR Study in the Roman Villa of Tourega, Portugal
Authors A.M. Correia, J.M. Maillol and B. BerardSummarySeveral radar surveys were conducted on the site of the Villa Romana da Tourega with a Sensors and Software ground penetrating radar (GPR). The main objective of the work was to test new GPR acquisition method. For this purpose, this site is ideal as it offers already excavated structures and very clear evidence of still buried continuation of these structures. For a successful completion of the tests in a timely manner it was necessary to have a high degree of certainty that buried structures were indeed present in the selected area. Only a portion of the results obtained during the field work are shown.
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Determination of Heavy Metal Contamination in Aliağa-İzmir Industrial Region with Magnetic Susceptibility Measurements
By C. SariSummaryEnvironmental pollution which is caused by industry increases with development of industry day by day. Especially hazardous particules including heavy metals are spread by industral plants cause health diseases on people and result with soil pollution. Main aim of this study is searching about heavy metals cause soil pollution and give damages to soil that are bruited by factories in industial zone and other plants. Field studies were carried out in an industrial zone in Aliağa district of İzmir. In Aliaga Industry District, the research about heavy metals cause pollution on the soil is done by applying measurements of magnetic susceptibility. Pollution investigation is performed in three different zones with the high resolution device produced by Bartington Company. While the expected mean values are between 0-50×10-6 cgs in the areas, the measured values are obtained higher 10 and 20 times than the normal values.
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To Determine a Place for the New Production Well by Seismic Inversion
Authors R. Aliev and T. AkhmedovSummaryIn this research work, we applied the most popular and effective method - Seismic Inversion. Seismic Inversion successfully fulfilled for this process. Our aim is to find a place of production well by Seismic Inversion. We used our special and new programs. Our programs differ from other companies’ programs.
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EUXINUS - Black Sea Security System - Two Years of Operation
Authors V. Radulescu, G. Oaie and I. SamoilaSummaryThe paper analyzes the first two years of activity of EUXINUS, the first early warning and monitoring system for marine hazards in the Black Sea, a network managed by the National Centre for Early Warning and Monitoring of the Marine Natural Hazards (GeoEcoMar - Constanta Branch, Romania). Since 2013, GeoEcoMar, as an institution dedicated to the research of the marine areas and using the financial support from the CBC Romania — Bulgaria Program, through MARINEGEOHAZARD Project (2010 – 2103), has built a complex network of three moored oceanographic buoys, one coastal gauge, a 2D seismic system (96 channels streamer), and an operational data center.
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Solar Influence on Decadal Climate Cycles over Balkan Peninsula
Authors Ya. Chapanov, M. Atanasova and N. NikolovaSummaryThe solar activity cycles affect various parameters of surface areas, including rains, snow covers, river streamflows and other hydrological cycles. These processes are due mainly to the total solar irradiance variations, followed by weather and climate changes. The interconnection between the solar cycles and decadal climate changes over Balkan Peninsula is investigated by means of reconstructed Total Solar Irradiance TSI, precipitation and temperature over Balkan Peninsula for the period 1766–2000 and measurements from station Sofia for 1901–2013. The decadal oscillations of precipitation, temperature and TSI with periods corresponding to the sunspots (11 years), solar magnetic cycle (22 years), equatorial solar asymmetry (45 years) and Gleissberg cycle (70–100 years) are compared and analyzed. The possibility to create decadal forecast models, based on solar activity cycles, are discussed.
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