7th Congress of the Balkan Geophysical Society

Resistivity electrical changes in vertical, horizontal and in the direction that is perpendicular to the survey line, is measured in 3D surveys. 3D electric data illustrate a 3D image from subsurface layers, therefore combination of3D electric results and surface geology is appreciated as helpful technique in electric data interpretation. What Is carried out for performing a 3D survey is as follows: first a 2D survey is carried out in the survey field and then collected data are interpretated. When the subsurface layers are defined clearly, an area is selected and a suitablegrid for 3D survey is designed. After data acquisition, by using a 3D interpretation software, data points areinterpretated. Finally, the results are compared with the result of 2D configuration. In this study, the mainobjective is the detection of a fault trend by using pole–pole electrode array which is commonly used for 3Dsurveys. This survey method by using a 3D interpretation model gives accurate results of subsurface structures. In order to confirm the abilities of this method for fault detection, after checking the final results of 2D Shlumbergerarray on a fault trend in Anarak area in Esfehan province, an square grid with a 60 meters long, .

The article presents an attempt to generalize the integrated geophysical data: Gravity, Magnetic, Paleomagnetic, Geothermal, Seismological and Remote Sensing images of zone, where it crosses the deep transversal fracture Shkodër – Pejë. Analyses of the geophysical data are based on regional geological setting data of Shkodër-Pejë sector of Mediterranean Alpine Folded Belt, which presents the existence of important disjunctive deep tectonics element. Shkodër-Pejë tranversal fracture represent the contact between the African and Eauasian plates contact transverse territory of folded belt of the Albanides. The geological mapping at the scale 1:25.000 up to regional ones at the scale 1:200.000, does not have traced at the Earth’s surface the outcrop of this thrust. Consequently, have brought about the different concepts on it, from “scharung” (1901) to “transform transversal fault” (1970-2012), and to silence about its existence, even to denial of its presence. These changes in the course of a century, not just in terms of use, were related to different geological schools over the geological setting of the Albanides. The integrated geophysical information has cast light on the depth of the area, where it crosses the transverse Shkodër-Pejë that represent a deep transverse vertical fracture, which affects the Moho Discontinuity.

The Van earthquake (ML 7.2, 23 October 2011) occurred in E-Turkey, typically “intraplate” earthquake. Aftershock seismicity pattern of the Van earthquake indicates the most prominent type of compound-complex earthquakes due to its multifractal dynamic complexity and uneven compressional nature, ever seen all over Turkey. Aftershock seismicity of the Van earthquake can’t be explained with linearly uniform, elastic fracture mechanics, because the time delays between the observed individual clusters are too long to result from elastic processes. The Van earthquake dynamically loads the surrounding volcanic region, such a compound earthquake can result from viscoelastic relaxation in the immediate postseismic period, resulting in nonlinear and heterogeneous redistribution of loads. Van earthquake as a composite system has input parameters more than one and strongly characterized by composite sequences of event instabilities. This brings an idea that is intraplate seismicity of accretions, giving a possibility of the extensive investigation of post-collisional rheology of accretionary complexes. We conclude that, in Lake Van, the deep-reaching zones of weakness allow magmatic intrusions into upper crustal layers, where magma-fluids or unstable fluctuations of the magma chambers themselves may cause the generation of unstable evolution and propagation of earthquake sequences.

Wavelet (Mathematical Microscope) analysis of seismic data is made fashionable for thin bed precise subsurface imaging and interpretation. 3D seismic data interpretation for subsurface imaging of thin bed contourite systems is integral part of research work . Seismic expression of bottom current deposits from that of other related deepwater sediments (turbidites, hemipelagites, debrites, etc.), and to maximising the information that can be derived from seismic data. A wide variety of seismic facies are common in contourites, most of which are equally present in turbidite systems. Seismic facies associations that may be typical of contourites are still to be defined. Seismic characteristics also depend very closely on the methods of seismic acquisition and processing. Sediment waves and channels are very common both in contourite and turbidite systems, and not specifically diagnostic of either system. Slope deformation, sediment creep, and large-scale water-escape may cause a hummocky seismic facies that can be misinterpreted as sediment waves. The identification of hydrocarbon reservoirs from seismic data is a key issue in the oil industry. Texture Segmentation of a 3D Seismic Section with Wavelet Transform is employed for pattern recognition.

