This study presents the results of three-dimensional finite element modelling of Gediminas Hill in Vilnius, incorporating existing buildings and the remains of the Upper and Lower Castles. The main objective is to assess slope stability using the strength reduction method and to identify potential critical failure scenarios considering the interaction between soil and structural elements. Both static and dynamic loading conditions are analysed. Static loading includes the self-weight of soil layers, technogenic deposits, structural elements, and infrastructure, while dynamic effects are represented by fireworks-induced impact loads. The comparison of analyses reveals differences in displacement development and failure mechanisms. Strength reduction results highlight the zones of concentrated deformation within the technogenic layer, which are further evaluated in relation to the effects of dynamic loading.
The paper provides an overview of the Mizarai impact structure located in southern Lithuania, discovered in the course of geological mapping in 1969 and identified in 1975. Since then, the structure has been investigated by the mapping of gravity and magnetic fields, 2D and 3D seismic surveys, drilling and core studies. The structure is in the form of an oval depression situated within the Precambrian crystalline basement filled with presumably Ediacaran to Lower Cambrian detrital sediments derived from target rocks and ejecta and overlined with Mesozoic and Quaternary sediments. Gravity and seismic data have not indicated the presence of a central uplift within the Mizarai depression, suggesting a simple form. We estimate that the recent size of the crater is 3.8 x 4.2 km, after erosion in the course of similar to 300 Ma. Before erosion, the primary crater had a rim-to-rim diameter of up to 5 km and a depth of approximately 1 km. The impact metamorphism manifested in the transformation of target rocks into impact breccias and impact melt rocks, displaying shock features such as shatter cones, isotropization of quartz and plagioclase, planar deformation features (PDFs) in quartz, and kink-bands in biotite. While most impactites reflect the target rock composition, suevitic impact breccias and impact melt rocks (glass) are enriched by potassium.
To investigate the frost damage of Zoige Plateau Peat Permafrost and the stability of engineering foundations in seasonally frozen regions, this study builds upon previous research on the optimal mix ratio of composite stabilized peat soil using mineral powder-steel slag and basalt fibre as primary materials, supplemented with polycarboxylate superplasticizer and carbide slag. Indoor mechanical tests (unconsolidated undrained triaxial shear test, unconfined compressive strength test, and scanning electron microscopy test) were conducted on stabilized soils subjected to varying freezing temperatures and freeze-thaw cycles to explore the mechanical properties and microscopic mechanisms under freeze-thaw action. Based on the experimental dataset, the peak strength of stabilized peat soil was predicted using a particle swarm optimization backpropagation neural network (PSO-BP). The results indicate that the unconfined compressive strength and residual strength ratio of stabilized peat soil are positively correlated with freezing temperature and negatively correlated with the number of freeze-thaw cycles. The stress-strain curve characteristics of stabilized peat soil are generally consistent under different conditions. With increasing cycles, the peak strength and cohesion of the stabilized peat soil first decrease and then stabilize, while the internal friction angle remains relatively unchanged. In the peak strength model constructed using MATLAB, the PSO-BP neural network model exhibited a higher correlation coefficient (R2) and better overfitting performance compared to the BP neural network model, enabling a more accurate strength prediction of stabilized peat soil.
This study investigates the deformation and failure mechanisms of gently layered surrounding rock during underground excavation in a hydropower station in Shaanxi Province, China, through base friction physical simulation tests. Results indicate rock mass instability is governed by weak discontinuities (layer planes, joints, and faults). Four failure modes emerge: (1) tensile crack collapse at the tunnel arch induced by stress concentration, (2) shear slip at the sidewalls and shoulders due to exceeding shear strength, (3) bulging deformation of thin-layered rock under compressive stress, and (4) slight uplift at the invert of the main powerhouse due to upward pressure. The physical simulation tests replicate the deformation and failure evolution of the surrounding rock mass during excavation. Initially, the process is characterized by tunnel arch spall and slight slip, progressing to rock mass collapse due to structural plane coalescence. The study reveals the complex mechanical behaviour of failure in gently layered surrounding rock. The tunnel arch exhibits a "tension crack collapse - shear slip - bedding" failure mode, while the sidewall is primarily influenced by shear slip. Findings confirm discontinuities' control on the stability of layered surrounding rock, offering guidance for deformation support and long-term maintenance. These results provide significant theoretical and practical implications for engineering applications.
