Search Results (3,667)

The stability analysis of rock slopes traditionally involves the evaluation of limit state conditions to determine the potential for rockslides and rockfalls. However, empirical evidence supported by experimental studies has highlighted the complex response of rock interfaces under differential loading. It is characterized by distinct pre-peak and post-peak stress–deformation relationships, which represent the deformation profile of loaded rock interfaces and, thus, capture dynamic and evolving events. The present research introduces an interpretation framework to reconcile these contradicting paradigms by interpreting empirically and explicitly the full stress–displacement relationship along active shear surfaces of rockslide events. The Complete Stress–Displacement Surface (CSDS) model was incorporated into conventional analytical solutions for a rock slope planar failure to describe the evolving stress conditions during an active rockslide event. The Ruinon rockslides (Italy), monitored and studied extensively at the turn of the century, are revisited using the adapted CSDS model to describe the evolving stress–deformation conditions. Empirical and experimental calibrations of the model are implemented and compared using the CSDS model for the description of evolving shear stresses in large rockslide events based on topographical monitoring. This paper contributes a detailed framework for correlating in situ topographical monitoring with relevant geomechanical information to develop a representative model for the evolving stress conditions during a rockslide event. Full article

This study focused on identifying Th-, Nb-Ta-, Zr-, and REE-bearing minerals with a multivariate statistical approach in alkaline syenite to evaluate their radiological risks, at Nikeiba, Egypt. Through microchemical analyses, by utilizing electron probe microanalysis, horite, microlite, monazite, zircon, columbite, and fergusonite were shown to bear uranium and thorium. These minerals have played an important role in higher radioactive zones in the studied alkaline syenite. REE-minerals comprising bastnäsite, monazite, and fluorite and apatite are well recorded. The total rare earth elements (TREE₂O₃) reveal higher concentrations in bastnäsite than monazite, with averages 74.87 and 63.8 wt%. Ce is considered the most predominant LREE in the analyzed bastnäsite and monazite. The mean values of radionuclide activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K are 108 ± 20 Bq/kg, 107 ± 9 Bq/kg, and 1255 ± 166 Bq/kg, respectively. Radiological assessments revealed a radium equivalent activity of 357 Bq/kg, below global limits, but an air-absorbed dose rate (166 nGy/h) and annual effective doses (0.81 mSv/y indoors, 0.20 mSv/y outdoors) exceeding safe thresholds. Additionally, the excess lifetime cancer risk (ELCR) was calculated at 0.00071, surpassing the acceptable limit of 0.00029, making these rocks unsafe for construction use. Statistical analyses further underscored the relationships between radionuclide concentrations and associated risks, highlighting the necessity for continuous monitoring and mitigation. Full article

This study examines the relative sea-level changes during the Upper Holocene period along the south coastline of Cyprus through the investigation of beachrock formations and their impact on archaeological sites. Beachrock, as a natural indicator of past relative sea levels, provides valuable insights into the dynamic interplay between sea-level fluctuations and human settlements. The research integrates field observations, mineralogical and geochemical analysis, geochronological studies, and archaeological data to reconstruct past sea-level variations and their implications for coastal archaeological sites. The results reveal significant fluctuations in relative sea levels during the Upper Holocene, influencing the development and occupation of coastal archaeological sites. By elucidating the complex relationship between sea-level changes and human activity, this study contributes to our understanding of past coastal environments and their socio-cultural dynamics. Moreover, it underscores the importance of considering geological factors in archaeological interpretations and coastal management strategies in the face of contemporary sea-level rise. Full article

