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7th Congress of the Balkan Geophysical Society
- Conference date: 07 Oct 2013 - 10 Oct 2013
- Location: Tirana, Albania
- ISBN: 978-90-73834-55-2
- Published: 07 October 2013
61 - 80 of 110 results
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Inversion of Magnetic Anomalies Using Affine Transforms of Geometrical Source Models
Authors P.Y. Stavrev and N. KrastevA method of magnetic data inversion is proposed and implemented. The magnetic source body is represented by a basic geometrical figure that undergoes affine transforms. The latter produce a family of figures in the affine space and among them the optimal solution can be found. If the basic figure in a 2D inverse problem is given as a circular one, then the affine family contains ellipsoidal figures. They represent solutions useful as a first approximation to more complicated source models. The model tests show that ellipsoidal solutions allow the magnetization direction, depth of the upper source surface, sizes and slope of the source body to be estimated. The inverse problem solution is stable and unique due to the small number of unknowns (less than ten in 2D problems) and because of the geometrical restriction over the ellipsoidal convex model with homogeneous magnetization. Two field examples from a lend magnetic survey in the area of the Bulgarian Antarctic base station at Livingston Island and from aeromagnetic investigations in the area of SE Bulgarian Black Sea shelf illustrate the effectiveness of the proposed method of magnetic inversion.
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Remotely Sensed Data for Water Volume Assessment in Inoperative Mines
Authors D. Borisova, H. Nikolov, D. Petkov and T. LubenovAbandoned open pit mines create serious ecological risk for the region of their location. This is valid especially for the quality of water since the rainfalls together with underground waters fill the open pit and form water body with different depth. One example for such opencast, inactive copper mine is Medet (Bulgaria). There are many cases reported for water pollution by heavy metals in the rivers running close to this open pit mine after autumn and spring rains. This justifies the need for long term and sustainable monitoring of the area of the water basin of this unused mine in order to estimate its acid drainage. The imaging spectroscopy combined with is-situ investigations is proved to provide reliable results about the area of the water table and the water volume in it. In this study we have investigated historical data gathered by remote sensing which allowed us to make conclusions about the year behavior of this area. The team expects that the results of this research will help in the rehabilitation process of this inactive mine and will provide the local authorities engaged in water quality monitoring with a tool to estimate the possible damage caused to the local rivers.
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Imaging of Karstic Carbonates Using Electrical Resistivity Data at Malia, Crete, Greece
Authors A. Vafidis, H. Hamdan, N. Andronikidis, G. Kritikakis and N. EconomouThis work involves the use of resistivity and borehole data for the delineation of weak zones in karstic carbonates at Malia, Crete, Greece, where two water reservoirs will be constructed. Site M mostly consists of cretaceous carbonates belonging to the Tripolis zone while Site K consists of upper triassic carbonates of the Tripolis zone. Electrical tomography data were combined with seismic refraction and borehole data. Electrical tomography imaged karstic structures of the Tripolis carbonates at sites M and K. A 3D resistivity image was generated by inverting resistivity data collected along parallel lines on a grid at site M. At this site, electrical resistivity imaging delineated fractured and weathered limestone zones whose thickness ranges from 20 to 40 m. 2D ERT images of the northern part of site M indicate a major low resistivity anomaly. The formations at site K are mostly characterized as slightly weathered limestone (H) with higher RQD values (more than 60). The existing voids are small and the fractured zones exhibit limited extent at site K.
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Effect of Datum Definition on Estimated Station Velocities from GPS Solutions - Case study
By K. VassilevaThe effect of datum definition changes on the estimated station horizontal velocity vectors by using Bernese software, version 5.0 have been studied for the case of a Bulgarian GNSS station network. The least squares method with minimum constraint conditions as a method for GNSS data processing has been briefly presented. Five slightly more or less different datums defined by different combinations of involved IGS reference stations have been applied in the combined solutions of GPS data processing. The magnitude of the obtained BULiPOS horizontal station velocities varies from 0,2mm/yr up to 3,8mm/yr. Comparison of the horizontal station velocities shows differences between all five cases almost the same magnitude of 0,4÷0,6mm/yr for the majority of the stations. For the stations with slow movements (0,2÷0,6mm/yr) these differences are comparable with the size of velocities themselves and the effect is significant. The case study of the Bulgarian GNSS BULiPOS network processed by applying the least squares method with minimum constraint conditions shows that changes in datum definition result different estimations of the station velocities and the effect is very important and significant in combined use of velocities from different sources as input data in geotectonic and geophysical investigations and interpretations.
