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8th Congress of the Balkan Geophysical Society
- Conference date: October 5-8, 2015
- Location: Chania, Greece
- Published: 05 October 2015
41 - 60 of 124 results
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Preliminary Results of an ERT in a Vineyard in Estremoz, Portugal
Authors A.M. Correia and J. PassosSummaryIn 2014 a geophysical survey was carried out in a vineyard in Quinta do Mouro, in the wine region of Estremoz, in southern Portugal, to understand and study the geoelectrical characteristics of the soil. The main objective of the geophysical work was to delineate and characterize the soil and bedrock in geoelectrical terms in the vineyard’s area. The area has patches where high quality grapes are produced and patches which produce mediocre grapes. The geophysical survey aimed to try to understand if there was any correlation between the electrical resistivity of the ground (related with the amount of moisture in the ground) and the quality of the vines and grapes. The results indicate that, in this case, the quality of the vines and grapes appear to be related with the moisture in the ground, the good vines and grapes being associated with higher moisture content of the ground and so lower electrical resistivities.
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Results of Geoelectrical Surveys in the Area of Crater 70, Deception Island, Maritime Antarctica
Authors A.M. Correia and G. VieiraSummaryIn February of 2013 a geophysical survey using geoelectrical methods was performed in the Crater 70 area of Deception Island in Maritime Antarctica. The area suffered volcanic eruptions in 1967, 1969, and 1970. Two electrical resistivity tomography (ERT) profiles and a vertical electrical sounding (VES) were done with the objective of detecting and evaluating permafrost depth and thickness. By direct measurement along the two ERT profiles the depth of the frozen ground varied from 40 and 70 cm. The geophysical survey indicates that the frozen ground has an average thickness ranging from 3 to 6 m. Furthermore, the electrical resistivity of the frozen ground is about 4,000 Ω.m. Since the geoelectrical surveys were done over young volcano-sedimentary deposits resulting from the recent eruptions, it is possible to conclude that permafrost is recovering in the area.
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Geoelectrical Exploration of Mineral Deposits Using Gradient Array
Authors P. Georgescu and F. ChiteaSummaryInvestigation of deep structures by means of non-symmetric arrays in a complex geostructural assemblage lead to difficulties in delineating the shape of the ore body and the area of interest for future metal exploration.
In the presented case study, the gradient array was applied with the objective of detecting the lateral variation of electrical resistivity and metallic factor values. As the measured values and distribution of apparent resistivity and polarizability depends to some extent by the type of device used for prospecting and of its orientation in relation to geological structure, we analyse the influence of the used geophysical array by means of 3D theoretical modeling. It resulted that a conductive body will give an anomaly shape elongated towards a direction perpendicular on the injection (AB) line. The resulted information was used for enhanced field data interpretation.
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Geoelectrical and Geoelectromagnetic Imaging in Durusu Basin, Istanbul
More LessSummaryDurusu Lake is the biggest and the most important freshwater source which supports drinking water supply to the European side of Istanbul. The formation of the lake is related to the development of a dune barrier that separates the lake from the sea. Because of the importance of lake as a drinking water supply it is urgent to reveal the characteristics of the subsurface system of the narrow coast line between the lake and the sea. In this study (DCR) and (TEM) measurements were applied to detect possible saltwater intrusion and to delineate the subsurface structure in the north of Durusu Lake. When the inversion of these data is interpreted along with the hydrogeology of the area, it is concluded that the salt water intrusion along the barrier is not common and it occurs at a special area where the distance between lake and sea is very close. Along a measurement profile where lake and sea is nearest a water resistivity model was prepared by using borehole data nearby the profile and salt water intrusion was determined. This study revealed the place of clay lenses at the lake system and the influence clay lenses on the water cycle with geoelectrical images.
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Frequency-normalised Impedance for the Efficient Data Visualization in Magnetotellurics
By A.T. BasokurSummaryA concept of the frequency-normalized impedance (FNI) function is introduced for the visualization of all components of the magnetotelluric impedance tensor. This definition provides some useful properties to obtain an initial information for the subsurface resistivity distribution.
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Amalgamation of Satellite Remote Sensing and Geophysical Prospection for the Investigation of Ancient Cities: Two Case Studies from Demetrias and Pherai at the Region of Magnesia, Thessaly, Greece
Authors A Sarris, J. Donati, T. Kalayci, F. Simon, M. Manataki, C. Garcia and G. CantoroSummaryRecently a number of ancient cities in Greece have been studied through the use of geophysical techniques (Lolos and Gourley 2012, Sarris and Jones 2000, Tsokas et al 2012, Williams 2005). Magnetic and soil resistance techniques, and more recently the employment of GPR, were the main tools of exploration, but the limitations of technology made the extensive coverage of the cities a tedious task. The recent development of multi-sensor geophysical instrumentation and improved resolution satellite sensors have radically changed the investigation of archaeological sites. Within this framework, the GeoSat ReSeArch Lab of IMS-FORTH initiated a number of experimental campaigns at various sites to investigate the efficiency of the methodology in mapping the urban details of ancient cities. The whole operation fell under the scope of the POLITEIA-KRIPIS project (www.politeia.ims.forth.gr).
