Geophysical Surveys Research Articles

Geological survey techniques and carbon storage: Optimizing renewable energy site selection and carbon sequestration

Geological survey techniques play a crucial role in optimizing site selection for renewable energy projects and identifying suitable locations for carbon storage to mitigate climate change. This abstract provides an overview of how geological survey techniques can be used to achieve these objectives. Renewable energy development, particularly solar and wind power, requires careful site selection to maximize energy generation efficiency and minimize environmental impacts. Geological surveys are instrumental in assessing factors such as subsurface geology, topography, soil composition, and hydrological conditions. These surveys help identify suitable locations with optimal wind or solar resources and geologic conditions for infrastructure development. Additionally, geological surveys are essential for identifying suitable sites for carbon storage, a critical component of carbon capture and storage (CCS) technologies aimed at reducing greenhouse gas emissions. Geological formations, such as deep saline aquifers, depleted oil and gas reservoirs, and unmineable coal seams, can serve as storage reservoirs for captured carbon dioxide (CO2). Geological surveys help characterize these formations to assess their suitability for long-term CO2 storage, considering factors such as porosity, permeability, and sealing integrity. Optimizing site selection for renewable energy projects and carbon storage requires a comprehensive understanding of subsurface geology and environmental conditions. Advanced geological survey techniques, such as seismic imaging, remote sensing, and geophysical surveys, are essential for acquiring detailed subsurface data. These techniques enable scientists and engineers to assess site suitability, evaluate risks, and design effective mitigation measures. In conclusion, geological survey techniques are invaluable tools for optimizing site selection for renewable energy projects and identifying suitable locations for carbon storage. By leveraging these techniques, stakeholders can make informed decisions that promote sustainable energy development and mitigate the impacts of climate change.

Topography and buildings of an early Islamic Andalusi city: evidence for Madīnat Ilbīra from excavations and ground penetrating radar

ABSTRACT Madīnat Ilbīra was the capital of one of the territorial organization units of the Umayyad state. The city was founded in the second half of the ninth century, and then abandoned in the eleventh century as a result of the collapse of the Caliphate of Córdoba and the transfer of the centre of the region to Granada. Its remains were located only in the nineteenth century. Modern excavations and non-invasive geophysical prospections carried out in this century allow the reconstruction of the spatial system of the city in the era of its greatest prosperity, the location of the citadel and the main mosque, and the reconstruction of the city’s buildings.

Investigation and Evaluation of Aquiferous Zones Within Orlu and Its Environs, Using a Geo-electrical and Physiochemical Approach

This study investigated the suitability of drinking water in Orlu, Nigeria, facing challenges due to limited surface water availability and environmental deterioration. To solve the problem of the availability of portable water, electrical resistivity surveys using a Schlumberger array were conducted to identify potential groundwater resources. Twelve locations were assessed, revealing resistivity values indicative of potential aquifers. Following the geophysical survey, the physicochemical properties of water samples collected from various locations were analyzed. Parameters including pH, dissolved oxygen (DO), total dissolved solids (TDS), and minerals were evaluated against WHO and Nigerian drinking water standards. The analysis indicated generally good water quality across the sampling sites. pH levels were within the recommended range, and DO concentrations met the minimum requirements. Similarly, TDS and BOD values suggested low levels of organic matter and dissolved solids. Mineral content also remained below WHO-permissible limits. A Water Quality Index further confirmed that the water quality within the study area can be graded from good to excellent in quality. These findings suggest that the groundwater resources identified in the study hold promise for providing safe drinking water in Orlu and its environs.