The Brazilian semiarid region faces water scarcity, with alluvial aquifers playing a crucial role in agricultural water security. This study assesses the spatiotemporal variability of groundwater quantity and salinity, analyzing natural and anthropogenic impacts, including post-pandemic trends. The investigation was developed in the Mimoso Alluvial Valley (MAV), Pernambuco State, mainly used for communal irrigation supply. The spatiotemporal dynamics of land use (LUC) was performed based on data provided by Mapbiomas for the years 2012, 2016, 2019, and 2023. Geostatistical analysis was applied for mapping water table levels and salinity. Changes in LUC suggest possible forest regeneration influenced by climatic factors and anthropogenic pressure alleviation. Electrical conductivity (EC) and groundwater level (GWL) exhibited medium to high variability. Temporal trends highlight climatic influences, groundwater abstraction, and recharge/discharge dynamics. Pre-2019 years were classified as dry, whereas the 2019–2023 years ranged from rainy to extremely rainy, leading to lower EC and GWL variability in 2023. Additionally, the COVID-19 pandemic temporarily reduced agriculture, lowering salinity and aiding groundwater recovery. The spatial analysis revealed critical distribution patterns, highlighting the interaction between natural processes and human activities. These findings provide valuable insights for optimizing irrigation and environmental strategies, supporting long-term groundwater sustainability in semiarid regions. Full article

Upper Cretaceous carbonate rocks in Jordan are the main resources for construction and paint-related industrial applications. This study evaluates the elemental composition, mineralogy, and petrography of two main geological formations from two localities in northern Jordan (Hallabat, Turonian age, and Ajlun, Santonian–Campanian age) to shed light on their composition, depositional environments, and potential industrial end uses. The elemental composition of the Hallabat Wadi Sir Limestone (WSL) Formation indicates notable variability between the middle and upper parts of the WSL carbonates in the area, with higher CaO content in the middle part (mean 55 wt.%) and higher silica content observed in the upper part (mean 2 wt.%) compared with the middle part (mean 0.9 wt.%). Meanwhile, analysis of the elemental composition of the Ajlun Amman Silicified Limestone (ASL) Formation indicates that the CaO content is relatively higher in the upper part (mean 56 wt.%). In addition, the lower part is more influenced by detrital input when compared with the upper part of the studied section, in contrast to the Hallabat WSL Formation. Petrographic analysis demonstrates that the WSL and ASL samples are predominantly micritic limestone. The XRD results for the Hallabat WSL and Ajlun ASL show that the mineralogical composition is dominated by calcite (CaCO₃). Statistical and PCA analyses also confirm these variabilities between the two sites, indicating that all samples from both sites were deposited under variable hydrodynamic and environmental conditions that affected their physical and chemical composition. The results show that all studied samples are in the range of pure limestone and can be used for specific industrial applications in addition to their current uses, including those in the pottery and porcelain ware, soda ash and caustic soda, steel industry, sugar, and textile production industries, thus contributing to the economic resources in Jordan. Full article

Deep gravitational slope deformations (DsGSDs) are a geological and engineering challenge with important implications for slope stability, the reliability of existing infrastructures, land use and, above all, the safety of settlements. This paper focuses on the DsGSD phenomenon that affects a large part of the Borrano hamlet, located in the municipality of Civitella del Tronto (Abruzzo Region, Central Italy). This instability is characterized by slow movements of large volumes of material. The main factors initiating deformations are a combination of geological and hydrogeological aspects. These factors include the complex local stratigraphy, composed of pelitic and arenaceous facies at high slope dip angles, and extreme natural events such as heavy rainfall and earthquakes. This study employs a multidisciplinary approach integrating in field activities such as remote-controlled surface monitoring (clinometers and strain gauges), in-depth monitoring (inclinometers and piezometers), aero-photogrammetric analysis and numerical modelling. These techniques permitted us to characterize the evolution of the slope and to identify both the critical sliding surfaces and the mechanisms governing the ground movements. Soil deformations were mainly observed in the central zone of the hamlet. Significant deformations were recorded along planes of weakness at depth between arenaceous and pelitic materials. These planes represent contact zones between the clayey–marly facies, characterized by low strength, and the arenaceous facies, characterized by higher stiffness, creating a mechanical contrast that favours the development of large deformations. The numerical analyses confirmed good correlation with the monitoring data, revealing in detail the instability of both local and territorial processes. The 3D numerical analysis showed how the movements are controlled by planes of weakness, highlighting the key rule of geological discontinuities. Full article

