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8th Congress of the Balkan Geophysical Society
- Conference date: October 5-8, 2015
- Location: Chania, Greece
- Published: 05 October 2015
1 - 50 of 124 results
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Refraction and Amplitude Tomography Based Methodologies on Evaluation of Engineering Properties of Rocks - A Case Study
Authors A.E. Babacan and K. GelisliSummaryThe main aim of this study was the reveal of internal structures and engineering properties of basalt bedrock aged Eocene-Neocene, north of Eastern Pontides, Turkey. In selected area for this purpose, the seismic data were collected at total 7 profiles. A shallow refraction and amplitude attenuation tomography survey in study area was performed to mapping of Vp velocities and attenuation coefficient for civil engineering plans. In order to determine shear wave velocity (Vs) of study area, multichannel analysis of surface wave (MASW) in was also used. The Evaluation results show that the study area has three layers. The upper layer was interpreted as topsoil having a P velocity range from 400 to 800 m/s. The middle layer was interpreted as weathering basalt having a wave velocity range from 1200 to 1600 m/s. The bedrock was interpreted as massive basalt. P-wave seismic velocities of this bedrock range from 1800 to 2800 m/s. The average Vs 30 velocity was found 730 m/s from MASW. Attenuation coefficient is an important parameter to identification rock mass structure and 1/α value of weathering and massive basalt was changed between 5 and 15. During site selection, it has to determine to engineering properties of foundation rock.
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A Rapid Mapping of Sarıçiçek Pluton from In-situ Gamma Ray Measurements
Authors S. Altundas and H. ÇinarSummaryThe concentrations of equivalent eU, eTh, K% and dose rate values were measured using in-situ gamma-ray survey in order to map rapidly the surface geology of the Sarıçiçek pluton and its surrounding area. Gamma-ray spectrometric data were collected with a 512-channel portable gamma-ray spectrometer (NaI (Tl) cyrstal) at 265 points in which duration for a single point measurement is 5 minutes. The average activity concentrations of 238U, 232Th, 40K and dose rate obtained in this study are 38.97 Bq/kg, 50.56 Bq/kg, 935.267Bq/kg and 88.78 nGy/h, respectively. Although distinct radioactive anomalies were found in the studied area, the radiometric values showed some minor variations with slightly higher values than the normal level. As the result of this study, the average values of the absorbed gamma dose rate in air, radium equivalent activity, annual effective dose rate and the external hazard index were also calculated and examined in terms of radiologic hazard in this area. Consequently, all of the radiometric parameters are in good agreement with the regional surface geology of the Sarıçiçek pluton and its surrounding formation and there is no significant radiologic risk for humans and environment in and around this area.
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The First Steps for a Joint Romanian-Bulgarian Regional Early-Warning System for Marine Geohazards
Authors N.D. Dobrev, O.V. Dimitrov, G.P. Nikolov and K.S. KostovSummaryAn overview on the main hazardous geological processes endangered the Romanian-Bulgarian Black Sea coast with emphasize on hazards related to Bulgarian side, and goals and objectives of the Cross border project MARINGEOHAZARD whose purpose is to create key core components of a joint early warning monitoring system approved on both countries. The basic geohazards concerning Bulgarian part of the coast are presented. This includes historical strong earthquakes with tsunamis. The effects from the catastrophic earthquake with M7.2 occurred on 31 March 1901 near Kaliakra Cape have been described. The area is characteristic with large size landslide affecting strongly the North Bulgarian shoreline. The installed monitoring equipment included network of complex automatic marine measurement equipment, onshore network of online GNSS stations, extensometers, marine seismic monitoring equipment, etc. The first results obtained from 3D extensometric monitoring performed around Kaliakra Cape have been presented.
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Nonlinear Dynamics of Regional Cyclogenesis with Wind Speed Variations
Authors N.S. Erokhin, N.N. Zolnikova, L.A. Mikhailovskaya and R.S. ShkevovSummaryA numerical analysis of a self—consistent small parametric model (SPM) of a regional large scale cyclogenesis (RLSC) has been performed by usage of connected nonlinear equations for mean wind speed and ocean surface temperature in the tropical cyclone (TC) zone. These equations may describe the different scenario of temporal dynamics of a powerful atmospheric vortex during its full life cycle. By means of numerical calculations it is shown that relevant choice of SPM’s incoming parameters allows to obtain the seasonal behavior of regional LLSC with a given number of TC during the active season. In addition, the model allows describe the wind speed variations within the TC. So in the reference frame of the nonlinear small parametric model it is possible to study the features of RLSC’s temporal dynamics during the active season in the region given, to analyze the relationship between regional cyclogenesis characteristics and different external factors like the space weather.
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Determination of the Amplitude Values with Nakamura (H/V) Method and Standard Spectral Ratio (Ssr) Method at Ktu Campus
Authors Y.B. Beker, N. Sayil and Ö. AkinSummaryMicrotremor 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. In this study, Nakamura (H/V) method and Standard Spectral Ratio (SSR) method have been applied to microtremor records taken with CMG-6TD three component broad band velocity seismometers in six profile with the aim of determining ground amplification of Karadeniz Technical University Campus area. The amplification maps of the study area are generated to the results of Nakamura (H/V) method and Standard Spectral Ratio (SSR) method and the results have been compared.