Abstract In Albania there are discovered phosphorite mineralization of the Upper Cretaceous (Coniacian) and Middle Jurassic. The application of radioactive methods have had concrete results and have solved concrete problems (Dafa F., Serjani A., 1994): theoretical solving of the character of distribution of useful components U and P2O5; determination of the mutual correlations between U, P, F and Gamma intensity, discovering the coefficients for the main chemical and radio metrical constituents etc. The differences of the uranium content between Coniacian Phosphate Horizon and Middle Jurassic uranium-bearing mineralization can be explained by their differences in genetically aspect. The formation of phosphate-carbonate-siliceous horizon happened into the pelagic, deep sea, reduced environment of Ionian Trough, where the clastic, terrigenous matter is totally missing, and phosphate beds are very clean, constituted only by phosphate and calcite minerals. Middle Jurassic uranium-bearing phosphorites were formed in photic zone, in shallow water environment, on submarine mountains (high parts) of break in sedimentation. Phosphate mineralization is accompanied by high content of organic matter, dolomite, pyrite, quartz and some other detritus minerals. The high content of uranium can be explained due to above mentioned accompanied constituents and by the absorption during digenetic processes.

The study presents a methodology for using standard seismic survey equipment for assessment of the impact of grouped blasts from quarries. Example from а limestone quarry situated at more than 1.5 km from the thermal spring “Merichlery” in South Bulgaria is discussed. After the two strong earthquakes from 14.04.1928 (М=6.8, Chirpan Earthquake) and from 18.04.1928 (М=7.0, Popovitsa Earthquake) the water from the spring disappeared. A survey was executed for assessing the impact of the blasts on the houses and the discharge of the mineral water from the exploitation borehole. The results are compared to the national and international criteria for the safety limits of accelerations and velocities of the ground in relation to the seismic frequencies. Reference to the maximum expected ground accelerations from earthquakes on the concerned site is also presented. The maximum vertical acceleration from the quarry blasts was calculated to be between 32.81 and 57.62 cm/s2, and the horizontal one – between 37.51 and 233.95 cm/s2 (single high frequency picks). These results indicate that no one record overpasses the normative level of accelerations from earthquakes for the area - 0.27 g (265 cm/s2). In average the recorded accelerations were 2.5 times lower than the normative.

Generally, the landslides study is aimed towards determination of their physical- geological characteristics and the peculiarities of their structure. The main tasks are detection of zones characterized by different degree of water-saturation, mapping of landslide surfaces and contact zones, along which is performed the rock mass movement, determination of the shape, the dimensions, and the spatial situation of the landslide body. The possibilities, provided by the non-invasive geophysical methods, for solving the above-defined problems depend mostly on the landslide physical-geological model. Usually the geo¬logical section of a landslide site is well differentiated according to electrical resistivity. For this reason geoelectrical techniques applied for obtaining high-resolution images of the underground resistivity have leading role in geophysical investigations of landscapes. In this study are presented results obtained from the application of electrical tomography for investigation of a landslide site on the territory of Bulgaria - near the town of Varna.

During the period of 20 years in near coastal Lowland of Albania, many geophysical studies have been carried out with Electrometric, Magnetometric, Gravimetric and Radiometric methods. Important place in these studies has taken Electrometry, mainly the method of resistivity. Results obtained in the most important regions of near coastal Lowland provide the supporting basis for all infrastructure projects and major works. Geophysical studies have provided research-scientific information to the surface and in depth, helping in solving geological, geoenvironmental, civil geology, geological-sedimentological, geological-engineering, hydrogeological and archaeological tasks in varying degrees. To standardize the information collected over the years, to coordinate and to annex it to any other type of support information for performing processing, further riinterpretations, it was necessary to use technology GIS (International Geographical System) in order to integrate them. Geological-geophysical studies included in these region resolved tasks: determining of the thickness of Quaternary deposits, the study of land for social buildings, exploration of minerals, researchs for waterbearing and the microzone of some regions. Based on existing technology (hard-software) was achieved to build GIS for geophysical studies at this region of Albania. Process has passed some phases like as: data preparation, informatization and processing etc.,

