- Home
- Conferences
- Conference Proceedings
- Conferences
11th Congress of the Balkan Geophysical Society
- Conference date: October 10-14, 2021
- Location: Online
- Published: 10 October 2021
1 - 50 of 86 results
-
-
Geotechnical Investigations in Lignite Open pit Mine Using Electrical Tomography (2D&3D) and Seismic Reflection Methods
Authors N. Andronikidis, G. Kritikakis, A. Vafidis, H. Hamdan, Z. Agioutantis, C. Steiakakis and N. EconomouSummaryThe application of seismic reflection and electrical resistivity methods (2D and 3D) in geotechnical investigations is explored through a case study in Northern Greece. These methods were employed to Mavropigi lignite open pit mine and the surveyed area is the next step in mining expansion. The main aim of the geophysical survey was to map the bedrock, the contact between the Neogene and Schist/Carbonate formations as well as to estimate the thickness of the carbonate rocks on top of the Schist formations in order to study the stability of the final mine slopes. These geophysical data provides a geotechnical model which will be used in mine planning from Greek Public Power Corporation.
-
-
-
Multidisciplinary Approach for Fluvial Architecture Modelling and Reservoir Properties Estimation
Authors G. Georgieva and A. KisyovSummaryA multidisciplinary study conducted as practical training for students is presented. It combines detailed lithofacial profiling and 2D mapping of the surface outcrop. In addition to the classical geological methods that were represented, the possibilities of different geophysical methods (2D electrical resistivity, seismic, seismology (H/V spectral ratio), gravimetry, magnetometry, georadar, and aero photogrammetry) were also demonstrated in the study. Based on the conducted geophysical and geological measurements main sedimentary sequences were delineated and an attempt was made to track them spatially within the studied area.
-
-
-
Use of Magnetic Susceptibility, Sedimentary, Geochemical and Mineralogical Determinations, in Research on Danube Delta Paleogeographic Changes
Authors I. Stanciu, R.G. Dimitriu, I. Stănescu, M. Barbu, D. Vasiliu, C. Gheablău and I. PojarSummaryThe data presented in this paper are the result of field and laboratory investigations carried out south of Sulina branch of Danube, close to its discharge into the Black Sea at Sulina city (Romania), as part of a multidisciplinary study on paleogeographic changes in the Danube delta, and the Romanian Black Sea coastal area. The results are presented in the form of a W-E longitudinal cross section built on detailed litho-stratigraphic columns of cores extracted from three boreholes (3 - 5 m deep) drilled in 2019 by a GeoEcoMar research team, correlated with volume magnetic susceptibility measurements and interpreted based on geochemical and mineralogical determinations.
-
-
-
Evaluation of the Landslide Hazard and Risk Assessment Using GIS and Remote Sensing –Dambovita County
Authors M. Gheorghe, I. Voda-Marc and F. ChiteaSummaryWe focused our research on a north part of the central region of Dambovita County, part of the relief unit known as Subcarpathians of Ialomiţa as severe events of the mass movement were reported during time, but have never been the subject of a detailed investigation with modern techniques.
According to the GIS-based risk analysis, the areas that are most prone to landslides are found in the eastern and south-eastern parts of the study area, in the Mercani and Baloiu Hills, where steep slopes are predominant and geology includes schist, flysch, and sandstones.
However, the landslide susceptibility model is theoretical, being an approximate prediction of the real dynamic of the actual situation in the study area, given in terms of probability. On the other side, InSAR techniques depict the real past and present dynamics of the surface, by measuring surface displacement. These two techniques can be cross-correlated in a future study for validating the results of the susceptibility model.
-
-
-
Applying the DInSAR Method for Surface Deformations Detection in Pernik Valley
Authors M. Atanasova-Zlatareva and H. NikolovSummaryThe need for regular monitoring of the ongoing surface displacements is highly recognized by local, national, and international authorities since they are responsible for losses of human lives and cause significant damages to homes, infrastructure, and industrial objects. In this research, the DInSAR method was applied to investigate the ground deformations in a highly populated and industrialized area of the Pernik valley. Outlined in it are the advantages of the technique used and the possibilities offered by processing freely available SAR data to produce reliable results concerning the Earth’s motions in the researched area.