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Assessment of Environmental Conditions Close to Abandoned Open Mines
Authors D. Borisova, H. Nikolov and B. BanushevAs main source of information spectral data from three different sources airborne, field and laboratory measurements are considered. The main assumption is that correlation exists between all mentioned data and this way extrapolation about the soil state can be made over larger regions based on single point measurements. The advantage is that these data are acquired digitally, at the moment there is a large series of them over same regions and they can be easily processed and utilized in various information formats. In order verify of the results gathered from satellite data additional spectrometric measurements of samples from test sites are performed in-situ and in laboratory. The final target is to estimate the damage caused by sample open pit mine to the neighboring soil cover. The obtained results show that the used data and the implemented approach are useful in soil condition estimation and the method proposed is economically attractive for the company responsible for maintenance of the ecological state of the region.
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Regional Variation of the w-Upper Bound Magnitude of GIII Distribution in the Different Regions of Western Anatolia
More LessThe expected maximum magnitudes are estimated for different regions of the Western Anatolian (WA). The whole examined area is divided into 15 seismic regions based on their seismotectonic regime. The database used in this work was taken from different sources and catalogues such as TURKNET, International Seismological Centre (ISC), Incorporated Research Institutions for Seismology (IRIS) and The Scientific and Technological Research Council of Turkey (TUBITAK) for instrumental periods. The technique of Gumbel-III method is applied. By using this method an upper bound to the magnitudes (ω) is estimated. Also, we compared ω and M_max from Kijko-Sellevol method to research any relation between these parameters. We can say that these parameters are clearly relation each other and reflect expected maximum magnitude for 15 source regions in WA. According to ω and M_max computed for each region Aegean Sea, Aegean Arc, Sultandağı and Tatarlı-Kumdanlı Faults and Dinar Graben have highest hazard potential.
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Recent Progress in National Strong-ground Motion Network of Turkey
Authors U. Ceken, E. Tepeugur, T. Kuru, A. Apak, D. Kokbudak, V. Ozsarac, S. Seze, K. Tekin, E. Ates and C. SahinWe present here the last situation of accelerometers where deployed along whole country, Turkey by efforts of the Earthquake Department of AFAD which directly belongs to the Prime Ministry of Turkey. As of May 2013, there are 10 local scale strong-motion networks including Turkish Republic of Northern Cyprus (KKTC), Iskenderun, IzmirNET, etc. Users can directly access to data via the web site of Earthquake Department of AFAD.
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Remote Sensing Techniques in Vegetation–environment Studies
Authors D. Borisova, R. Kancheva and G. GeorgievRecent developments in environmental studies are related to worldwide ecological problems associated with anthropogenic impacts on the biosphere. Pollution is an undesirable product of human activity. Industrial, agricultural, forestry, and transportation all generate substances and by-products that are considered pollutants. Remote sensing technologies are an effective tool in numerous environmental investigations relevant to ecosystems preservation, biodiversity conservation and other problems of global importance. In agriculture, remote sensing is used for assessing plant growth, condition, and for identification of stress situations. This paper is devoted to the study of the impact of heavy metal contamination on species performance and the possibility to detect pollution stress from measurements of plant spectral characteristics. A main goal is to study the relationships between the stress factor and plant spectral features, and to assess the ability of various spectral indicators to detect plant heavy metal-induced stress. Multispectral measurements were performed over spring barley and pea plots subjected to Ni and Cd pollution. Significant correlations were observed between plant bioparameters and different spectral features. Meaningful statistical relationships were established between the heavy metal pollution amounts, plant bioparameters and spectral properties that allow detection and quantification of the stress factor affect on plant performance.
