Abstract: Conventional drilling and coring methods are inherently limited to providing one-dimensional geological data, which hinders accurate characterization of the spatial distribution of rock mass structures and properties. Mechanical disturbances during drilling often cause core breakage, further compromising the fidelity of in-situ geological representation. This study proposes an integrated approach combining borehole optical imaging and ground-penetrating radar (GPR) for enhanced characterization of rock mass structures. A dynamic exploration methodology is introduced, defined as an adaptive drilling layout workflow based on phased information feedback. The fundamental concept, key assumptions, boundary conditions, and field implementation procedures of this dynamic survey are systematically described. The integrated method was applied to a high-speed railway investigation project in the Tengzhou section, Shandong Province, China, where six boreholes were surveyed using both techniques. Results demonstrate that fused analysis of borehole optical images and GPR data effectively reveals rock morphology, fracture distribution, joint systems, fractured zones, and geological features such as rock veins. The method's complementary strengths—optical imaging providing high-resolution orientation data at the borehole wall and GPR extending detection radially into the surrounding rock mass—enable spatially enhanced characterization while partially mitigating the azimuthal ambiguity inherent in single-borehole radar measurements. A triangular borehole survey scheme is shown to be feasible for locating subsurface anomalies. The proposed dynamic exploration method effectively reduces borehole requirements compared to conventional grid layouts while successfully identifying common anomalous features through integrated analysis of optical imaging and GPR data. The method demonstrates practical applicability for detecting fractures with apertures greater than 1 cm and meter-scale cavities, with good consistency between the two techniques validating the feasibility of this integrated approach. The method's limitations, including resolution constraints and detection omission risks, are explicitly acknowledged, and risk control strategies are proposed. Overall, the dynamic exploration approach reduces investigation costs, accelerates project time-lines, and provides a practical framework for spatial characterization of rock mass discontinuities with minimal borehole requirements.

Abstract: Underground water flow in karst areas and changing water levels due to extreme rain can lead to creation of caverns and sinkhole hazard. Such is the historical experience of the Valaská village in central Slovakia. To better understand the current sinkhole threat in the village, we aim at detecting shallow caverns using microgravimetry. Our broader objective is to examine the capabilities of the Growth inversion methodology to detect and characterize shallow cave space. In our study we focus on the benefits and weak points of the Growth inversion approach, which is a free-geometry inversion method based on model exploration and growing source bodies. Since a sole gravimetric inversion produces ambiguous results, we pay attention to the role and setup of the several free user-adjustable inversion parameters of Growth. We examine tuning these parameters for specific needs of shallow cavities detection. Valaská experienced sinkholes in 1964, 1968 and 2019. That of 1964 is known for a curious loss of a horse sunk into a karst chimney. Our gravimetric work shows that the sinkhole hazard at the exposed lot in Valaská is ongoing despite the taken mitigation construction measures. The Growth approach proved to be applicable and useful in microgravimetric identification of sinkhole threat and detection of shallow caverns in karst.

Abstract: This paper presents an outline of a historical stone: the Marble of Campiglia, from Tuscany (Italy). A comprehensive review of the literature and archival documents, combined with a new detailed field survey, allowed us to revise the geological setting and exploitation history of this cultural heritage marble, which has been sporadically used since Etruscan times up to the present day. The Campiglia Marittima Marble (CMM) has a thermal-metamorphic origin related to the intrusion of a granitic pluton dated at about 5.4 Ma. This gave rise to a marble with peculiar textural, grain-size, and fracturing features that influenced the cultivation approaches and methods. The main exploitation periods of the CMM as an ornamental stone were the Etruscan-Roman age, the Renaissance, and the nineteenth century; currently, it is used only for industrial purposes. A great number of ancient quarries are located on the western slope of Monte Rombolo, probably due to the high variety of commercial marble types that can be found in the area and to its strategic position with an easy transport way to the Tyrrhenian Sea. This research is aimed to recall to the memory this historical marble and can also support the possible reopening of a few quarries for conservation purposes, for ensuring the Authenticity of the historical artefacts in which it was used.