The integrated geophysical surveys at the Greek settlements of Pherai and Demetrias in Magnesia were carried out during March 2014, aiming to the identification of architectural features that could contribute to the study of the organization of the urban fabric of the two cities. Prior to the geophysical surveys, processing of satellite images was used as a guide of where geophysical measurements should focus.
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Imaging of Shallow Underwater Ancient Ruins with ERT and Seismic Methods
Authors G.S. Kritikakis, N. Papadopoulos, K. Simyrdanis and T. TheodoulouSummaryThe present geophysical research aims in evaluating the applicability of the Electrical Resistivity Tomography (ERT) and seismic (Multichannel Analysis of Surface Waves - MASW and refraction) methods on mapping shallow underwater ancient remnants. The preliminary results from a single seismic line and its corresponding ERT section (surveyed at the site of Agioi Theodoroi area located 10 km eastern of Heraklion, Crete, Greece) are presented. This work demonstrates that ERT as well as MASW are very promising geophysical methods for the delineation of underwater antiquities. High resistivity anomalies were attributed to building walls and are in accordance with some of their mapped outcrops. Furthermore, MASW method exhibits significant correspondence with ERT showing lateral S-wave velocity variations at the positions where the high resistivity anomalies exist. Surface waves traveling through the shallow sediments (Scholte-waves) demonstrate relatively low velocity values. This makes them suitable for the detection of relatively large (> 0.5 m) underwater manmade structures, providing the use of a high frequency source and thus, the creation of relatively short wavelengths (< 2 m). These preliminary results show the potential in employing modern tomographic techniques in the revealing the cultural dynamics in shallow off-shore archaeological sites.
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AncientCity - A new Frontier in Ancient Greek Urbanization through Geoinformatics
Authors N.G. Papadopoulos, J. Donati, G. Cantoro and I. MoffatSummaryAncientCity is a project consisting in the use of new perspectives in studying the ancient Greek urbanism through modern and advanced technological tools. The understanding, reconstruction and development of ancient Greek cities is approached through an integrated protocol composed of satellite / aerial remote sensing, multicomponent geophysical prospection and spatial analysis within a Geographical Information System platform. This approach involves the use of digital applications to detect patterns in the buried ancient built environment, the identification of surface and subsurface features through non-destructive archaeological fieldwork and the creation of digitized thematic plans of ancient Greek settlements. Five archaeological sites from two different greek geographical regions (central Greece and Peloponnese) were chosen to incorporate new urban models and recalibrate the traditional narratives about the development of the Greek city. The encouraging results of this integrated approach can be used as a prototype model for the employment of Geoinformatics in the historical and archaeological sciences within the subfield of Mediterranean archaeology and Greek Urbanization.
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Investigating the Interior of Tumuli: Problem Setting and Case Studies from N. Greece
Authors P. Tsourlos and G.N. TsokasSummaryThe geophysical techniques are used for investigating the interior of tumuli in order to locate burial monuments covered by the embankment. This is a contribution towards saving the integrity of the construction since the tumuli by themselves comprise monuments which must be preserved. The electrical resistivity tomography (ERT) comprises a fully non destructive, efficient and reliable method for investigating the interior of tumuli. Several examples on the conduct, processing and interpretation of ERT surveys data are presented here, all of which are coming from N. Greece. Further, comments on the merits and disadvantages of the method are made. The arrangement of the ERTs along rectangular and radial grids is also discussed.
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Geophysical Survey at the Area of the Ancient Theater of Aptera
Authors N.S. Spanoudakis, A. Vafidis, A. Paganis, N. Andronikidis, N. Hatzidakis and V. Niniou-KindeliSummaryIn this paper we present the latest results of the geophysical surveys performed during the autumn 2013 in Ancient Aptera, Chania, Crete, Greece. It is part of the continuous collaboration of the Applied Geophysics Lab, Technical University of Crete and the local Ephorate of Antiquities. The main scope of the geophysical studies is to detect buried structures in the area of the ancient theater. We managed to detect walls, pavements and a well utilizing GPR, magnetics, ERT and EM profiler.