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Method for Modelling of High-resolution Quasi-geoids
Authors Ch. Tzankov, S. Avdev, R. Radichev, S. Dimovski and A. KisyovThis abstract presents a new technique for creating geoids of high resolution and precision. The first step is to find unique and stable models of the mass distribution in Earth’s core, mantle and crust. This is followed by computation of the gravity potential of the optimized models which are used to find the geoid’s surface. The created models consist of finite number of point-masses and the initial data are the absolute values of the gravity acceleration on Earth’s surface. The Gauss-Newton method combined with an additional regularization algorithm is used in order to fulfil the optimization. The approach is tested upon gravity data taken from the GRACE Gravity Model 02 (GGM02C) released October 29, 2004 and published to the public on http://www.csr.utexas.edu/grace/gravity/. Currently, the optimized models enclose 177 point-masses. This gave us the opportunity to compute the European geoid on a 0.5°x0.5° grid with 134 cm accuracy. It’s obvious that by a continuous increment of the number of point-masses the method will not only reach but overtake the current geoid heights accuracy on a relatively simple and economical way. The only obstacle for the method is the higher computational cost of the procedure.
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Preprocessing of Field Spectrometric Data
Authors D. Borisova, D. Petkov, V. Atanassov and G. JelevRemote sensing using geophysical principles begins with the development and design of equipment for performing research of objects remotely and without disturbing their integrity. In geological remote sensing studies the determination of the chemical/mineral composition and the structure of the objects within the field of view of the instrument either obtained in the lab, with a field spectrometer, or with a remote sensor is a main goal. The aim of this study is to present and test the procedure of preprocessing of the field spectrometric data. Field spectrometric studies of rocks were made to collect spectral signatures of different rock types for the reliable detection and identification of their mineral and chemical composition. The experiments are based on major physical principles such as light scattering, absorption of light, and reflection of light in the electromagnetic spectrum (EMS). Field spectral measurements were made with Thematically Oriented Multi-channel Spectrometer designed and constructed in Remote Sensing Systems Department at SRTI-BAS. The spectrometer with increased spectral resolution works in (400-900) nm range of EMS. The results are compared with similar data from spectral libraries. They correspond to the shape of reflectance spectra in the same range of EMS obtained with other spectrometers.
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Electric Resistivity Tomography (ERT) Measurements in Area of an Old Salt Mine
Authors F. Chitea, D. Ioane, C. Marunteanu and G.F. GarbaceaA large number of old salt exploitations are presently abandoned in Romania as a consequence of mine flooding, determining in many cases active subsidence and collapse. The geophysical study carried out in 2012 at Ocna Dej salt mine had as main objective the detailed illustration by means of ERT and VES resistivity data the actual extent of underground voids. The ERT geophysical measurements were executed above the area of the old Iosif Mine, using a multi-electrode resistivity meter (SuperSting R1- AGI). Two ERT profiles 270m long (D1 and D2) have been measured using the Schlumberger, the Wenner-Schlumberger and the Wenner arrays. According to the resistivity distribution the vertical shaft sector was divided in 3 layers:a) a high resistivity layer due to recently added filling material; b)a very low resistivity zone represented by the upper part of an old filling material, impregnated with salty water originating from the salt lens roof and c) an intermediate resistivity layer at the bottom due to more compacted filling material. ERT method proved to be a powerful geophysical technique in locating and illustrating in detail underground voids in mined salt bodies, its higher resolution allowing interpretations for both geotechnical and hydrogeological use.
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On the Seismic Vulnerability of Pernik Region (West Bulgaria)
Authors E. Botev, S. Simeonov and K. HadjiyskiOn May 22, 2012 the seismically quiet Pernik area produced the strongest Bulgarian earthquake for the latest 80 years with Mw=5.6 and maximum observed intensity of VIII degree EMS. Thus the real seismic impact on structures has to be assessed and vulnerability of the local building stock has to be revised accounting for the physical characteristics of this event, the actual response of affected structures and their post-earthquake condition. For this purpose data from the local digital SGM Network of Sofia, that recorded this earthquake, is processed and used to evaluate the characteristics, relevant to aseismic design of structures. Damages induced to buildings in Pernik area by the main event and the aftershocks are investigated on site. They are illustrated and the vulnerability aspects are discussed. Finally implication about the reasons for current vulnerability of damaged buildings in Pernik area is provided.
