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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
21 - 40 of 158 results
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Inversion of First Breaks on Multilayered Media
Authors A.N. Paripas and T. OrmosIf we assume layered models, usually such methods have been developed before that can calculate 2-layered models - with one layer boundary in the structure. Recent development and utilization follows the direction of tomographic methods using diving waves that can deal with multilayered structures as well. A method has been developed in the Department of Geophysics, University of Miskolc, which is able to invert more than one layer at a time in case of a properly chosen measuring system. However, inversion evaluation in a multilayered case can lead to uncertain ambiguous results – similar to equivalence problems. Thus, for having more reliable inversion results, adequately set inversion parameters and a measuring configuration is needed that results in appropriate quantity and quality of information. Investigation results and examples are shown in this study.
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First Arrival Picking in Seismic Refraction Data by Cross-Corelation Technique
Authors M. Senkaya and H. KarsliThe quantified interpretation of the seismic refraction record depends on correct and confident picking first arrival times. However, if the refraction data are poor, traditional first arrival picking techniques are not enough. For this reason, novel techniques are necessary to obtain first arrival times from such data. In this study the cross-correlation technique (CCT), commonly used in reflection data processing, was applied to determine first arrival times. By means of the technique, the process of the first arrival time picking is realized semi-automatically and erroneous picking to be arise from noises was decreased and picking procedure was attributed to mathematical base. Also, effectiveness of semi-automatic picking was especially evaluated with seismic refraction tomography.
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Seismic Wave Velocity and Anisotropy of Devonian Limestones, Nw Turkey
By C. KurtuluşDevonian limestones crop out at various places at northwestern part of Turkey. In situ geophysical and geotechnical studies were conducted to determine their dynamic engineering parameters such as: P-and S-wave velocities, Poisson’s ratio, shear modulus, elasticity modulus, and natural period. Geophysical and geotechnical laboratory tests were performed: ultrasonic measurements of compressional pulse velocity (UPV), uniaxial compressive strength (UCS), point load index (Is(50)), were carried out on cylindrical specimens cored across and along the foliation planes; effective porosity (n), Bulk density (d), and absorption of water by mass (Wm) sets of the rock specimens were determined. Finally, statistical correlations were performed by regression analysis to evaluate the relationships between UCS , Is(50),d, n, Wn and UPV.
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Deghosting of Seismic Data Based on Adaptive Subtraction Algorithm
Authors A.A. Bocharova and M.A. Poluboyarinov.Ghost-waves is a traditional problem for seismic processor, however there is no efficient solution of this problem until now. It is considered, that ghosts are less obvious then long-path multiples and are less easily removed by seismic processing. This paper propose a new approach for ghost-wave removal. It is based on adaptive subtraction of a ghost-wave model from the original wave field. The method was applied to synthetics seismic data and field seismic data recorded in several areas. Results show that the described approach is effective in all cases.
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Regional Magnetic Field Model for Croatia and Hungary
More LessWithin the framework of a Croatian-Hungarian bilateral project, joint field surveys were carried out and common geomagnetic field data base was compiled with the aim of constructing a reference geomagnetic model for the two countries. The magnetic maps were obtained by polynomial expansions in latitude and longitude (PA) and by adjusted spherical cap harmonic analysis (ASHA). It was shown that good fit between model and observations could be achieved by the traditional PA method. However, it was argued, that since PA could not satisfy the physical condition of curl-free property of the field, ASHA was superior to it. With ASHA, the determination of at least 25 coefficients or the selection of big half-cap-angle was required to achieve similar residuals than obtained in PA. We showed also that the residuals of the global IGRF11 model were comparable to that of the PA and higher-degree ASHA models. It is suggested that this is resulted in by the fact that the RSs of Croatia and Hungary are located in non-anomalous area. We think therefore that the real power of ASHA technique can be exploited in local anomaly studies carried out on the basis of the observations of country surveys rather than RS campaigns.