The construction of a deep geological repository (DGR) for the spent nuclear fuel and high-level long-lived radioactive wastes is prescribed in Lithuanian legislation. Therefore, geological investigations for DGR host formation and site selection are being carried out. This paper presents a comparative suitability evaluation of two potentially suitable Lithuanian clayey formations. The suitability evaluation of Lower Cambrian and Lower Triassic clays was performed using the data set of laboratory test results from two decades. The results of laboratory investigations performed on clay material obtained from the unpreserved cores of nine boreholes were analysed in order to quantify the parameters relevant to the formation suitability. The data set contains the results of hydraulic conductivity measurements of several samples, mineralogical analysis of clay minerals, determination of Atterberg limits, chemical analysis (EDS method), and particle specific surface area measurements (BET method). Analysis of laboratory test results allow to compare the suitability for DGR installation of two Lithuanian clayey formations according to several properties. The clay fraction of the Lower Triassic potentially suitable formation is dominated by smectite/montmorillonite group minerals (60-88%), and the dominance of illite (60-95%) is characteristic of Lower Cambrian clay. The determination of Atterberg limits indicates a similar (medium) plasticity of both formations. The specific surface area of particles ranges from 30.9 to 54.8 m(2)/g in Lower Triassic samples and from 28.0 to 32.7 m(2)/g in Lower Cambrian samples. A higher smectite content and a larger specific surface area show a greater swelling and sorption capacity of Lower Triassic clay. Clay swelling and sorption capacity are important features causing geological environment suitability for the DGR. Although the tests were conducted on unpreserved and degraded samples, their results support the conclusion that the suitability of the Lower Triassic potentially suitable formation is comparatively greater.
Artificial intelligence (AI) is increasingly used in hydrogeological analysis for forecasting groundwater levels and properties, discovering hydrochemical facies and anomalies, and modelling spatio-temporal signals. Current practice emphasizes spatio-temporal validation, interpretability, and uncertainty quantification, while generative AI (GenAI) is emerging to accelerate data curation, documentation, augmentation, and code prototyping. This report summarizes representative applications of AI and machine learning (ML) in hydrogeology and describes an open, reproducible course developed for university students and professional hydrogeologists. This continuously updated online course is one of the outcomes of the GRANDE-U “Groundwater Resilience Assessment through Integrated Data Exploration for Ukraine” project. It covers Python fundamentals, environment setup, data engineering, and documented case studies in time-series and spatio-temporal modelling. Application examples are drawn from recent teaching materials and GRANDE-U and related studies and include predicting terrestrial water-storage anomalies, groundwater-level forecasting, isotope estimation from routine chemistry, risk or prospectivity mapping, and automated lineament/facies mapping.
This study aimed to investigate the structural configuration of the reservoir in Concession 82, located in the Sirte Basin, Libya, with a particular emphasis on identifying faults and associated fractures that contributed to water invasion during drilling operations in one of the wells within the study area. The methodology involved the application of the ant tracking seismic attribute to extract lineaments indicative of fault structures. Several faults and fractures were successfully identified and delineated in the vicinity of the non-productive well. A statistical analysis of the extracted faults was conducted to assess variations in fault trends and density across the study area. The findings revealed that the non-productive well was drilled directly along a fault plane, which facilitated water invasion. The inability to detect this fault prior to drilling was attributed to the poor quality of the original seismic data. Further analysis demonstrated that the study area is characterized by a complex fault system exhibiting a range of orientations, magnitudes, and depths. This finding is consistent with and supports several previous studies on the tectonic and structural evolution of the Sirte Basin. Understanding these fault characteristics is crucial for mitigating drilling risks such as water invasion. Notably, the failure of the non-productive well is directly linked to the presence of the identified fault. Despite this issue, the structural configuration of the area suggests a strong potential for hydrocarbon accumulation.