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Measuring Natural Radiation Backgrounds for Natural Hazard Evaluation in the Aspiring Buzău Land Geopark, Romania
Authors R.G. Popa and R. StochiciSummaryBuzău Land aspiring Geopark is a 1036km2 territory located in Romania, at the Carpathians Bend, in the close proximity of the Vrancea seismogenic area. Our work deals with natural hazards and risk in the aspiring Geopark territory. One of the hazards approached, which is the subject of this paper, refers to the exposure to natural radiation of inhabitants and visitors alike. Our work is still in progress, and we shall present its development so far. The measured values for radioactivity dose vary between 7.82 nSv/h and 56.83 nSv/h. Th levels vary between 1.38 ppm and 11.69 ppm, U levels vary between 0.31 ppm and 4.5 ppm and K levels vary between 0.32% and 2.12%. So far it seems that the natural radioactivity dose does not pose risk towards the inhabitants of Buzău Land Geopark or to its visitors, as the dose values are about 10 times smaller than the world average. We shall continue our measurements in order to optimally cover the entire territory and all lithological units, to have a comprehensive overview of the distribution of background radioactivity levels.
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Remote Sensing Observations of the Total Solar Eclipse and Incident Solar Radiation
Authors D. Krezhova, A. Krumov and K. KrezhovSummaryThe results from ground-based remote sensing investigations of changes of the environmental conditions (dramatic brightness reduction, local cloudiness, behaviour of the incident solar radiation) during the total solar eclipse on 29 March 2006 are presented. Series of digital images of the solar disk and corona as well as of a near-sun sky area were obtained during the all eclipse phases using a photometric CCD camera. Synchronous data for the dramatic changes and spectral behaviour of the incident solar radiation were collected by means of a portable fiber-optic spectrometer in the spectral range 350–1100 nm. The images were used to trace back the atmospheric conditions during the spectrometric measurements and to match the spectral data to the eclipse phases. The appeared fluctuations in the spectral behaviour of the solar radiation within several time intervals after the eclipse totality were caused by appearance of fine cloudy structures in front of the solar disk. We have found also changes in the spectral distribution of the solar radiation before and after the eclipse totality expressed in decrease of the solar radiation at the lower wavelengths and an increase in the spectral range after the spectra maximum due to the limb darkening effect.
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Imaging of Alpine and Post-Alpine Formations Using ERT at Loutsa- Remeri Open Pit Mine, Scourta, Viotia, Greece
Authors A. Vafidis, N. Andronikidis, H. Hamdan, I. Pyliotis, G. Panagopoulos, E. Manoutsoglou, L. Kikidis and N. BotosSummaryA geophysical survey carried out at Scourta plateau in Central Greece employed the electrical tomography method in order to image the interface between Alpine and Post-Alpine formations and estimate the thickness of Terra Rossa deposits. The later are crucial for TITAN-SA cement company open pit mine. This mine provides row materials for cement production. This survey is related with future extension plan of the existing Loutsa-Remeri open pit mine. Scourta is an active polje and is filled with a thick Terra Rossa deposit which is a row material for cement industry. The geophysical survey revealed two distinct layers, the upper is characterized by lower resistivity values (less than 20 Ωm), minimum thickness to the east (25 m) and maximum thickness at least 50 m and is attributed to Terra Rossa deposits. The underlying layer exhibits higher resistivity values (more than 70 Ωm) and is attributed to karstified carbonate relief. The variation of the polje depth is accosiated with tectonokarstic processes. The E-W direction fault system delineates the karstic structure and the N-S ridge in the east part of the survey area is delineated by N-S direction faults.
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Numerical Study of the Air Quality in the City of Sofia
Authors I. Georgieva, G. Gadzhev, K. Ganev, M. Prodanova, D. Syrakov and N. MiloshevSummarySome extensive numerical simulations of the atmospheric composition fields in the city of Sofia have been recently performed. The simulations were carried out using the following set of models: the model WRF used as meteorological pre-processor; CMAQ - the Community Multiscale Air Quality System — the chemical transport model; SMOKE - the Sparse Matrix Operator Kernel Emissions Modelling System — the emission model. As the NCEP Global Analysis Data with 1 degree resolution was used as meteorological background, the WRF and CMAQ nesting capabilities were applied for downscaling the simulations to a 1 km resolution over Sofia. The national emission inventory was used as an emission input for Bulgaria, while outside the country the emissions were taken from the TNO inventory. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The biogenic emissions of VOC are estimated by the model SMOKE. Different characteristics of the numerically obtained concentration fields will be demonstrated in the present paper.
