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6th Congress of the Balkan Geophysical Society
- Conference date: 03 Oct 2011 - 06 Oct 2011
- Location: Budapest, Hungary
- Published: 03 October 2011
41 - 60 of 158 results
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Electromagnetic Profiling for Pollution Studies on Land Contiguos with a Landfill Facility in Kumasi, Ghana
By V.S. AsareThis study aimed principally to ascertain if any, and to what extent, leachate has communicated into the adjoining lands from the operation of the landfill facility. In this investigation an EM ground conductivity survey was done using Geonics EM34-3 instrument. The EM34-3 has three intercoil spacings of 10, 20 and 40 m to vary the effective depth of exploration from 7.5 m to a maximum of 60 metres. Traverse lines were located at both sides of a creek into which the treated effluent is discharged. The equipment was set at 10 m, 20 m and 40 m interval spacing in both the vertical and horizontal dipole modes. At each station the horizontal dipole (HD) mode reading was taken first, followed by the vertical dipole (VD) mode, to probe different depths based on the respective intercoil spacing. Regions close to the banks of the stream were found to have high terrain conductivity but only limited to roughly 30 m on both sides of the creek. The apparent conductivity values are however, mitigated at depths. The results of the study, for now, do not project an eminent threat to the groundwater system.
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Integration of Geological and Geophysical Data in Thrace Basin, Turkey and Modeling of Gravity Anomalies
Authors A. Aydemir, D. Demir, F. Bilim and A. AtesThe Thrace Basin located in the European part of Turkey is the most important basin for natural gas production. In this work, the geology and geophysical data of Thrace Basin are integrated in respect of natural gas potential and to determine the possible “kitchen areas” for hydrocarbon generation. Although the region has been investigated by the petroleum geologists and geophysicists for a long time, the thickness of the sedimentary units is still under debate. In this study, the basin was modelled from the gravity data and it was correlated with the available seismic data. In the conclusion, a good consistency between two different data sets was obtained and depth of the sedimentary basin was found changing from 3 km to 7 kilometres.
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Geopgysical Investigations in Cankiri-Corum Basin, Turkey
Authors A. Aydemir, Y. Aslan, A. Buyuksarac, N.Y. Erik and A. AtesThe Cankiri-Corum Basin is one of the most important Tertiary basins located in the central Anatolia, Turkey. This basin is situated on a complex region and it can be classified as an “unexplored” basin. In this study, gravity anomalies, seismic and borehole data were used to investigate sub-surface structure and thickness of the sedimentary units in the Cankiri-Corum Basin. 2D modelling results of the gravity anomalies with the correlation of the seismic sections indicate that there is good consistency for a basin-fill composed of sedimentary units with thickness of 5 km. This thickness is enough for the hydrocarbon generation in case of having possible source rocks in the deeper parts of the basin that could be accepted as the “kitchen area”.
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Geophysics Entering INSPIRE
By L SőrésGeophysics is going to be involved in the INSPIRE process as part of the Geology theme of Annex II. The first public version of the data model (v2.0) was released in June 2011 (INSPIRE Thematic Working Group Geology [2011]). Consultation and testing period will be closed in October 2012. The core data model will become part of the European legislation and will control the data provision of Legally Mandated Organisations (LMO). To support the INSPIRE framework directives with a coherent data model an application schema for geophysical feature types were specified. The Data model is based on ISO and OGC standards and the INSPIRE General Concept Model. It supports two schemas, a simple one for legal data provisioning obligations and an other one for more detailed data descriptions.
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Enhancement of Linear Features from Gravity Anomalies by Using Curvature Gradient Tensor Matrix
By B. OruçIn this study, a new edge enhancement technique based on the eigenvalues and determinant from the curvature gradient tensor matrix (CGTM) has been described. The performance of the technique has been tested by using theoretical examples. It has been shown that the zero values of smallest eigenvalue of CGTM are suitable for mapping in source boundaries with a high resolution. The method has been applied to CGTM computed from the gravity anomaly data from Aydın-Germencik geothermal area in the western region of Turkey. The small eigenvalue provides a detailed image of the edges of basin and uplift and therefore give the results which tend to structural trends. I have also compared the Euler deconvolution (ED) position estimates with the small eigenvalue map obtained from the CGTM of residual gravity anomaly. Both techniques have agreed in detecting the basin and uplift edges in the subsurface.