Detrital zircon (DZ) ages of Cretaceous sandstones in the United States contain critical spatial and temporal information on their sedimentary provenance and on the reorganization of drainage patterns. Herein, we report zircon U-Pb ages of sandstones from Lower Cretaceous and Upper Cretaceous formations of Arkansas. All Arkansas sandstones studied, except for those from the Upper Cretaceous Nacatoch Formation, display dominant Appalachian-Grenville DZ ages from among the Appalachian-Ouachita DZ grains that were studied. Our work shows that the sedimentary provenance of Arkansas sandstones started to change during the middle part of the Cretaceous. Notably, DZ grains from the Woodbine formation, which was deposited during the middle part of Cretaceous, show moderate contributions from Western Cordillera sources (275–55 Ma), and DZ grains from the Upper Cretaceous Nacatoch Formation exhibit dominant Western Cordillera sourcing. Our Arkansas-based DZ data suggest that the onset of DZ contribution of the Western Cordillera began at about 94 Ma, and the peak of the Western Cordillera source contribution occurred at about 73 Ma. Therefore, we can show that North American drainage reorganization with regard to Western Cordilleran DZ sourcing in Arkansas began during the time span 94–73 Ma, which is earlier than the previously reported onset of drainage reorganization with regard to Texas (i.e., 66–55 Ma). Full article

The prediction of structural fractures in concealed coal-bearing strata has always been a complex problem. The purpose of this study was to clarify the tectonic evolution of the study area, i.e., the Tucheng syncline, since the coal-forming period and to predict the development of structural fractures. The tectonic evolution of the study area was divided into three stages using regional tectonic analysis. The paleotectonic stress field of the study area was reconstructed through the field investigation, statistics, and analysis of joints. Based on the tectonic deformation analysis, numerical simulation was used to reveal the stress field characteristics of different tectonic deformation stages, and combined with the Mohr–Coulomb criterion, the degree of structural fracture development in the target layers (No.17^# coal seam) of the study area was predicted. This study concludes the following: (1) The study area underwent two tectonic deformations during the Yanshanian period, transitioning from an ellipsoidal columnar shape to a semi-ellipsoidal and stereotyped form, forming a superimposed short-axis syncline, and then tilting southeastward as a whole, and was locally cut by faults during the Himalayan period. (2) The distribution characteristics of the stress field in different tectonic stages vary. The stress concentration zones in the first and second stages have a more obvious symmetry, and the present-day stress concentration zone is located in the center of the syncline basin. (3) The superimposed rock fracture indices are larger in the edge zone parallel to the long axis of the syncline and at the bottom of the syncline, which also indicates a higher degree of structural fracture development at the corresponding locations. Full article

Landslides present remarkable hazards in the Himalayan region, particularly in areas with young and fragile topography. Mitigating vulnerability requires assessing susceptibility, which relies heavily on the accuracy of susceptibility maps generated through various approaches that consider different conditioning factors at various resolutions. This study, conducted in Jajarkot District within the Karnali Province of Nepal and covering 2230 km², aims to identify suitable conditioning factors at appropriate resolutions. Sixteen factors, encompassing topography, hydrology, geology, and anthropogenic activities, were analyzed alongside a landslide inventory of 159 occurrences compiled from satellite imagery, the literature, and field surveys. A genetic algorithm (GA) was employed to determine the optimal set of conditioning factors, while Maximum Entropy (Maxent) modeling produced landslide susceptibility maps (LSM) at spatial resolutions ranging between 12.5 and 200 m. Resolution selection was guided by Receiver Operating Characteristic (ROC) curve and Area Under the Curve (AUC) analyses. Multicollinearity testing identified 15 influential factors, with land use ranking highest at 22.7%, followed by stream power index (SPI), drainage density, and aspect. The GA consistently highlighted land use and slope as effective factors across subset sizes. The results indicated resolutions finer than one hundred meters enhanced discrimination between landslide and non-landslide areas, emphasizing the need to balance resolution with computational resources and data availability. This study emphasizes the intricate interplay of conditioning factors, the GA’s efficacy in subset selection, and the crucial role of resolution in the improvement of susceptibility models. The findings provide practical insights for policymakers and disaster management authorities, aiding evidence-based decision making in the mitigation of landslide risk in Jajarkot and similar regions. Full article