A comparative study of the behaviour of three null-arrays, midpoint null-array (MAN), Wenner-g null-array and Schlumberger null-array in response to a fracture, both in profiling and in azimuthal mode is presented. The term “geoelectric null-array” is used for direct current electrode configurations yielding a potential difference of zero above a homogeneous half-space.The main objective is to determine which array(s) best localise vertical structures or best identify their orientation. Forward modelling of the three null-arrays revealed that the Wenner-g and Schlumberger null-arrays localise vertical fractures the most accurately, while the midpoint null-array combined with the Schlumberger null-array allows accurate orientation of a fracture. Field test measurements were carried out to verify the theoretical results above a quarry in Les Breuleux with the three null arrays and many classical arrays. The results were cross-validated with quarry-wall geological mapping. In real field circumstances, the Wenner-g null-array showed to be the most efficient and accurate in localising fractures. The orientations of the fractures in accordance with the numerical results, were most efficiently determined with midpoint null-array, however Schlumberger null-array adds accuracy to the results. This study shows that geoelectrical null-arrays are better than classical arrays for the characterisation of fracture geometry.

The g11n arrays, which were until now outside of the interest of the geophysicists will be introduced. These so called quasi null arrays can be more effective in detection and characterisation of anomalies have just a small impact on the potential (due to their small size, resistivity contrast to the host rock, and/or their large depth) than the traditional arrays. In many investigations they proved to be even better than the Stummer array which was constructed by an optimisation procedure from the set of the traditional arrays. The g11n arrays proved to be moreover significantly better in horizontal and vertical resolution investigations and in some more models, as well, than even the optimised array. According to our theoretical and numerical investigations the usefulness of these arrays can be expected in numerous other geophysical research areas, as well. It is however already seen that the g11n arrays can be valuable tools for solution of many problems similar to the investigated one, like e.g.: in the research of tunnels, caves, cables, abandoned riverbeds, or discontinuities in the clay layer below a waste deposit. The applications of these arrays require moreover less time to carry out the measurements than those of the traditional arrays.

Albania is characterized by intense microseismic activity and small and medium-size earthquakes and only seldom by large event. We present here the results of the analysis in parameters of events and some features of Seismicity that have occurred in the Albania and surrounding area during 2012 year. On that territory 39°00’-43°00’ N and 18°50’-21°50’E there are 869 located earthquakes with magnitude M≥1.5 (Richter), 196 with magnitude M≥3.0, 19 with magnitude M≥4.0. The most of local earthquakes about 92% are distributed in depth between 0 and 25 km, with maximum concentration between 4 and 12 km. The earthquake foci are concentrated mostly along the some active faults: 1) In the Vlora-Elbasan-Dibra transversal fault zone. In the vicinity of Fieri was registered a small series of earthquakes that have the same level of of magnitude and supposed to be an inducted seismicity. 2) In The Korca-Leskovik seismogenetic zone. 3) In the Ionian seismogenic zone. 4) In the Lezha-Ulqini seismogenic zone. Increased seismic activity was registered on the Greece territory, nearby of southern Albania.

Microtremor method used for engineering seismology is very important for determining of dynamic ground parameters and its variations. Method based on frequency of horizontal and vertical component microtremor records provides to quick and economical estimation of dynamic ground parameters. Most important advantage of Nakamura method defined as single station method isn’t required reference point and it can be applied easily in the area with low seismic density and without base rock. In this study, Nakamura (H/V) method has been applied to microtremor records taken with CMG-6TD three component broad band velocity seismometers in 6 profiles and 40 points with the aim of determining ground predominant period and magnification parameters of the Gumushane University and its surrounding area located in Northeast of Turkey. Maps of magnification, predominant frequency and ground classification (Z2 and Z3) according to the predominant period are created by derived values.

The near hemispheric dichotomy of Mars is attributed to a giant impact called Borealis impact[Andrews-Hanna et al., 2008]. In this work, we investigate the effect of Borealis impact ,happened 4.5 Gyr ago, on the thermal evolution of the Martian planet. We show that the impact increases the rate of crustal production for a period of about 50 m.y. after the impact, reduce score mantle boundary heat flux significantly for a period of less than 5 m.y. after the impact but does not change significantly the total volume of melt production of the Mars. We discuss implications of our results on the postulated equivocal theories on the demise of Martian dynamo and conclude that none of them is capable to explain the demise of the Mars magnetic filed happened about 4 Gyr ago

