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Each nuclear weapon test contributes to a global burden of released radioactivity. Between 1945 and 1996, more than 2,000 nuclear tests were conducted, three-quarters of which were underground. Underground nuclear tests involved placing the nuclear device in a cavity drilled or excavated beneath the surface. The goal was to contain the explosion and its effects to the immediate vicinity of the detonation point, ultimately minimizing the release of radioactive materials into the atmosphere. While these tests successfully curtailed the atmospheric release and radioactive fallout, they created dynamic responses within crustal formations caused by local shock waves from the explosion. This paper discusses the legacy of underground nuclear testing, addressing issues from containment failure to the phenomenological effects after underground detonations and the pathways of subsequent dispersal of radionuclides to the environment. [ABSTRACT FROM AUTHOR]

Converting surplus renewable energy into hydrogen is considered an efficient technique to balance renewable energy generation and demand, which necessitates large-scale underground hydrogen storage (UHS) in geological formations. While the H 2 trapping mechanisms and fluid flow behavior have been rigorously reported in past studies, the performance of UHS is strongly influenced by the formation conditions and well configurations, which have not been explored thoroughly. To this end, this study investigated the sensitivity of UHS efficiency to variations in formation temperature, brine salinity, well placement, and well perforations. For each scenario, key aspects such as plume migration dynamics, residual trapping, dissolution trapping, structural trapping, H 2 recovery factor, and water production were thoroughly analyzed. The results indicate that factors such as formation temperature, brine salinity, and well perforations have a negligible impact on the shape of the overall H 2 plume. However, these significantly influence local H 2 saturations. Formations with higher temperatures, central dome well placement, and production wells in the top layers exhibit a higher H 2 recovery factor (as high as 69.93 %), whereas salinity plays a minor role in H 2 trapping and withdrawal (maximum change observed is ∼1.7 % and ∼1.4 % for trapping and withdrawal respectively with a 20 wt % increase in salinity). In addition, brine production is strongly influenced by the formation conditions and well configurations (e.g., ∼3965 m3 brine produced under at 343 K and ∼26,000 m3 for non-central well placement), due to variations in H 2 /brine properties, such as density and viscosity, and the extent of H 2 accumulation. [Display omitted] • Higher temperature reduces residual trapping and enhances the H 2 recovery factor. • Higher salinity observes a decrease in brine production. • Well placement strongly influences plume migration behaviors. • Well placement away from the central dome increases brine production. • Wells produced at the bottom layers demonstrate the highest percentage of mobile H 2. [ABSTRACT FROM AUTHOR]

Over the past three decades, Sri Lanka has observed a substantial rise in landslide occurrences linked to intensified rainfall. However, the lack of comprehensive landslide inventories has hampered the development of effective risk analysis and simulation systems, requiring Sri Lanka to rely heavily on foreign-developed models, despite the difficulty of fully examining the similarities between the characteristics of landslides in Sri Lanka and the areas where the model has been developed. Satellite images have become readily available in recent years and have provided information about the Earth's surface conditions over the past few decades. Thus, this study verifies the utility of satellite images as a cost-effective remote-sensing method to clarify the commonalities and differences in the characteristics of landslides in two regions Ikawa, Japan, and Sabaragamuwa, Sri Lanka, which exhibit different geological formations despite similar annual rainfall. Using Google Earth satellite images from 2013 to 2023, we evaluated land-slide density, types, and geometry. The findings reveal that Ikawa exhibits a higher landslide density and experiences multiple-type landslides. In contrast, both areas have similar initiation areas; however, Sabaragamuwa predominantly experiences single landslides that are widespread and mobile. The findings also reveal that various characteristics of landslides are mainly influenced by varied topography. Here, we confirmed that even in areas where comprehensive information on landslides is conventionally lacking, we can understand the characteristics of landslides by comparing landslide geometry between sites using satellite imagery. [ABSTRACT FROM AUTHOR]

A total of 66,894 landslides were observed in North Dakota. The characteristics of these landslide locations were compared with the properties of areas without landslides to assess the factors that may be contributing to the landslides. Specifically, 68,395 control point locations randomly distributed across the state were selected for these comparisons. All the landslides for this study were found in areas with slopes less than 64°, with the majority of the failures occurring on slopes with inclinations between 9° and 14°. The largest fraction of the landslides occurred in the Sentinel Butte Formation (34,063 or 51% of the total), followed by Bullion Creek (8695 or 13% of the total) and river sediment of the Oahe Formation (6421 or 9.6% of the total). In the t tests, all of the surficial geologic formations had statistically significant differences between the landslides and control points. The t test for the slope inclination indicated statistically significant differences with a p-value less than 0.001 and a huge effect size between the landslide and control points. The sodium adsorption ratio and total dissolved solids were also found to be statistically significant from the t test results. Pearson's correlation matrix showed a negative correlation between the amount of rainfall and various measures of the salt concentrations at the landslide locations, pointing to the reductions in shear strength and slope stability that might result as pore fluid salinity is leached. [ABSTRACT FROM AUTHOR]

Here, the prediction of friction characteristics for pipe jacking drives during soil traversing has been explored. This work is done in the context of no great understanding of how drivers negotiate highly weathered rock formations. Based on a series of jacking force prediction models, including the Staheli model, Pellet-Beaucour and Kastner models (PK-O models) and proposed modified Pellet-Beaucour and Kastner models (PK-M models), direct shear tests are performed on initial-contacted specimens to obtain the friction coefficient μavg using back-analysis. The evaluation of the reliability of the parameter μavg and the modified vertical pressure σv is carried out through a three-dimensional finite element in ADINA in combination with the "wished-in place" method (WPM). The shear stress of the pipe–rock interface and the compressive stress of the end area are obtained by numerical analysis and in good agreement with the measured jacking force predicted by the proposed PK-M-1 model, indicating the correctness and necessity of considering the degree of the arching effect when modeling strong weathering rock masses. According to these results, the friction coefficient μavg of back-analysis can be used as a reliable input parameter for the finite-element modeling of pipe-jacking force in highly weathered geological formations. Highlights: The modified Pellet-Beaucour and Kastner models (PK-M models) have been established. A modified simulation method for rock pipe jacking in highly weathered rocks has been studied in ADINA. The correctness and superiority of the PK-M models have been discussed and verified. [ABSTRACT FROM AUTHOR]

Geological hazards in Xinxian County, Xinyang City, Henan Province, are characterized by their small scale, wide distribution, and significant influence from regional tectonics. This study focuses on collapses and landslide hazards within the area, selecting twelve evaluation factors: aspect, slope shape, normalized difference vegetation index (NDVI), topographic relief, distance from geological structure, slope, distance from roads, land use cover type, area of land change (2012–2022), average annual rainfall (2012–2022), and river network density. Utilizing data from historical disaster sites across the region, the information quantity method and hierarchical analysis method are employed to ascertain the information quantity and weight of each factor. Subsequently, a random forest model is applied to perform susceptibility zoning of geological hazards in Xinxian County and to examine the characteristics of these geological disasters. The results show that in the study area, the primary factors influencing the development of geohazards are the distance from roads, rock groups, and distance from geological structure areas. A comparison of the susceptibility results obtained through two methods, the analytic hierarchy process information quantity method and the random forests model, reveals that the former exhibits a higher accuracy. This model categorizes the geohazard susceptibility in the study area into four levels: low, medium, high, and very high. Notably, the areas of very high and high susceptibility together cover 559.17 km2, constituting 35.99% of the study area's total area, and encompass 57 disaster sites, which represent 72.15% of all disaster sites. Geological hazards in Xinxian County frequently manifest on steep canyon inclines, along the curved and concave banks of mountain rivers, within watershed regions, on gully inclines, atop steep cliffs, and on artificially created slopes, among other sites. Areas with very high and high vulnerability to these hazards are mainly concentrated near the county's geological formations. The gneiss formations are widely exposed in Xinxian County, and the gneisses' strength is significantly changed under weathering, which makes the properties of the different degrees of weathering of the rock and soil bodies play a decisive role in the stability of the slopes. This paper provides a basis for evaluating and preventing geologic hazards in the Dabie mountainous area of the South Henan Province, and the spatial planning of the national territory. [ABSTRACT FROM AUTHOR]