The present study aims to perform statistical analyses on rock mass class differences estimated during the investigation and encountered during excavation phases of various tunnel projects and to quantitatively evaluate these differences. Using data obtained from 14 different highway tunnels constructed in T & uuml;rkiye, the differences between the rock mass classes predicted during the investigation phase and the actual values encountered during excavation were analyzed with the parameter of Mean Percentage Absolute Difference (MPAD). The effects of the parameters introduced in the study, such as the drilling length ratio to tunnel length (LDn), total core recovery ratio (TCRn), rock quality designation ratio (RQDn) and uniaxial compressive strength test number ratio (UCSn), on these differences were investigated with regression and Random Forest algorithms. The results showed that TCRn and RQDn have a strong inverse relationship on MPAD, in other words, the rock mass class differences decrease with the increase of these parameters. In addition, it was determined that the drilling length and total core recovery values are of critical importance in reducing the uncertainties in the tunnel route. This study is expected to contribute to more accurate predictions and to reduce cost and time losses by providing a quantitative approach to minimize uncertainties in tunnel constructions during the excavation phase.
This study examines bioclimatic conditions in Vilnius, Lithuania, from 1993 to 2024, using the Universal Thermal Climate Index (UTCI) to analyze trends in human thermal stress. RayMan software was employed to calculate UTCI data based on input parameters such as average air temperature, relative humidity, wind speed, and cloud cover. The Mann-Kendall trend test was applied to identify statistically significant changes in thermal stress over time. The second part of this research compares data from three different meteorological stations (located outside the city, north of the city centre, and within the city centre), focusing on extreme heat stress conditions from 2022 to 2024. Results show an increase in moderate and higher heat stress events, along with a decrease in strong and lower cold stress events. The variation in UTCI category frequencies over the years demonstrates a shift toward higher thermal stress levels and more instances of no thermal stress. A comparison of data from the three stations reveals that extreme heat stress conditions are more common in the city centre than in the northern part and outskirts of the city. These findings have implications for public health, urban planning, and climate adaptation strategies in Vilnius, highlighting the city’s growing need for heat mitigation measures.
The validation of recent global geoid models is essential for improving the accuracy and reliability of geodetic applications in T & uuml;rkiye. This study aims to assess the performance of global geoid models, such as the Earth Gravitational Model 2008 (EGM2008) and other satellite-based models by comparing them with regional and national geoid models constructed using high-precision local GNSS and levelling data. The geoid undulations from global models are compared with those obtained from the Turkish national geoid model, developed from gravity measurements and geodetic surveys conducted by national agencies. The analysis involves statistical evaluation using Root Mean Square Error (RMSE) and standard deviations to quantify discrepancies. The results show significant variations in geoid heights, especially in tectonically active regions, highlighting the limitations of global models in accurately representing local geoid features. Based on the validation results, suggestions for improving the global models by incorporating local geophysical data are discussed. The findings emphasize the importance of region-specific geoid models for precise height transformations and geodetic applications in T & uuml;rkiye.
In recent decades, rising winter and spring temperatures have led to an earlier onset of the growing season. However, this shift is often accompanied by false spring (FS) events-situations when the last spring frost (LSF) occurs after the start of the growing season (SGS). This study evaluates future changes in the recurrence and intensity of FS events in the eastern part of the Baltic Sea region. The SGS and LSF dates for each grid cell within the study area for each year were determined to identify FS events. An FS event was recorded when LSF occurred later than the SGS date. The intensity of FS events was assessed using growing degree days (GDD) accumulated until the event. Future projections were generated using five CMIP6 models (CanESM5, ACCESS-CM2, GFDL-CM4, MPI-ESM1-2-LR, and NorESM2-MM), two SSP scenarios (SSP2-4.5 and SSP5-8.5), and data obtained from the NASA NEX-GDDP-CMIP6 dataset. The period from 1995 to 2014 was used as the baseline, and projections were made for the years 2041-2060 and 2081-2100. Analysis showed that SGS and LSF dates are projected to shift significantly earlier under all models and scenarios. However, FS recurrence projections are less consistent. Most models indicate a decline in FS events by midcentury, while forecasts for 2081-2100 are mixed-two models suggest an increase, while the other three suggest a decrease. The mean GDD sum accumulated until the FS event increases only when the frequency of FS events is projected to rise, suggesting that future FS events may be more intense.