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Determination of Buildings Period and Vulnerability Index Using Microtremor Measurements
More LessSummaryMicroremor data has an important role on determining the ground dominant periods. Another way of use of the method is the application on the constructed buildings for investigating the strength and periods of each floor. It is possible to define the period of each floor and calculate the floor spectral ratio (FSR) parameter using microtremor data. This parameter is being used to estimate the transfer function (amplification, natural frequency and vulnerability index) of the buildings. In this study, microtremor data were collected in Folkart Towers which have a length of 200 m. The data were recorded at 14 floors for 40 minutes. The validation of frequencies were determined using FSR in order to obtain damping ratios accurately. The variation range and tendency between damping ratio and frequency of each floor with damping ratios and vulnerability indices, along with the preliminary influence factor, were presented and discussed. In addition, a fitting curve was plotted indicating the relation between the damping ratio and dominant natural frequencies of the floors. Furthermore, evaluation of strength, damping ratio, natural dominant frequency and vulnerability index of the building were estimated by interpreting microtremor data. The dominant frequencies of 44th, 22nd and 7th floors of the buildings were calculated as 0.4 Hz, 0.4 Hz–1Hz and 1.1 Hz respectively. It was determined that the buldings have 2 dominant periods. They are 1.1 Hz from 1st to 22nd floors and 0.4 Hz from 23 to 44th floors.
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Relationship Between Quasi Transfer Spectrums and Dynamic Amplification Factor
More LessSummaryQuasi Transfer Spectrums (QTS) and Dynamic soil amplification factor defining which ratio earthquake acceleration will reach the soil surface by changing is one of the most important factors in seismic risk studies. When computing the value of DAF at a point without a strong motion station, peak horizontal acceleration values at the bedrock and soil transfer function are needed. PGA value at the bedrock can be obtained by using either real seismic records or the earthquake scenario. However, the soil transfer function can be computed observationally and theoretically. Observational soil transfer function is defined by microtremor horizontal/vertical spectral ratio. In case of theoretical computation, the density belonging to the soil layers between the bedrock and the soil surface is used together with the change of P-S wave rates with the depth and the damping factor. In this study, the dynamic amplification factor has been computed for 57 points by using observational QTS obtained by microtremor horizontal/ vertical spectral ratio as well as the earthquake scenario. Also, theoretical soil transfer function at 1 point was obtained through spatial autocorrelation method study and determined to be compatible with observational result.
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Analysis of Reliability of the Microtremor Method
More LessSummaryMicrotremor method has often been used for determination of the fundamental frequency of the sediments covering the bedrock. Relatively, it is easier to apply than drilling, cost-effective and reliable method and has become widespread recently. There are some important issues that need to be considered during the measurements such as cultural noise level, recording time and terrain conditions. It is possible to obtain reliable results from this method, if both data collection and processing stages were carried out adequately. With respect to the suggestions of SESAME Project, the reliability of H/V curves and the apex on the H/V curve representing a possible ground resonance frequency were investigated. There are 3 main suggestions of SESAME Project in order to determine the predominant period (T0) and investigate the reliability of H/ V curves. These conditions are determining suitable number of windows, number of periods should be more than 200 and according to f0 value, standard deviation (σ) of H/V curve should be less than 3 if f0<0.5 Hz and σ<2 if f0>0.5 Hz. Besides, at least 5 over 6 criteria of SESAME Project should be proved in order to obtain a reliable result from the calculated apex of a H/V curve. Thus, the apex of H/V curve can be accepted as a reliable peak and this proves the observer to determine reliable ground parameters as well. In this study, output file of the H/V curve obtained from the evaluation of the microtremor data using Geopsy software was evaluated by an Excel-based program to examine the criteria determined in the context of the SESAME Project. Also the flowchart of the algorithm is presented. Data were collected from the Bornova district of Izmir. The measurements were analysed and the results were interpreted.
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Geophysical Characterization of the Havuzlu Landslide in Artvin Dam Area, Eastern Turkey
Authors K. Gelisli, S. Goren, H. Ersoy and C. CelikSummaryThe Artvin Dam and hydroelectric power station that has been built on the Çoruh River will have an average of production 1 billion kWH per year. It is far 20 km from south-west of the Artvin Province (Eastern Turkey). Havuzlu Landslide is located in a slope in boundaries of the Havuzlu village on the Artvin dam reservoir. The Havuzlu Landslide which has complex structure and including groundwater is paleo-landslide. The structure of paleo-landslide, potential sliding surface, possible fractures, crushed zones, geotechnical properties of formations and situation of groundwater were investigated by 2D electrical resistivity imaging method, self-potential (SP) measurements, microtremor and boreholes data. To calculation of slope stability possible sliding surface was determined between the landslide material and bedrock. Distribution of landslide materials along vertical and horizontal directions was determined. Structure of landslide mass and bedrock were extremely heterogeneous. Silty-clay and saturated zones were identified in the landslide mass. The crushed zones were estimated on bedrock layer. In the landslide area was calculated slope stability for three selected profile was demonstrated to be unstable.