Carbon capture and storage technologies play a crucial role in mitigating climate change by capturing and storing carbon dioxide emissions underground. Saline aquifers, among other geological formations, hold promise for long-term CO2 storage. However, accurately assessing their storage capacity and CO2 behavior underground necessitates advanced numerical simulation and modeling techniques. In this study, we introduce an approach based on a solubility thermodynamic model that leverages cubic equations of state offline from the simulator. This approach enables the precise prediction of CO2–brine equilibrium properties and facilitates the conversion of compositional data into black oil PVT data suitable for black oil simulations. By incorporating industry-scale saline aquifer properties, we simulate a carbon storage scheme using the black oil model technique, significantly reducing computation time by at least four times while preserving the essential physical phenomena observed in underground carbon storage operations. A comparative analysis between black oil and compositional simulations reveals consistent results for reservoir pressure, CO2 saturation distributions, and mass fraction of trapping mechanisms, with differences of less than 4%. This validation underscores the reliability and efficiency of integrating the black oil model technique into carbon storage simulations in saline aquifer formations, offering tangible benefits to industry operators and regulators by striking a balance between accuracy and efficiency. The capability of this approach to extend to temperatures of up to 300 °C and pressures of up to 600 bars broadens its applicability beyond conventional CCS applications, serving as a valuable tool for optimizing decision-making processes in CCS projects, particularly in scenarios where profitability may be marginal. [ABSTRACT FROM AUTHOR]

The growth of the geothermal industry demands the constant search of techniques with the aim of reducing exploration efforts whilst minimizing subsurface uncertainty. The exploration of geothermal resources is fundamental from the exploitation point of view, especially in those regions where this energy is not as widespread as the rest of renewable sources. This research shows how geoelectrical methods can contribute to the investigation and characterization of medium–low enthalpy geothermal resources until about 800 m of depth. A 2000 m long electrical-resistivity tomography profile was performed in a region of Southern Spain with previous evidence of moderate geothermal potential. Results of this geophysical campaign (together with a preliminary geological characterization) allowed for the obtainment of a 2D profile and a pseudo-3D model with extensive information about the subsoil in terms of geological composition and formations. The interpretation of geophysical results denotes the existence of a potential formation constituted by carbonate materials with thickness greater than 300 m, crossing different fractures. Once the ideal location for the geothermal exploitation is defined, the research evaluates the contribution of the possible energy source, deducing that the energy extraction in the potential fracturing area would be double that of the one in the vicinity of the site. [ABSTRACT FROM AUTHOR]

• Mapping lithounits of Nidar ophiolites using high-resolution multi-spectral data. • First time characterization of Nidar ophiolites using hyperspectral (PRISMA data) • ML based classification of Nidar Ophiolite & associated rock exposures. • Spectral characterisation of lithounits of Ophiolites and validation from field. Ophiolites represent s a distinctive variety of igneous rock that comprises fragments of oceanic crust with the underlying mantle portion. Their mineral assemblages and distribution relation, both spatial and temporal are in close association with the complex mantle dynamics of the Earth. Nidar ophiolite complex located towards SE of Ladakh is one of such ophiolite assemblages exposed well in the Indus Suture Zone of Himalayas. It represents parts of Neo-Tethys ocean that existed during Mesozoic-Cenozoic period between continental plates of India and Eurasia. The earlier studies for Indian ophiolites are mostly field and analytical based with a limited work carried out using remote sensing techniques and that adds scope to apply this approach for further exploration of ophiolites. Advanced tools and techniques especially, hyperspectral remote sensing and machine learning based approach can be effective operational tools for exploration of ophiolites that provide assessable terrains for characterization of Earth's mantle, serve analogs for planetary crustal rocks and also have economic significance. This study has utilized high-resolution multispectral (Landsat OLI and ASTER) and hyperspectral data from various missions including the recent PRISMA mission which has provided the first hyperspectral datasets for lithological mapping of Nidar ophiolite section. The multiple high-resolution datasets were used for identification and mapping of the various lithounits of the Nidar ophiolites together with the underlying and overlying associated rocks based on band ratioing, derived spectral compositional indices and spectral characterization. The differentiated lithounits of the Nidar ophiolites are interpreted based on spectral response of lithological units in different bands. In addition, classification based on machine learning techniques have been applied to the PRISMA data to generate a detailed classification map of the study area where the various lithological units of the ophiolites and associated rock exposures belonging to various geological formations are clearly discernible. The results have been validated from geological field visit to the study area and spectral analysis of the field samples. [ABSTRACT FROM AUTHOR]

This study evaluated the public health risks of radon (222Rn) in groundwater of Neyyar River Basin (NRB), southwest India. Among the 68 samples, 222Rn activity ranged from 0.25 to 61.7 Bq/L. Most geological formations, excluding charnockite, exhibited localized radon anomalies (> 11.1 Bq/L). Infants were the most radio-vulnerable age group and probabilistic health risk using Monte Carlo Simulation ranked infants (63.42%) > children (59.31%) > adults (58.57%) in the worst-case scenario. The integration of dose estimation, geospatial risk mapping, and Monte Carlo analysis presents an efficient approach for comprehensively evaluating the health risks associated with radon in groundwater. [ABSTRACT FROM AUTHOR]

The Guxiang–Tongmai segment of the Jiali fault is situated northeast of the Namche Barwa Syntaxis in northeastern Tibet. It is one of the most active strike‐slip faults near the syntaxis and plays a pivotal role in the examination of seismic activity within the eastern Himalayan Syntaxis. New study in the research region has yielded a 1:200000 gravity dataset covering an area 1500 km2. Using wavelet transform multiscale decomposition, scratch analysis techniques, and 3D gravity inversion methods, gravity anomalies, fault distributions, and density structures were determined across various scales. Through the integration of our new gravity data with other geophysical and geological information, our findings demonstrate substantial variations in the overall crustal density within the region, with the fault distribution closely linked to these density fluctuations. Disparities in stratigraphic density are important causes of variations in the capacity of geological formations to endure regional tectonic stress. Earthquakes are predominantly concentrated within the density transition zone and are primarily situated in regions of elevated density. The hanging wall stress within the Guxiang–Tongmai segment of the Jiali fault exhibits a notable concentration, marked by pronounced anisotropy, and is positioned within the density differential zone, which is prone to earthquakes. [ABSTRACT FROM AUTHOR]

Residual soils are found all around the world. Their behaviour is different from 'classic' soils due to the structure resulting from the geological formation processes, which can eventually undergo degradation under static and cyclic loads, with a decrease in both stiffness and strength. In this context, the aim of the present study was to evaluate the behaviour of weakly bonded residual soil in the face of loading and unloading cycles using field plate load tests. Preliminary field and laboratory tests were carried out to characterise the residual soil at the experimental site. Monotonic and cyclic plate load tests – with circular and square plates – were performed under three different load amplitudes. The results showed no shape effect of the loaded area for both monotonic and cyclic loading, considering the same loading pattern. Also, there is a threshold load, which indicates a yielding point and a change in soil behaviour and can be estimated from simple laboratory tests. Below this load, the residual soil presented a rigid behaviour even when subjected to cyclic loads. [ABSTRACT FROM AUTHOR]