Abstract: Porphyry copper deposits are strategic resources characterized by complex mineralization and high spatial non-stationarity. Traditional linear estimation methods like Ordinary Kriging often fail due to "smoothing effects" and a reliance on manual partitioning. This study proposes the GDF-ML framework, which integrates Geological Distance Fields (GDF) with machine learning to achieve high-fidelity grade modeling. By utilizing cKDTree for efficient spatial indexing, absolute coordinates are translated into Signed Distance Fields (SDF), creating "Spatial Fingerprints" that encode topological relationships between samples and geological entities. Results demonstrate that GDF-ML significantly outperforms Ordinary Kriging, increasing the R2 score from 0.3080 to 0.7696 on an independent test set while accurately reproducing the "barren core" and irregular high-grade zones. Furthermore, SHAP analysis validates the model's decision-making logic, aligning "intra-domain gain" effects with established metallogenic theories. This framework provides a scalable, automated methodology for dynamic resource evaluation, eliminating the inefficiencies of traditional workflows and supporting the digital evolution of modern smart mines.

Abstract: The Devene fault system, a major strike-slip structure at the boundary between the Balkan Range and the Moesian Platform in NW Bulgaria, remains a subject of debate regarding its Quaternary activity. This study investigates the shallow expression of the fault at two representative sites, Tri Kladentsi and Beli Breg, using high-resolution electrical resistivity profiling to differentiate tectonic deformation from climatically driven landscape evolution. At Tri Kladentsi, resistivity profiles confirm a steeply dipping structural boundary within the Miocene bedrock, juxtaposing limestone against sands. The overlying 25 m thick loess cover, however, remains sub-horizontal and undisturbed. Likewise, at Beli Breg, the complex architecture of stacked channel sequences and tributary deposits at the Ogosta River confluence reveals no identifiable fault displacement. Our results suggest a high degree of morphological mimicry, where asymmetric river valleys produced by selective erosion and differential loess accumulation superficially converge with tectonic signatures. The long-term left-lateral slip rate is estimated at 0.14–0.19 mm/yr based on a 20 km Miocene offset. Nevertheless, the lack of modern surface rupture indicates a deceleration of fault slip rate and a transition to a buried fault top during the Quaternary. These findings necessitate a re-evaluation of regional seismic hazard assessments, because the absence of continuous surface traces physically constrains the maximum earthquake potential.

Abstract:

The tectonic framework of the 2019 Mirpur seismic sequence was investigated using local seismic data. Moment tensor inversion was performed for the Mirpur mainshock (Mw=5.8) and its largest aftershock (Mw=4.7). The mainshock exhibited a low dip angle (~10°) and shallow focal depth, suggesting association with the Main Frontal Thrust (MFT). Contrary, the largest aftershock showed a comparatively higher dip angle, indicating deformation along a ramp or ramp-anticline structure. The stress regime was evaluated using moment tensor solutions from two locally inverted events, two Global CMT solutions and a published focal mechanism. The results indicated a maximum horizontal stress (SHmax) orientation of N07°E, consistent with the stress orientation of the 2005 Kashmir earthquake sequence and the regional compression driven by the Indian plate convergence. Aftershock relocation and spatial distribution patterns suggested post-seismic stress relaxation and possible activation of a higher-dip fault segment or ramp-anticline structure. Although a seismogenic depth of approximately 15 km was estimated, the concentration of seismicity around 10 km depth may involve the Main Himalayan Thrust (MHT). The Mirpur mainshock was triggered primarily by the movement along the MFT, whereas the subsequent aftershocks reflected post-seismic relaxation associated with the MHT and related ramp-anticline structures.