Geophysical Survey as Part of Rescue Archaeological Excavation on Large Construction Projects—Case Study: Road I/16 Slaný–Velvary (Czech Republic)

Geophysical Survey as Part of Rescue Archaeological Excavation on Large Construction Projects—Case Study: Road I/16 Slaný–Velvary (Czech Republic)

Marine exploration and its environmental impact assessment: insights from international standards

Rising demand for marine resources has led to a great interest in seabed exploration and mining, while deep-sea environments are faced with cumulative effects of many human activities. Currently, conducting an environmental impact assessment for deep-sea exploration and mining is challenging due to the dynamic nature and a lack of high-quality data. The International Seabed Authority (ISA), which charges with regulating human activities on the seabed beyond the continental shelf, requires contractors to establish both geological and environmental baselines. Also, the ISA provides a general environmental guideline for exploring various seabed resources. However, standardization of its implementation would need to be addressed with specified technical international standards. The marine technology subcommittee of International Standardization Organization (ISO) contributes to the study of standards on deep-sea geological, geophysical and biological surveys, also on marine environmental protection. In this review, we explore two broad aspects of ISO standards: (1) the development of marine geological and geophysical exploration standard, which may help to establish geological map in the seabed area. (2) the current state of development of a series of Marine Environmental Impact Assessment (MEIA) standards, which could standardize the environmental surveys and monitoring activities in the seabed area. We also consider the standardization gap between MEIA and seabed mining, and propose future focus on coordination relationship between marine exploration and environmental protection.

Unravelling the influence of heterogeneities and abstraction on groundwater flow and solute transport in a fractured carbonate aquifer, Sicily, Italy

The migration of a groundwater contaminant plume consisting of light nonaqueous phase liquids (LNAPLs) along the Ionian coastline of Sicily, Italy, has been reported to follow a trajectory that is inconsistent with the regional hydraulic gradient. The influence of several faults affecting the fractured carbonate bedrock aquifer, and groundwater abstraction from a well, were hypothesized to be responsible for the anomalous trajectory of the contaminant plume. A conceptual hydrogeological model was developed for the study area that incorporated structural information derived from geophysical surveys and the mapping of fractures in bedrock outcrops. This conceptual model was incorporated into numerical groundwater flow and solute transport models to simulate the groundwater transport of the light nonaqueous phase liquids. Four model scenarios representing different levels of complexity were tested to assess the relative influence of geological heterogeneity and groundwater abstraction on the migration of the contaminant plume. Results show that underground major discontinuity systems, invoking the presence of the faults in the model domain accounted for the observed migration of the contaminant plume, act as conduits for groundwater flow. Conversely, groundwater abstraction from a well was found to result in relatively minor, localized impacts to the migration of the contamination plume. This study demonstrates the importance of incorporating geological heterogeneity into groundwater modelling and environmental risk assessments associated with the storage of LNAPLs.

The KISS Network in 2015–2016: Catalogs and Comparison of the Processing Results with Operational Estimates from the Permanent Network

As part of the international collaboration of several research groups from Russia, France, and Germany, 77 temporary seismic stations were installed in the summer of 2015 for one-year period to conduct a detailed study of the deep structure of the Earth’s crust and upper mantle in the region of the Klyuchevskoi Volcano Group (KGV) in the Kamchatka Peninsula. One of the results of the KISS experiment (Klyuchevskoi Investigation – Seismic Structure of an extraordinary volcanic system) was the final catalog of the joint data from the temporary stations and the permanent network of the Kamchatka Branch of the Geophysical Survey of the Russian Academy of Sciences (KB GS RAS). The catalog comprises 2136 events, including 560 for which the permanent network catalog lacked sufficient data for correct processing. The catalog in .xlsx format and the station bulletin in .isf format are presented in the supplementary material to the paper. A comparative analysis was conducted on the joint solutions of two catalogs: one obtained solely from the data of the KB GS RAS permanent network stations and another from a denser seismic network integrated with KISS stations.

Analysis of Spatial Clustering of Seismic Events by the DPS Topological Filtering Algorithm: Lake Baikal Region

The paper presents the results of applying the Discrete Perfect Set (DPS) topological filtering algorithm to analyze the spatial clustering of seismic epicenters in the Lake Baikal region. The study utilizes earthquake data recorded by the seismic network of the Baikal Branch of the Geophysical Survey of the Russian Academy of Sciences within the latitude range 48°N, 58°N and longitude range of 99°E, 122°E for the period from 1964 to 2018. Clustering characteristics are obtained for (i) the recording period from 1989 to 2018 with varying parameters of the DPS algorithm and four levels of the minimum energy class KР of seismic events and (ii) six non-overlapping time intervals from 1964 to 2018 and seismic events of energy class KР ≥ 8.6 with fixed parameters of the DPS algorithm. The dynamics of the clustering parameters from 1964 to 2018 may characterise the variability of the seismic regime of the region. Specifically, the decrease in the linear size of the areas of identified epicenter groups from about a thousand km to tens km may indicate a significant change in the seismic regime of the Lake Baikal region at the end of the 1990s and the beginning of the 2000s compared to the period between 1964 and 1997.

