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11th Congress of the Balkan Geophysical Society
- Conference date: October 10-14, 2021
- Location: Online
- Published: 10 October 2021
21 - 40 of 86 results
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Current State of Geodetic Investigations on Contemporary Crustal Movements in the Region of Sofia
Authors P. Danchev and A. IvanovSummaryThe paper summarizes the research of the contemporary crustal movements on the region around Sofia performed with geodetic methods. Geodetic data provides important information in the study of the crustal movements. Geodetic methods in investigation of recent crustal movements occupy a particularly important place because they provide quantitative information on the condition and development of geodynamic processes. Brief tectonic characteristics of the region of Sofia are given. Information about the geodetic networks built over the years in order to study the movements of the earth’s crust and the results from their measurement and analysis obtained up to now is given. The results of analysis show the presence of active faults in the area that need to be investigated. All of this sets the important task for modern science to estimate and research these processes.
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Mapping the Foundations of Neoria (Venetian Dockyards) in Chania, Greece, Using ERT, SRT and GPR Methods
Authors G. Kritikakis, J. Brintakis, N. Economou, E. Manoutsoglou, N. Skoutelis and A. VafidisSummaryThe mapping of buried targets without having access directly above them, such as the buildings foundations, using geophysical methods, is quite a challenging task. This work presents the geophysical results from the mapping of Neoria (Venetian dockyards) foundations in Chania, Greece, using 2D and 3D Electrical Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT) and Ground Penetrating Radar (GPR) methods, under the framework of a project for the restoration and rehabilitation of these Venetian monuments. The space accessibility allowed the deployment of the surveyed lines mostly parallel and limited perpendicular to the walls. High seismic velocity and electrical resistivity values, depicted in SRT and ERT sections respectively, directly below Neoria walls, are attributed to their foundations, which extend to a depth of approximately 3m. ERT and GPR sections indicate that the foundations do not exhibit remarkable lateral extent. SRT sections showed that foundations probably are based on the rocky substratum of the surveyed area.
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Geophysical Survey Prior to new Road Construction for Engineering and Archaeological Issues
Authors G. Apostolopoulos, S. Karizonis, D. Karaiskos, E. Hila and D. PapadimitriouSummaryThe Technical Service of Peloponnese Region in Greece has planned a new country national road in Messinia with part of the road to avoid passing through Petalidi Village. Engineering works revealed archaeological monuments with the Messinia Ephorate of Antiquities starting excavation works to see how much these monuments extend, especially near the route of the new road. As these works need a lot of time and the Region authorities had to speed up the whole procedure a geophysical survey was decided. A geophysical survey was carried out and gave valuable information both on the extent of archaeological monuments as well as on the engineering issues for the various solutions that had to be followed both the road to be constructed and the monuments to be preserved.
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Supervised Machine Learning Techniques Applied to Wireline log Data for Automated Lithology Prediction
Authors M. Popescu, R. Head, T. Ferriday, K. Evans, J. Montero, J. Zhang, G. Jones and G. BainesSummaryThis paper presents advancements in machine learning and cloud deployment that are revolutionising lithology interpretation. A supervised machine learning technique is described that enables rapid, consistent, and accurate lithology prediction alongside quantitative uncertainty from large wireline or logging-while-drilling (LWD) datasets.
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Air Pollution Assessment for Sofia City - Dominant Pollutants Recurrence Which Determines the air Quality Status
By I. GeorgievaSummaryOn the basis of 3D modelling tools, the extensive database was created and used for studies of the atmospheric composition, carried out with good resolution using up-to-date modelling tools and detailed and reliable input data. The simulations are carried out in the frame of The Bulgarian Chemical Weather Forecast and Information System (BgCWFIS), based on the US EPA Model-3 system. On this basis a statistically significant ensemble of Air Quality indexes (AQI) was calculated, and their typical recurrence, space and temporal variability was constructed.
The numerical experiments with a horizontal resolution of 1 km. for Sofia city are going on. The AQ impact on human health is evaluated in the terms of AQI, which give an integrated assessment of the impact of pollutants and directly measuring the effects of air quality. All the evaluations are on the basis of air pollutants concentrations obtained from the numerical modelling and make it possible to reveal the AQI status spatial/temporal distribution and behaviour.
The results presented in this paper, allow to estimate the highest recurrence of the indices for the whole ensemble annually, and to analyse the possible reason for high values in different bands and different AQI statuses.