-
-
-
Gpr Data Migration Velocity Estimation Using a Local Diffraction Multi-focusing Criterion
Authors N. Economou, J. Brintakis, N. Andronikidis, G. Kritikakis, E. Kokkinou, N. Papadopoulos, N. Kourgialas and A. VafidisSummaryWe use constant velocity migration of Ground Penetrating Radar (GPR) sections over a predefined range of migration velocities for the validation of diffraction focusing, using local slopes distribution, with the scope to estimate a migration velocity model. We avoid the user dependent diffraction analysis to circumvent subjectivity and use overlapping x-t windows to retrieve diffraction focusing validation for the entire dataset. The estimated migration velocity is utilized as an attribute whose sensitivity in water variation saturation is tested as a complementary method to the Electrical Resistivity Tomography (ERT) method for the assessment of soil moisture.
-
-
-
GNSS and InSAR Monitoring of Landslides and Troposphere in Bulgaria: State-of-the-art
Authors K. Vassileva and G. GuerovaSummaryHigh precision Global Navigation Satellite System (GNSS) and Synthetic Aperture Radar Interferometry (InSAR) are widely used today for various applications ranging from ground deformation to weather prediction. For both InSAR and GNSS products require correction of the atmospheric disturbances. In this work, a brief review of the state-of-the-art of both techniques and their application for monitoring of landslides and troposphere in Bulgaria is presented and future synergy is discussed. In particular, exploiting the combined GNSS and InSAR tropospheric products for severe weather monitoring.
-
-
-
Application of ert in the Study of Debris-flow Source Area: Case Study Selanac Debris Flow
Authors D. Đurić, J. Krušić and B. AbolmasovSummaryDuring the extreme and extensive rainfall period in Serbia during May 2014, the western part of Serbia was the most affected area with landslides, flash floods, etc. In a period of 72 hours, a maximum of 200mm rainfall was recorded in the Loznica region. As a consequence, numerous landslides and floods occurred within the area. The largest debris flow ever observed in Serbia, named Selanac, was among them. This work aims to investigate whether is the upper part of the Selanac debris flow conditionally stable area by applying the 2D ERT technique.
-
-
-
Some new Insights on the Correlation of Isoseismal Maps With Terrestrial and Satellite Gravity Data
Authors S. Dilalos and J.D. AlexopoulosSummaryBased on the results of a previous terrestrial gravity survey that was carried out in Athens basin (Greece) some indications of correlation between terrestrial gravity data and isoseismal maps of Athens earthquake (7/9/1999) had been revealed. In this paper, we will present a research for the same area based on a new approach, which investigates the possible correlation of the same isoseismal maps with only satellite gravity data from GOCE and GRACE but also with a combined gravity model of updated terrestrial, marine and satellite data. The combined gravity model of Greece was constructed based on the least-squares collocation.
The previous correlation of isoseismal maps with the older terrestrial gravity data was quite obvious and clear since the areas with the lower gravity values were simultaneously the ones with the greatest damage distribution. On the other hand, from the satellite gravity data and the combined gravity model we could not identify a clear and obvious correlation, as was expected, due to the smaller resolution spacing of the satellite data.
-
-
-
3D Modeling of Water-saturated Layers by Using the HVSR Method of Poisson
Authors E. Oynakov, D. Solakov, I. Aleksandrova, M. Popova and D. DragomirovSummaryWaters under Earth’s surface are difficult for direct observation, and so the monitoring, mapping and modeling are needed to determine the presence of subsurface waters. Usually, the geoelectrical method is used to determine the presence of underground waters. The present study shows that the HVSR method can be used in the research of underground waters.
The present study is aimed at researching the underground aquifer and the local geology of a landfill which spreads under three institutes of the Bulgarian Academy of Sciences (Institute of information and communication technologies, National institute of geophysics, geodesy and geography and Institute of Mechanics) with the use of HVSR method (Horizontal to Vertical Spectral Ratio).
-
-
-
Earthquake Scenario for the City of Veliko Tarnovo
Authors D. Solakov, S. Simeonova and P. RaykovaSummaryEarthquakes adversely affect large parts of the Earth. Global seismic risk and vulnerability to earthquakes are increasing steadily as urbanization and development occupy more areas that a prone to the effects of strong earthquakes.
