Applied Geophysics Research Articles

Groundwater Study in Limestone Area using Geophysical Methods

Applied geophysics is important for groundwater investigation. Drilling groundwater boreholes without geophysical survey is probably unsuccessful. Meth district, Vientiane Province is the study site due to the most area coving with limestone area. The objective of this study is to define the groundwater model including location, depth and thickness of aquifer using 2D resistivity measurement, groundwater flow direction using self potential measurement. In addition, basic groundwater quality (pH, Ec and TDS) is also defended. 2D-Electrical Resistivity Tomography (2D-ERT) meauremnt using Wenner arrray was conduced for 2 lines with 300m of length and a varying from a=5m to 100m. Self Potential measurment using fixed-base method was performed for 3 lines with 300m of leng and 10m spacing of each measurming point. The results of the 2D-ERT show that low resistivity from 10 to 80 ohm-m at depth of 20-28m interpreted as aquifer layer. But high resistivity from 200 to 600 ohm-m is resulted from base rock. The volage from SP measurment varying ranging from -14 to 24 mV can be defined the flowdirection from NE-SW direction. It is correlating with the topography of the area. The result of physical properties from 3 samples show that pH=6.8±0.5, Ec=480±115 mS/cm, and TDS=343.3±80.2 mg/l. are under the standard values issued by Minstry of Health, Laos.The water qulity is good . The geophysical survey is effective usful methods for groundwater suvey due to low cost and rapid for survey. Geophysical result could be intributed to comunity, government sectors in order to high effective management the groundwtater resources in the future. Moreover, the data is also usfull for researcher and students.

Introduction to this special section: Geophysics and sustainability

Unprecedented levels of greenhouse gasses in the atmosphere drive climate change by trapping heat and raising global temperatures. This warming effect disrupts weather patterns, increases the frequency of natural disasters, and contributes to rising sea levels. Applied geophysics can significantly alleviate anthropogenic emissions and accelerate the transition to cleaner energy sources such as wind, solar, geothermal energy, and hydrogen. One solution at the core of energy transition is the broad application of carbon capture, utilization, and geologic storage (CCUS) at the scale of gigatonnes of sequestered CO2 to reduce greenhouse gas emissions during the transition to a carbon-neutral future. Geophysical monitoring is central to the success of CCUS. In particular, seismic methods serve as a primary tool to ensure compliance and safety in CCUS projects. However, the role of geophysics in sustainability is a broader topic extending beyond carbon geosequestration.

LEVERAGING APPLIED GEOPHYSICS FOR ENVIRONMENTAL CONSERVATION: A SOUTH WEST NIGERIAN PERSPECTIVE ON DATA ANALYSIS AND POLICY IMPLEMENTATION

This research aimed to delve into the potential of applied geophysics in environmental conservation, with a specific focus on the South West Nigerian context, and its implications for data analysis and policy implementation. Through a comprehensive review of peer-reviewed articles, case studies, and primary research, the study explored various geophysical techniques and their applications in environmental conservation efforts. The research highlighted the efficacy of these techniques in the South West Nigerian region, emphasizing their significance in shaping environmental policies. Despite the evident potential, challenges and limitations associated with these techniques were also identified. The study further provided suggestions for improved environmental conservation strategies and highlighted potential areas for continued research in the realm of applied geophysics. In conclusion, while applied geophysics offers promising tools for environmental conservation, a holistic approach, integrating both scientific and policy-driven strategies, is essential for sustainable conservation efforts in South West Nigeria. Recommendations include fostering collaborations between geoscientists, policymakers, and local communities, and investing in further research to address identified gaps.
 Keywords: Applied Geophysics, Environmental Conservation, South West Nigeria, Policy Implementation, Data Analysis.