The scope of the project THERMTEC is to model thermal-tectonic orogenetic processes in the Eastern Alps. Regional geothermal regimes are influenced by tectonically induced processes in terms of uplift or depression, which in combination with exogene processes like erosion and sedimentation lead to significant geothermal anomalies. This study aims to investigate the influence of two antithetic tectonic processes on the recent geothermal regime for the Tauern Window in order to detect possible zones of positive and negative heat flux anomalies. Geophysical, geochronological and petrophysical investigations as well as 3D geological modeling (using GocadTM) are part of the research. Using the software package COMSOL MultiphysicsTM coupled thermal-tectonic modeling will be carried out during several steps focusing on a regional scale geometric 3D model covering the whole Tauern Window. Starting with a conductive, steady-state model and leading to more complex simulations (transient advection and mass movement). Results will be compared with observed recent terrestrial heat fluxes, palaeothermal conditions gained from geochronological data.

The studied area is located in the north-west of Albania in urban areas of that area. Radon activity in indoor air was measured by passive and active detectors. Radon concentration survey has been carried out in schools and kindergartens. Depending on the detectors used in measurements, the long term and in a few cases is the use short term methods have been applied. In this research, it is included the results taken only for the 26passive and 15active detectors in schools and kindergartens. In addition, the results of the other 25 detectors are in the procedure of analyzing. The choice of the measured areas is related to the different geological formations. The investigation area shows low- medium – high radon indoor concentration. Keywords: radon, indoor air, soil, red clay, permeability, terra rossa.

Broadband vibratory seismic measurements are suited for deep signal penetration, improving reflector continuity and inversion. Seismic vibrators have serious mechanic and hydraulic limitations in emitting very low frequencies, hence special low-dwell non-linear sweeps are the most common drive signals, but pseudo-random sweeps are also considered to achieve satisfactory results. In this study a global optimisation technique used tailored to include several optimisation targets concurrently to reach a workable solution. Since a simple random sweep generated by vibrator manufacturers’ software has serious disadvantages, our optimisation minimises amplitude fluctuations in frequency domain, correlation side-lobe amplitudes and maximises total seismic energy of the sweep. By controlling maximum amplitudes below a certain vibrator specific lower frequency and by minimising instantaneous frequency changes vibrator mechanic and hydraulic limitations are taken into account. The resulting optimised pseudo-random sweeps have much better correlation and spectral properties than a simple random sweep. Also sweep length could be reduced substantially compared to a simple random sweep and a typical non-linear broadband sweep due to the increased total seismic energy achieved by the optimisation process. As a consequence optimum pseudo-random sweeps could be used in high productivity broadband seismic acquisition where resonance effect reductions are important, too.

The ‘minimum 1-D’ velocity model (Ormeni 2011) was used as initial model and, therefore, a reliable velocity model for the region was derived. Interesting features and details of the Albania upper and middle crust can be recognized in the final tomographic images. The results show that the velocity distribution is influenced from the geology and the seismotectonic regime of the region. At shallow depths (less than 4 km) the velocity increases gradually with respect to the depth without any sharp variation. On the contrary, the lateral variation of velocity seems to be affected from the geological regime of the region. Our new velocity model solving low-velocity features at shallow depths in the basins and some high-velocity features in the uppercrust.

Summary Volcano-sedimentary formation of Porave - Miliska area is constituted by high titanium basalts and sedimentary intercalations represented of argillaceous and argillaceous – radialarite. This formation is characterized by a very complicated structural construction. The area is highly saturated with copper-pyrite sulfur mineralization and up to now 42 sulphide ore showings are found. Three types of mineralization have been identified: (VMS) volcano massive sulphide ore type with almost sharp contacts with the surrounding rocks, quartz-sulphide mineralization (or vein type) with sharp contacts with the surrounding rocks and hydrothermal-metasomatic mineralization characterized by large mineralized zones within which are meet the massive lenses. All field-spreading of volcano-sedimentary formation is covered with complex geological-geophysical works with 50x20 m grid. These works have identified a number of IP anomalies related to known ore bodies and in sectors with no ore showings. Measurements of IP with Dinpol apparatus provide clear differences between the ore body and surrounding rocks (Porave deposit case). The method of body charged also gives very good results (case of Geraj ore deposit). Key words: volcano-sedimentary formation, copper ore, IP measurements.