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Assessment of Geodynamic Phenomena in Dams of Water Reservoirs Through Seismic Methods
By E. SiloSummaryThe applied seismic methods, today, have an important role in theoretical and applicative studies, which are done through studying the propagation of natural and provoked seismic waves in the rocky ground. There are different types of waves and through seismic methods, the propagation velocity, the acceleration of rock particles, amplitude and energy, frequency, phase, and spectrum characteristics are determined. Seismic studies use the natural seism-acoustic impulses (passive seismic) and artificially provoked waves (active seismic). Depending on the geological task, the frequency band of the signal varies from (1÷1000) Hz. For the assessment of geodynamic phenomena such as damage, sustainability, inefficiencies, etc., in the body of dams of water reservoirs, the seismic methods of refracted and surface waves were used. This assessment was done through seismic surveys carried out along the top of dams and was digitally processed on the computer. The dams of Bunavi reservoir, in Vlora city and Libofsha reservoir, in Fieri city are taken into consideration.
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Application of Active and Passive Seismic Methods for the Study of Landslides
More LessSummaryActive and passive seismic methods have been widely used for the study of landslides. For this purpose, refracted and surface seismic waves, artificially generated (active seismic), and natural (passive seismic) were used. The study area is included in the Peri-Adriatic Depression, Synej region, where on March 21, 2009 a landslide occurred, which completely destroyed 9 houses. This region is part of the Molasses basin of the Peri-Adriatic Depression area. For the identification of the geological and tectonic construction of the study area, mainly the seismic works performed for the search of hydrocarbons have been used, through which tectonic faults with very large amplitude up to those with small amplitude of several tens of meters have been identified.
To study what had actually happened, two seismic profiles were done in the sliding area, by the method of refracted and surface waves, using geophones that accept vertical and horizontal oscillations. The digital processing of the records was performed using the software packages “SeisImager/2D” and “SeisImager/SW”. The results show that the slide is combined with vertical cracks and is evidenced to a depth of 36m.
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Near-tropopause Ozone – a Driver of the El Nino Southern Oscillation’s Phase Changes
Authors N. Kilifarska and T. VelichkovaSummaryThe multiyear fluctuations of climatic variables over the world are largely attributed to the El Nino Southern Oscillation (ENSO). Oscillating between its cold phase (La Nina) and warm one (El Nino), this climatic mode impacts the global atmospheric circulation, temperature and precipitation in many regions over the globe. Although the existence of ENSO mode is attributed to the atmosphere – ocean interactions, the mechanism of transition between its main phases is still unknown.
This analysis shows an evidence for important role which has the lower stratospheric ozone in the phase changes of ENSO. We show that the reduction of the lower stratospheric ozone density in the central Pacific could serve as a trigger mechanism for transition from La Nina to El Nino phase. The ozone influence on the near surface temperature should be explained by its impact on the near tropopause temperature and humidity, which in turn affect the temperature near the surface through modulation of the greenhouse effect.
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Mines (Salt and Gold) and Infrastructure Underground Built Heritage Survey: Romania, Contribution to the COST Action
Authors M. Bostenaru Dan, M. Anghelache, A. Petrisor and Ș. HalmagiSummaryIn this paper, there are approach the particularities of Romanian heritage, from the point of view of endangered sites of mining and infrastructure.
There are addressed several examples like salt mines from Ocna Dej and Turda, mining heritage which includes the Roman galleries from the Rosia Montana region as well as the underground infrastructure heritage, with the example of Suceava water plant conversion.
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Study of the Seasonal Changes of the Amplitude-frequency Characteristics of the Microseismic Noise
Authors E. Oynakov, D. Solakov and I. AleksandrovaSummaryThe aim of the present study is to assess and analyze the amplitude-frequency composition of microseismic oscillations and their possible seasonal variations in the territory of the seismic network NOTSSI (National Operating Telemetry System for Seismological Information) with the method of spectral relations (H / V).