Seismic moment tensor solutions and geophysical settings in the Philippine Sea basin mapped by GMT

The study is focused on mapping geophysical settings on the margins of the Philippine Sea Plate (PSP). Active volcanism and seismic situation along the margins of the Philippine Sea Basin (PSB) shows earthquake events demonstrating high seismicity of the region caused by tectonic plate subduction. The aim was to perform cartographic mapping of the earthquake events using Generic Mapping Tools (GMT) modules, to analyze seismic situation through visualization of the geophysical datasets. The data was processed by GMT using multi-source data: GEBCO, CMT and ISC seismic data. Technically, a set of GMT modules was used ('psmeca', 'psvelo', 'grdtrack', 'grdimage') for data modelling and mapping. An application of GMT functionality is presented by selected code snippets with selected code snippets for 'psmeca' and 'psvelo', 'img2grd', 'img2grd' modules. Current paper presents a report on the cartographic techniques applied for geophysical mapping. Centroid moment tensor solutions are visualized for shallow depth earthquakes of Mw <10 along the PSB margins from 1976 to 2010. Earthquakes along the tectonic plate subduction zone are shown by GMT. Data from Global Centroid-Moment-Tensor (CMT) Project. Presented and explained GMT code snippets contribute to the development of methods in geological mapping using GMT scripting toolset, for visualizing focal mechanisms.

Heuristic algorithms for design of integrated monitoring of geologic carbon storage sites

Designs for Risk Evaluation and Management (DREAM) is a tool developed under the National Risk Assessment Partnership (NRAP) to enhance geologic carbon storage safety and efficiency. Using potential leakage scenarios generated externally by the users preferred history-matching approach, DREAM constructs ideal combinations of sensor locations in the right place at the right time to detect as many leaks as possible, detect them as early as possible, and minimize cost. This user-friendly tool, developed in Java, features a window-based GUI for input and a 3D visualization tool for viewing the domain space and optimized monitoring plans. DREAM's latest version accommodates real-world usage by allowing for joint optimization of wellbore point sensor placements and surface geophysics survey geometries, and by using more efficient multi-objective optimization algorithms. In an example shown here, these two improvements combined allow us to support containment assurance and go from detecting 80–90 % of the potential CO2 leakage to +99.7 %, a step-change improvement that can make the deciding difference in whether a site is suitable for geologic carbon storage. Though developed for geologic carbon storage, this tool would be equally applicable in many surface or offshore environmental monitoring projects.

Explicit observation of tertiary magnetic field in TDEM transients; plausible explanation towards induced polarization effect in geophysical prospecting

In time domain electromagnetic central loop sounding or coincidence loop measurements often a sign reversal is observed in the recorded decay transients. These negative decay transients are generally attributed to induced polarization effect. We observed a similar sign reversal in the decay transients recorded with SQUID as a receiver in central loop sounding measurements at later decay times. The magnitude of the secondary magnetic field observed in the negative decay transients is considerably high and the SQUID output never reaches its noise floor even at decay times of >155 ms. This observation stimulated us to record the current flow in the transmitter loop and therefore a small resistor is connected in series with the transmitter loop. Decay transients have been recorded simultaneously across the resistor and the SQUID which is located at the centre of the transmitter loop. To our surprise, the time at which the sign reversal occurred in the recorded decay transients with SQUID and across the resistor confirmed that the SQUID is recording the magnetic field produced by the flow of the induced current in the transmitter loop in addition to the decay of the secondary magnetic field from the ground. A novel hypothesis has been proposed to explain the flow of induced current in the transmitter loop and extensive laboratory experimental simulations have been performed to prove it. The proposed novel hypothesis explains the occurrence of sign reversal in TEM systems not only in single loop but also in coincidence loop and central loop TEM configurations. In all cases, the sign reversal is due to the self induced tertiary magnetic fields. In this work, a set of transient measurements have been carried out with different targets and different thicknesses. The experiments have been repeated by locating the targets at different depths in order observe the response of the tertiary magnetic field in the decay transients. The experimental data and subsequent analysis confirmed our hypothesis that the self induced tertiary magnetic field is responsible for the sign reversals rather than the induced polarization effects.