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Last Decade Gravity Data Processing in the ELGI
Authors J. Kiss, E. Prácser, L. Vértesy and Á. GulyásThe Bouguer anomaly map shows an integrated image of the geological structures of the given area which depends on the density distribution of the rocks. It means that Bouguer anomaly map gives a summarized gravity effect of all geological formations to be found from the surface until a depth of several tens of kilometres. The different depths of the Moho in Central-Europe is determined by different crust thicknesses of the Carpathian Basin and its surrounding mountains (Alps, Carpathians and Dinarides) which are connected, first of all, to the isostatic roots of the mountain regions. A formula to calculate the isostatic effect of oceanic antiroots — or in case of Hungary the effect of deep sedimentary basins which cause the same effect — is known for a long while. So we realized full isostatic correction to get gravity Bouguer anomaly maps of Hungary without regional isostatic effects. We can get more information about the depths of gravity sources using spectral analysis and spectral depth estimations. The longest wavelengths are connected to crustal anomalies, while the shortest ones to the near surface gravity sources. We can separate gravity effects of different depths by spectral (matched) filtering of the Bouguer anomaly map.
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Major Principles in Spectrometric Studies of Vegetation
Authors D. Borisova and R. KanchevaAn essential application of remote sensing with significant importance for practice is vegetation monitoring. In agriculture for instance regular and timely information is needed about crop state and development, about the occurrence of stress situations for undertaking of respective measures, and etc. This paper has the goal to summarize issues related to vegetation peculiarities as a biological system and as an object of spectrometric studies, and on this ground to analyze a number of specific problems typical in vegetation monitoring, to point out some difficulties that data interpretation runs on, to suggest some approaches for their overcoming. Spectral reflectance specifics of the soil-vegetation cover as a dynamical system and a mixed class is scrutinized, the use of reflectance properties as an indicator of plant state is substantiated basing on their adequate relationship with plant bioparameters.
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Geoelectric Survey of the Hypotetchical Mithras-temple in Porolissum
Authors D. Raáb, K. Kelevitz and L. LenkeyIn this paper we present the results of a direct current geoelectrical surveying made for exploring an underground building in the Roman age fort of Porolissum. It was assumed that the building was a Mithras-temple. It was made of volcanic rock surrounded by clayey soil. We carried out the measurements along two sets of sections perpendicular to each other. We made two surveys: first using Wenner-Schlumberger array and second time a dipol-dipol array. We inverted the apparent resistivities as a 3 dimensional dataset with the software RES3DINV. The boundaries of the building could be easily identified, and we got information about the building’s inner structure, too. The reisistivity distribution showed where bigger rocks, the former archeological trenches, the walls and the collapsed parts of the building were located. There were no significant differences between the results of Wenner-Schlumberger and dipole-dipole arrays, the lateral distribution of the resistivity was almost the same. Later the archeological excavations proved the results of the geophysical measurements in detail.
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Combined geophysical investigation for the detection of ancient metallurgical installations near Keratea City, Greece
Authors G. Apostolopoulos, P. Karalis, G. Amolochitis and K. LeontarakisThe area of Lavrion, south part of Attica, is important in Greece for its mining and industrial history. Ancient times mining activity and metallurgical processing has left galleries and circular laundries for enrichment, tanks for the water used and forges for melting. A geophysical survey has the target to detect walls and tanks in an area near Keratea city some ancient installations have been revealed by archaeological excavation. Electromagnetic measurements with a conductivity meter have found elongated features of low conductivity (walls) and circular features of high conductivity (tanks full of conductive material). ERT and GPR sections have approved these results giving additional quantitative information. The results can be used as guideline in future archaeological excavation.