This study reconstructs the sequence of secondary mineral transformations in the Kabeliai granite (southern Lithuania) based on detailed petrographic, mineral chemical, and isotopic data from samples obtained from a drill core Marcinkonys-7. The selected samples represent various lithologies and grades of alteration, from melanocratic diorite to pegmatitic granite. Several alteration steps were identified. The earliest is marked by the late-magmatic re-equilibration of feldspars and accessory minerals. The following subsolidus re-equilibration leads to perthitic textures and albite replacement. The later stage reflects infiltration of Na-Ba-SO4-bearing fluids, which caused feldspar metasomatism, biotite alteration, barite precipitation, and partial titanite breakdown. Finally, F-CO2-rich fluids induced advanced replacement of titanite by anatase, calcite, and REE-carbonates, accompanied by widespread albitisation, hematite formation, and REE mobilisation. The observed mineral assemblages and textural relationships are consistent with progressive fluid-driven modification under increasing fO2 and decreasing temperature. These results demonstrate that accessory minerals such as titanite and apatite can preserve complex records of post-magmatic processes and highlight the role of oxidising REE-bearing fluids in the late evolution of granitic systems.
The present study investigates the mineralization potential of the Ar & imath;zl & imath; ophiolitic complex in Afyon, Turkey, employing an integrated methodology that combines sophisticated geophysical and geochemical techniques. The area, characterized by ultramafic rock types and intricate structures, exhibits significant enrichment in chromium (Cr2O3, up to 49.51%) and nickel (Ni levels exceeding 2,000 ppm), particularly in serpentinized dunite regions. High-resolution drone-based magnetic surveys have detected anomalies indicative of ore-rich zones, with spatial data refined to resolutions of 50 m, 100 m, 150 m, and 250 m. Complementary IP/ERT profiling has identified chargeability and resistivity anomalies that align with the geochemical results. The geochemical investigation, performed using XRF, ICP-MS, and XRD, has confirmed these anomalies, revealing a complex mineralization framework mainly consisting of chromite, serpentine, and sulfide minerals, including pyrite and pentlandite. A comparative examination with global chromite-bearing ophiolites, including those in Oman and Greece, underscores the Ar & imath;zl & imath; region's correlation with economically significant deposits. The research highlights the influence of structural discontinuities, fault-induced hydrothermal modifications, and brecciation processes on the distribution of minerals. This research highlights the benefits of integrating geophysical and geochemical techniques for studying chromite and nickel in ophiolitic environments. The employed methodology may act as a reference framework for analogous studies in structurally intricate ultramafic terrains.
Peru is located above the damaging Peru-Chile Trench, which is the line where the Nazca Plate is subducting under the South American Plate. The two plates are approaching one another at a velocity of around 78 millimetres each year. There is a history of really big earthquakes in southwest Peru. The Arequipa, southern Peru, earthquake of 23 June 2001 had a moment magnitude of 8.4, a maximum Mercalli severity of VIII (severe), and occurred at 20:33:15 UTC (15:33:15 local time). It was the worst earthquake to ever strike the world since the 1965 Rat Islands earthquake and the most destructive earthquake to strike Peru since the disastrous Ancash earthquake of 1970. In this study, the horizontal and vertical displacements before and after the Arequipa, southern Peru, earthquake were analysed (kinematic GNSS results were compared with static GNSS results). As a result of these GNSS investigations (pre-motion on 20-21 June 2001), the obtained GNSS data for the precursor of the Arequipa earthquake were used. The AREQ IGS station before the earthquake, the movement in the horizontal components that occurred on 20-21 June 2001, and the decrease of this movement on 22 June 2001 seem to be a harbinger of the earthquake. In addition, the effects of the earthquake that occurred on 23 June 2001 were continued with aftershocks on 24 June 2001. In addition, this study may serve as a basis for understanding potential precursory patterns in this region.