Underground flow in fractured aquifers depends on the connectivity of the fractures, considered as a set of conduits and the main drainage axes. Quantitative analysis of fracture networks using multifractal characterisation therefore provides the backbone for assessing the connectivity of these networks. The aim of our work is to carry out a multifractal characterisation of lineament networks while performing related geometric, spectral and fractal analyses. The approach used is based on the box counting method to estimate the multifractal spectrum using the method of moments. The generalized fractal dimensions were estimated using the partition function and the multifractal spectrum using the Legendre transform. The work was carried out using a calculation code that we developed ourselves and that we named: 2D Calculation Code for Multifractal Analysis of Fracture Networks (2D-MAFN).Four lineament maps at different scales were analyzed, corresponding to the Upper Jurassic and Cretaceous geological formations of the El Gada region in the Central Algerian Saharan Atlas. The geometric analysis of the lineament networks showed good consistency between the lineament networks and the geological structure of the Atlas Range and its fault network. It also showed that the distribution of the lengths of the lineaments fits the power law. This analysis also revealed that, on a larger scale, diffuse fracturing appears to be more prevalent. In addition, the spectral analysis, through the decrease in spectral power according to a power law, characterizes a self-similar behavior and already seems to prove the scale invariance of the lineaments. The fractal dimension values obtained reflect the extent of fracturing and the degree of complexity of the network of lineaments. These values show that the lineaments are also well correlated with each other. The partition functions show that the points line up on the adjustment lines according to a law characteristic of multifractal behavior. In addition, the curves of generalized dimensions as a function of moments show a clear decrease, highlighting the multifractal nature of the fracturing process. In addition, the multifractal spectra in the form of bell curves also confirm the multifractal process for the four lineament networks analyzed. The results obtained are very encouraging and open up the prospects of modelling fracture networks for a variety of purposes, including assessing the connectivity of a fracture network. [ABSTRACT FROM AUTHOR]

Investigating the mineralogical compositions of soils under different geological formations becomes imperative for maximizing agricultural productivity and ensuring the long-term viability of agricultural practices. Therefore, studies were carried out on mineral compositions and diversities of soils developed over the Basement complex rock, Coastal plain sands and Ewekoro formations in Ogun state Nigeria. A total of nine profile pits (three per location) of 2 m × 1 m × 2 m size were dug in all the three locations. Soil samples were collected from the pedogenic horizons of each profile pits in replicates into a well labeled polyethylene bag. Using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) the mineral contents and their relative abundance, elemental compositions and morphologies of the fine sand, coarse silt and clay fractions of the soils at different topographic positions were identified, described and compared. Results obtained from XRD and SEM analyses exhibited similarities. The most abundant elements in the basement complex and Ewekoro pedon were oxygen, carbon and silicon whereas in the coastal plain sand pedon, oxygen, carbon and aluminum were the most abundant element. The presence of mixed-layer illite, mica, kaolinite, quartz, hematite, anatase, goethite, and chlorite at varying degrees was observed in the pedons developed on these geological formations, although kaolinite and quartz dominated the soil matrix. The mineralogical complexity of the pedons followed the order of basement complex > coastal plain sand > Ewekoro formation. Profiles developed on the Ewekoro formation exhibited the highest degree of weathering, as evidenced by their chemical properties and mineralogical compositions. The petrographic evaluation of the three geological formations revealed that all pedons were rich in quartz and exhibited varying degrees of mineral complexity and maturation. The overlapping and distinct characteristics among the geologies indicated different stages of weathering. By using the mineral maturity index, profiles developed over the basement complex rock and the coastal plain sand could be regarded as sub-matured and this could have contributed significantly to the native fertility of these soils and profiles from the Ewekoro formation were the most weathered. The use of Ewekoro formation for agriculture would necessitate significant investments in agro-inputs and sound principles of soil management through integrated soil fertility management. [ABSTRACT FROM AUTHOR]

Geoscientists now identify coal layers using conventional well logs. Coal layer identification is the main technical difficulty in coalbed methane exploration and development. This research uses advanced quantile–quantile plot, self-organizing maps (SOM), k-means clustering, t-distributed stochastic neighbor embedding (t-SNE) and qualitative log curve assessment through three wells (X4, X5, X6) in complex geological formation to distinguish coal from tight sand and shale. Also, we identify the reservoir rock typing (RRT), gas-bearing and non-gas bearing potential zones. Results showed gamma-ray and resistivity logs are not reliable tools for coal identification. Further, coal layers highlighted high acoustic (AC) and neutron porosity (CNL), low density (DEN), low photoelectric, and low porosity values as compared to tight sand and shale. While, tight sand highlighted 5–10% porosity values. The SOM and clustering assessment provided the evidence of good-quality RRT for tight sand facies, whereas other clusters related to shale and coal showed poor-quality RRT. A t-SNE algorithm accurately distinguished coal and was used to make CNL and DEN plot that showed the presence of low-rank bituminous coal rank in study area. The presented strategy through conventional logs shall provide help to comprehend coal-tight sand lithofacies units for future mining. [ABSTRACT FROM AUTHOR]

The innovative cutting mechanism of multi-dimensional teeth presents a groundbreaking approach to drill bit design, particularly optimizing drilling efficiency in challenging geological formations such as interlayers and gravel-rich layers within the Changqing Oilfield. Nevertheless, compared to conventional flat-tooth PDC drill bits, several aspects of the cutting mechanism and design parameters for multi-dimensional teeth require further elucidation. This article employs a linear cutting finite element model to establish cutting models for traditional flat teeth and two distinct types of multi-dimensional teeth, designated as Ridge and Benz. It systematically investigates the influence of varying cutting parameters on the effectiveness of rock-crushing within the multi-dimensional tooth-cutting mechanism. This study conducts laboratory-based single-tooth rock-crushing experiments to validate the numerical simulation results. Furthermore, applying principles derived from soil plastic mechanics contrasts the stress states experienced by rocks during the rock-crushing process between multi-dimensional teeth and conventional flat teeth, shedding light on the rock-crushing mechanism employed by multi-dimensional teeth. This research categorizes PDC cutting teeth on the drill bit into two groups: those near the center and those near the outer shoulder. A linear cutting model for teeth positioned near the outer shoulder is developed to analyze the impacts of different rake angles, side clearance angles, and welding errors on the tooth helix angle and the rock-crushing efficiency of the Benz tooth. This comprehensive study is a valuable reference for tailored drill bit design and holds potential for publication in a prestigious scientific journal. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a suffocating gas resulting either from industrial activities from combustion or explosion. There may also be carbon dioxide deposits under pressure, quartered in porous geological formations. This gas can show slow or violent releases with accumulation at ground level. Carbon dioxide is a gas that is both toxic and asphyxiating. This gas can accumulate in closed spaces and when it exceeds the concentration of 12% vol. it becomes lethal. For the protection of working personnel, it is necessary to identify and apply the most effective preventive measures. This requires an understanding of carbon dioxide's behaviour during the build-up phase. The research gives a CFD analysis for determining the dynamics of carbon dioxide dispersion in a confined enclosure. [ABSTRACT FROM AUTHOR]

In this study, the geological and petrophysical methods were combined to investigate the reservoir characteristics of the Asmari Formation in one of the gas fields in the Persian Gulf. The key focus of this study is to categorize rock types and define reservoir zonation. Initially, sedimentary facies were identified through the analysis of the core samples and the petrographic studies. Subsequently, the depositional environments of each facies were interpreted. After assessing the reservoir quality of sedimentary facies, various rock typing methods, including FZI, R35, and Lucia methods, were used to categorize the reservoir rocks. Finally, reservoir zonation was carried out based on the integration of information and the NCRQI method. According to this study, the Asmari Formation in the studied field consists of 10 sedimentary facies deposited in a carbonate ramp environment during the Rupelian and Chattian stages. From the perspective of frequency, coralgal reef facies play a significant role in this platform, while from a reservoir standpoint, the thin-bedded ooid grainstones are the most important reservoir facies. The high variability in porosity and permeability data for each facies indicates the importance of diagenetic changes in reservoir quality and porosity distribution. A comparative analysis of rock typing methods revealed that the reservoir rock is composed of five reservoir rock types, associated with different sedimentary facies, pore sizes, and reservoir properties. Finally, based on the integration of geological and petrophysical information, the reservoir rock was divided into five reservoir zones, with reservoir zones As-2 and As-4 being the most important due to their relatively high porosity and permeability. [ABSTRACT FROM AUTHOR]