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Geophysical Investigation for Environmental and Geotechnical Projects in the Lavrion Technological and Cultural Park
Authors G. Apostolopoulos, A. Kallioras, G. Amolochitis and G. MakrisSummaryA tailored geophysical investigation was designed to provide useful information in two of the activities/ priorities of the Lavrion Technological and Cultural Park (LTCP): a) identification of optimal location for the construction of an advanced Soil-Aquifer-System (SAT) which will be used to monitor geo-purification processes within the unsaturated zone; b) detection and mapping of an old (abandoned) mining tunnel that is envisaged to serve the educational purposes of the LTCP. Electromagnetic measurements in a regional and local mode have given useful information as a reconnaissance method in the positioning of the best area for the first activity outlining mainly areas of problematic anthropogenic features. ERT method clarified in a great detail the underground features in order to better design the structures for the two activities/priorities of the LTCP.
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Fracture System Mapping Using Pressure Probe Method
Authors S. Szalai, M. Metwaly, K. Szokoli, Á. Tóth and V. WesztergomSummaryMechanically weak zones may arise e.g. due to rock realignment in the subsurface having an effect to the near surface-, or even to the surface sediments. If they are not directly seen from the surface a new method, the so-called pressure probe (Pre-P) method may be used to detect and characterise them. This method is presented on the example of the investigation of the fracture system of a landslide. Repeatability of the Pre-P measurements, adequate sampling distance, resolution of the method and the possible data processing steps are also investigated. We know from these investigations that: 1. there are consolidated zones on the slope side of the fractures whose broadness correlates with the broadness of the given fracture; 2. both the large and the small fractures follow each other periodically; 3. even the structure inside the blocks which belong to the large fractures can be well seen which refers to the very good resolution of the method. The here presented Pre-P method seems to be the most favourable tool to map the fracture system of such kind of landslides according to its resolution capacity, speed, simplicity of its application, the interpretation of the data and its costs.
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Geotechnical Characterization of a Tailing Pond Dam
Authors Zs. Pronay, E. Törös, G. Taller and P. TildySummaryThere are about 30 tailing ponds of different size situated in Hungary. One of them was broken in 2010 and about 40 km2 was flooded by red mud causing 10 casualties and 140 injured. Since this incident Mining Authorities are responsible for the regular inspection of the dams. For testing the available geophysical methods intensive field tests were completed by the Geological and Geophysical Institute of Hungary to help the Authorities.
In this presentation the geotechnical and geophysical investigation of a selected tailing dam will be discussed. To investigate the dam 2D and 3D multielectrode DC method together with P- and Rayleigh-wave seismics and CPTu sounding was applied. There were triaxial or direct shear laboratory tests on undisturbed core samples as well. The geotechnical and lab results were compared with the values calculated using the seismic velocities.
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Application of ERT to Map Earth Fissures at the Valtotnera Area (Amyntaion, NW Greece)
Authors P. Tsourlos, G. Vargemezis and I. FikosSummaryIn this work we present the results of the application of the electrical resistivity tomography (ERT) technique into the mapping of the fissures that appeared in the Valtonera area (Amyntaion Munisipality, NW Greece). The results of ERT provide a satisfactory explanation to justify the expression of surface cracks in specific areas and this approach can be used to provide areas that are likely to be associated to fissures in the future.
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Application of Electrical Resistivity Tomography Method to the Mapping of Explored Caves and Detection of Possible New Chambers: Case Studies from Greece
Authors G. Vargemezis, I. Fikos and P. TsourlosSummaryCave detection and mapping is one of the most common targets of the resistivity method since the infinite resistivity of the air filled void of the cave is at a high contrast to the resistivity of any geological structure. In the case studies presented in this work (Maroneia and Andritsa, Greece) the caves are formed in limestone because of the karstification in addition to the local tectonics.
The geophysical method applied in both case studies is the Electrical Resistivity Tomography (ERT). The existing chambers have been observed in the resistivity models and new chambers are detected.
However, resistivity values attributed to the caves are of wide range. In Maroneia values of several thousand of Ohm.m have been measured while in Andritsa the values characterizing the chambers are small (maximum of 1610 Ohm-m).
The different behaviour of resistivities can be explained by the different geological formation hosting the caves and emphasizes the need for calibration measurements. This can be overcome with ERT measurements on the same geological formation but far from the surveyed area in order to measure the resistivity of the formation itself. In this case a forward modelling will suggest the expected values in the presence of a void.
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Sedimenthological Model of Lom Lignite Basin (North Bulgaria) - Integrated Use of Geophysical and Geological Data
Authors M. Yaneva and S.B. ShanovSummaryThe sedimenthological Model of Lom Lignite Basin (North Bulgaria) is represented by a set of maps, elaborated for the principal geological layers (sedimentary complexes) on the base of integrated analysis of data from boreholes, seismic profiling, seismic well logging, and vertical electrical sounding.