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Magnetic Anomalies of Central Volcanics in Slovakia
Authors Ö. Bektaş, A. Büyüksaraç and K. RozimantThe Central volcanics, located in Central part of Slovakia, is characterized by andesitic volcanic activity, andesite stratavolcanoes, dome complexes dating Middle and Late Miocene. Magnetic anomalies of the region exhibit a highly complex pattern. A 3-km upward continued magnetic anomalies do not appear to be correlated with topography and reflect anomalies of the deep-seated magnetized bodies. Pseudogravity transform was performed on the upward continued anomaly. Then, pseudogravity anomalies were modeled as a three-dimensional. The top and bottom of the body are at 4.4 km and 8.5 km, respectively. Volcanic structures, which are known and some lineaments, are presented on the maxima of the horizontal gradient of pseudogravity anomalies. They are well correlated with structural map of Central Slovakia Volcanic Field (CSVF).
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Electromagnetic Imaging with Tensor Invariants and Classical Magnetotelluric Interpretation along the CEL-07 Profile
More LessBesides the traditional electromagnetic data processing, nowadays one can see more and more transformation solutions (especially for very large data systems), which provide images about deep geological structures and their dimensions free of the orientation of the measuring system. The key parameters of these transformations are called tensor invariants. In this paper the detailed information about the quality, joint interpretation possibilities and applicability of the most used tensor invariants in electromagnetic investigation is presented. Comparison of various invariant results (together with dimensionality analysis) with results of classical magnetotelluric interpretations (inversions) to a 2D datasets in a research area in West-Transdanubia (Hungary) was applied and the main tectonic lines could be identified. In the contact zone of three tectonic units (Pannonian Basin, Eastern Alps and Dinarides), in a complicated – basin and range – geological situation magnetotelluric deep soundings were carried out along a 140 km long profile with a site distance of 2 km. The MT sites followed the Hungarian part of the CELEBRATION-07 (CEL-7) deep refraction profile, and the MT spacing was the same as the seismic one.
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A new analytical modeling of Asphaltene-Induced Formation Damage under Ultrasonic Stimulation
Authors A. Rabbani, M.H. Gazanfari and I. NajafiAlthough there are evidences on efficiency of the ultrasonic waves in asphaltene damage removal, a little is known about the modeling of permeability enhancement due to ultrasonic waves radiation towards the asphaltene-induced damaged formations. This study presents a novel analytical stimulation on formation asphaltene damage with an approach to the ultrasonic stimulation. By attending the hydraulic radius concept, filtration theories in porous media and ultrasonic effects on asphaltene particle size, a theoretical and relative statics model has been developed. In addition to examining the effects of asphaltene particle size distribution on permeability impairment, a Sensitivity Analysis has been presented to clarify the relationship between asphaltene adsorption parameters and permeability alteration. Literature experimental results confirm the permeability damage predicted by the current modeling for five volume injection of Asphaltenic oil. Furthermore, it has been proved that sonicated samples of crude oil cause less asphaltene-induced damage in the porous media due to solvent injection.
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Developing of Dynamical Evolution Model of Rock Massif State as a Response on a Changing of Stress-deformed State
By O.A. HachayThe first feature of the state evolution is: the local volume massive does not immediately respond on the changing of the surrounded it stress state. Therefore it stores the response energy and then extracts it through a high energy dynamical effect. It is very significant to define the time of reaction lagging, in spite of the influence on the massive can be assumed as elastic. The unique model which can explain that effect is a model of the massive with a hierarchic structure. We developed a mathematical algorithm using integral and integro-differential equations for 2-D model for two problems in a frequency domain: diffraction a sound wave and linear polarized transverse wave through a arbitrary hierarchy rank inclusion plunged in an N-layered medium. That algorithm differs from the fractal model approach by a more free selecting of heterogeneities position of each rank. And the second the problem is solved in the dynamical approach. The higher the amount of the hierarchic ranks the more is the degree of nonlinearity of the massive response and the longer can be the time of massive reaction lag of the influence.
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Structural Investigation of the Western Transdanubian Hills – a Transition Zone between the Alps and the Pannonian Basin
Authors G. Kovács and T. TelbiszThe investigated study area is situated in the transition zone between the still uplifting Eastern Alps and the subsiding Little Hungarian Plain (Joó 1992). The contrasting forcing of the differentially uplifting neighbour regions created here a distinctive low relief, hilly surface morphology and a characteristic drainage network pattern. Our study aimed at the reconstruction of the surface evolution. First, we determined the geomorphic domains based on their geomorphometric characteristics. Second, we proved neotectonic origin of some specific area. Last, we analyzed the connection between the surface morphology and the deeper structure.