Spectral transform, known as a curvelet, enables sparse representations of complex data. Denoising wave propagation in disordered media and pattern recognition are just a few of the numerous domains in which denoising has a potential application. Based on directional basis functions, this spectral method represents objects with discontinuities along a smooth curve. In this study, we used this technique to eliminate ground roll, an unwanted feature signal that can be seen in seismic data obtained by sonating the earth's geological formations. Additionally, we improved the curvelet transform threshold denoising method combined with a fast non-local mean to remove seismic random noise. First, cyclic translation and block complex domain threshold methods were introduced into the curvelet transform threshold denoising, and the traditional curvelet threshold denoising method was improved to obtain the best denoising results; Subsequently, the removed noise was filtered using a fast non-local mean method to obtain a valid signal. Finally, the data obtained in the above two steps were added to obtain the final denoising result. The results of the model tests and actual seismic data denoising showed that the denoising results obtained using this method had a higher signal-to-noise ratio and fidelity than that using the other methods. [ABSTRACT FROM AUTHOR]

Thermal pressurization of the trapped pore fluid is considered to be a widespread fault weakening during fluid injection in confined geological formations. Tremendous amounts of heats will be generated within the narrow shear zone during fault slip. Considering the melting of the fault gouge, the fault seal zone is adopted to construct the fluid pressurization model, thermal pressurization implemented in Comsol Multiphysics is established to illustrate the fault weaken coefficient and effective normal stress during fluid injection. The friction weakening coefficients mT and mF are proposed to research the performance of fault weakening during fluid injection. The results indicate that, the friction coefficients mT and mF both exhibit the initially decreasing and then increasing tendency, and thermal-induced fault weakening of CO2 injection occurs earlier than that of water injection. It was found that initial pore pressure and fault sealing porosity have a negligible influence on the evolutions of friction weakening and effective normal stress. Initial normal stress and fault sealing permeability have certain obvious influences on fault weakening during CO2 injection. Fault thickness is the primary factor influencing the friction weakening coefficient. When the fault thickness is over 1 mm, the variation of fault weakening is totally different from that when the thickness is less than 1 mm. This investigation of friction weakening during fault slip provides an effective reference for fluid injection. [ABSTRACT FROM AUTHOR]

Assessing microbial risks is key to feasible hydrogen storage in geological formations. This work quantitatively analyses the impacts of bio-methanation on hydrogen storage performance. Fine-scale flow simulations, coupled with the bio-methanation reaction, are presented to analyse its impact on the storage performance. Based on the reported rates in literature, methanogenesis may slightly degrade the recovery performance of hydrogen but is considered minor compared with the issue of gas mixing. The impacts of methanogenesis on a time scale of months (330 days) becomes observable in the system configured here, when the methanation rate is above 1746 nano molality per hour. The assumed methanation rate is two times greater than the rate reported from the Olla filed. Validated scaling theory generalises findings for gravity-dominated scenarios. But viscous-dominated flows see complications from property variations due to pressure changes at high rates. This study provides definitions of "target properties" (e.g., acceptable methanogenesis rates) for screening hydrogen storage projects. • A new synthesis incorporating methanogenesis and flow dynamics is developed. • Effects of methanogenesis should be considered if the reaction rate is greater than 1746 nm h−1. • Fluid mixing driven by viscous fingering may amplify the process of methanogenesis. • The methanation process may lead to or accelerate the water breakthrough. • Scaling theory is validated for a gravity-dominated scenario with methanogenesis considered. [ABSTRACT FROM AUTHOR]

Deep crustal production of hydrogen (H2) is a potential source of primary energy if recoverable accumulations in geological formations are sufficiently large. We report direct measurements of an elevated outgassing rate of 84% (by volume) of H2 from the deep underground Bulqizë chromite mine in Albania. A minimum of 200 tons of H2 is vented annually from the mine’s galleries, making it one of the largest recorded H2 flow rates to date. We cannot attribute the flux solely to the release of paleo-fluids trapped within the rocks or to present-day active and pervasive serpentinization of ultramafic rocks; rather, our results demonstrate the presence of a faulted reservoir deeply rooted in the Jurassic ophiolite massif. This discovery suggests that certain ophiolites may host economically useful accumulations of H2 gas. [ABSTRACT FROM AUTHOR]

The data of gas-geochemical studies of bottom sediments of the Laptev—Siberian Sea transition zone are presented. The established isotope–geochemical parameters indicate the domination of epigenetic hydrocarbon gases of various gas sources in the sediments. Methane concentrations up to 8.3047 cm3/kg and the sum of homologues up to 0.0260 cm3/kg indicate the formation of hydrocarbon anomalies exceeding the anomaly criteria for Arctic shelf sediments by a factor of 166 and 26. The main geological factors for the formation and distribution of anomalies in the bottom sediments of the Laptev–Siberian Sea transition zone are the high gas content of the underlying sediments and gas sources, the fold and fault tectonics, the geostructural position, the seismic activity, and the depth of occurrence of hydrocarbon gas sources. [ABSTRACT FROM AUTHOR]

Accurate identification and understanding of various metallic minerals are crucial for deciphering geological formations, structures, and ages. Giving their pivotal role as essential natural resources, a microscopic exploration of metallic minerals becomes imperative. Traditional analytical methods, while helpful, exhibit certain limitations. However, terahertz time-domain spectroscopy, distinguished by its high signal-to-noise ratio, expansive frequency band, and low incident wave energy, is a promising complement to conventional techniques in characterizing metallic minerals. This study employs terahertz time-domain spectroscopy to examine samples of Stibnite, Sphalerite, Galena, and Pyrite originating from diverse geological conditions. The vibrations of molecules within these metallic minerals induce discernible changes in the terahertz spectra. Our findings untiate the extensive potential of terahertz time-domain spectroscopy in the characterization of metallic minerals, affirming its considerable practical value in mineral resource exploration. [ABSTRACT FROM AUTHOR]

The Taoudeni basin occupies a large portion of the West African Craton in Mauritania, Mali, SW Burkina Faso, and Algeria. The multi-layer Taoudeni aquifer system (TAS) occurs in geological formations extending in age from the Infra-Cambrian to the Quaternary. These groundwater resources support local livelihoods, maintain vital ecosystems, and strongly affect terrestrial water and energy budgets in the region. Hydrogeochemical and stable (δ2H, δ13C, δ18O) and radioactive (3H, 14C) isotope analyses were carried out with the aim of identifying the major geochemical processes controlling groundwater quality and the recharge mechanisms. The analyzed groundwater samples showed a wide range of chemical compositions based on major ions, with limited variability, regardless of the aquifer lithology or stratigraphy. The predominant water type, Mg–Ca–HCO3, was found in most geological and hydrogeological settings. A principal component analysis of the hydrochemical data revealed the two major processes governing the geochemistry of groundwaters in the TAS. These are water–rock interaction (leaching, weathering, ion exchange) and anthropogenic contamination. Environmental isotopes revealed the presence of groundwaters with heterogeneous signatures, reflecting different recharge processes and varying groundwater ages. A widespread present-day recharge by direct infiltration of rainwater and/or by surface water was highlighted by significant tritium levels in most wells and high 14C activities occurring mainly in shallow aquifers. However, isotopically depleted δ18O contents with low 14C activities were found in the confined part of the Continental Intercalaire aquifer, particularly in the Algerian part, indicating the presence of fossil groundwater, recharged under colder past climatic conditions. [ABSTRACT FROM AUTHOR]

Tabular Middle Atlas of Morocco holds the main water reservoir that serves many cities across Morocco. Dolomite and limestone are the most dominant geologic formations in this region in which water resources are contained. The recent studies conducted to evaluate the quality of this water suggest that it is very vulnerable to pollutants resulting from both anthropogenic and natural phenomenon. High and very high-resolution satellite imagery have been used in an attempt to gain a better understanding of this karstic system and suggest a strategy for its protection in order to reduce the impact of these phenomenon. Based on the surface reflectance of land cover benchmarks, the karstic system has been horizontally delineated, as well as regions with intense human activities. Using band combination in the portion of the infrared, shortwave infrared, and visible parts of the electromagnetic spectrum, we identified bare lands which have been interpreted as carbonate rocks, clay minerals, uncultivated fields, basalts rocks, and built-up areas. Other classes such as water and vegetation have been identified. Carbonate rocks have been identified as areas with a high rate of water infiltration through their fracture system. Using a Sobel operator filter, these fractures have been mapped and their results have revealed new and existing faults in two major fracture directions, NE-SW and NW-SE, where NE-SW is the preferable pathway for surface water infiltration towards the groundwater reservoir, while the NW-SE direction drains groundwater from the Cause to the basin of Saiss. Over time, the infiltration of surface water through fractures has contributed to a gradual erosion of the carbonate rocks, which in turn developed karst landforms. This karst system is vulnerable due to the flow of pollutants in areas with shallow sinkholes. Using GDEM imagery, we extracted karst depressions, and their analysis shows that they are distributed along the fracture system and many of them were located on curvilinear or linear axes along the NE-SW fracture direction. We found also dolines scattered in areas with a high intensity of fractures. This distribution has been validated by both on-the-ground measurements and very high-resolution satellite images, and depressions of different forms and shapes dominated by dolines, poljes, lapiez, and avens have been identified. We also found many water springs with a highly important water output, such as the Ain Maarrouf water spring. The aim of this study is to enhance the understanding of the hydrogeological system of TMA, to improve the existence of the fracture database in the Cause of Agourai, and to establish a new morpho-structural picture of the Ain Maarrouf water spring. [ABSTRACT FROM AUTHOR]