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A Preliminary Results of Fault Plane Solutions of the Recent Earthquakes in and Around Eastern Black Sea Region
Authors Y. Bayrak, T.S. Irmak, B. Doğan, H. Çınar, Ş. Yılmaz, D. Kalafat, A. Karakaş and E. BayrakThe present study shows preliminary results using the fault mechanisms of small-moderate earthquakes in the Eastern Black Sea Basin and defines relation of fault mechanism with the tectonics. For this purpose, 13 earthquakes which occurred in the time period of 2004 – 2012 were analyzed. Focal mechanisms were determined using focmec algorithm and the analyzed earthquakes characterized a reverse (thrust) faulting mechanism with presence of strike slip component. The earthquakes occurring in the Eastern Black Sea basin and surroundings indicate the active tectonic lines in the region. Additionally, the Greater Caucasus thrust faults with ENE-WSW trend and dipping both south and north directions continue into the sea and the thrust faulting is accompanied with the strike-slip faulting according to the fault plane solutions of the earthquakes. Accordingly, main origin of the earthquakes are associated with the thrust faults related to subduction and accompanied with the secondary strike-slip faults developing in the upper parts of the oceanic crust during the deformation process.
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Terrestrial Photogrammetry in Albania and Its Contribution in Geophysical Researches
By V.D. DinajAlbania is a mountainous Mediterranean country with numerous natural energy resources. There are many rivers flowing from the mountains where seven hydro-power plants have been built. In this paper we present photogrammetric work in an engineering geological-geophysical investigation of the Koman landslide, Shkoder area, Albania. Our ability to make highly precise maps has been crucial to our success. We rely on photogrammetry in general as a key tool to help accurately capture different formations. The photogrammetric project on the state of landslide in Koman hydro power included studies on changes in both banks of Koman dam. The study included work field by taken photographs in a very difficult ground for both banks of dam. Our terrestrial photogrammetry enabled us to capture data from large scale stereo models in preparing digital topographic map (topo map) with high quality and efficiency. CAD drawings were the most effective way to document technical drawings and related information in an organized manner. CAD combined with GIS enables data to be analyzed
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Investigation of Bafa Lake with Seismic and Marine Magnetic Method
By S. EdremitThe surface area of the Bafa Bay is about 75 km², it’s the location above the sea level 5 m, and it’s the deepest part 20-25 m. The Bafa Lake is located at the watery area about 37° 31´ N and 27° 27´ E which is accepted on the international important area list. Besides, the Bafa Lake is very important area for the archaeological case. The scientific data of the Bafa Lake is too limited. For that reason, the geophysical studies are planned on the first step of the project. After completion of this study, the formation and morphology of the lake will be found out by using seismic and magnetic techniques. To perform this study, an equipped research boat with 4-6 m of the length will be used for the marine investigation at shallow water.. At the first step of the study, data acquisition will be completed and according to the methods which are stated on the study that high resolution seismic and total magnetic area measurement performed. In the result, this study will be the first study, especially, for the lakes. Keywords: Magnetic Area, Latmos Bay, Geophysic, Shallow Water, Seismic Studies.