When rivers impinge on the steep bluffs of valley walls, dynamic changes stem from a combination of fluvial and mass wasting processes. This study identifies the geomorphic changes, drivers, and timing of a landslide adjacent to the Apalachicola River at Alum Bluff, the tallest natural geological exposure in Florida at ~40 m, comprising horizontal sediments of mixed lithology. We used hydrographic surveys from 1960 and 2010, two sets of LiDAR from 2007 and 2018, historical aerial, drone, and ground photography, and satellite imagery to interpret changes at this bluff and river bottom. Evidence of slope failure includes a recessed upper section with concave scarps and debris fans in the lower section with subaqueous features including two occlusions and a small island exposed from the channel bottom at lower water levels. Aerial photos and satellite images indicate that the failure occurred in at least two phases in early 2013 and 2015. The loss in volume in the 11-year interval, dominantly from the upper portion of the bluff, was ~72,750 m³ and was offset by gains of ~14,760 m³ at the lower portion of the bluff, suggesting that nearly 80% of the material traveled into the river, causing changes in riverbed morphology from the runout. Despite being along a cutbank and next to the scour pool of a large meandering river, this failure was not driven by floods and the associated lateral erosion, but instead by rainfall in noncohesive sediments at the upper portion of the bluff. This medium-magnitude landslide is now the second documented landslide in Florida. Full article

This study examines four shallow-water, reef-coral-bearing carbonate successions belonging to the Jhill Limestone Unit of the Gaj Formation, exposed in the area near Karachi (southern Pakistan). Sixty-two samples were collected for the quantitative analysis of the skeletal and foraminiferal assemblages. The analysis of large benthic foraminifera suggests a placement within the late Oligocene, characterized by the setup of the Late Oligocene Warming Event. Thanks to quantitative analyses and multivariate statistics, three biofacies were identified: (1) the reef coral biofacies (BFA), indicative of a sheltered, shallow-water environment above fair-weather wave base; (2) the coralline algal biofacies (BFB), deposited within a mesophotic setting and representing the deepest biofacies among the three recognized ones; and (3) the large benthic foraminiferal and coralline algal biofacies (BFC), subdivided into two sub-biofacies, namely (a) the miogypsinid, thin and flat large benthic foraminiferal and coralline algal sub-biofacies (BFC1), indicative of deeper setting, comprised between BFA and BFB, and (b) the miogypsinid and coralline algal sub-biofacies (BFC2), indicative of shallower settings than BFC1, and bearing evidence of paleo-seagrass meadows. All these biofacies were developed within the photic zone, in a relatively flat seafloor punctuated by patch reefs and seagrass meadows and characterized by a notable nutrient influx. Foraminiferal-based experimental paleobathymetric parameters, including the lepidocyclinids/miogypsinids, the flat nummulitids/lepidocyclinids, and the hyaline/porcelaneous foraminifera ratios, were tested and confirmed as reliable tools for paleodepth and paleoenvironmental reconstructions. Full article

Electrical Resistivity Tomography (ERT) is a widely used geophysical technique for imaging subsurface resistivity variations, providing critical insights for geological engineering and hazard assessment applications. While open-source inversion tools such as BERT and PyGIMLi offer accessible solutions for geoelectrical modeling, their comparative performance across different electrode configurations and noise conditions remains underexplored. This study evaluates the effectiveness of these software packages in reconstructing subsurface anomalies related to cavity detection and landslide assessment. Four commonly used electrode configurations—dipole–dipole, Schlumberger, Wenner-Alpha, and Wenner-Beta—were tested on two synthetic models designed to simulate real geological conditions: one representing cavity detection and the other simulating a landslide scenario. Inversions were conducted under both ideal conditions and with synthetic noise to assess their robustness against measurement uncertainties. Results indicate that while all configurations successfully identified major subsurface features, the dipole–dipole array provided the highest resolution for detecting small-scale anomalies. BERT demonstrated superior accuracy under ideal conditions, while PyGIMLi showed consistent performance across multiple configurations, particularly in resolving smaller features under noisy conditions. These findings emphasize the importance of selecting appropriate electrode configurations to enhance imaging accuracy and ensure reliable geo-electrical data interpretation. This study highlights the robustness of open-source geophysical software for subsurface investigations and provides practical insights into optimizing geoelectrical survey configurations for shallow hazard detection. Full article