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Correlation of Geophysical Methods to Investigate an Archaeological Site at Bujang Valley, Kedah, Malaysia
Authors S.Y. Moussavi Alashloo, M. Moussavi Alashloo, R. Saad, M.N.M. Nawawi and R. AsadpourAn integrated geophysical survey using electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and magnetic techniques was performed with the purpose of locating buried artifacts and defining shallow structures at the Bujang Valley archaeological area, Kedah, Malaysia. Bujang Valley is considered to be the earliest commercial and religious center in Malaysia. The geophysical investigation was conducted in three steps. First, a magnetometry survey was performed using a G-856 proton precession magnetometer over 15 profiles. Then, a resistivity survey was designed in 6 profiles utilizing a pole-dipole array. Later, 2 lines of seismic refraction were measured and correlated with resistivity survey results. The magnetic survey revealed six anomalies which two anomalies had a high magnetic value, related to buried structures. The ERT and SRT techniques displayed three main layers of alluvium soil mixed with sand and clay, saturated zone and the bedrock layer. A joint analysis of results showed that the obtained information well suited to determine the archaeological remains and subsurface geological properties. An excavation test confirmed the geophysical results. Consequently, the results of this study reconfirmed that the integrated geophysical techniques yield satisfactory results and useful information upon which archaeologists can base further investigations of the site.
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Investigating the Interior of Tumuli in N. Greece (Regions of Macedonia and Thrace)
Authors G.N. Tsokas, P.I. Tsourlos, A. Stampolidis and G. VargemezisTumuli are anthropogenic constructions to host funeral constructions (burial chambers, simple burials, altars, etc). These must be located, unearthed and studied but the tumuli are also monuments of the past that must be not being destroyed. Geophysics comprise the reasonable means for this task since they can provide imaging of the interior of the tumuli and guide the subsequent excavation. The geophysical techniques used for this purpose are reviewed in this paper. Examples of successful operations are also given dealing with tumuli in the Regions of Macedonia and Thrace (N. Greece).
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GPR Imaging at Aptera Archaeological Site
Authors N.S. Spanoudakis, M. Manataki, V. Niniou-Kindeli and A.P. VafidisA Ground Penetrating Radar (GPR) survey was conducted at the Aptera archaeological site in order to map the buried relics in two main areas. Cisterns and baths to the north and a theater to the south were located during archaeological excavations. The GPR survey indicates anomalies attributed to a small cistern south of the monastery and a small well west of the Roman cistern.
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Magnetic Surveying in the Roman Age Fort of Porolissum
More LessThe researchers and students of the Department of Geophysics and Space Sciences, Eötvös Lóránd University have been carrying out geophysical surveying in the Roman age town Porolissum. Porolissum is located 20 km east to Zalau, Romania. Magnetic surveying is one of the most frequently used geophysical methods in archaeological prospecting. We used GSM-19 Overhauser magnetometers. When the soil is disturbed its susceptibility also changes. That is why we can see these structures in the magnetic anomaly map. We were able to map the structure of the fort in Porolissum with magnetic surveying. The results and their interpretation are in agreement with the results of the former archaeological explorations.
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Magnetic and Electric Surveying in the Medieval Fortress of Moresti and in the Deserted Village of Csittfalva
More LessIn spring 2010 we carried out geophysical surveying in Moresti and Csittfalva. These former medieval villages were located in Transylvania along the river Mures. In Moresti we prospected the medieval fortress, and in Csittfalva we searched the ruins of the temple, which was demolished in the XVIIth century. We carried out magnetic surveying, and then based on the results we made electric measurements. We identified the location of the medieval fortress of Moresti and the ruins of the temple of Csittfalva with magnetic surveying. In Moresti the magnetic surveying revealed the detailed structure of the fortress. The geoelectric measurements in Moresti did not provide further information, but in Csittfalva they gave a more detailed structure of the temple, and the depth of the foundation was established, too. In both places the results of the geophysical prospectings are in agreement with the former archaeological information. Additionally, some new features, e.g. the inner trench in the fortress of Moresti and the tower of the temple of Csittfalva were discovered.
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One Solution for Hardware Realization of Probe for Measuring Temperature and Conductivity of Liquids in Boreholes
Authors M. Brkic, Đ. Dragojević, D. Živković, M. Živanov and V. DoganShort description of borehole tool for measurement of temperature and conductance of liquid is given. Borehole tool is measuring these two parameters in same time. Conductance of liquids is important water quality parameter. Measurement of temperature is useful for normalization of conductivity readings and for locating at which depth liquids flows into the borehole. Principle applied is known as “four wire measurement” where maintaining of constant voltage on inner electrodes is accomplished by regulating of current through outer electrodes. Current flowing through liquid is proportional to its conductivity. Measurement of temperature is realized with platinum resistance thermometer PT100. In this paper description of the tool and mechanical realization of measurement elements are given.