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The Investigation of Geothermal Potential of Gülbahçe Bay(Karaburun Peninsula) by Single Channel Seismic Reflection Dat
Authors Z. Altan, N. Ocakoglu, D. Dusunur-Dogan and D. YagcıIn this study, a N-S trending, internal bay that geothermal potential of Gülbahçe Bay, which is between the Gulf of İzmir and Karaburun Peninsula, is aimed to investigate by seismic reflection data and thermal modelling. The area of study locates at the most western part of Gediz Graben which has a highly geothermal potential. Even though, many previous studies have investigated geothermal system and potential reservoirs onland in this region, the continuation of these reservoirs under the sea has not been researched enough. For this purpose, single channel seismic reflection data was conventionally processed and interpreted and related thermal and fluid flow modeling were performed to understand both major tectonic features which delineate the possible ground water flow paths and geothermal capacity in the gulf. The results show that hot water goes out on N-S trending active strike slip faults along, commented on two lines on E-W trending. At the reflection levels along the vertical axis seen rising structures have been interpreted as the hot water outflow. This outflow zones are also consistent with the thermal modeling results.
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Thermal Conditions for Geothermal Energy in Transcarpathian Depression
Authors D. Majcin, R.I. Kutas, D. Bilčík and V. BezákThe contribution presents the results of our cooperative geothermal works in the Transcarpathian depression - very perspective region for exploitation of geothermal energy both for Slovakia and for Ukraine. The activities were focused on interpretation of temperature and heat flow data, geothermal modelling results and relations of the thermal state of the lithosphere to the tectonics in the region under study and surrounding geological units. These results and additional modelling works afforded us the opportunity to construct the terrestrial heat flow density map and maps of the temperature distribution in various depth levels and consequently to analyse the thermal conditions for the exploitation of geothermal energy in separate basins of the Transcarpathian depression.
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3D FE Modelling of Gravity-driven Rock-deformations for the Estimation of Cavity Effect and Sensitivity
More LessIn this paper authors performed 3D finite element modellings in order to analyse gravity driven rock deformations, as well as the effect of the cavity system embodying the equipment, and the sensitivity of planned or existing equipment arrangements. The cavity effect is one of the most important factors influencing the absolute accuracy of geodynamic and gravity-driven (tidal) deformation measurements. Data sets compiled from different observatories should be improved by the estimation of this effect, in order to be conformed and processed together. Results of a method development are presented where the sensitivity and the cavity effect rate are qualitatively and quantitatively characterized by the proposed formulas (parameter fields), based on the output displacement matrix of the 3D FE modelling. As an application example finite element modellings were carried out in order to estimate the influence of the complicated cavity system surrounding the Matyashegy Gravity and Geodynamical Observatory of the MFGI, Budapest.
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Determination of Earthquake Early Warning Parameters τc and Pd for City of Istanbul
Authors S. Turan, S. Karabulut and O. ÖzelEconomic, social and society damages caused by earthquakes is an important issue for developed or developing countries. Generally, there are three main reasons for damage caused by the earthquakes. These are the properties of earthquake sources, site effect and the structural properties of engineering buildings. Especially, when we interest the properties of earthquake sources, two different solutions of this issue can be produced such as short-and long-term. Early warning is quite a short-term of them. Principal aim of this study is evaluation for a potential damage of Istanbul after a disastrous earthquake and using of earthquake early warning system for this city. For this purpose, we used the peak displacement and velocity amplitudes of the first 3-sec of the P wave. The vertical component records was used to analysis and applied high-pass filtered at 0.075 Hz. The relationship between the peak initial-displacement amplitude (Pd) and the peak ground-motion displacement (PGD) and velocity (PGV) at the same site. When Pd 0.5 cm, the event is most likely damaging. If Pd is combined with the period parameter c determined in an earlier study, then cxPd provides an even more robust parameter for assessing the potential for damage.
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Tectonic Implications of Microseismic Activity and Fault Plane Solutions around Izmir City
Authors O. Polat, E. Gok, I. Ozen, C. Mihbuken, M. Kececioglu and U. CekenWestern Anatolia is one of the most seismically active and expeditiously extending regions in the world. The large-scale deformation in the Western Anatolia is dominated by the collision of the African and Arabian plates with Eurasia. This collision causes a westward migration of the Anatolian block from the east to the Aegean Sea in the west. Izmir city is the capital of Aegean region, and also 3rd biggest city of Turkey with its more than 4 millions inhabitants. This study aims to reveal present micro-seismic activity and seismotectonic features obtained from a local-scale accelerometric array.
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