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Development of an Earthquake Shake Map Routine with Low Cost Accelerometers: Preliminary Results
Authors G. Tanırcan, H. Alçık and Y. KayaSummaryVast amounts of high quality strong motion data are indispensable inputs of the analyses in the field of geotechnical and earthquake engineering however, high cost of installation of the strong motion systems constitutes the biggest obstacle for worldwide dissemination. Today, for a high quality system, about 10,000 USD budget per instruments is required. In recent years, MEMS based (micro-electro-mechanical systems) accelerometers have been used in seismological research-oriented studies as well as earthquake engineering oriented projects basically due to precision obtained in downsized instruments. In this study two accomplishments were done. In the first phase; MEMS based instruments available in the Institutes’ inventory were modified so as to be used for real time monitoring. In the second phase a Matlab based shake map routine was developed to calculate various ground motion parameters in per-second basis only after triggered by an event. Hence, synchronized real time data transfer from instruments served to create a rapid response network in an affordable way. Functionality of the software has been investigated through shake table tests. The successful realization of this product also allowed us to set up a test network at Tekirdag Province, the closest city to moderate size earthquake activities in central Marmara Sea.
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Application of Machine Learning Method in Classification of Rock Types in Open Pit Mines
By H.S. NikolovSummarySupport vector (SV) method for classification originates from supervised machine learning methods. Although theoretically developed in the 70-ties of the 20-th century it was significantly improved in theory and practically implemented in the late 90-ties. Originally intended and elaborated as two class separation procedure it was latter transformed in robust multiclass classification technique. In this research the SV based technique for classification has been used for discrimination of rock types found in and around the open pit mines of Asarel-Medet mining complex located in the Srednogorie copper-porphyry mining region. The data used for the experiments are from the multispectral instruments TM/ETM+ onboard Landsat satellites from the same season of two different years. For ground trutning polygons having nomenclature under CORINE EU project were taken and adapted to the needs of this research. The results after classifying the area under study confirmed that the method selected is robust and offers good alternative to other approaches used for this task. In conclusions it is mentioned that for improvement of the outputs better spatial resolution is essential, but also more and narrower spectral bands would be offer an advantage.
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Remote Sensing Methods in Studying Stone Quarries
Authors D. Borisova, H. Nikolov, D. Petkov and B. BanushevSummaryIn Engineering and Environmental Geophysics different methods and techniques are applied. In this paper a remote sensing method has been tested in the segmentation of human made land covers such as open pit mines and stone quarries. The idea is to exploit to larger extent the possibilities offered by multispectral imagers having mind Thematic Mapper /TM/ onboard satellite series Landsat. The method has been used in the framework of our research is to find consistent statistical dependencies between multispectral data gathered in-situ and the corresponding ones in the images offered by airborne-based sensors. After correct identification of the pixels the subsequent segmentation forming the shape of the artificial feature is determined much more reliable. We have been combined ground spectrometry of stone quarry near Smolsko village, Landsat images of region of interest /RoI/, and in-situ condition surveys for assessment of the quarry area. For the purpose of the study geological observations, petrographical investigations, photo documentation and in-situ spectrometric measurements have been performed.
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Prospection of Wind Farm Site Using Geophysics
By P.S. SoupiosSummaryThe last decade, the use of geophysical surveys prior to completion of the initial subsurface monitoring and characterization for constructing wind parks, is very common. Geophysical models can provide critical, valuable, accurate and reliable information concerning the status of the ground on the site where the wind turbine are going to be founded and such information can be used by the engineers in the most appropriate and cost-effective way. This paper presents the use of surface wave method for the exploration of the subsurface in order to define the optimum places for wind turbine foundation.
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Strong Motion Network in the Bodrum Peninsula, Turkey
Authors H. Alcik, G. Tanircan, A. Korkmaz, O. Cirag and E. OzdemirSummaryThe Bodrum peninsula with a population of one million in summer season is one of the most populated touristic centers of the southwest coast of Turkey. The region is also located in one of the seismically active regions of the southeast Aegean Sea. Frequent occurrence of historical destructive and of instrumental earthquakes clearly demonstrates high seismic hazard in Bodrum and its surrounding area. Seismic activity has been monitored by three instruments located in the peninsula, however, currently there has been no strong motion network for use in generating parametric information for urban rapid response system after a damaging earthquake. Considering the high seismicity and high population of the region, a strong ground motion monitoring system, called as B-network, consists of 5 accelerometric stations was deployed on 2nd June 2015. Primary aims are to provide input for future earthquake rapid reporting and early warning implementation projects which turn out to be a crucial step and essential tool to mitigate the impact of strong earthquakes on urban environments in the Bodrum peninsula and the surrounding areas. So far the network recorded more than 5 local events (Ml>3.0). Preliminary analyses are underway. Possible future cooperation and coordination of mutual interests through joint projects may obviously give an opportunity to implement an empowered early warning system may serve to the whole region.
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Tsunami Modeling Scenarios for Some of the Seismic Sources in the Black Sea Area, Using Tsunami Analysis Tool Software
Authors R. Partheniu, M. Diaconescu, D. Ioane and A. MarmureanuSummaryAlthough a rare phenomenon, tsunamis in the Black Sea were generated in the past, studies showing more than twenty events observed ( Altinok Y., 1999 ). Earthquakes monitoring in the Black Sea as well as a database with tsunami modeling Scenarios could lead to a better understanding of such phenomena.