A Case Study of the Integration of Ground-Based and Drone-Based Ground-Penetrating Radar (GPR) for an Archaeological Survey in Hulata (Israel): Advancements, Challenges, and Applications

This study delves into the fusion of ground-based and drone-based ground-penetrating radar (GPR) technologies in archaeological exploration. Set against the backdrop of the Hulata solar panel construction site in Israel, the research confronts daunting obstacles such as clayey soil, accurate detection of small objects, and the imperative of timely reporting crucial for construction management. The drone-based GPR, a testament to technological innovation, showcases remarkable adaptability to challenging terrains, dispelling doubts about electromagnetic wave decay in clayey soil. Methodologically, the study employs detailed orthophoto mapping and grid-type surveys. The correlation of the results significantly bolsters the reliability of archaeological discoveries, uncovering scattered artifacts buried approximately 1–1.5 m below the surface. Meticulous excavations validate the geophysical surveys, affirming the presence of structures constructed from boulders. The application at the Hulata site validates the adaptability of drone-based GPR in challenging terrains. It provides a swift, cost-effective, and minimally invasive alternative to traditional excavation techniques, thereby transforming the field of archaeology.

Groundwater Exploration and Assessment in Arid and Semi-Arid Regions of Basaltic Terrain of Solapur: Lessons Learned and Future Prospects

This research delves into the intricate dynamics of groundwater exploration and assessment in the arid and semi-arid basaltic terrain of Solapur, India. The study investigates the hydrogeological complexities of the region, emphasizing the importance of community involvement and sustainable practices in groundwater management. Employing advanced geophysical surveys, borehole logging, and hydrogeological modeling, the research uncovers the challenges and successes encountered during the study, providing valuable insights for future exploration strategies. Key findings highlight the heterogeneity of basaltic formations, the significance of local community engagement, and the need for adaptive approaches in groundwater exploration. Lessons learned from successes in geophysical surveys and challenges faced in borehole logging contribute to the knowledge base for effective exploration techniques in similar geological settings. The research's significance for Solapur lies in its potential to guide sustainable water management practices, empower local communities, and inform policy formulation. The emphasis on community involvement, awareness, and regulatory measures serves as a foundation for addressing water scarcity challenges in the region. Beyond Solapur, the study holds broader implications for arid and semi-arid regions globally. It contributes to scientific knowledge, informing policy frameworks, and promoting community-centric approaches to groundwater management. The research provides a blueprint for addressing water resource challenges in diverse geographical contexts, ensuring the resilience of communities and the preservation of vital groundwater resources.

Determination of Earthquake Depths Using Data of Cross-Sectional and Areal Deep Seismic Studies in Siberia