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Estimation of carbonates permeability using numerical image processing
Authors A. Rabbani and S. JamshidiCarbonate rocks heterogeneity and anisotropy has always caused an uncertainty in the permeability estimation methods. In many cases the actual permeability of this rock type cannot be exactly specified just by performing experiment. In the present study a new numerical method has been used in analyzing the results of image processing on scanning electron microscope (SEM) images. Here, estimation of permeability has been presented by developing a modification on effective medium theory in consideration the phenomenon of dead end pores. Random numbers play a prominent role in this simulation corresponded on the randomized nature of carbonate fabrics. Mont Carlo simulation has led to presenting a distribution function of medium permeability. Results of simulation has been confirmed by two literature data which had been obtained by computational fluid dynamics (CFD) methods on a three dimension scanned samples.
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Inversion of Well Log Data with Apriori Information
More LessIn the hydrocarbon exploration the well is a complex source of information, beside the well logs the results of coring, mud logging and well test also can be used in the petrophysical interpretation. In the traditional procedure only the log values are used in the parameter estimation, which based on the maximum likelihood principle. The additional information is only used after the inversion, for confirming the results. The additional information also can be used in the inversion if they are regarded as an apriori information related to the rock parameters. In my work, the apriori information – core porosity data - was built in the inversion procedure by Bayes principle. The estimated probability distribution of core data involves the measurement error and also the effect of vertical inhomogenity of layers. In order to increase efficiency of Bayes type procedure, quality control has been built in. The log data and core data are compared statistically before the inversion, and in the case of significant differences the apriori data are not used. The efficiency of the modified inversion procedure is demonstrated by synthetic and field examples as well.. In both cases the modified inversion gives more accurate results than the traditional.
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Utility of the Gravity Method for Resolving the Conflict over a Mine Panel Claimed to Infringe a Permit Boundary
Authors A. Karaman, T. Seyhan and M.F. IşıkCoal mine panel claimed to infringe a permit boundary, or mine subsidence inflicting damage to buildings has been the subject of lawsuits in several countries. We study at Soma, Manisa, the footprint of a lignite coal mine panel at a depth of about 170 m by mapping all of the surface fractures we could observe, and developed a post-subsidence conceptual density model that we verified through gravity measurements with positive Bourger anomaly. With the utility of the gravity method, we were clearly able to detect the anomalous mass that was created with denser overburden material filling up the space after the extraction of less-denser lignite. The orientations of the fractures we mapped at the ground surface, the Bourger gravity map, and a test borehole all together left no doubt about the existence and the dimensions of the mine panel. This presented approach is expected to find application at sites with similar disputes, and for abandoned mines.
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Evaluation of SP Anomalies in Mine Field
By M. AsciIn this study, an example is given about the approach to SP maps prepared in sulfurous mining areas. For this purpose, a way was determined about how to arrive a real earth model examining through the results of different SP models. The solutions indicated that the examination of 2D SP map obtained in the mining area do not reflect the real earth model all the time. A prediction related to sulfurous metallic mining area was done. At first, although four sources had been thought to produce SP anomalies, later it was understood that seven sources produced SP anomalies in the map.
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GPR Measurements for Engineering Damaged Zone (EDZ) Investigation
More LessAs a part of underground research of intermediate and low level radioactive waste disposal site in Bátaapáti geophysical measurements were carried out after the excavation immediately and one year later for determination of extension of the EDZ (Excavation Damaged Zone) evolved in the granite. The measurements of borehole radar have given very good, while the measurements on the wall (radar, acoustic and tomography) have given good results. The GPR method has proven itself to be the most usable obtaining valuable information about the rock. Several typical differences can be observed that have been arisen on the sections of the two (base and repeated) measurements. These are appearing and strengthening of new reflections and diffractions. New processing techniques were developed for examination of amplitude and phase changes of different wave types on the borehole radar sections. The physical changes of the surroundings of tunnel can be mapped by these results. These changes can be explained only by realignment of stress and enlargement of classical EDZ.
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