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Monolithe Churches Underground Built Heritage Survey: Romania in European Context, a Contribution to the COST Action
Authors M. Bostenaru Dan, A. Petrisor and M. AnghelacheSummaryThis paper highlights the particularities of Romanian heritage compared to the European one, approaching a particular type of religious monuments, the ones excavated within the rocks, including endangered sites. The focus is on religious heritage, especially monolithic churches and catacombs
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Geophysical Study and Geological Considerations on Neogene Volcanites from Eastern Carpathians
Authors N.S. Asimopolos and L. AsimopolosSummaryThe Eastern Carpathians comprise three major units: the northern part (Oas-Gutai mountains), the middle part (Tibles-Rodna-Bargau mountains) and the southern part (Calimani-Gurghiu-Harghita mountains). Neogene volcanic activity took place in the Badenian-Pliocene interval, during which periods of paroxysm alternated with periods of calm. This began with an explosive episode when a volcanic-sedimentary formation was put in place, represented by volcanic tuffs and rhyolite agglomerates, followed by andesitic lava flows.
For a good image of the Eastern Carpathian anomalies, we present, in our paper the maps, made with the Surfer program, based on the data obtained through digitalizing geophysical maps of Romania and data from the Bureau Gravimetrique International, using Surfer software, kriging method for interpolation. Also, we made maps with other geophysical parameters after smoothed and filtrated of geophysical data (Magnetic anomaly, Bouguer anomaly, Free Air anomaly, Isostatic anomaly, geoid) and correlations between them.
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Solar Harmonics and ENSO Variations
By Y. ChapanovSummaryOne of the reasons of ENSO excitation is the influence of solar cycles. The solar activity is reveling mainly by the Total Solar Irradiance (TSI) variations, solar wind and variations of solar magnetic field. The TSI variations affect directly all weather and climate indices. The solar wind and solar magnetic field modulate changes of the heliosphere, geomagnetic field and cosmic ray variations. Recently a new mechanism of climate modulation, based on cosmic ray variations and ozone production in low stratosphere near the tropopause, has been discovered. Some disturbances of solar magnetic field are connected with the North-South (N-S) solar asymmetry. The index of N-S solar asymmetry is highly correlated with ENSO variations in large number of frequency bands with interannual, decadal and centennial periodicity. The common harmonics of solar and ENSO cycles are determined by means of recently developed Method of Partial Fourier Approximation, where the trigonometric coefficients are estimated by the Method of Least Squares. The obtained results of high correlation between interannual harmonics of N-S solar asymmetry and ENSO events may resolve the questions about solar influence on Pacific temperature anomalies.
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Mean sea Level Jumps During Last 13.8 Ma
By Y. ChapanovSummaryRecently, mean sea level variations for the last 66 Ma has been derived by Miller et al. (2020). A part of their solution for time interval 3.5–13.8 Ma Before Present (BP) is analyzed. Eight data jumps are determined by means of Method of Jump Detection. This Method is able to discover very small jumps, whose level is below the random noise, due to the property of selective frequency filtration during time series integration, when the high-frequency noise is suppressed and low-frequency signals are amplified. The detected jumps are close to the beginning of several stages of Miocene and Pliocene. The long-term rate of these jumps are relatively small between –1.4 and +2.5 cm/ka., whose values suppose very slow change of the paleo climate. Two data segments between the detected jumps keep zero rate for a long time period. The MSL variations from 3 segments (10.8–13.8 Ma BP) are almost identical to the modern sea level. The climate during 4.5–10.8 Ma was relatively colder, when the MSL was 5–22 m below the present level. The last investigated MSL segment is 9 m higher than the present level, which is a signature of warm period before the beginning of Ice Ages.
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Analysis of Major Geomagnetic Disturbances from the First Half of Year 2021
Authors N.S. Asimopolos and L. AsimopolosSummaryBased on the planetary geomagnetic indices we make some considerations about geomagnetic disturbations at the beginning of the 25th Solar Cycle.
The most important event in this new solar cycle was the geomagnetic storm of May 12, 2021. We performed Fourier and wavelet analyses, based on data from five geomagnetic observatories from INTERMAGNET For this analysis of the geomagnetic data sampled at one minute, we used the North component of each observatory and comparative physical parameters related to this geomagnetic storm, from available data. Also, we used wavelet coherence between observatories, for North, East, and vertical geomagnetic component, on May 12, 2021. Can be seen a very good correlation between the physical parameters of the solar activity and the geomagnetic data recorded in the planetary geomagnetic observatories.