Determining the elastic modulus of rocks is one of the crucial parameters in civil and petroleum engineering. Asmari geological formation is widely outcropped in a significant part of the west and SW of Iran and NE of Iraq. Understanding the static elastic modulus of host rocks is crucial because of the design and construction of numerous geotechnical structures and the presence of large hydrocarbon reservoirs in this formation. To determine the elastic modulus of intact rocks, the uniaxial compressive strength test is typically used. However, in jointed rocks and deep areas, where obtaining samples may be challenging, costly, or even impossible, correlations between static–dynamic elastic modulus (Es − Ed) is more frequently employed. Although some scholars have proposed correlations between Es − Ed, they had determined dynamic modules based on the ultrasonic test. In the aforementioned test, intact samples are used and the effect of discontinuities would not be considered; hence, the results cannot be considered as rock mass representative. In this study, to consider field geotechnical conditions, the dynamic modules were determined based on the downhole seismic test (DS) in a tunnel in located the west of Iran. Then from the results of static elastic modulus, which were obtained from core samples, a linear correlation was proposed between Es − Ed. The root-mean-square error and variance accounted showed that the predicted static elastic modulus by the proposed correlation is more accurate to a large extent. In addition, unlike the ultrasonic-based Ed, the results showed that the DS-based Ed is less than Es. [ABSTRACT FROM AUTHOR]

Geologic carbon sequestration requires CO2 injection into the storage formation at high‐injecting pressure. Such high pressure could induce choked flow accompanying huge variations in thermodynamic properties of CO2 at a converging‐diverging (CD) fractures in the storage formation. In this study, high‐velocity CO2 transport through CD fractures was investigated to quantify the effect of fracture morphology on occurrence of both choked flow and shockwave that constrain the mass flow rate of fluid. In addition, variations in thermodynamic CO2 properties including Mach Number (Ma), defined by the ratio of fluid velocity to sound speed, and shock properties were investigated. The morphological characteristics of CD fractures were determined by nine properties, such as throat diameter, throat length, inlet diameter, outlet diameter, throat diameters of two‐connected CD fractures, fracture wall curvature, roughness amplitude, and frequency. As a result, the throat diameter crucially affected choked flow occurrence and maximum Ma. When the inlet and outlet diameters varied, the profiles for Ma variation were consistent in the converging and diverging segments, respectively. In addition, regardless of change in the throat length, the position of maximum Ma was nearly constant with showing the position length ratio of 0.13–0.14. However, roughness of fracture wall significantly influenced the Ma variation and occurrence of shock. In particular, backflows segregated from the main CO2 flow were observed near the wall roughness. Plain Language Summary: Choked flow is a fluid‐mechanical process that restricts the mass flow rate of fluid and it can be occurred when fluid velocity overcomes its sound speed. When CO2 is injected into the targeted geologic formation, choked flow can occur due to highly pressurized flow within the fractures located near the CO2 injection well. Once choked flow occurred, the shock, which accompanies substantial changes in the thermodynamic properties of CO2, follows in the fractures. In the study, choked flow is generated within the converging‐diverging (CD) fracture which serves as a pathway of injected CO2, and its cross‐sectional area decreases and increases again after the "throat." We assumed that the CD fractures have various morphologic properties and analyzed the relationship between the fracture morphology and shock properties. The results highlighted that the throat diameter and fracture roughness mainly affected choked flow occurrence and shock properties. Findings here are applicable to other site‐specific studies, such as volcanoes, geysers, geothermal fields, and underground hydrogen storage sites where highly compressed fluid often migrates through subsurface fractures or any types of geologic conduits. Key Points: CO2 flow within the fracture was simulated to evaluate the effect of fracture morphology on choked flow and shock generationMorphologic properties including throat diameter and length, inlet and outlet diameter, number of throats, and wall roughness were variedThroat diameter influenced the Mach number (Ma); a complicated trend of Ma and backflow were observed owing to wall roughness [ABSTRACT FROM AUTHOR]

Anomalous solute migrations in fractured rocks are governed by geometric characteristics and flow regimes. Although existing inverse models can describe this behavior, the underlying physics for quantifying key transport coefficients remains largely unexplored. Here, we investigate the quantitative impacts of geometric heterogeneity and flow regimes on solute transport in rock fractures. We conduct numerical experiments to simulate water flow and conservative solute transport in 3D fractures with varying geometric features and Reynolds numbers. Our results show that the non‐Fickian transport is prevalent across the entire flow regime, with Darcy flows attributed to geometric heterogeneity and non‐Darcian flows influenced by additional eddy zones. We employ the mobile‐immobile (MIM) domain model and continuous time random walk (CTRW) model to inversely model simulated breakthrough curves. Inverse analyses demonstrate that both models effectively characterize anomalous transport behaviors. The fitted transport coefficients of the MIM model exhibit stronger quantitative relationships with aperture and roughness parameters, as well as Reynolds number, compared to the CTRW model. By incorporating parameterized transport coefficients, we propose physics‐ and statistics‐based models to directly predict anomalous transport behaviors under different flow regimes. These prediction models accurately reproduce solute transport processes of all simulated cases with acceptable errors. The feasibility of directly predicting solute transport under varying flow regimes using geometric information is thus validated. Our study not only supports the study of substance migration based on geometric structure features, but also serves as a foundation for investigating geological activities based on substance migration information. Plain Language Summary: The migration of substances within geological formations is governed by their geometric pore structure, while information about substance migration can reveal the geometric characteristics of these formations. In this context, these two aspects form an interdependent feedback system. Investigating quantitative relationships and models between the geometry of geological formations and substance migration is thus crucial for understanding various geological processes related to geometric structure changes and hydrogeochemical signals (i.e., chemical information carried by groundwater or surface water, which reflects various natural and anthropogenic geological processes) evolution. Here, we explore the impact of both geometric structure and hydrodynamic conditions on solute transport in rock fractures. We conduct extensive direct numerical simulations to determine the inherent quantitative relationships between key transport coefficients and geometric parameters under different flow regimes. Based on these relationships, we establish upscaling models for directly predicting solute transport processes using only geometric parameters within both physics‐ and statistics‐based frameworks. This research has significant implications for predicting solute migrations using measurable physical properties and offers potential applications for studying geological activities related to fractured rocks through analyzing released hydrogeochemical signals. Key Points: Non‐Fickian transport behaviors in 3D fractures under different Re were characterized within physics‐ and statistic‐based frameworksTransport coefficients within mobile‐immobile and continuous time random walk frameworks were systematically parameterized by geometric and hydrodynamic parametersDirectly predicting solute transport via geometric parameters under different Re is feasible in both physics‐ and statistic‐based frameworks [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) visualization of geological structures and the dynamic simulation of geological evolutionary processes are helpful when studying the formation of renowned geological features. However, most of the existing 3D modeling software is based on raster models, which are unable to generate smooth geological boundaries. This work proposes a 3D temporally dynamic (i.e., four-dimensional (4D)) modeling method using parametric functions and vector data structures, which can dynamically build geological evolutionary vector models of well-known geological features. First, we extract the typical features of different kinds of geological formations and represent them using different parameters. Next, we select appropriate parametric functions to simulate these geological formations according to the characteristics of the individual structures. Then, we design and develop 4D vector modeling software to simulate the geological evolution of these features. Finally, we simulate an area with complex geological structures and select six real-world geological features, such as the Piqiang Fault in China and the Eye of the Sahara in the Sahara Desert, as case studies. The modeling results show that a regional geological evolutionary model that contains smooth boundaries can be established within minutes using this method. This work will support studies into the formation of renowned geological features in terms of providing visualizations and will make the representation of geological processes more intuitive in 3D. [ABSTRACT FROM AUTHOR]