Abstract: A method for analyzing long-term (1997-2025) continuous records of low-frequency global seismic noise measured at a network of 229 broadband seismic stations distributed across the Earth's surface is proposed. The method is based on the use of nonlinear multifractal and entropy statistics, evaluated daily in successive time intervals. The method is based on the use of first-principal component analysis, correlation analysis, and parametric models of point process intensity. The relationships between changes in seismic noise properties and the response of noise properties to the irregularity of the Earth's rotation with the sequence of strong earthquakes, including those of a predictive nature, are investigated.

Abstract: Organic facies distribution exerts a primary control on hydrocarbon generation potential in clastic-dominated passive margin basins. This study evaluates the spatial and stratigraphic distribution of organic facies and their hydrocarbon potential in the Niger Delta Basin using an extensive organic geochemical dataset. A total of 715 source rock samples from onshore, shallow offshore, and deepwater wells were analyzed using total organic carbon (TOC) and Rock-Eval pyrolysis parameters (S1, S2, S3, HI, OI, Tmax). Organic facies were classified following the Pepper organofacies scheme to assess variations in organic matter type, richness, and generative potential across depositional settings and depobelts. The results show that source rocks of the Akata Formation are dominated by organofacies B and D/E, reflecting mixed marine and terrigenous organic matter with moderate to high hydrogen indices and predominantly oil-prone to mixed oil–gas generative potential. In contrast, source rocks of the Agbada Formation are characterized mainly by organofacies F, dominated by terrestrial organic matter with low hydrogen indices, indicating a gas-prone character. Cretaceous shales beneath the Niger Delta contain mixed organofacies D/E and F and locally exhibit fair to good hydrocarbon potential. TOC values range from 0.1 to 16.9 wt%, with the highest organic richness concentrated within the Akata Formation at depths of approximately 2800–4000 m. Spatial variations in organic facies distribution across depobelts reflect changes in depositional environment, sedimentation rate, and preservation conditions. These results confirm the Akata Formation as the principal effective oil-prone source rock in the Niger Delta Basin and provide important constraints for petroleum system analysis and deepwater exploration risk reduction.

Abstract:

The Dongchuan District of Kunming City lies in the transition zone between the Yunnan-Guizhou Plateau and the Sichuan Basin, hosting numerous landslides that pose a serious threat to local lives and property. Therefore, compiling a comprehensive landslide inventory and analyzing the relationships between landslide spatial distribution and influencing factors are of significant importance for geological hazard prevention. This study focuses on the Dongchuan District. High-resolution remote sensing imagery was interpreted to establish a landslide inventory, and the spatial distribution and geometric characteristics of landslides were systematically analyzed. The results show that a total of 1,623 landslides were identified, covering an area of 10.36 km². Landslides predominantly occur at elevations of 1,000-2,000 m, on slopes of 20°-45°, with aspects of 255°-285°, relief between 150-400 m, annual rainfall below 825 mm, and within a distances of 1,000 m from rivers and 3,000 m from faults. Four landslide clusters were delineated along the Xiao River Fault, highlight the significant influence of the fault on the spatial distribution of landslides. Most landslides are longitudinal in planform, with travel distances (L) of 50-450 m and heights (H) from 25 to 350 m, exhibiting allometric relationships between these parameters and volume. The mean H/L ratio is 0.56 (corresponding to a mean reach angle of 29°), significantly higher than that observed in Baoshan City (mean reach angle of 21°). The results would be helpful for further understanding landslide initiation mechanisms and spatial distribution patterns on the northern margin of the Yunnan-Guizhou Plateau and providing valuable data support for subsequent landslide hazard risk assessment in this region.

Abstract: Since September 2021, numerous seismic events with spectral peak below 1 Hz occurred on the island of Vulcano, Italy, 131 years after its last eruption. The local monitoring network recorded microseismicity mostly in the form of months-long swarms, concurrent with anomalous values of other geophysical and geochemical parameters. By applying a machine learning technique (Self-Organizing Maps, SOM), we obtained an inventory of ~6600 seismic signals, identifying distinct families of events. These families were located below La Fossa Crater (where the last eruption of the volcano happened) from the surface to a depth of 2.2 km b.s.l. Based on the seismic signature and source location of these events, we hypothesize unsealed/sealed processes through a network of shallow fractures favored by fluid pressure. After the return to background values of geochemical and geophysical parameters in 2023, a resumption of microseismicity occurred between May and June 2024. A test application of the SOM to the new data confirmed the non-destructive source of the new recorded signals, which shared families, location, and depths as our previous inventory. This test showcased that SOM can be an effective tool to support monitoring and warning of future unrest at Vulcano.