Climate change manifests not only through shifts in mean conditions but also through increasing extremes. We analyzed changes in 12 extreme temperature and precipitation indices in Lithuania for the 1961-2020 period. We assessed trends and compared change in exceedance probabilities between 1961-1990 and 1991-2020. Results shows that the probability of hot days exceeding the 95th percentile more than doubled at both Vilnius and Klaip & edot;da stations, while the probability of experiencing 10 very cold nights per year decreased from 65% to 25%. Over the past 60 years, the growing season length increased by 10 days, with the largest extension in Nida (27 days). Tropical nights began to emerge; however, a statistically significant increasing trend was determined only in Nida (0.5 nights per decade). Extreme precipitation also intensified: days with more than 20 mm of rainfall increased from 1 to 7 per year by the end of the study period. At the same time, the number of consecutive dry days also increased, indicating the increasing weather extremes in Lithuania as the global climate changes.
A comprehensive analysis of b-value for the Albanian earthquakes was conducted using the instrumental earthquake catalogue of Albanian region. A total of 38,816 seismic events with magnitudes M-L >= 0.1 on the Richter scale were utilized. Statistical characteristics of the seismicity were examined based on b-value, as defined by the Gutenberg-Richter law. Considering the magnitude completeness (Mc-value) as 2.7, b-value was estimated as 1.09 +/- 0.08 and it indicates a normal stress regime in the region. The Mc-value varies from 1.5 to 3.4, and spatial distribution of b-value ranges from 0.79 to 1.16. Higher b-values (> 1.0) were detected in the southernmost part of Albania, whereas lower b-values (< 1.0) were found in the western part, particularly within the Adriatic-Ionian fault zone and the Lushnje-Elbasan-Dib & euml;r transversal fault zone, as well as in the south-eastern Leskovik-Erseka-Kor & ccedil;a fault zone. Regions with lower b-values correspond to areas with larger-magnitude events, while higher b-values are associated with smaller earthquakes. These findings suggest that b-values across Albania generally round 1.0, with lower values indicating moderate stress accumulation in the western region and within two other active seismic belts. The b-values less than 1.0 may signal areas of increased seismic potential. The occurrence probability of earthquakes across varying magnitudes was found to be very high (99%-100%) for seismic events with M-L between 0.5 and 4.5, and lower (less than 95%) for events with M-L >= 5.5; it varied from 1% to 60% for events with larger M-L >= 6.0 for different Tr values. Recurrence periods for smaller magnitudes are relatively short (less than 1 year for magnitudes from 1.0 to 4.2), whereas for larger magnitudes (5.0 to 6.0), recurrence periods are longer, about 100 years. The Albanian region is characterized by a complex geological setting and significant seismic activity, and, thus, it can be stated that these types of analyses may be important in terms of seismotectonic evaluation and seismic hazard.
This study explores the use of neural network-based machine learning techniques to predict yearly changes of the foredune height, beach height, and beach width. The research focuses on the evolution of the Curonian Spit coast based on cross-shore profile long-term field measurements (1993 to 2018) supported by the analysis of empirical and modelled annual wind, wave, and sea level data. The performance of two types of recurrent neural network models – LSTM and GRU – was assessed by monitoring training progress and validating on unseen data. Both demonstrated the ability to predict general trends; however, the LSTM model exhibited a superior performance in accurately discerning the direction of cross-shore profile parameters development. However, the models showed limited accuracy in predicting more stable morphometric parameters, such as foredune height, likely due to constrained variability in the available data. The signs of overfitting observed during training further highlight the insufficiency in both the variability and duration of the training data set. The findings demonstrate a high potential of machine learning methods to support coastal change forecasting, although the effectiveness of these models remains highly dependent on the quality, temporal span, and spatial coverage of the input data. Incorporating a longer time series with additional factors, such as nearshore seabed morphology and sediment type, may further enhance model performance.