A set of 6 past earthquakes were taken into consideration for generating tsunami modeling Scenarios, using the earthquakes Depth, Latitude and Longitude as initial conditions. For preset parameters of fault dimensions and plane solution (Strike, Dip, Rake, Width, Length) a set of 36 different tsunami modeling Scenarios have been run, varying the Magnitude (Mw = 7, 7.5 and 8). These tests using the Tsunami Analysis Tool (TAT) software for modeling tsunamis in the Black Sea resulted in moderate to high tsunami waves, with the highest waves of 3.2 m, for an earthquake with M = 8 in Novorossisk area, generated at 15 km depth. Some of the Scenarios did not generate tsunami waves at all, for a Magnitude of 7 or 7.5.
The computations in this study need more thoroughness, in order to have a better correlation of the results from the tsunami modeling Scenarios and the tsunamis observed in the past.
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Study of Products from Neutrophilic Iron Bacteria by Prompt Gamma/Neutron Activation Analysis and X-Ray Diffraction
Authors K. Krezhov, R. Angelova and I. Sziklai-LaszloSummaryThe Fe(II)-oxidizing bacteria (FeOB) and Fe(III)-reducing bacteria (FeRB) were among the first groups of microorganisms to be recognized for carrying out a fundamental geological process - the bacterial iron redox cycling. The deposition of iron ions by the bacteria from the Sphaerotilus-Leptothrix group of neutrophilic FeOB is extracellular in the form of biogenic products contained in tubular structures (sheaths). We report on the determination of the concentration of elements in these products and the relative amounts of biogenic iron oxides/(oxy) hydroxides resulting from the bacterial metabolism. The Fe (II)-oxidizing organism was isolated from freshwater wetland surface sediments in Vitosha Mountain. Biogenic nanostructured materials were obtained after growing the genus Leptothrix in SIGP and Adler’s nutrient media. Formation of sheaths was observed only in case of dynamic cultivation in SIGP medium. High enrichment level of iron was found by the PGAA and NAA techniques in the products of cultivated isolates as compared to the reference sample (product of nature). Three iron oxide phases were found after cultivation in Adler’s medium: lepidocrocite (γ-FeOOH), non-stoichiometric magnetite (Fe3-xO4) and goethite (α-FeOOH). The cultivation in the SIGP medium yielded a single phase bacterial product — lepidocricite of poor crystallinity.
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Remote Sensing Techniques In Soil Degradation Detection
Authors R. Kancheva, D. Borisova and G. GeorgievSummarySoil salinization as a result of natural or human-induces processes is a serious global-scale problem. Numerous studies and efforts in assessing and controlling soil salinity have been made. Nearly sixty percent of the salt-affected soils around the world are in irrigated farmlands, and this trend is increasing. Salinization is a major reason for degradation of soil resources and decline of soil fertility. From an ecological and economic point of view it is extremely important to establish the occurrence and distribution of soil salinization as well as the intensity of the process. Remote sensing techniques are widely used in soil surveys to detect and map salt-affected areas. However, many constrain in monitoring and evaluating the spatial and temporal variability of the salinization process has been found out. Difficulties also arise in applying remote sensing to the assessment of slightly affected soils. The goal of this paper is to examine the spectral reflectance properties of soils with different degree of salinization and the feasibility of using spectral indicators derived from Vis/NIR data as detectors of salt-affected soils and quantitative estimators of soil salinity level.
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Subsurface Structure of Tympaki Basin (Crete, Greece) Based on Well and Geophysical Data
Authors G. Panagopoulos, E. Manoutsoglou, A. Vafidis, P. Soupios and S. BellasSummaryTympaki basin has been studied in the past years from a hydrogeological point of view. Whatsoever, less are known on the subsurface structure of the plain part of the basin in terms of sediments thicknesses and faults existence. A way of identifying in-ferred faults is the integrated use of geophysical and well-data which finally give an insight of the subsurface within a content of a well-established knowledge of the geo-logical regime of the study area. In this paper the use of 3D geological modelling technique is described as a mean to identify fault structures and horizon depths. The data used include the digital elevation model (DEM) of the area, the boundary sur-face between geologic formations and the litho-stratigraphic data from wells, geo-physical measurements of Vertical Electrical Soundings (VES) and Transient Electro-magnetic Method (TEM). The first step was to develop a 3D stratigraphic model that approximates the subsurface position of the Plio-Quaternary and the Neogene depos-its. The inferred faults came out from this model were cross-checked with the TEM measurements providing an updated subsurface structure. All the newly identified faults and along with the depth of stratigraphic horizons give finally an overall tecton-ic pattern of the Tympaki basin.