Prediction of the intensity of earthquake-induced motions at the ground surface attracts extensive attention from the geoscience community due to the significant threat it poses to humans and the built environment. Several factors are involved, including earthquake magnitude, epicentral distance, and local soil conditions. The local site effects, such as resonance amplification, topographic focusing, and basin-edge interactions, can significantly influence the amplitude–frequency content and duration of the incoming seismic waves. They are commonly predicted using site effect proxies or applying more sophisticated analytical and numerical models with advanced constitutive stress–strain relationships. The seismic excitation in numerical simulations consists of a set of input ground motions compatible with the seismo-tectonic settings at the studied location and the probability of exceedance of a specific level of ground shaking over a given period. These motions are applied at the base of the considered soil profiles, and their vertical propagation is simulated using linear and nonlinear approaches in time or frequency domains. This paper provides a comprehensive literature review of the major input parameters for site response analyses, evaluates the efficiency of site response proxies, and discusses the significance of accurate modeling approaches for predicting bedrock motion amplification. The important dynamic soil parameters include shear-wave velocity, shear modulus reduction, and damping ratio curves, along with the selection and scaling of earthquake ground motions, the evaluation of site effects through site response proxies, and experimental and numerical analysis, all of which are described in this article. Full article

This study incorporates the comprehensively observed proxies of in situ geotechnical, geophysical, petrophysical, and lithological datasets to estimate groundwater presence. Two machine-learning approaches, random forest regression (RFR) and deep neural network (DNN), are applied. The constructed RFR and DNN models are validated using observed depths of groundwater levels at 772 K-NET sites in Japan. The RFR model exhibited effectiveness and robust performance compared to the poor-fitting performance of the DNN model and previous groundwater detection physical-based approaches. The RFR and DNN models yielded a remarkable 1:1 agreement between the observed and predicted groundwater levels at 733 and 470 K-NET sites, respectively. During the RFR training process, all datasets at the 772 K-NET sites were split into training, validating, and unseen testing datasets with the ratio set at 1:1:11. This k-fold cross-validation strategy demonstrates better-fitting performance for the RFR model. The contributions and interactions among the in situ observed proxies utilizing the variance-based global sensitivity analyses can be understood. The P-wave velocity and the standard penetration test values have exhibited prominent contributions among other proxies at groundwater depths. To apply the RFR model at any given site, reliable and detailed P- and S-wave velocity structures are crucial to building the needed source datasets. Full article

The geoheritage present on the “Tindari Cape and Marinello Lakes” site (TCML, Messina Province, NE Sicily, Italy) drew our attention due to the acquired contrasting information. Indeed, the TCML geoheritage was classified in the geosite national catalogue as a geosite (albeit under a non-evaluated status and with regional scientific interest), whereas it was classified in the geosite regional catalogue as a site of attention. The coastal geoheritage included in this site was analyzed by means of a literature review, field work, and a sedimentological and petrographic investigation. Moreover, the reconstruction of the historical to modern evolution of the lagoon and spit’s shapes was carried out across a time span of 85 years. The investigation results were used for the inventorying and quantitative assessment of the TCML geoheritage with the Brilha method. The primary and preeminent scientific interest was geomorphological, the lagoon and spit being an active geomorphosite. This system showed elements of rarity, representativeness, and exemplariness. Secondary-type geomorphological, structural, and palaeontological aspects were also evidenced in geological elements found on the cliffs of the Tindari Cape. For the quantitative assessment of the geodiversity, the scientific value (SV), potential educational use (PEU), potential touristic use (PTU), and degradation risk (DR) were evaluated. The obtained weighted scores were 320 (SV), 250 (PEU), 290 (PTU), and 285 (DR). The high SV suggested that the TCML, due to its geodiversity, could be classified as a geosite. Notwithstanding, the moderate PEU, PTU, and DR (fragility and vulnerability depending on natural climate and anthropogenic factors) values indicated that it was not fully compatible with educational and touristic purposes. The results of the inventorying and quantitative assessment of the TCML site provide scientific data that are useful in establishing the TCML as a global geosite, placing it in the national catalog of geosites. Full article