A Mediterranean drifter dataset

Abstract. Over a hundred experiments were conducted between 1998 and 2022 in the Mediterranean Sea using surface Lagrangian drifters at coastal and offshore levels. Raw data were initially unified and pre-processed manually by eliminating spikes and wrong positions or date/time information. The integrity of the received data packages was checked, and incomplete ones were discarded. Deployment information was retrieved for each drifter and integrated into the PostgreSQL database, realized and maintained by the National Institute of Oceanography and Applied Geophysics (OGS) in Trieste (Italy). This database also collects a variety of metadata about the drifter model, project, owner, and operator. Subsequently, data were processed using standard procedures of editing and quality control developed for the OGS drifter dataset to remove spikes generated by malfunctioning of the sensors and to obtain files with common characteristics. Drifter data and plots of each track were also visually checked to remove any point not identified by the automatic procedure and which were clearly erroneous. Drifter trajectories were split into two or more segments that are considered different deployments in the case of specific drifter behaviour. Data were interpolated at defined time intervals providing a dataset of 158 trajectories, available from the public open-access repository of SEA scieNtific Open data Edition (SEANOE) at https://doi.org/10.17882/90537 (Ribotti et al., 2022), in two versions (one compliant with the Copernicus format and the other one usable with Panoply netCDF viewer), and of SeaDataNet at https://cdi.seadatanet.org/search/welcome.php?query=2610&query_code={9F00DF80-1881-42DD-9DF1-B9BD0282F2B0} (last access: 5 October 2023).

Editorial for the Special Issue “Applied Geophysics in Hydrocarbon Exploration, Energy Storage and CCUS”

Since its inception, applied geophysics methods have been crucial in the oil and gas exploration industry [...]

Reprocessing 2-D airgun seismic reflection data SALTFLU (salt deformation and sub-salt fluid circulation in the Algero-Balearic abyssal plain) in the Balearic promontory and the Algerian basin

In an ever more challenging context for the acquisition of seismic data in the Mediterranean Sea, reprocessing to improve the quality of legacy data has become increasingly important. This work presents the newly reprocessed, open access dataset SALTFLU acquired in the Algerian basin by the National Institute of Oceanography and Applied Geophysics (OGS) in 2012. We apply a ‘broadband’ reprocessing strategy adapted for offset-limited (3 km streamer for a target 4 km below the sea level) airgun reflection seismic data acquired in deep water settings. We then assess if the reprocessed images provide new geological insights on the Mediterranean sub-surface. The workflow relies on an integrated approach combining geophysics and geological interpretation to iteratively build the velocity model. In this way we aim to tackle some of the challenges linked to imaging deep complex geological structures containing high velocity contrasts with 2-D, offset-limited seismic data. We first broaden the bandwidth of the data through multi-domain de-noising, deghosting and a source designature using an operator derived from the seabed reflection. We then perform iterative migration velocity analysis, pre-stack time migration and multiple attenuation in the Radon domain to obtain time-migrated images. The initial velocity model is derived from the resulting time migration velocities, and geologically driven model updates are generated using a combination of travel-time tomography, seismic interpretation of the major salt horizons and velocity gradient flooding. The gradient flooding aims to reproduce the large scale first-order velocity variations, while the travel-time tomography aims to resolve the smaller second-order velocity variations. The results improve our deep geological knowledge of the under-explored Algerian basin down to the base salt and the pre-salt. Fluid indicators are imaged within the Plio-Quaternary of the Algerian basin, which we interpret as thermogenic or biogenic gas sourced from either the Messinian Upper Unit or from the pre-salt, migrating through a hydro-fractured salt. The reprocessed data image lateral and vertical seismic facies variation within the Messinian units that could shed new light on the tectono-stratigraphic processes acting during the Messinian Salinity Crisis. It also reveals numerous previously unresolved volcanic structures within the Formentera basin.