The Aegean region is a key component of the Eastern Mediterranean basin and covers the subduction of the African Lithospheric Plate beneath the Aegean along the Hellenic Arc and the western movement of the Anatolian Plate. In this research, simultaneous inversion of teleseismic P- and S-Receiver Functions (RFs) is used to investigate the crust and upper mantle structure of the Aegean region. For this purpose, data from the different band-type seismic stations arranged along the Hellenic Arc are used to calculate receiver functions. The study involves 452 P-Receiver Functions and 237 S-Receiver Functions from 8 stations. Although the seismic stations are nearby, the S-wave velocity models in the south and north turn out to have different structural discontinuities. Also, the results of stacking P-Receiver Functions indicate the significant Ps and Sp phases from the Aegean Moho and the African Slab. The Moho depth of the African Slab along the Hellenic Arc ranges from 45 to 56 km, with an average crustal shear wave velocity of Vs = 4.5 km/s. The lithosphere-asthenosphere boundary (LAB) is observed at depths of approximately 155 km around the Hellenic Arc and corresponds to the subduction of the African Slab. However, the LAB depths of the eastern and western stations are consistent with the Anatolian and mainland Greece. Finally, these observations can be interpreted as part of the African subduction system and the Anatolian lithospheric system in the study region.
In recent years, remote sensing methods and Geographic Information Systems (GIS), particularly their analytical tools, have been widely used to assess landslide susceptibility and evaluate landslide hazards and risks. These technologies provide significant advantages in collecting and analyzing data related to landslide susceptibility. This study analyzes the landslide susceptibility of the Middle Araz Basin (Nakhchivan, Republic of Azerbaijan) using GIS. Landslides are a serious natural hazard in our country, including in the Nakhchivan Autonomous Republic, where 76% of the territory is mountainous. Landslide events cause substantial damage to residential areas and pose significant threats to human life, impacting environmental structure and local ecosystems. Early detection and analysis of landslide-prone areas are essential to mitigate these impacts and to implement necessary preventive measures. Assessing landslide susceptibility in the Middle Araz Basin is a novel undertaking. In this study, the weighted overlay method (WOM) was employed to develop a landslide susceptibility map. Field studies and observations provided landslide inventory data specific to the region. Various conditioning factors affecting landslides – including slope, aspect, elevation, relief curvature, proximity to river networks, distance to roads, NDVI, distance to faults, and precipitation – were analyzed to identify high-risk areas. The resulting susceptibility map categorizes the Middle Araz Basin into five risk levels: very high (1.8%), high (14.5%), moderate (25.5%), low (34.6%), and very low (23.6%). This classification aids in understanding the risk levels across different areas, thereby supporting the implementation of appropriate protective measures. Keywords: weighted overlay method (WOM); remote sensing; landslide conditioning factors; gravitational force; slope; hazard mapping
Predicting the lifetime of rock materials based on their physical and mechanical properties is essential in engineering geology. This study investigated chemical weathering that may occur after three years in natural building blocks tested in examination tanks at meteorological stations in seven major cities. All tested samples were obtained from quarries within the borders of the Türkiye provinces where the examination tanks were located. X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), thin section examinations, methylene blue tests, capillary water rise tests, and colour change determination analyses were performed at the end of the third year. In a short period, colour changes were observed, and the dissolution of the carbonate rock samples was determined. The capillary level and the weight gain due to capillary water absorption of the field samples was higher than that of the fresh samples. The increase in the electrical conductivity (EC) values of the water accumulated in the examination tank after three years showed that the travertine samples in the tank had dissolved. In addition, the chemical weathering index (CIW)and Parker index (PI) values of the ignimbrite samples exhibit slight changes. Keywords: ignimbrite; travertine; colour change; chemical weathering indices; capillary water rise; dissolution