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Travel Time Residuals at the Contact of the Dinarides and Pannonian Basin
Authors F. Šumanovac, D. Dudjak and E. HegedűsTeleseismic earthquake records from a passive array of 15 short-period and 4 broad-band seismometers are used to estimate traveltime residual patterns at the contact of the Dinarides and Pannonian basin. Estimation of relative residuals is achieved with fast and powerful stacking procedure through iterative alignment of traces. Global ak135 propagation model is used for achieving initial alignment by selecting the time window around the desired phase. Final alignment is obtained by rapid convergence of introduced time-shifts between reference trace and traces from each station. Similar residual patterns are caused by events arriving from the same region, but patterns differ if the events originate from various locations. Stations situated in the south-western part of the array show positive residuals, and stations situated in the north-eastern part of the array show negative residuals. Stations that show positive residuals are situated on thick Dinaridic crust, which explains later arrivals. Early arrivals correspond to stations situated on much thinner Pannonian crust, hence the negative residuals. Residual pattern that occurs between these two distinctive groups is characterized by alternating negative and positive residuals. This feature corresponds to ophiolitic Transitional zone characterized by strong lateral heterogeneities in the lithosphere.
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The Crustal Structure Beneath the Marmara Region, Turkey using Receiver Function Method
Authors T. Tezel, B. Kaypak and T. ShibutaniWe determined the Moho depth and velocity discontinuities in the crust and uppermost mantle using receiver function method in Marmara region, Turkey. We used teleseismic earthquake data recorded between 2005-2010 by the national broad band seismic stations operated by Earthquake Department of Disaster and Emergency Presidency of Turkey and Boğaziçi University Kandilli Observatory (KOERI). In this study, we selected 21 broadband stations that are located in the Marmara region in Turkey. The Moho depth changes from 28 to 39 km and upper mantle velocities varying between 4.0-4.5 km/s in the study region.
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Dynamic Topography in Europe
More LessAccording to the classical theory of isostasy topography is controlled by the variations of crustal thickness on a regional scale because the crust floats on the mantle. However, the existence of over- and undercompensated areas indicates that the classical isostatic theories are not enough to explain the topography. Mounting evidence indicates that a significant proportion of Earth’s topography results from the viscous stresses created by flows within the underlying mantle. This portion of the topography is commonly referred as dynamic topography. In a case study on the European continent I analyzed the coherency between topography and free-air anomaly and it was found that dynamic topography may play an important role in the Pannonian basin.
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The Effect of Different Geometries on the Thermal Mantle Convection
More LessA leading tool for understanding thermal convection in the Earth’s mantle is numerical modeling. To solve Boussinesq equations a finite element code has been applied. This is the first time this method has been used in Hungary, namely, modeling mantle convection on the Cartesian coordinate system. The simulations have been run in 2D Cartesian and cylindrical coordinate systems as well as in a “mantle-like” cylindrical-shell. The mantle dynamics are controlled by the Rayleigh number, which is the ratio of the buoyancy to viscous forces. The effect of Ra has been studied in the range of 1e4 to1e7. The significance of the cylindrical geometry is that at a given rms velocity the convection can carry the most heat to the surface and the results were close to the three dimensional case. This may imply that the upwelling part of the 3D mantle convection is cylindrical (mantle plume). In the cylindrical-shell domain an impressive approximate picture of the chaotic structure of the mantle convection has been shown. With the comparison of the three geometries it could be said that the cylindrical coordinate-system seems to be the most appropriate geometry to investigate the physical properties of an individual mantle plume.
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Facies Variations Detected by Well Log Correlation in a Geothermal Reservoir (Újfalu Formation) around Debrecen, Hungary
Authors T. Buday and Z. PüspökiA sequence stratigraphy based well-to-well correlation was performed as part of a regional geothermal project to determine the geometry and hydrogeology of a reservoir from which two famous spas produce thermal water. The most important thermal reservoir in Cenozoic formations in Hungary is the Újfalu Formation, which was mainly deposited in a delta front environment. In this paper a facies variation is presented in the Újfalu Formation, above a thrust wedge of the basement. Parasequences were determined by well log correlation, the appearance of parasequences is different in the sub-basins (sandy) and above the thrust (silty with sand layers). The silt and clay deposits in the reservoir decrease the hydraulic conductivity, modify the water movement. The difference could be formed by the relative vertical movement of the thrust during the deposition and local character in the surroundings of it. This information refines the sub-regional solid and hydrogeological model, thus helps the sustainable, economic and various utilization of geothermal energy in a famous thermal bath area.