The territory of Bulgaria represents a typical example of a high seismic risk area in the eastern part of the Balkan Peninsula. Over the centuries, Bulgaria has experienced strong earthquakes. Some of Europe`s strongest earthquakes in the 20th century occurred in the territory of Bulgaria.
The present study is a comprehensive earthquake scenario study. A deterministic earthquake scenario for the city of Veliko Tarnovo is generated. The study is guided by the perception that usable and realistic ground motion maps have to be produced for urban area. The local ground shaking levels are computed using six ground motion prediction equations (GMPE’s). The scenario maps account for soil amplification effects using the geotechnical zonation of the considered urban area. The results show that macroseismic intensity varies between 8.3 and 8.6 MSK, the peak ground acceleration and velocity vary between 0.30 and 0.37 g, and 26.9 and 38.5 cm/s, respectively.
-
-
-
Geomagnetic Events Recorded in PAG Observatory During the First Year of Solar Cycle 25
Authors M. Metodiev and P. TrifonovaSummaryGeomagnetic observatories placed all over the globe determine some parameters which show the geomagnetic activity as a signature of the response of the Earth magnetosphere and ionosphere to solar forcing. Indices might be local, which are calculated from data of a single geomagnetic observatory, or planetary, which characterize the planetary disturbances of the geomagnetic field as a whole. We use the (local) K-index which is a 3-hour quasilogarithmic scale developed to measure magnetic activity ranging from 0 to 9, with 0 indicating completely quiet conditions and 9, representing extreme magnetic activity. The Solar Cycle24 finished in December 2019 and started the Solar Cycle 25. There are prediction that SC25 will be similar in size to SC24 with a maximum expected to be in 2025. A different hypothesis is also published suggesting that SC25 could be among the strongest sunspot cycles ever observed. We examine the geomagnetic activity events during the first year of the new cycle. Our data show that 2020 had calm geomagnetic conditions. Only 12 days have reached the levels of a minor storm in the records of PAG observatory. Two autumn periods are chosen to display the local geomagnetic response of the observed solar impacts.
-
-
-
Importance of Using a Reference Base Station in Geomagnetic Surveys - Case Studies from Bulgaria
Authors P. Trifonova, C. Tzankov and M. MetodievSummaryDuring ground magnetic surveys are recorded signals from a wide variety of sources – from terrain, natural and man-made surface features, as well as instrumental, geological, and planetary sources. Such signals directly disturb the subsurface effects over the Earth’s surface causing errors in the measurements. External variations which are due to the Solar-Earth interaction are one of the “noise” signals which are always removed as a preprocessing procedure. This could be done by using a locally installed base station or using the data from the nearest geomagnetic observatory.
We analyze records from six ground surveys accomplished on the territory of Bulgaria using a reference base station to see what would be the errors if such station was not available and Panagjurishte observatory data were used instead. Our results show that the differences in the recorded daily variations are limited to ± 5 nT and the frequency interval is large enough to prevent the misinterpretation of signals from the real sources.
-
-
-
Izmir and Uzunada Faults (Chirp Profiles)
By M. SenozSummaryTurkey is expressed between Arabian and Eurasian plates and this pressure cause extension towards westward and this movement creates an N-S extension regime. As a result, we observe active faults at a range in scales in different directions in the extensional tectonic regime at the Aegean region, western Turkey. The Gulf of Izmir is located in this tectonic region. Recently, high-resolution reflection seismic data were acquired and processed in the region. Data interpretation gives detailed information about various faults and complex morphology of the Izmir Gulf region. Multibeam echosounder and CHIRP seismic data enable the identification of offshore faults. In the southern offshore only E-W directional normal fault (Izmir Fault) is observable. In the west of the Gulf of Izmir, SE-NW directional - Uzunada Fault is observable. Uzunada Fault splits into many segments, controlled by the tear fault. An active graben in the Gulf was observed parallel to the Uzunada Fault Zone. Seismic data showing that tectonic activity in Uzunada Fault Zone has a great influence on the deformation of the sea bottom of the inner, central, and outer Gulf of Izmir. New seismic data enable to the identification of another offshore fault named Foça-Suzbeyli Fault.