The utilization of geological formations, distinguished by natural porosity and permeability and protected by low-permeability caprock, has emerged as an effective strategy for carbon dioxide (CO2) storage. This method significantly contributes to mitigating anthropogenic greenhouse gas emissions and addressing the challenges of climate change. Recent research has unveiled the potential of CO2 to enhance geothermal heat energy extraction in geothermal reservoirs by acting as a subsurface heat exchange fluid. This review paper explores the viability of CO2 in augmenting geothermal heat energy extraction, comparing it to conventional water-based geothermal systems. Special emphasis is placed on CO2 plume geothermal (CPG) systems, characterized by rapid deployment and long-term utilization of geothermal energy resources. With the overarching objective of establishing net-zero energy communities, the analysis of such systems offers a comprehensive understanding of their features, providing a fresh perspective on extracted energy within the context of energy supply in integrated, sustainable energy in built systems. Notably, these systems demonstrate efficacy in meeting the power requirements of an energy community, spanning both distinct heating and electricity needs. However, the key challenge lies in selecting suitable locations. This scientific review aims to comprehend the characteristics of CPG under specific temperature and pressure conditions while optimizing subsurface permeability. This insight is pivotal for identifying future locations for CPG operations with the intent of powering small energy communities. [ABSTRACT FROM AUTHOR]

Carbon Dioxide (CO 2) emissions from fossil fuel consumption have caused global warming and remain challenging problems for mitigation. Underground Hydrogen Storage (UHS) provides clean fuel and replaces traditional fossil fuels to reduce emissions of CO 2. Geological formations such as depleted oil/gas reservoirs, deep saline aquifers and shale formations have been recognized as potential targets to inject and store H 2 into the subsurface formations for large-scale implementation of CCS and UHS. However, the presence of H 2 with cushion gas at different fractions under different geo-storage conditions, which can influence Hydrogen's flow properties, was not investigated widely. Until now, studies of interfacial properties between water and a mixture of cushion gas (CO 2 , N 2 or CH 4) in the presence of H 2 are very limited or unavailable data in experiments and simulations. In this study, many predictions by using molecular dynamics simulation were conducted to predict the interfacial tension (γ) for the systems of H 2 /CO 2 /H 2 O, H 2 /N 2 /H 2 O and H 2 /CH 4 /H 2 O at different pressures, temperatures, and fractions of cushion gases A comparison between the predicted γ results from the simulation and previous research were also made. The findings of this study indicated that γ of H 2 /CO 2 /H 2 O, H 2 /CH 4 /H 2 O, and H 2 /N 2 /H 2 O, as a function of pressure, temperature, and fraction of H 2 , decreased with increasing pressures and temperatures and increased with increasing H 2 % in the mixture. Additionally, an extending or new γ data in simulation for the CO 2 /H 2 /H 2 O, N 2 /H 2 /H 2 O and CH 4 /H 2 /H 2 O systems from this study were reported and support evaluating the stability and storage capacity of H 2 combined with the cushion gas in geological formations. Furthermore, it can contribute to de-risking and proceeding safely and efficiently for the large-scale implementation of Underground Hydrogen Storage. • Predict interfacial tension between water and cushion gas (CO 2 , N 2 , and CH 4) in the presence of H 2. • Interfacial tension, as a function of pressure and temperature, decreased with increasing pressure and temperature. • Interfacial tension, as a function of H 2 fraction, increased with increasing the fraction of H 2 in the mixture gas. • Investigate the effects of cushion gas on the stability and storage capacity of H 2 in geological formations. [ABSTRACT FROM AUTHOR]

Hydrogen storage in subsurface geological formation is a complex process requiring information at multiple scales for successful understanding and implementation. While some laboratory investigations and pore-scale studies showed evidence of hydrogen and water cyclic hysteresis, field-scale underground hydrogen storage considering the cyclic hysteretic effect received little or no attention and thus remains poorly understood. This is particularly important due to the fact that an underground hydrogen storage project typically involves repeated cycles of hydrogen injection and withdrawal. In this work, numerical simulations were performed to examine the impact of the cyclic hysteretic effect on the dynamics of hydrogen saturation and the associated efficiency of storage and withdrawal cycles. The results indicate that the cyclic hysteretic effect impedes the injected hydrogen distribution in the formation and results in a greater ultimate hydrogen recovery factor during subsequent withdrawal phases (∼77%). However, the accumulated hydrogen in the formation top will, in turn, increase the formation pressure. The impact of capillary pressure and H 2 dissolution in brine were also investigated. The results suggest that capillary pressure and dissolution could alter the hydrogen saturation distribution while depicting a negligible effect on the ultimate hydrogen recovery factor. It was found that the loss of hydrogen due to dissolution can be compensated by avoiding more significant residual trapping in our study. [Display omitted] • Impact of the cyclic hysteretic effect on the dynamics of hydrogen saturation is examined. • Cyclic hysteretic effect impedes the injected hydrogen distribution in the formation. • Cyclic hysteretic effect results in a greater ultimate hydrogen recovery factor. • Accumulated hydrogen in the formation top cause formation overpressurization. • Capillary pressure and dissolution influence the injected hydrogen distribution. [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) within sealed geological formations is an essential strategy to reduce global greenhouse gas emissions, the primary goal of the 2015 United Nations Paris Agreement. Large-scale commercial development of geological CO2 storage requires high-resolution remote sensing methods to monitor CO2 migration during/after injection. A geological formation containing a CO2 phase in its pore space commonly exhibits higher electrical resistivity than brine-saturated (background) sediments. Here, we explore the added value of the marine controlled-source electromagnetic (CSEM) method as an additional and relevant geophysical tool to monitor moderate to significant changes in CO2 saturation within a fluid conduit breaking through the seal of a CCS injection reservoir, using a suite of synthetic studies. Our 2-D CSEM synthetic models simulate various geological scenarios incorporating the main structural features and stratigraphy of two North Sea sites, the Scanner Pockmark and the Sleipner CCS site. Our results show significant differentiation of leakage through the seal with CO2 saturation (⁠|$S_{{\rm CO}_2}$|⁠) ranging between 20 and 50 per cent, while our rock physics model predicts that detection below 20 per cent would be challenging for CSEM alone. However, we are able to detect with our 2-D inversion models the effects of saturation with 10 and 20 per cent CO2 within a chimney with 10 per cent porosity. We demonstrate that simultaneous inversion of Ey and Ez synthetic electric field data facilitates a sharper delineation of a CO2 saturated chimney structure within the seal, whereas Ez synthetic data present higher sensitivity than Ey to |$S_{{\rm CO}_2}$| variation, demonstrating the importance of acquiring the full 3-D electric field. This study illustrates the value of incorporating CSEM into measurement, monitoring and verification strategies for optimal operation of marine CCS sites. [ABSTRACT FROM AUTHOR]

Many anthropologists have now adopted a relational view of the culture concept. Much research has shown that, far from being bounded or self-replicating, cultures emerge through interactions between social Others. These findings are particularly important to research on borderlands and peripheries, where communities routinely encounter wide-ranging social and political diversity. We present ceramic frequencies alongside petrographic analysis from the Late Woodland component at Esseneca (38OC20) to illustrate two main points: (1) pottery types previously understood as culture historical isolates co-occur in parts of Upstate South Carolina, and (2) potters collected clays from two main geologic formations near the site. This research shows that communities in the region traveled freely, crossing cultural boundaries while acquiring potting clays. We suggest that this level of interaction between disparate social groups laid the foundation for some aspects of Mississippianization in the region. [ABSTRACT FROM AUTHOR]