Abstract ––Information on the distribution of earthquake hypocenters for many seismically active zones of Siberia remains insufficient, which is associated with sparse networks of seismological observations. The paper presents the results of determining the earthquake depths in several seismogenic areas in the Altai-Sayan region, Cisbaikalia, Transbaikalia, and Yakutia using the travel time of longitudinal refracted waves from the Mohorovičič discontinuity (Pn waves) from earthquakes and the recently obtained information about the deep structure of these regions. The depth determination algorithm is tested using data from aftershocks of large earthquakes occurring in Tuva in 2011 and 2012 (ML = 6.7 and 6.8), recorded both by the regional seismological network and by a local group of seismic stations. Different methods are applied to reveal that some aftershock depths have a close match, including those for the main shocks – the Tuva-1 and Tuva-2 earthquakes. Another good match of earthquake depths is obtained using Рn waves with materials from regional and detailed studies of the Baikal branch of the Geophysical Survey of the Russian Academy of Sciences in the Muyakan activation site in the Baikal rift zone. The resulting data complement the information on the hypocenter of the main shock and confirm the change of the Muyakan activation cluster from large depths to shallow ones since the onset of activation in 2014. New information on the earthquake depths using Рn waves is obtained in Yakutia along the border of the largest Eurasian and Okhotsk tectonic plates. It is revealed that they decrease to 6–12 km as compared to higher depths of 20–30 km in adjacent areas. The resulting series of new information on the distribution of earthquake hypocenters using Рn waves is extremely important mostly because it indicates the possibility of identifying and redefining earthquake hypocenters using previous seismological observations in seismically active zones of Siberia.

Geophysical survey and radiometric assessment of aquifer strata and vulnerable groundwater quality of Ukwuani Ommunities in Delta State

The study assessed the aquifer strata and groundwater quality of Obeti, Umuaja, and Ebedei communities of Ukwuani, Delta State, Nigeria using electrical resistivity technique and sodium iodide [Na(TI)] detector. The electrical resistivity technique revealed that lithology has five to six geoelectric strata, which ranged from topsoil to clay formations with thickness of 0.6 to 6.0 m sits and aquifer resistivity range of 182.1– 6032.0 Ωm with depth of 29–70 m. These ranges indicate significant changes in the aquifer level and sufficient reservoirs for groundwater. To assess the activity concentrations of 238U, 232Th and 40K at the aquifer depth of 29–70 m groundwater, a total of fifteen groundwater samples were collect for analysis and the mean results are 9.00±1.24Bql−1, 4.82±2.95Bql−1 and 57.93±4.20Bql−1 respectively. These results are all above world threshold limits. However, the computed mean radiological health risk values for radium equivalent (Raeq), representative index (Iy), external hazard index (Hin), internal hazard index (Hex), absorbed dose rate (D), annual effective dose equivalent (AEDE), outdoor and indoor, and excess lifetime cancer risk (ELCR) outdoor and indoor are 20.35±5.78 Bql−1, 0.15mSvy−1, 0.056mSvy−1, 0.08mSvy−1, 9.55μGyh−1, 11.71mSvy−1, 46.84mSvy−1and 0.04×10−3, 0.16×10−3 and 0.20×10−3 for the addition of (ELCR) outdoor and indoor respectively. The computed mean radiological values are below world threshold limits. Hence, the studied communities’ drinking groundwater is safe radiologically. It is advised that government, oil and gas operators and individuals should drill above 30 m depth for quality groundwater and should be treated before usage. These values will serve as baseline data.

Shallow geothermal field multidisciplinary exploration: New data from Campi Flegrei caldera (CFc) for low—middle enthalpy resource exploitation

In the framework of the GeoGrid project, with the specific goal to look for shallow geothermal resources suitable to test the developed technologies, the Agnano geothermal field, a relatively unexplored sector of the eastern Campi Flegrei caldera, was investigated through a multidisciplinary geophysical, stratigraphic and hydro-chemical surveys. Such multidisciplinary approach allows us to reconstruct the subsurface morphology below the Agnano Hyppodrome (AH), interpreted by gravimetric, seismic and stratigraphic data, as a complex structure characterized by a gradual southward and south-eastward deepening of a high-density contrast interface. Moreover, the inferred models show two pronounced lateral depressions in agreement with the existence of known lateral faults bounding the western and eastern flanks of AH, while the hydro-chemical survey of the entire Agnano caldera revealed discontinuous manifestations of thermal waters along the groundwater flow direction. Furthermore, it was found that, within the southern sector of the Agnano caldera, mineralized waters predominantly align with a primary NE-SW buried structural lineament, a feature only hypothesized in previous studies and that in this sector local fresh groundwater likely receives endogenous inputs, including CO2 at elevated temperatures, potentially leading to the mixing of seawater or deep brine. Finally, our results individuate an area north of the Agnano Hippodrome characterized by a significant presence of higher temperature mineralized water, but lacking of seawater enrichment, making it a favorable site for further exploitation of low-to-medium-enthalpy geothermal sources.