Abstract: The Noto Peninsula is a seismically active region where spatial patterns and shallow seismic zones play a critical role in understanding earthquake behavior. While visualization techniques for seismicity have advanced, their effective application still requires practical experience and region-specific interpretation, as earthquake susceptibility varies spatially. In this study, we analyze earthquake catalogues and mesh-based magnitude parameters for events occurring between 2023 and 2024 to investigate seismic anomalies in the region. Temporal variations in the magnitude locator and scale, combined with spatial patterns of shallow seismicity, reveal anomalous behavior in the offshore area west of Noto. This area is characterized by persistently elevated locator values and locally reduced scale—features that resemble precursory patterns observed in volcanic settings. The seismic sequences of 5 May 2023 (M6.5) and 1 January 2024 (M7.6) illustrate how such combined signals may precede large events, while also highlighting how aftershock decay and resurgence complicate post-event energy assessments. These findings suggest the possible influence of submarine volcanic or volcano-related structures, as well as ongoing orogenic deformation. The results support the need for continued, targeted monitoring of epicentral activity in this region and may offer insights applicable to other tectonically complex areas.

Abstract: Submarine gas emissions represent a key expression of fluid migration processes in volcanic and hydrothermal marine environments and provide valuable analogues for monitoring strategies relevant to sub-seabed carbon storage. This study investigates the feasibility of using marine Distributed Acoustic Sensing (DAS) to detect natural CO₂ bubble emissions in a shallow-water setting offshore Panarea (Aeolian Islands, Italy). A 1.1 km armored fiber-optic cable was deployed on the seabed and interrogated using two different DAS systems to acquire continuous passive acoustic data. The DAS recordings were complemented by controlled gas releases from scuba tanks to provide reference signals, as well as by independent high-resolution boomer seismic survey and side-scan sonar imaging to characterize the shallow subsurface and seabed morphology. The results show that DAS is sensitive to acoustic signals associated with both artificial and natural bubble emissions, despite the complex acoustic conditions typical of shallow marine environments. The integration of passive DAS monitoring with independent geophysical observations provides a robust framework for interpreting gas-related signals and seabed processes. These findings demonstrate that marine DAS represents a promising geophysical tool for monitoring of submarine volcanic–hydrothermal systems and offers important insights for the development of sub-seabed CO₂ leakage detection in offshore CCS contexts.

Abstract: This article addresses the limitations of traditional petrophysical interpretation and lithofacies analysis methods used in commercial software solutions, such as sub-jectivity, insufficient detail, and reliability, particularly in cases of complex reservoir structures. Accordingly, the development of automated lithofacies analysis tools using Artificial Intelligence (AI) and Machine Learning (ML) is a relevant objective for en-hancing the reliability of geological modeling and reservoir evaluation. The authors have developed an innovative methodological approach for auto-mated lithofacies classification of well logging data, demonstrated via case study of Gran Field. The methodology is centered on the k-means unsupervised clustering al-gorithm, specifically adapted for comprehensive petrophysical data analysis. It is demonstrated that the proposed approach effectively partitions the geological section into lithofacies and ensures the reliability of petrophysical interpretation re-sults. The optimal number of clusters (k=3) was determined using the Silhouette Coef-ficient, and the results were visualized using the Principal Component Analysis (PCA) method, confirming that the identified groups correspond to petrophysical patterns. The clustering results, incorporating PCA, showed clear separation into clay, silt-stone, and sandstone lithofacies. The k-means-based approach mitigates the primary limitations of traditional methods reliant on the subjective selection of cut-off values and forms a reliable foundation for building advanced geological and hydrodynamic models. To facilitate practical application, a Python-based web interface was developed using the Streamlit framework. This application offers a user-friendly interface for preprocessing well-log data, performing clustering, and visualizing results, bridging the gap between advanced ML algorithms and specialists without programming ex-pertise. Comparative analysis reveals that the k-means algorithm outperforms alternative methods across several key metrics, notably in interpretability and the structural co-herence of the results. Future development prospects include the integration of densi-ty-based clustering algorithms, such as DBSCAN, to increase the system's adaptability in complex geological sections. This will open new possibilities for intelligent analyti-cal systems in the field of reservoir evaluation and resource assessment.