-
-
-
The Serie of Korca Earthquakes 2019 to 2020 (Mmax=5.3) and its Seismogenic Zone
Authors R. Ormëni, N. Frasheri, I. Hoxha, A. Berberi and E. SilloSummaryA series of earthquakes of maximal magnitude (Mmax=5.3) started on June 01, 2019, at 04:26 (UTC), in Flloq village about 15 km southwest of Korca town, epicenter coordinates 40.47°N dhe 20.71°E and the focal depth 14 km. This earthquake expresses the increased seismic activity of the Korca-Erseka seismogenic zone. We present results from an analysis of local and regional data concerning epicenter location, focal mechanism of main shock, and its aftershock activity. Composite focal mechanism of the main shock according to GFZ shows a normal fault: Strike=216°, Dip=52°, and Rake (Slip)= -90°. The larger aftershocks occurred southeastern of the main shock epicenter. In this fault zone were located 947 earthquakes with ranging magnitude 0.6 to 5.3 Richter with an average depth of 11km and maximum depth of 63 km. The main shock was generated by the activation of a NNEStriking normal fault. The region affected by this series of earthquakes together with the strongest earthquake of May 1960, forms a roughly NNE trending active seismotectonic zone in southeastern Albania presents a threat to nearby urban areas in Albania.
-
-
-
Evaluation of Macroseismic Field of June 1, 2019, Korca Earthquake in Albania
Authors R. Ormëni, A. Berberi, N. Frasheri and O. GjuziSummaryA macroseismic investigation of a moderate earthquake with ML=5.3 at the depth of 14 km occurred on June 1st, 2019 near Floq village about 13 km S-SW of Korça town were carried out. Macroseismic investigation based on online web survey, the degree of damage to structures of human origin. The macroseismic data has been collected through the Institute of Geosciences, Energy, Water and Environment web and Emsc-csem web. This moderate shock was felt throughout southern and middle Albania, in neighboring countries, Greece and North-Macedonia, and in the epicentral area, EMS intensity reached VII-VIII degree. The maximum reported damage was in villages in the epicentral area of Korca district. Statistical analysis was applied to the macroseismic data collected in order to investigate the spatial distribution of intensity of the main-shock. Drawing of the isoseismic map consist of the geographical distribution of intensities averaged value for each town or village. The intensity map indicates areas of amplification and de-amplification of earthquake intensity. This paper gives an assessment of intensity, of attenuation function for the intensity of this earthquakes and intensity isoseismal map.
-
-
-
Experimental Evaluation of the Dynamical Parameters f0 and A0 Using the Method HVSR
Authors M. Popova, E. Oynakov, D. Solakov, I. Aleksandrova, D. Dragomirov and R. IvanovSummaryMicrozonation is one of the main tasks in the analysis of the seismic hazard, seismic risk and the following political planning to lower damage from earthquakes. For the purposes of microzonation first the dynamical capabilities of the soil have to be determined. This information can be attained by invasive and time-consuming methods. Extra problems arise in a city area where the measurements are affected by industrial noise and traffic. It is necessary the development of quick, effective and non-invasive methods aimed at the evaluation of the seismic characteristic of the upper layers of Earth`s crust. Passive seismic methods depend on the registration and analysis of microseismic noise from a natural, as well as from anthropogenic origin, the latter being very common in cities.
In this research for the purpose of evaluating the resonance effects by seismic waves is used the method of Horizontal to Vertical Spectral Ratio (HVSR) of microseismic noise, which can evaluate the relation between soil/construction. For areas with potentially high seismic risk, like the one that is observed in the area of Sofia, this method is suitable. This method is suitable for a city area because it does not need sources of artificial origin.