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Data Integration in Archaeological Prospection - A Synthetic Approach
Authors M. Manataki, T Kalayci, N. Papadopoulos and A. SarrisSummaryGeophysical data integration in archaeological research is an emerging topic. As researchers increasingly have better access to multiple geophysical sensors it is now possible to use numerous techniques in order to explore different physical characteristics of buried phenomena. In return, a feature which is “invisible” to one sensor might be detected with another sensor so that a complete inventory of buried features might be achieved. Current research, however, usually investigates results of prospection in isolation and follows a simplistic comparative approach. In fact, “true” data integration in archaeological prospection may offer more information than sensors can individually provide (i.e. 1+1=3).
Variations in spatial layouts and physical characteristics of material culture, post-depositional processes, and complexity of natural background, all add significant task for the interpretation of archaeological prospection results. Therefore, evaluating the success of data integration remains as further challenge. In order to overcome this difficulty we can create a controlled environment with the help of geophysical model simulations. Artificially induced noise levels over simulation data may mimic complex natural environments and a measure of success may be calculated with the help of an original image.
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Low Enthalpy Geothermal Resource Development in India
By S.K. SharmaSummaryOil and gas have a head start on various other forms of energy. They are easily transported, easily converted and, in today’s market still relatively available. But due to its exhaustible nature, more attention is now needed to develop alternative non-conventional energy sources in parallel to keep the energy requirements going. It is in this context that the geothermal resources stands out as a promising long term salvation due to its bounty in nature among various non-conventional energy sources in India. Nearly 10,000 MWe power generation potential has been estimated from the total geothermal resource base in India and it can be used for space heating and cooling, heating of green houses for cultivation, cooking etc. especially in the high altitude and the colder regions. Geothermal springs are also used for balenotherapy and the promotion of tourism in several countries of the world. Electricity can be generated from geothermal fluids where higher temperatures are available with the help of binary power plants based upon the Organic Rankine Cycle (ORC).
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On the Fractal Behavior of the Total Organic Carbon in Shale Gas Reservoirs with an Example from the Barnett Shale (USA)
Authors S. Ouadfeul and L. AliouaneSummaryThe main objective of this paper is to show the behavior of the fractal analysis using the continuous wavelet transform in shale gas reservoirs. Analysis is based on the estimation of the so-called Hölder exponent by analyzing Total Organic Carbon (TOC) well-log using the continuous wavelet transform, the Morlet is the analyzing wavelet. Application to the TOC well-log data of a horizontal well drilled in the Worth basin (USA) where the main objective is the lower Barnett clearly shows no special behavior of the Hölder exponents in case of the sweet spots. We suggest application of the whole process to other well-logs data of shale gas reservoirs to compare results and generalize a rule about the fractal behavior in shale gas reservoirs.
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Natural Discharge Related Geothermal Evaluation of Carbonate Ranges, Example of Transdanubian Range, Hungary
Authors Á. Tóth and J. Mádl-SzőnyiSummaryReservoir, heat and fluid should be investigated for the study area during reconnaissance phase of a fluid-based geothermal exploration. Without proper borehole information the determination and evaluation of reservoir, especially heat and fluid are quite complicated. In turn, springs, which are natural discharge points of flow systems, can reflect the subsurface flow and temperature conditions, therefore they can provide information about the groundwater flow pattern and temperature conditions. Namely, characteristics of springs and their areal distribution can be indicative for gravity-driven groundwater flow systems, as well as geothermal potential via their outflowing water volume and temperature. Geothermal potential of the Transdanubian Range, Hungary was examined based on the results of multidimensional data analysis of natural springs. The modifying effect of geological build-up and basin geometry on groundwater flow and heat pattern, with special emphasis of heat accumulation for geothermal utilization, was analyzed by numerical simulations. The geothermal interpretation of the previous studies, statistical data analysis and numerical simulation led to the conclusion that siliciclastic cover is responsible for heat accumulation in carbonates therefore position of unconfined and confined parts is decisive in geothermal heat utilization in carbonates.
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Pre-production Pressure Evaluation for Geothermal Purposes in the Duna-Tisza Interfluve, Hungary
Authors S. Simon and J. Mádl-SzőnyiSummaryThe paper introduces the method of regional hydrodynamic analysis based on pore pressure evaluation into the preliminary geothermal evaluation, in sedimentary basins influenced by overpressured and superimposed gravity-driven flow. This novel approach complements the usual reservoir and temperature analysis. Understanding of subsurface pore pressure distribution is also beneficial during planning of thermal water reinjection. The approach is demonstrated for the Duna-Tisza Interfluve of the Pannonian basin and the results are compared with operational experiences. The results can give basis for numerical modeling and provide background for aligned utilization of drinking water, thermal water and hydrocarbons in sedimentary basins.