Abstract: The Santorini volcano, Greece, attracts global scientific interest and constitutes a top tourist destination. The 17th century BCE eruption, known as the Minoan event, was likely the largest ever occurred in the Holocene. The evaluation of an enriched collection of documentary sources combined with scientific observations showed that during historical times 14 small-to-moderate eruptive episodes were reported from the 2nd century BCE up to 1950 CE. Among them two little-known episodes occurring in 1667 CE and 1773 CE were uncovered and analyzed based on European documentary sources. For the first time a reliability score has been assigned to each one of the 14 episodes. The completeness of the recorded eruption history after the 14th century CE looks like ten times higher than in the previous period but it remains unclear whether this reflects real eruption rate or reporting incompleteness. The eruptions occurring after the 17th century CE are characterized by lower size, in terms of Volcanic Explosivity Index (VEI), than in the previous period. However, this may be due to the incomplete record of earlier eruptions of low VEI magnitude.

Abstract: Highly deviated wells commonly exhibit large errors in horizon calibration because the logging path follows an inclined borehole trajectory, whereas post-stack seismic processing effectively treats wave propagation as vertical. This mismatch has received limited attention. Here we performed horizon calibration and velocity-model building for drilled highly deviated wells in the Mahu Sag, Junggar Basin, and obtained three key findings. First, the assumed vertical travel path in post-stack data is the primary cause of the initial mis-tie for highly deviated wells. Second, calibration in the deviated interval requires a strategy distinct from that of vertical wells and may +involve substantial stretching or squeezing of the original logs to achieve a consistent time–depth relationship. Third, the map-view projection of a highly deviated well is essentially linear; relative to vertical wells, it provides denser in-situ velocity constraints and, with pseudo-well control, supplies 2D velocity information along the well-trajectory plane, thereby improving velocity-field modeling. Validation against drilling data showed that this workflow improved well ties and refined the velocity model, providing practical guidance for geological well planning and reducing drilling risk.

Abstract: In the field of geophysics, several erroneous theories were long accepted as fundamental laws and formulas. Recent corrections to these misconceptions have been made possible through the application of Exploratory Data Analysis (EDA). This article outlines how EDA contributed to these breakthroughs and provides a brief guide for those interested in adopting this approach. In addition, while introducing new data analysis methods based on EDA, I will also discuss the remaining challenges that warrant further clarification.

Abstract: By visualising seismic data in three dimensions, it becomes evident that hypocentres cluster along boundaries formed by colliding plates. These boundaries appear to be solid structures, established years before the mainshock, and remain largely stationary even after the event concludes. Major earthquakes tend to occur along such surfaces, and because seismic activity increases in these regions prior to a mainshock, their observation may provide a basis for earthquake prediction. With plate positions near Japan now more clearly defined, existing models require revision. Furthermore, analysis reveals that both the number of aftershocks and the seismic energy released during a mainshock decay with distinct half-lives. This represents a fundamentally different decay pattern from the formula long regarded as correct. Employing modern statistical methods therefore yields more accurate insights, essential both for advancing our understanding of earthquake mechanisms and for improving predictive capability.