-
-
-
Magnetotelluric Studies and Regional Seismic Activity in the Central Part of Balkans
Authors B. Srebrov, I. Logvinov and E. BotevSummaryThe geomagnetic transfer function for periods of variations duration from 5 to 8000 seconds and some quasi-1, 2 and 3D magnetotelluric inverse modeling has been calculated. For these calculations the data for the components of the magnetotelluric field vector, obtained both in the Bulgarian geomagnetic observatories Panagyurishte (PAG) & Plana (PLN) and during the magnetotelluric field survey on the entire territory, have been used. The transfer function over a long period of time and the results of the various kind of inverse modeling have been compared with the regional seismic activity and a correlation has been found between them. This shows that the geomagnetic transfer function could be used to predict the regional seismic activity in the central part of the Balkans.
-
-
-
Ecological Problems in Forest Funds of Vitosha Mountain
Authors P. Ivanova-Radovanova and G. BelevSummaryRecently climate change and active anthropogenic activity in the region of Vitosha Mountain have generated serious environmental problems in the forest fund. The increase of temperatures within territory of the Sofia Valley caused by several reasons, such as global warming, the active recreational activity of the inhabitants of Sofia and the rapid construction at the Vitosha foothills cause a significant reduction of the areas of natural vegetation. Based on the analysis of climatic data and processing of satellite images, the reduction of the size of the natural habitats of important plant communities had been observed. As an important indicator, the results of the analysis of the moisture index and the normalized vegetation index (NDVI) are used for the purposes of the study, based on data from Sentinel Hub. The analyzes show an critique decrease in the forest fund in the respect of the role and importance of the mountain as an ecological “island” within the territory of Sofia valley.
-
-
-
Refraction Correction for Connection of the National Leveling Network First Order to Tide Gauge Station Varna
Authors N. Dimitrov, P. Danchev and I. GeorgievSummaryThe paper outlines some problems when applying refraction correction in order to reduce the effect of vertical atmospheric refraction in precise leveling observation. An example for calculating the refraction correction for a leveling line that connects the National Leveling Network first order to tide gauge station Varna is given. The estimation is using the model described in new Instruction № RD-02-20-1 of 15 January 2021 for the Establishment and Maintenance of the National Leveling Network. The results show that that the refraction correction is commensurable with correction for rod scale and must be applied for each set-up, appropriate weather conditions when the air temperature changed slightly throughout the day is better to be chosen. The applying of the refraction correction does not eliminate the requirements related with the maximum length of sight, minimum high of sight, balancing of the length of sights, and the choice of appropriate weather conditions.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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).
-
-
-
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
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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.
-
-
-
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).
-
-
-
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.
-
-
-
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.
-
-
-
Shear-wave Velocity Database as key Input for Seismic Site Amplification Models in Bucharest City, Romania
Authors A. Bala and D. Toma DănilăSummaryThe contribution of local site effects to seismic hazard is significant in cities located on thick stack of loose Quaternary layers of sediments such as Bucharest City. Here, strong-motion recordings of major intermediatedepth Vrancea earthquakes in 1986 and 1990, as well as the disastrous effects of previous major earthquakes (in 1940 or 1977) proved the necessity and importance of microzonation maps not only for new building design, but also for a great part of Bucharest old buildings stock, which is in a critical need for urgent retrofitting. Some studies emphasized the conclusion that mean shear-wave velocities (Vs) corresponding to the main 7 geological layers in the Bucharest underground: i) are important and must be known until deeper depth of 100- 150 m, making Vs-30 an insufficient and obsolete proxy for the explanation of spectral acceleration peaks at surface (Bala et al., 2014); ii) in surface the values of Vs may vary considerably across the city in just a few hundreds of meters.
-
-
-
Time Series Analysis of Monthly sea Level Data at Varna Tide Gauge Station
Authors A. Ivanov and I. GeorgievSummaryThis article contains time series analysis of tide gauge data to solve for short and long-term sea-level variations at the Varna tide gauge station. The period of observation is 1928 – 12.2020.
Тime series data includes average monthly sea level data corrected for subsidence of the tide gauge staff. Applied methods are Single spectrum analysis, Fourier, and Least-squares linear regression model. Determining the mean sea level and trend plays a key role in determining the results of global warming.