A couple of studies show that Saudi Arabia has promising geothermal resources. The most prominent sites are located around Al-Lith, with four hot springs, where Ain Al-Harrah has the highest temperature. Previous studies suggest that this hot spring's geothermal reservoir is promising and may provide the Al-Lith region with long-term electricity. Our key objective is to investigate and explore more comprehensively the prospect of geothermal resources around the Ain Al-Harrah hot spring. To achieve this goal, we acquired broadband magnetotellurics (MT) data in the period range 0.001–60 s for three different sampling frequencies at 15 soundings along one profile. The 2D inversion results show three main units. A conductive anomaly (< 30 Ω.m) at a depth > 3.5 km below the surface is most likely related to a geothermal heat source. The high resistive zones (roughly 200–4000 Ω.m) are associated with hard-rock geological formations. Although uncertain, a detected medium resistive body (30–200 Ω.m) at a depth of 800 m below the surface possibly indicates the pathway of geothermal fluids forming a convection cell between the hot body and the surface. A lateral resistivity discontinuity is considered a fracture zone acting as a pathway for the fluids to reach the surface forming the hot spring. [ABSTRACT FROM AUTHOR]

The 20220918 Chishang earthquake impacted the Yuli area in the Longitudinal Valley of eastern Taiwan. Longitudinal Valley is situated near the boundary of the Philippine Plate and Eurasian Plate boundary with frequent seismicity and historical earthquakes. This study uses RTK GNSS measurements to characterize the 0918 seismic effects, revealing different coseismic displacement patterns in the Central Range, Coastal Range, and Longitudinal Valley blocks. Ruptures were mainly in the Longitudinal Valley, extending into downtown Yuli township. The influence on these geological formations highlights the complex interactions between the structures and underlying tectonic forces. Our investigations show that the Central Range block experienced a 1.17 m SW horizontal displacement and 1.1 m vertical uplift, while the Coastal Range block displayed a 1.18 m NW horizontal displacement and 0.65 m subsidence. The Longitudinal Valley block was divided by recent ruptures, with its western part impacted by the Central Range block, experiencing a 0.79 m SW displacement and 0.63 m uplift, and its eastern part influenced by the Coastal Range block, experiencing a 1.02 m NW displacement and 0.13 m subsidence. Our data indicates that different blocks were all affected differently, reflecting complex relationships between the subsurface faults to the surface fault traces. The result suggests the Central Range Fault have triggered the Yuli Fault for west-side up motion and possess a westward dip connected to the Central Range Fault. The post-seismic surveys reveal complex interactions between the Central Range and Longitudinal Valley Faults, vital for advancing earthquake mitigation strategies. [ABSTRACT FROM AUTHOR]

Stratigraphic identification from wire-line logs and core samples is a common method for lithology classification. This traditional approach is considered superior, despite its significant financial cost. Artificial neural networks and machine learning offer alternative, cost-effective means for automated data interpretation, allowing geoscientists to extract insights from data. At the same time, supervised and semi-supervised learning techniques are commonly employed, requiring a sufficient amount of labeled data to be generated through manual interpretation. Typically, there are abundant unlabeled geophysical data while labeled data are scarcer. Supervised and semi-supervised techniques partially address the cost issue. An underutilized class of machine-learning-based methods, unsupervised data clustering, can perform consonant classification by grouping similar data without requiring known results, presenting an even more cost-effective solution. In this study, we examine a state-of-the-art unsupervised data clustering algorithm called piecemeal clustering to identify lithofacies from wire-line logs, effectively addressing these challenges. The piecemeal clustering algorithm groups similar wire-log signatures into clusters, determines the number of clusters present in the data, and assigns each signature to one of the clusters, each of which represents a lithofacies. To evaluate the performance, we tested the algorithm on publicly released data from ten wells drilled in the Hugoton and Panoma fields of southwest Kansas and northwest Oklahoma, respectively. The data consist of two major groups: marine and non-marine facies. The study herein is centered around addressing two fundamental research questions regarding the accuracy and practicality of the piecemeal clustering algorithm. The algorithm successfully identified nine distinct clusters in our dataset, aligning with the cluster count observed in previously published works employing the same data. Regarding mapping accuracy, the results were notable, with success rates of 81.90% and 45.20% with and without considering adjacent facies, respectively. Further detailed analysis of the results was conducted for individual types of facies and independently for each well. These findings suggest the algorithm's precision in characterizing the geological formations. To assess its performance, a comprehensive comparative analysis was conducted, encompassing other data clustering algorithms, as well as supervised and semi-supervised machine learning techniques. Notably, the piecemeal clustering algorithm outperformed alternative data clustering methods. Furthermore, despite its unsupervised nature, the algorithm demonstrated competitiveness by yielding results comparable to, or even surpassing, those obtained through supervised and semi-supervised techniques. [ABSTRACT FROM AUTHOR]

Capturing and storing CO2 (CCS) was once regarded as a significant, urgent, and necessary option for reducing the emissions of CO2 from coal and oil and gas industries and mitigating the serious impacts of CO2 on the atmosphere and the environment. This recognition came about as a result of extensive research conducted in the past. The CCS cycle comes to a close with the last phase of CO2 storage, which is accomplished primarily by the adsorption of CO2 in the ocean and injection of CO2 subsurface reservoir formation, in addition to the formation of limestone via the process of CO2 reactivity with reservoir formation minerals through injectivities. CCS is the last stage in the carbon capture and storage (CCS) cycle and is accomplished chiefly via oceanic and subterranean geological sequestration, as well as mineral carbonation. The injection of supercritical CO2 into geological formations disrupts the sub-surface's existing physical and chemical conditions; changes can occur in the pore fluid pressure, temperature state, chemical reactivity, and stress distribution of the reservoir rock. This paper aims at advancing our current knowledge in CO2 injection and storage systems, particularly CO2 storage methods and the challenges encountered during the implementation of each method and analyses on how key uncertainties in CCS can be reduced. CCS sites are essentially unified systems; yet, given the scientific context, these storage systems are typically split during scientific investigations based on the physics and spatial scales involved. Separating the physics by using the chosen system as a boundary condition is a strategy that works effectively for a wide variety of physical applications. Unfortunately, the separation technique does not accurately capture the behaviour of the larger important system in the case of water and gas flow in porous media. This is due to the complexity of geological subsurface systems, which prevents the approach from being able to effectively capture the behaviour of the larger relevant system. This consequently gives rise to different CCS technology with different applications, costs and social and environmental impacts. The findings of this study can help improve the ability to select a suitable CCS application method and can further improve the efficiency of greenhouse gas emissions and their environmental impact, promoting the process sustainability and helping to tackle some of the most important issues that human being is currently accounting global climate change. Though this technology has already had large-scale development for the last decade, some issues and uncertainties are identified. Special attention was focused on the basic findings achieved in CO2 storage operational projects to date. The study has demonstrated that though a number of CCS technologies have been researched and implemented to date, choosing a suitable and acceptable CCS technology is still daunting in terms of its technological application, cost effectiveness and socio-environmental acceptance. [ABSTRACT FROM AUTHOR]