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Two Dimensional Joint Inversion of Seismic refraction, Radiomagnetotelluric and DC Resistivity Data: an example from Bafra plain, Turkey
Authors M.E. Candansayar, I. Demirci, A. Vafidis, P. Soupios, N. Economou, N. Andronikidis and H. ArslanSummaryA new two dimensional joint inversion algorithm for Seismic refraction, Radio-magnetotelluric and DC Resistivity data was developed. We used synthetic data to show advantage of the algorithm. The developed joint inversion algorithm found resistivity and velocity model better than the individual inversion of each data set if one compare with the real models. We also tested the algorithm with the field data collected in the Bafra basin to image the saltwater intrusion at this area. The field data inversion is also showed that the joint inversion recovered the resistivity and velocity model better than the individual inversion of each data set.
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Interpretation of IP Measurements Using an Inversion Based TAU-Transform Method
Authors E. Turai, M. Dobroka, E. Prácser, T. Ormos and Á. GyulaiSummaryThe paper presents the TAU-Transform of the Time-Domain IP curves and gives an approximate solution for TAU-transformation using inverse problem theory. A method for estimation of the type and the measure of soil contaminations will also be introduced. The determination of the contamination type (metallic or chemical) comes from the time constant spectra. The estimation of the soil contamination is based on the waited amplitude values of the time constant spectra. The application of the method is demonstrated in a contaminated industrial area in Hungary.
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An Investigation of Environmental Radioactivity Effects of Moloz (Trabzon, Turkey) Municipal Waste Dump Site
By H. ÇinarSummaryEnvironmental radioactivity level of the former Trabzon municipal solid waste dumpsite were investigated by in-situ gamma-ray spectrometric method. The natural radioelement concentrations on the surface of dumpsite were measured using a portable gamma-ray spectrometer. Spectrometry data were collected on the ground surface at 231 points along 21 profiles, parallel to each other, where the interval for both measurement points and each profile are 10 m. The measuring time was set to be 300 s at each point. The average activity concentrations of 238U, 232Th, 40K and dose rate in the dumpsite are 42.68 Bq/kg, 49.88 Bq/kg, 417 Bq/kg, and 67.91 nGy/h respectively. In addition, radiation hazard parameters were calculated and compared with the international standard values. Consequently, it was found that there is no significant radiologic hazard and risk for humans and the environment in studied area.
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Imaging the Saline/Fresh Water Interface at Bafra, Turkey Using Joint Inversion of Seismic Refraction and ERT Data
Authors H. Hamdan, E. Candansayar, I. Demirci, N. Economou, N. Andronikidis, H. Arslan, P. Soupios and A. VafidisSummaryA geophysical survey was conducted at Bafra, Samsun, Turkey, Greece in order to support the geological and hydrogeological studies of the existing phenomenon of seawater intrusion. This survey employed seismic refraction tomography (ST), time domain electromagnetic (TDEM) and geoelectrical methods.
The later, consisted of Electrical Resistivity Tomography (ERT). The objective of this survey was to image the saltwater intrusion at this area and map possible favorable sea water pathways. We present the interpretation of geophysical data obtained under the research project ClearWater project. We applied both individual and joint inversion of electric and seismic data from Bafra. At Bafra, the geophysical survey provided images of the saltwater intrusion which is present at the north eastern of the study area. These geophysical methods proved useful as prediction and prevention tools in qualitative characterization of water bearing formations for an optimum groundwater management plan for the Bafra basin.
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Application of Self-Potantial (SP) Method for Monitoring Contaminants Movement
Authors P. Soupios and M. KaraoulisSummaryThis paper presents the application of self-potential (SP) method in environmental application. The resulted SP model was compared with the resulted tomographic electrical resistivity models which acquired at the same time period with SP data. Both geophysical methods applied in Western Crete in Chania territory to delineate contaminants movements from a waste disposal site to the main river of Chania basin through the alluvial permeable formation. The main purpose of the SP method was the determination of the subsurface contaminants flow direction. The final resulted images showed a good correlation with geoelectrical resistivity model. The self-potential method has proved to be an important qualitative monitoring tool for assessing the environmental quality in contaminated lands.
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Preliminary Results from Lab Experiments on the Use and Sensitivity of Spectral Induced Polarization (SIP) Method
Authors K. Gerodimou, P. Kirmizakis, P. Soupios and A. VafidisSummaryThis paper presents the application of spectral induced polarization (SIP) method in a controlled laboratory experiment using known fluid concentrations. Specifically, we employed different fluid samples with variable concentration in order to record the temporal change of SIP response over time and test the sensitivity and reliability of SIP method. The SIP method has proved to be an important qualitative monitoring tool for assessing the environmental quality in contaminated lands.