-
-
-
Infrared Spectral Measurements of Quartz, Malachite and Hematite in Interpretation of Remote Sensing Data
Authors D. Borisova and M. GoranovaSummaryInfrared spectral measurements as a part of remote sensing are used in mineral deposit investigations. The objective of the present paper is to compare infrared spectral measurements made in laboratory and spectral data from USGS spectral library. In the present investigations laboratory spectral reflectance measurements of quartz, malachite and hematite in the infrared range (2–25 micrometers) of the electromagnetic spectrum are performed. The obtained data of the performed spectral measurement could be used for filling in the database and for better interpretation of satellite data. This work is supported by Bulgarian National Science Fund under Contract number KP-06-M27/2 (КП-06-М27/2).
-
-
-
Joint Interpretation of Dissimilar Geophysical Data from Philippi, n. Greece, Using the Curvelet Transform
Authors A. Karamitrou, G. Tsokas and A. StampolidisSummaryImage fusion between different types of overlapping data offers significant advantages in archaeological research. For example, it complements the information that exists in images from dissimilar geophysical methods, enhances elusive yet systematic features and can reduce the effect of noisy spurious signals. Such improvements allow the identification of buried structures of archaeological importance with higher accuracy and greater confidence. In this work we use the curvelet transform to combine geophysical images from different modalities to detect possible archaeological targets in Philippi, Northern Greece. We jointly interpret overlapping data from two surveys, one utilizing the method of magnetic gradiometry and another measuring the apparent electrical resistivity. The images show several possible rectangular anomalies whose dominant orientation lies along the azimuths of 0 and 90 degrees which coincide with prior knowledge about this region. We utilize one of the main advantages of the curvelet domain that is the ability to express the imaged features as a function of their orientation and wavelength and we produce fused images that exploit the prior information about dominant building orientations. Our initial results are promising, showing several prominent features and possible excavation targets with sharp rectangular boundaries that possibly depict buried masonry of archaeological interest.
-
-
-
Uniaxial Deformations Estimation in the Vrancea Area Based on GPS Data
Authors N.D. Mateciuc and A. BălăSummaryThe present paper aims to analyze the state of crustal deformation in the Vrancea area using GPS measurement data. Unlike previous approaches that used station networks, uniaxial deformations method on profiles has now been used. A brief description of the extended Vrancea network was made, whose nodes were used to draw the measurement alignments. For each subnet Northern Vrancea and Southern Vrancea respectively, separate alignments were drawn, the analysis being carried out for each subnet separately. The analysis takes into consideration 21 alignments, 8 in the Northern Vrancea subnet and 13 in Southern Vrancea subnet. The results are presented in the form of result tables, in which the uniaxial strains and the variation of the angle with respect to the North direction at the two moments of the determinations, t1 and t2 were determined. For each measurement alignment, a graphic representation that contains all the calculated elements was made. The conclusions refer to the characteristics of the two subnets in terms of calculated values, to the strain magnitudes and to their possible connection with the local fault system.
-
-
-
Astronomy Teaching and the Impact of NEA Asteroids on Earth
Authors A.L. Boldea and M. StavinschiSummaryThis paper aims to present and implement modern training methods, as efficiently as possible, through the e- Learning platforms Moodle, Googleclass, and Mooc for teaching an Astronomy course to students. An interdisciplinary approach, Mathematics-Geography-Geophysics-Astronomy leads even more to the explanation of the phenomena of appearance and development of the Solar System, as well as to find out the data referring to the age of our Solar System, approximately 5 billion years. We propose a brief presentation of the component of our Solar System, as well as the study of other small celestial bodies, such as NEA, Near Earth Asteroids and their impact on Earth. The paper presents several applications of Astrometrica software for the detection of NEA asteroids, and which have proven to be effective and useful, using active teaching-learning methods, such as learning through investigation and discovery. Some of these mixed teaching-learning methods have been successfully used to teach astrometry and astrophysics to students at the University of Craiova, using real astronomical data obtained from the Isaac Newton Astronomical Observatory in La Palma, Spain.
-
-
-
Building up a Seismic Network in the Early Days of Seismology in Romania
Authors V. Adina, M. Popa, C. Ionescu and D. PaulescuSummaryThe science of seismology is relatively new. In the last 100 years, important milestones were achieved both in the understanding of the geological particularities which influences the earthquakes occurrences and in the development of seismological instruments.