In order to assess the influencing factors of the presence of mercury in a river within the Savanna biome (Cerrado), we surveyed total mercury (THg) in bottom sediment from 50 lakes along 750 km of the Middle Araguaia floodplain. The sampling sites included non-urban and urban surroundings over three distinct geomorphologies. We measured water physicochemical parameters at each site and tested statistically if land use nested within the geological formation influenced the THg concentration in bottom sediments and related water parameters. Multivariate results indicate that the interaction between geological groups and land use is statistically significant (p < 0.05). Nested ANOVA and Tukey HSD tests confirmed that the geological formation with its nested land use influences the THg, pH, DO, conductivity, and TDS (p < 0.05). THg was significantly lower in Quaternary terrains (p < 0.05) and differed significantly between non-urban and urban areas in Neoproterozoic terrains (p = 0.02). The spatial projections of the THg eigenvector on the main axes with the scoring factors of the Neoproterozoic/Paleoproterozoic terrains, and urban/non-urban, confirmed the spatial correlations. These results indicate that the association of land use and geology could be the main driver of THg in the bottom sediments of lakes from the Middle Araguaia floodplain. [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) technology is regarded as the feasible solution to mitigate CO2 emissions from the burning of fossil fuels in large-scale industries to meet energy demand. The storage of CCS requires the injection of CO2 gas captured from bulk sources into geological formations. Deep saline aquifers are the largest identified storage potential formations for injecting high volumes of gas. The safe storage of CO2 gas requires a better understanding of the gas migration and pore pressure buildup in the aquifer. In the present work, a numerical has been developed to study the various factors impacting the CO2 gas migration in the formation of both homogeneous and multi-layered deep saline aquifers. The numerical model has been history matched with an analytical solution and the plume thickness data reported by Nordbotten, J. M., M. A. Celia, and S. Bachu. (2005). "Injection and Storage of CO2 in Deep Saline Aquifers: Analytical Solution for CO2 Plume Evolution during Injection." Transport in Porous Media 58 (3): 339–60. The saturation distribution and pressure buildup in the aquifer are different for each case. The relative permeability of gas increases in the homogeneous case. The drainage efficiency increases along with injection time in any formation. However, the drainage process is less in layered formation compared with homogeneous formation. The parameterized storage efficiency factor (Ɛ) is calculated to understand the storage capacity of the aquifer along the lateral direction near to injection well. The formations having low permeability in the top and below layers of the aquifer, the storage efficiency factor is high indicating more amount of gas is stored. [ABSTRACT FROM AUTHOR]

A number of parameters and characteristics of geological formations have a major influence on the long-term performance of ground heat exchangers. Some of these parameters can be measured, others in the laboratory and their evolution over time can be modelled using dedicated software. One of the commonly used software is EED (Earth Energy Designer) which can model, based on characteristics measured in the field and/or laboratory, the evolution over time of the temperature taken from geological formations, the evolution of loads, cooling, heating versus load introduced/extracted from geological formations over certain periods of time. [ABSTRACT FROM AUTHOR]

Shear wave splitting (SWS) is currently considered to be the most robust seismic attribute to characterize fractures in geological formations. Despite its importance, the influence of fluid pressure communication between connected fractures on SWS remains largely unexplored. Using a 3-D numerical upscaling procedure based on the theory of poroelasticity, we show that fracture connectivity has a significant impact on SWS magnitude and can produce a 90° rotation in the polarization of the fast quasi-shear wave. The simulations also indicate that SWS can become insensitive to the type of fluid located within connected fractures. These effects are due to changes of fracture compliance in response to wave-induced fluid pressure diffusion. Our results improve the understanding of SWS in fractured formations and have important implications for the detection and monitoring of fracture connectivity in hydrocarbon and geothermal reservoirs as well as for the use of SWS as a forecasting tool for earthquakes and volcanic eruptions. [ABSTRACT FROM AUTHOR]

In most water balance studies, basins are considered closed systems; however, interbasin groundwater flow (IGF), which is an unaccounted hydrological component in most studies, could occur at basin boundaries where there is a hydraulic gradient and appropriate permeability of the geologic formations. IGF is a complex hydrogeological process and hidden from direct observation, thus identifying and characterizing it is difficult. This study investigated IGF in the case of the contact between the Tana and Beles basins, located at the northwestern margin of the Ethiopian Highlands, using a multimethod approach: (1) morphotectonic analysis; (2) lithostratigraphy and geological structure analysis; (3) regional groundwater potentiometric-surface map; (4) presence of large-volume springs; (5) hydrochemistry and isotope tracing; and (6) water budget imbalances. Primary data (geological investigation, water point inventory, and water sampling), satellite images and gravity data, and other secondary data, were collected and analyzed. The results illustrate the extension of the fractured basaltic aquifer, high topographic contrast, and high lineament density along the boundary between the Tana and Beles basins. The connection of the hydro-stratigraphic units, fracture distribution and orientation, high hydraulic gradient, spatial distribution of high-flux springs, and water budget imbalance of Tana Basin revealed that there is IGF from Tana Basin to Beles Basin, despite poor indications from results for hydrochemistry and stable isotopes. These findings will have practical implications for groundwater and water balance studies of the two basins. The study demonstrates the importance of a multimethod approach to investigate IGF where a single approach is imprecise. [ABSTRACT FROM AUTHOR]

In order to ensure the sustainability of cultural, historical and architectural heritage, preserving and restoring historical buildings and transferring them to future generations is one of the important issues of today. Restoration decisions regarding the repairs of historical buildings are of great importance in this context. Developing correct intervention decisions requires the thorough analysis of the structure, the determination of the structural and material properties meticulously, and the use the most appropriate materials for repairing it. However, only physical and chemical analyses are not sufficient to determine material properties of historical buildings; therefore, archaeometric analyses are needed to determine them more appropriately. In this study, it is aimed to determine the components and characteristics of the filling mortars of Oshki (Öşvank) Church, one of the most magnificent structures of the Eastern Anatolia region, in order to preserve the masonry structure and guide the restoration studies in the light of archaeometric analyses. The raw material properties of the samples taken from the filling mortars of the church were determined by the physical, chemical and petrographic analyses. As a result of the analyses, the aggregate-binding properties of Oshki Church filler mortars were determined. It was revealed that the aggregate content was determined as petrographic, lime was used as a binder and all samples contained pozzolan whereas no cement was used in any of the samples, and the samples did not contain marble rice/powder and organic additives like oil, protein etc. It has also been observed that the aggregate in the mortar content is compatible with the geological formations of near surrounding of the church. In this context, this study emphasizes the importance of archaeometric analysis in restoration of historical buildings. Moreover, differing from other studies in the literature, this study proposes mortar recipe to be used in the restoration of the church, which can pioneer to future studies in the field of architectural restoration. [ABSTRACT FROM AUTHOR]

Study of inclusions in gems from secondary deposits can give valuable clues on the geologic (and sometimes geographic) origin of these displaced materials. For the present study, seven gem quality fancy‐coloured sapphires from Songea, Tanzania, were selected with, rarely observed in these gems, garnet inclusions in order to better understand their formation. Therefore, Raman spectroscopy was used to study garnet, as well as rutile, aluminosilicate and mica inclusions. Garnet composition calculations were made using the MIRAGEM Raman spectra software, which was further improved for the purpose of this study. A couple of garnet inclusions were also analysed by energy dispersive X‐ray spectroscopy (EDS) attached to a scanning electron microscope (SEM). All garnet inclusions presented similar Raman spectra, thus similar chemical composition. Chemical analysis demonstrates that these are pyrope‐rich (>40%) garnets with over 30% of almandine and over 20% grossular without any detectable titanium, chromium and sodium. Calculations made using the updated/improved MIRAGEM software were able to indicate the same composition as compatible with the obtained chemical analyses. Muscovite and sillimanite were also identified using micro‐Raman spectroscopy. This inclusion scene is not similar to those described in fancy‐coloured gem sapphires from other localities. The exact geological formation of these gems is yet not understood but might be eclogite or upper mantle related. [ABSTRACT FROM AUTHOR]

Terrestrial gamma radiation is the major source of outdoor radiation exposure to human being. Because of the variation of underlying geological characteristics of surface soil, the terrestrial gamma radiation dose (TGRD) rates vary significantly with the soil type. This work performed in situ measurements of the TGRD rate for a range of geological formation and soils of Katsina State, Nigeria by using a portable hand-held radiation survey metre, RADOS. The TGRD rates ranged between 45 and 271 nGyh−1 with an overall mean value of 116 nGyh−1, which is two times higher than the world average value of 59 nGyh−1. Geological formation (Silicified sheared rock) was found to have the highest mean TGRD value of 163 nGyh−1. Likewise, soil type (lithosols, ferruginous crusts and ferruginous tropical soils) appeared to have the highest mean TGRD value of 134 nGyh−1. One-way ANOVA was used to investigate the variation of the significant difference between the geological formations and soil types with TGRD, which shows the influence of geological formation and soil types on the measured TGRD values of the study area. Measured data could further be used to evaluate the public radiation exposure and in formulating safety standards and radiological guidelines. [ABSTRACT FROM AUTHOR]