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Geothermal Anomalies of Gas Hydrate Deposit
By A. VasilevSummaryMeasurements of cruise MSM34 in the frame of the German project SUGAR of 11 heat flow stations in the BEEZ are the first in the Black Sea, purposefully conducted for gas hydrate (GH) study. Maps for the fields of temperature’s background and anomaly are gridded with different step and with stations within BSR areas exclusion from the input. Result of the maps’ analysis are three hypotheses: 1) GH deposit grows laterally with sequential addition of external subvolumes; 2) the cyclical process of GH subvolumes appearance consists of 7 subprocesses; 3) hypotheses 1 and 2 explain qualitatively the diversity of anomalous geothermal fields over GH deposits.
To confirm these hypotheses a 2D straight problem of conductive heat transfer is solved. Input parameters are data from MSM34 and publications from GH research in the region.
The results present geothermal evolution of key points in the study volume - curves of temperature (20) and heat flow (12) changes. The times to reach steady state are determined for the main 7 subprocesses. This work is a base for a new quantitative study of GH with the methods of marine geothermy.
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The Efficiency of Vertical Magnetic Gradient in the Discovery of Archaeological
By Mu ALmutairiSummaryThis report displays the magnetic surveys that were conducted at Archaeological site in the northwest of the Kingdom, along the line of 38˚03”08” east longitude and latitude 26˚30”14 north which is located within the province of AlUla approximately 400 m away from the town of al Medina.
Part of this area was selected with length of 40 meters and width of 20 meters for the purpose of the study based on surface phenomena in this chosen area, The use of vertical magnetic gradient.
The Gradient Magnetic data were processed using two different processing software for all surveyed Areas; to get more enhancements of results and to keep quality control. The magnetic response is different form high to low values, that is depend on the Magnetic susceptibility of geological, host materials and the hidden targets through it; on the survey area. This response of Gradient Magnetic methods were appear as variation anomalies which are indicated to a variation in the medium, and that interpreted as archaeological features, boundaries between buried rooms, walls, the existence of archaeological findings, buried walls and may be some of that walls are damaged and discontinued.
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High-resolution Geophysical Study of Somma-Vesuvius Offshore (Southern Italy)
Authors V. Paoletti, C. Marino, M. Fedi, S. Passaro and S. TamburrinoSummaryModern technologies in the field of marine geophysical surveys allow us to obtain accurate and detailed information on the characteristics of the seabed and the marine substrate. In this paper we present a new magnetic high-resolution map of the Somma-Vesuvius offshore (Gulf of Naples, Southern Italy) depicting some main volcanological and tectonic structures of the area. The analysis of a new marine magnetic dataset, acquired during the oceanographic survey “SAFE_2014”, highlighted the presence of a group of NNW-SSE trending anomalies. This magnetic alignment suggests a volcano-structural correlation with the major faults in the area. We was also identified a NE-SW trend of magnetic anomalies, which may be associated with a tectonic structures interpreted as a magma preferential path of Somma-Vesuvius. Furthermore morphological irregularities of the seabed, shown by new morpho-bathymetric data, were found in correspondence with some of the main magnetic anomalies of Vesuvius offshore. This confirms the hypothesis of a possible connection between the Vesuvian volcanic structures and the tectonic regime of the Gulf of Naples, which controls this region since the Neogene-Quaternary.
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Determination of Beam-position Dependent Transfer Functions for Tidal Recording LCR Gravimeters
Authors M. Kis, A. Koppán, J. Benedek, G. Papp, P. Kovács, L. Merényi, E. Szűcs and G. VadaszSummaryAuthors propose a method for the determination of transfer characteristics and fine calibration of LCR relative gravimeters without feedback system used for earth-tide recordings, by means of the moving-mass gravimeter calibration device of Budapest-Mátyáshegy Gravity and Geodynamical Observatory. Beam-position dependent transfer functions of two relative LCR G type gravimeters were determined and analyzed and a new anisotropic correction of long-time recordings was introduced based on the anisotropic transfer characteristics.
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First Results of an Investigation for the Ionospheric Conductivity Variation Using Lunar Tide
By C. CelikSummaryThe fundamental difference between solar, S, and lunar, L, is that L results from purely gravitational tidal movements. The difference in frequency between the L tidal movements and that of the ionospheric conductivity makes it possible to distinguish between the two effects, whereas for S the motions and conductivity both have the same frequency.The amplitude of lunar semi-diurnal tide, L2, was determined for each solar hour at an observation site of IZN, and compared with ionospheric conductivity.
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