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Investigation of Roadside Pollution Related to Traffic Density by Using Mangnetic Susceptibility Method
More LessSummaryThere is a rapid increase in traffic caused environmental pollution due to increasing population and number of motor vehicles. Especially many detrimental particles emitted by the vehicles reason grave soil pollution in roadsides. In addition, many scientific studies propose that these particles are detrimental for human health. Main purpose of this study is investigation of heavy metal pollution along several roadsides in city of İzmir by magnetic susceptibility measurements are often applied for investigating rock magntic properties, fire sites, landslide deposits, industrial, geothermal and soil pollution studies. Also one of the most frequent geophysical applications is traffic-related heavy metal pollution. In this study, magnetic susceptibility studies were carried out along the roads at Konak, Aliağa, Gülbahçe and Buca districts of İzmir. The measurements were performed by using MS2E high-resolution surface scanning device produced by Bartington Company. The Bartington Instruments MS2 Magnetic Susceptibility System became popular for use in the laboratory and field in universities around the world. The highest magnetic susceptibility value was observed, as 15 times higher than the normal value, along Çanakkale-İzmir highway which has the highest traffic density. Other study areas were Tınaztepe Campus road, Gülbahçe Village road and Konak-Bornova Highway and magnetic susceptiblity values were observed 6,7 and 14 times higher than normal values respectively. Consequently, it was determined that roadside pollution degree can be determined precisely by using magnetic susceptibility measurements.
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An Assessment of Groundwater Seepage beneath Dams Sites in Al-Bahah Region Using Resistivity Imaging
By B. AlhenakiSummaryThis study aims to conduct a hydrological evaluation of the wells located after the dams to estimate the ground nutrition of it through the geoelectrical. four dams are selected. A study is conducted by using electrical resistivity imaging for the study of layers and knowing the resistivity of underground water through dams. Results are shown as follows a semi complete discontinuation of feeding the wells located after the concrete dam and the ground dam which is considered the foundation of cement bases of both of them to reach the base rocks. it has become impossible for the underground water to leak through the dam. as a result, the wells located after the dam are not fed with the underground water. Rockfill dams and the wells located after the dams are not greatly affected due to the penetration of the underground water through sediments under the dam, feeding the wells. We recommend that the concrete dam is periodically and constantly opened to feed the sites located after the dam to avoid the depletion of wells. However, damage of the ground dam is lesser than the concrete dam due to the complete smooth movement of the surface water.
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Field Applicability of the g11n Configuration
Authors S. Szalai, V. Wesztergom, K. Szokoli, A. Frigy and E. PrácserSummaryFirstly a short introduction is given about the theory of the g11n configurations which belong to the group of the geoelectrical quasi null arrays. On the basis of our numerical investigations the application of these arrays seem to be rather perspective. Their field application is however difficult because of the complexity of the inversion of the data of these arrays. These arrays have very large geometric factor, they may change their sign and they can produce very sharp changes. Using an own developed code we inverted field data. The very first results show the field applicability of these configurations.
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Utilisation of Magnetotelluric Sounding for Geological Interpretation of Crustal Structures (Western Carpathians)
More LessSummaryIn the paper we present a geological interpretation of magnetotelluric sounding along the southern part of the seismic 2T profile situated in the southern Central Slovakia (Western Carpathians). The complexes with higher conductivity are imaged in the shallow depths, formed by the Tertiary sediments and volcanics. In the northernmost part of the profile, the influence of non-conductive complexes composed of orthogneisses and overlying Mesozoic carbonates is significant. In the central part of the profile, the low conductive granitoid complexes are superposed over the metamorphic rocks with higher conductivity. This structure is a remnant of the Hercynian middle crust nappes. The most outstanding phenomenon of the profile is the sudden, almost step, change in the conductivity parameters of the crust in the southern part. The significantly high conductivity of the crust in this area is most probably not related to its lithological composition, but by the abundant supply of fluids in the crust after the Neogene tectonic and volcanic processes.
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Aplication of the DC Resistivity Method to Landslide Study; Case Study - Church Ratesti
Authors D. Constantin, D. Constantin, S. Rasvan and P. RazvanSummaryIn the case were made three geoelectrical profiles, the first profile length 20 m, was located at a distance of 10 m west of the monastery direction. For research we used a Schlumberger device with AB = 2m and MN = 1 and I = 20 mA. Here, you see a fairly uniform distribution resistivity resistivity values ranging between 10–60 Ohmm. Area high resistivity depth is in the range AB / 2, between 2 and 6 m. In the interval AB / 2 5 to 30 m, resistivities are smaller, ranging between 2–10 Ohmm.
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Mapping the Bedrock Using ERT for Slope Stability Studies at Mavropigi Lignite Open Pit Mine, Northern Greece
SummaryThe application of the electrical resistivity method in geotechnical investigations is explored through a case study in Northern Greece. This method was employed at a lignite surface mining operation where fracture zones and discontinuities have been recently observed close to the pit boundaries. The main aim of the geophysical survey was to estimate the inclination of the contact between the Neogene and Schist/ Carbonates formations south of the pit. Two configuration arrays proved essential in such conditions, and helped improving the resolution of the geoelectrical section. The geoelectrical sections were then calibrated by boreholes indicating that the bedrock is dipping to the Northeast. Furthermore, the geophysical survey provided invaluable data regarding the geometry of the bedrock which was essential for the slope stability calculations.
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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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