Exploring Medium and Low-Temperature Convective Geothermal Resources Through Controlled Source Audio Magnetotelluric Mothod

Medium and low-temperature convective geothermal resources are a crucial component of China's geothermal wealth, primarily concentrated in the eastern coastal regions. To maximize the utilization of these resources, geophysical surveys are essential, with controlled source audio magnetotelluric(CSAMT) being a prominent and effective method employed in geothermal resource assessments. This study focuses on applying CSAMT to survey specific geothermal sites, including the Xiu Yan Gou Tang Hot Spring, Fengcheng Gou Tang Hot Spring, and Hai Cheng Xi Huang di Geothermal Field. The results obtained through this method provide detailed insights into the distribution of both deep and shallow thermal storage spaces within these fields, shedding light on the intricate thermal circulation systems associated with them. These findings serve as a reliable foundation for planning and executing further geothermal resource development projects. CSAMT emerges as a comprehensive tool for understanding the nuances of medium and low-temperature convective geothermal resources.

Subsurface Mapping of Groundwater Contamination Pathway at Using Very Low Frequency Electromagnetic Method at Waste Site of Kubanni Basin, Zaria, Kaduna State

Subsurface Mapping of Groundwater Contamination Pathway at Using Very Low Frequency Electromagnetic Method at Waste Site of Kubanni Basin, Zaria, Kaduna State

Predicting the compressive strength of tight sandstone based on the low field NMR and pseudo-triaxial compression measurements

The compressive strength is very important for petroleum and other engineering studies. However, the effect of pore size and fluid distribution on the rock’s strength is not fully understood. We developed comprehensive research to study the controlling factors of the compressive strength based on low field nuclear magnetic resonance (NMR) measurements and pseudo-triaxial compression test for tight sandstones. The relationship between the compressive strength and the NMR obtained parameters are investigated completely, aiming for a better estimation of the compressive strength using the NMR data. The result shows that the rock’s strength is strongly controlled by the pore size distribution and the fluid existing state. Generally, the compressive strength is negatively correlated with the average transversal relaxation time, the movable water saturation, and the porosity, but positively correlated with the irreducible water saturation. The result reveals that the rock with larger pore radius and higher percentage of movable fluid is easier to reach the failure state. Further, the precision of the empirical model by multiple regression of the geometric mean of the relaxation time and the porosity is greatly improved compared with the model established by the brittle minerals, which is potentially to be use for geophysical prospecting when the NMR logging data is available.

Ground Prediction by Markov-ANN Hybrid Analytics Using Baseline Geotechnical Data and Observed Field Data

ABSTRACT Geology along the tunnel length usually differs from the anticipated data as per Geotechnical Baseline Report (GBR), sometimes quite significantly. This has always led to the disruption of the planning, resource mobilisation, cost and duration of the project. One way to minimise this uncertainty is by exhaustive investigation like probe holes and geophysical prospecting. Forecasting or prediction of Geology can also be done by soft computing and analytical methods. Using the analytical tool of the Markov Model and the learning powers of Artificial Neural Networks (ANN) has been attempted in this study. The idea is to build a hybrid model that would combine both capabilities and do a probabilistic prediction of the ground condition ahead of the tunnel face in real time to better suit the site, accommodate complexities and can capture the associated uncertainties. The Geotechnical Baseline Report (GBR) having the initial survey details of the tunnel geology is used to build the Markov Model while the deterministic borehole data in the GBR is used to build the ANN model. Bayesian joint probability theorem is used to update the model with the face observed geological parameters. This hybrid model demonstrated to be a good complement to the physical forecasting methods and the geological uncertainty of a complex and challenging Himalayan region was well captured by the present approach. The window of the prediction was for a region of approximately 250m where it showed a very good prediction of ground class. The model can help in systematic planning and resource mobilisation in a better way and subsequent key decisions for the upcoming excavation method and corresponding support measures.