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Vibration on the Surface Due Underground Mining in Karviná Region, Czech Republic
Authors Z. Kaláb, R. Kořínek, E. Hrubešová and M. LednickáKarviná region, part of the Upper Silesian Basin (Czech Republic and Poland), where intensive mining induced seismic events have been documented for a long time, is the area with underground exploitation of black coal. This exploitation manifests also as negative effects on the surface, mainly deformations of surface, changes of hydrogeological conditions and induced vibrations. Experimental investigation documents intensive vibrations that for more intensive mining induced seismic events exceed the value of 10 mm/s. One example from interpretation using time-frequency map of measured digital signal is included.
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Possibilities of Potential Mapping for BHE Heat Pump Systems
By E. PulayThis study is aiming to develope a mapping method that can be used as an aid for designing smaller borehole heat exchanger geothermal heat pump systems. This is yet a not widely researched, undeveloped topic. For the mapping method assessment a study area near Budapest was used. The results showed that besides rock composition mapping and guideline-based heat extraction calculations, the thermal conductivity estimations are the most precise and the most informative way to complete this task. With these maps favorable and less favorable areas can be distinguished within a study area. These maps allow for more precise estimation of necessary borehole lenghts for given projects. Also, after consulting with companies, this information can be used for payback time analyses.
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Trends of Wastewater Discharge and Pollutant Content in Rivers of Shanghai
By J. C. KangWater Environment in Shanghai got more and more attentions. The hotspots are wastewater discharge and pollutant content in Changjiang and Huangpu rivers. From 1981 to 2009, the city wastewater discharge was fluctuated between 18*108 ton and 24*108 ton. Inside, the gross of industrial wastewater was trendily decreasing from more than 13*108 ton at 1980s to about 7*108 ton recently years. The gross of living wastewater was increasing trendily, it related with increasing of city population. The month flux of chemical pollutant discharged by Changjiang River was between 25.9*104 ton to 209.6*104 ton in recently years. The average pollutant gross carried by Changjiang River in year, was about 593.45*104 ton among 2002 to 2009; about 83.68% was COD. Other pollutants were nutrients, oil, heavy metal and arsenic, the variability was larger with year. The month flux of pollutant carried by Huangpu River was 2.56*104 ton, more than 63% was COD averagely. The pollutant gross had an increasing trend year by year. Generally, the percent of pollutant from Huangpu River was about 3.6 to 4.4% compared with that in Changjiang River.
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Transport of Pollutants around a High Building: Integrated Magnetic, Mineralogical and Geochemical Study
More LessWe studied the degree and distribution of traffic induced pollution at a 40 m high building at the side of a major road in Budapest by making magnetic, mineralogical and geochemical analysis on settled dust samples collected at different levels and at the front and back sides of the building. We observed strong seasonal dependence of the amounts of anthropogenic pollutants, which were highest during summer. This season was also characterized by strong vertical variation of the amounts of dust, of the magnetic susceptibilities (reflecting best the traffic induced pollution) and of the concentrations of Pb. All these have maximum values at 9 m, on both sides of the building. The pattern of the distribution does not correspond to what is predicted by an air flow model published for high buildings with similar morphology and wind conditions.
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Monitoring Water Quality in Open Basins of Non-operating Mines and Dumps
Authors D. Borisova, H. Nikolov and B. BanushevWithin this research we explore time and seasonal behavior of multispectral satellite data with middle to high spatial resolution in order to estimate the content of metal particles in the water basins formed by non-operating copper mine and dumps. The aim is to test if regression model could be created between metal polluted water and the spectral response of the basins. As basis the spectral response of the embedded rocks of the copper mine and sands on the beaches of the dump site have been investigated. Similar to the well known vegetation indices such as NDVI several spectral indices are suggested, analyzed and the results are reported. The obtained results showed that the analyzed data and the implemented approach are proved to be useful in environmental monitoring process for the mining company responsible for the ecological state of the region. Also the successful implementation of method could be considered as basis for establishment of airborne monitoring of the ecological state of these areas.
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