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Arsenic Distribution in the Vineyard Soil from Winegrowing Huși Area (NE Romania)
Authors R. Huzum and D.S. Sirbu-RadasanuSummaryArsenic is an essential element for animals and beneficial for plants in very low concentrations, but is the most famous for the environmental toxic effects. As arrives in soils through the natural processes of erosion and alteration of rocks and ores with As, but anthropogenic activities such as the industry and some agricultural practices are the main source of contamination of soils and water. In the vineyards, As contamination can be induced by the use of pesticides which have been forbidden to end of the XXth century. The purpose of the present study follows only the distribution of As in the Husi vineyard soils by applying the sequential extraction method proposed by Zeien and Brümmer (1991). For the modelling on sequential extracts and a better geochemical understanding of the ways of trace elements bounding to the soil components, major element as Fe and Mn were taking into account. The possible contamination was estimated on the base of comparison with legislative limits for arable soils and on the base of enrichment factor estimation. In addition, this study enhances the understanding of As sources in agrosystem that helps predicting and limiting the potential of As contamination exposure for people and ecosystem.
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Subdecadal Synchronisation of Near Surface air Temperature and Lower Stratospheric Ozone
Authors T. Velichkova and N. KilifarskaSummarySubdecadal variations of the near surface temperature are the subject of intensive research and discussion. These variations are usually attributed to the various strength and/or interactions between regional climate modes. The driving factors of the latter, however, are still unclear, which raises the question about the actual forcing of subdecadal variability with particular urgency.
The present analysis shows an evidence for existing spatial similarity and temporal synchronization between deviations of lower stratospheric ozone and air surface temperature from their dynamically changing decadal means. The strength of covariance of both variables is irregularly distributed over the globe and depends on the phase of El Nino Southern Oscillation climate mode, during the examined period 1900–2019. The short memory of the analysed anomalies could not allow us to determine the causality links between them. However, some regions of strong interdependence between lower stratospheric ozone and air surface temperature have been detected.
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Examples of Data Fusion Methods in Road Detection
Authors D. Borisova and V. DimitrovSummaryIn this study, some examples of the data fusion methods in merging the remotely sensed images in road detection are presented. The process of image merging methods is meant to integrate the data with various spatial and spectral resolutions obtained by sensors based on aerial and satellite platforms. The goal of the current paper is to show some examples of realization and determination of the suitable method for precise integration of multisource data. For this purpose and the correct image categorization the performance of technical tasks such as extraction of features, classification and segmentation as the biggest advantages of the fusion technique are done. This work is supported by Bulgarian National Science Fund under Contract number KP-06-M27/2 (КП-06- М27/2).
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GIS and Remote Sensing for Disaster Management: a Case Study of Landslide in Shillong Plateau, Meghalaya, India
More LessSummaryIn northeast India, the Shillong Plateau is an actively deforming tectonic “pop-up” horst, south of the Himalayas and west of the Indo-Burmese mountains. The Shillong Plateau-Eastern Himalayan flank offers a unique system for measuring interconnections between climate, tectonics, and erosion, that aid Earth movement. The identification and monitoring of mass movement of vulnerable slopes are critical in reducing danger and mitigating severe damage caused by creeping slopes and landslides. This study highlights the current status of hazard mitigation research. It uses ArcGIS to interpret structural data as a corollary to understanding landslide probability and reviews available landslide prediction methods.
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Effects of a Strong Thunderstorm on the ULF Geomagnetic Field Variations
Authors M. Chamati and B. AndonovSummaryOn 24 May 2018, a severe thunderstorm, bringing rain and hail, occurred at Panagjurishte Geomagnetic Observatory, Bulgaria, lasted for a few hours.
The data sets of geomagnetic field variations in ULF range, recorded by the acquisition system of triaxial induction magnetometer sampled at 1 Hz are analyzed and the results are discussed. Morlet wavelet analysis over time scales 1–2000 s for the X (north-south direction), Y (east-west direction) and Z (down direction) components is performed. The Power spectra for the few hours before and after the beginning of the thunderstorm along the Z component are obtained. They mark powerful disturbances during and after the storm with periodicity in time scales 500–1350 s.
It is found that the influence of the strong thunderstorm on the geomagnetic variations along the three directions is significant. The time behavior of the three geomagnetic components shows that the strong lightning at 10:25 UT affects the absolute value of the Z component, unlike X and Y components values over fifteen hours. The induced voltage by the atmospheric electric current system in the Z component is about 5 Volt.
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