Abstract: Submarine canyon-channel system plays a critical role as potential conduit for warm water upwelling in Antarctica, thereby influencing ice sheet stability. In this study, we identify 29 canyon-channel systems along the Adélie Land margin and conduct sys-tematic morphometric analysis of their length, width, depth, width-to-depth (W/D) ratio, and sinuosity. The results reveal pronounced differences in the distribution and morphological evolution of canyon–channel systems between the Adélie Depression and the Adélie Bank. We propose that these differences are primarily controlled by the shelf-slope topography, sediment supply, and ice sheet dynamic process. As the main catchment area of the Wilkes Subglacial Basin (WSB), the Adélie Depression is fed by a focused, high-flux supply of glacial debris, leading to the development of large-scale progradation wedges and mass transport deposits. These conditions promote the formation of extensive canyon–channel systems with elongated, tortuous, and dendritic morphologies. In contrast, canyon–channel systems on the Adélie Bank are smaller, more isolated, and irregularly distributed, reflecting dispersed and episodic sediment supply combined with strong bottom-current reworking. This study eluci-dates how canyon-channel system morphology responds to the topography, sedi-mentation, and ice dynamics in high-latitude glaciated margins, providing important constraints on sediment transport pathways and ice-sheet–ocean interactions in Antarctica.

Abstract: The article examines the behavior of seismic noise fields over the Japanese islands recorded by the F-net seismic network for 1997-2025. The paper uses nonlinear noise statistics: the entropy of the wavelet coefficient distribution, the Donoho-Johnston (DJ) wavelet index, and the multifractal singularity spectrum support width. These parameters were chosen because their changes reflect the complication or simplification of the noise structure. Changes in the structure of seismic noise properties are analyzed in comparison with a sequence of strong earthquakes. Using a model of the intensity of interacting point processes, the effect of the leading of local noise property extrema relative to the seismic event times is estimated. Using the Hilbert-Huang decomposition, the synchronization of the amplitudes of the envelopes of noise property time series for different IMF levels is estimated. A sequence of weighted probability density maps of extreme values of noise properties is analyzed in comparison with the mega-earthquake of March 11, 2011 and the preparation of a possible next strong seismic event.

Abstract: Marine controlled source electromagnetic (CSEM) surveys have been proven to be an effective tool in hydrocarbon exploration, principally due to the method’s ability (in the right circumstances) to identify electrical resistivity contrasts between hydrocarbon-saturated and brine-saturated sedimentary units. However the sensitivity of such surveys decreases in shallow water, for deeper targets, and for targets with limited horizontal extent. In principle, the resolution and sensitivity of a survey can be improved by moving either the transmitting or the receiving dipoles into the sub-surface. We have therefore investigated the sensitivity of Seafloor to Borehole CSEM (sbCSEM) survey geometries, specifically for the case of targets with small lateral dimensions in shallow water areas – including targets whose depth of burial substantially exceeds their lateral extent. The results are encouraging. Neither small target size nor shallow water present obstacles in principle to the use of this approach. Our models reveal distinct lobes in the patterns of electric field and current density amplitudes around a sub-seafloor transmitting dipole. The shape, positions and amplitudes of these lobes are all strongly modified by the presence of one or more small resistive targets, and in particular are strongly influenced by the positions of target edges. These effects significantly modify the pattern of electric fields at the seafloor, and hence result in good sensitivity for realistic survey geometries. Small targets can be detected by seafloor receivers when the sub-seafloor transmitting dipole is located at some distance laterally outside the targets - leading to potential applications in ‘step-out’ prospecting. The asymmetry of responses at the seafloor from targets that are offset with respect to transmitter location has potential applications in field appraisal; while monitoring of reservoirs during production provides another possible application. Varying the depth of the transmitter down the borehole generates a Vertical EM Profiling (VEMP) survey – analogous to Vertical Seismic Profiling (VSP) – and we demonstrate that this too can have useful applications. Modelling for deeper (3 km sub-seafloor) targets continues to yield encouraging results, and suggests that step-out sbCSEM may be effective at depths beyond the detection limit of conventional seafloor-seafloor CSEM.