In Romania, the seismological service was founded at the end of XIX century by the initiative of some dedicated researchers in the field of astronomy, geosciences, mathematics and physics. In 1902 in Romania there were two seismological services at Bucharest and Timisoara.
Through hard work and devotement, these earthquake study initiatives extended in organizing the first seismic stations in Romania. In time, the seismic stations activity was organized in a more durable context, by creating the Romanian Seismic Network.
Nowadays, the Romanian Seismic Network has over 200 stations both in Romania and in neighboring countries, fully equipped with digital instruments of high precision.
-
-
-
A Possible Seismic gap in Vrancea (Romania) Zone at Depths below 150km
Authors I. Moldovan, B. Enescu, C. Ghita, C. Ionescu and A. MarmureanuSummaryThe Vrancea seismic zone is located beneath the Eastern Carpathians in Romania and characterized by persistent, well-confined seismicity. The main seismic activity occurs at intermediate depth (60 - 180 km). The purpose of this study is to explore a possible seismic gap of seismicity, similar to that reported by Marza (1979) before the 1977 Mw 7.2 Vrancea earthquake. The earthquake data is provided by the ROMPLUS earthquake catalogue (Oncescu et al., 1999 – updated).
The results of the analysis show a clear decrease in the number of Vrancea earthquakes (Mw >= 2.5) with depths below 150 km, starting in the year 2014. The number of recording seismic stations in the eastern part of Romania, as well as in and around the Vrancea region, does not change significantly in 2014, so the decrease in the number of deep events may not be related with the station coverage. Further exploration is, however, necessary. We have also found some intriguing changes of hypocentral depth, for the same earthquake, when comparing the output of the Early Warning System (EWS), automatic and manual locations. We will further analyze the reasons behind these changes and confirm whether the current seismic gap is genuine or not.
-
-
-
Tsunami Waves in the Region of Southeast Europe: Analysis and Modeling
Authors L. Dimova and R. RaykovaSummaryThe aim of this study is to review and model tsunami waves in the region of Southeastern European sea basins. The strongest earthquakes are revised using several seismic catalogues over the period 1000–2021. Tsunami data was collected from a historical catalog, as well as more recent tsunami tide-gauge records from the mareographic network. The geometry of the faults is calculated via formulas or directly taken from the European Database for Seismogenic Faults (EDSF). Thirteen seismic sources placed in the broad Eastern Mediterranean are analyzed in order to build a reliable input for tsunami simulation. Recent tsunami events in the Aegean Sea are simulated using numerical code UBO-TSUFD: 20 July 2017 (Bodrum-Kos, Mw=6.6), 2 May 2020 (Crete, Mw=6.6) and 30 October 2020 (Samos-Izmir, Mw=7.0). In all three cases the focal mechanisms favor the formation of a tsunami, as well as the generated waves were registered by several tide-gauges and a comparison between computed synthetic mareograms and observed tsunami was made.
-
-
-
Importance of Post-project Evaluation and its Implementation Method - GwB Project in Serbia and BiH
Authors S. Komatina, T. Aizawa, K. Suto and J. SugawaraSummaryHeavy rain in May 2014 triggered thousands of landslides in Balkan region. In order to help in overcoming difficult situations, humanitarian expert project was performed by AGES and financially supported by SEG GwB.
The project brought students, researchers and practitioners in Serbia and BiH together with experts - volunteers from seven other countries. They cooperated towards a common goal of geophysical surveys, data analysis and design of countermeasures for landslide disaster mitigation, overcoming the divisive history of wars, race, religion and culture.
But, evaluation of geophysical surveys often accounts for the technical aspects alone, while social, economic and environmental evaluations are rarely discussed in professional societies. The importance of achieving the SDGs is increasing in all the social activities; geophysics is expected to deliver value to the world and that is why geophysical projects should be assessed in terms of social, economic and environmental impacts as in the SDGs.
Among various methods of project evaluation, the Development Assistance Committee of Organization for Economic Co-operation and Development (OECD-DAC) proposed six evaluation items. These assessment criteria are tools for business evaluation from the perspective of sustainable humanitarian benefits and often involve volunteers across national borders and set standards based on international consensus.
-