Accurate picking of dispersion curves is the most critical stage in Multichannel Analysis of Surface Waves (MASW) method. Although there is several acquisition and numerical techniques for the optimal extraction, sometime, this requirement cannot be valid due to interference, which includes different modes, noises, and also lateral inhomogeneity in the near-surface earth. Hence, the interference between the different modes of surface waves can be so serious that neither fundamental, nor higher mode dispersion curve can be extracted with an accurate and a reliable. For this, we calculate surface waveforms, including geometrical and intrinsic dispersion, based on the summation of the particular seismic impulses corresponding to particular frequency-phase velocity curve points for geophone positions from the seismic source. This methodology is demonstrated by using both synthetic and real shot gathers. Synthetic calculations provide us a simple way to check accuracy of dispersion curve picking on a shot gather, which it is the fundamental or higher mode.

We present a software dealing with focal mechanisms solutions for educational and research purposes. It gives reasonable results by performing graphical interface of the beachball diagrams. Plots can facilitate to understand the kinematics of fault ruptures. The program is used to examine the nodal planes, calculate the orientation of the Strike, Dip and Rake, and to plot the possible structural model on the block diagram representing the beachball diagram. It is written in Visual Basic 6, and has all the advantages of the Windows OS.

This study aims; - Using the acceleration records as well as the displacement traces to determine the spectral source parameters described above by using P & S waves and noise records, - Showing the possibility of obtained the corner frequency (Fo) without converting acceleration traces into displacement, - Determining evidences of the parameter Fmax, and, - Comparing the spectrum characteristics obtained from noise, P and S waves both of acceleration and displacement data. Spectral seismograms of 10 earthquakes recorded by acceleration stations of IzmirNet, are presented, here, to discuss spectral behaviour of seismic signals included both acceleration and displacement records. Earthquake parameters of events are also given in the text.

Based on processing seismic data, a new interpretation is accomplished to evaluate the possible gas bearing targets. In this paper we give some aspects of true amplitude seismic data processing and seismic attributes for gas detection in some areas of Peri-Adriatic Depression. From the whole of factors that affect in seismic signal amplitude, we have compensated in true amplitude processing the spherical divergence, absorption effect, changes of source energy in different shot points of the line, amplitude distortion caused by near surface heterogeneous, etc. Preferably, also, the data ought to be migrated with careful attention to preserving the correct angle-dependence of amplitude. Computer modeling of the available data and correlation of AVO information with other geologic evidence may be required to determine whether or not observed variations of amplitude with angle can be considered indicative of hydrocarbon accumulation. Many aspects of seismic data are not evident on individual CMP gathers, and are visible only when viewed from a broader perspective. The integrated all analysis of seismic attribute displays, integrated also by well data and modeling results have allowed a detailed seismic stratigraphic interpretation.

The seismic refracted method has been used extensively around the world for geological and geotechnical investigations for hydro power projects, etc. Due to the seismic parameters measured in the field and according to the borehole log for all drilling, the Ashta area sites are classified to rock Ashta2 and to stiff soil Ashta1 which are taken into account for the re-evaluation of seismic hazard. Using the multi-channel analysis of surface waves MASW apply through the "SURFSEIS" method have taken the vertical profile of shear waves velocities. A summary of the profile velocities Vp and Vs estimated from seismic refraction measurements and the method of surface waves “MASW” performed in Ashta2 site are shown. Based on the provided Vs30 and SPT-N data, the specific site conditions according to International Building Code, for the sites under investigations are classified as follows: HPP Ashta 1 site to C site class (i.e. very dense soil and soft rock site), HPP Ashta 2 site to B site class (i.e. rock site). The results of seismic hazard for HPP Ashta sites on their specific site conditions at probability 10%/50 years are taken into consideration for HPP Ashta site design.

On 22nd of May 2012 an earthquake with magnitude Мs=5.8 occurred in the town of Pernik about 20 km SW from the capital Sofia causing moderate damages in a wide area including the main city. According to the reports of the seismological agencies and the rapid determination of Bulgarian national seismic network the depth of the event is shallow - about 10 km. The epicentre of the shock is in an area which is relatively quite for the last 120 years minimum. The orientations of the fault plane solutions and distribution of the aftershock epicenters coincide with the NW direction of Pernik-Belchin fault tectonic lineament. As a result, a dislocation model using Okada definitions based on the complex analysis of the dataset is proposed.