Creation of the first UXO detection test site in Slovakia at the Rohožník military training range

In the development of geophysical methods for unexploded ordnance detection, a very important role is played by UXO test sites, where known ordnance and other explosive/nonexplosive items are buried in the ground at defined positions. At such sites, various detection methods can be compared, developed and tested. Based on a cooperation between the Department of Applied Geophysics (Comenius University), Institute of Forensic Science (Slovak Ministry of Interior) and Rohožník military training range a project was performed, which was focused on the creation of the first UXO detection test site in Slovakia. It was restricted to one type of ordnance – inert tank projectiles with diameter of 100 mm. These were buried in the ground at different depths and with different orientations. Data acquisition mapping the test site was performed from the ground surface, using total field intensity magnetometers, vertical difference magnetometers and ground penetrating radar (GPR). Data acquired from all methods were processed, interpreted and archived for future reference. Most of the items were readily detected by each of the detection sensors used but the deepest items at the least favourable orientation exceeded the detection limit of the magnetometers trialled with total field performing better than the vertical gradiometers. For the application of GPR, this site was found to have favourable soil conductivity conditions permitting even the deepest items to be detected when favourably oriented. Vertical orientation presenting the smallest reflective cross-section was least favourable with some shallow items escaping detection. The most accurate depth estimations for detectable items were obtained from GPR data presented as 2D non-migrated vertical sections. Geophysical data sets acquired at seeded test sites such as the one now established at the Rohožník military training range can provide important base-line data for comparison from which development of new detection and data interpretation technologies can be evaluated.

Structure of the Kathmandu basin inferred from microtremor measurements: a preliminary study

SUMMARY This research aims at characterizing the deep sedimentary basin of Kathmandu (Nepal) from microtremor measurements, by using two surveys carried out in November 2015 and November 2018. The data collected are sufficient for a qualitative investigation of the seismic response of such a complex basin. The measurements were undertaken in the framework of a collaboration between the NSET (National Society for Earthquake Technology, Nepal) and the OGS (National Institute of Oceanography and Applied Geophysics, Italy). During the two campaigns, a series of passive seismic surveys were made, taking into consideration both single broad-band sensors and arrays. The 2015 study initially focused on the Lalitpur area (southern part of Kathmandu) and was later extended to the northern and more urbanized area of the capital city of Nepal. The 2018 survey focused on estimating the S-wave velocity field of the entire stratigraphic sequence by array and a repetition of some Horizontal to Vertical Spectral Ratio (HVSR) measurements close to two boreholes with reliable stratigraphy. Two inversion methods, using the data from the seismic arrays, were useful to infer the S-wave velocity profiles of the shallower layers and to interpret some HVSRs. The outcome is a map of the periods of single station data representing the seismic response of the basin. Comparing these results with the strong motion data of the Gorkha 2015 main shock, we confirm that the longer periods are not only the effects of the earthquake source, but also of the local response of the basin itself.

Inaugural Camp for Applied Geophysics Excellence (CAGE)

Inaugural Camp for Applied Geophysics Excellence (CAGE)

LZER0: A Cost-Effective Multi-Purpose GNSS Platform.

Recent advances in Global Navigation Satellite System (GNSS) technology have made low-cost sensors available to the mass market, opening up new opportunities for real-time ground deformation and structure monitoring. In this paper, we present a new product developed in this framework by the National Institute of Oceanography and Applied Geophysics-OGS in collaboration with a private company (SoluTOP SAS): a cost-effective, multi-purpose GNSS platform called LZER0, suitable not only for surveying measurements, but also for monitoring tasks. The LZER0 platform is a complete system that includes the GNSS equipment (M8T single-frequency model produced by u-blox) and the web portal where the results are displayed. The GNSS data are processed using the RTKLIB software package, and the processed results are made available to the end user. The relative positioning mode was adopted both with real-time and post-processing RTKLIB engines. We present three applications of LZER0-cadastral, monitoring, and automotive-which demonstrate that it is a flexible, multi-purpose platform that is easy to use in terms of both hardware and software, and can be easily deployed to perform various tasks in the research, educational, or professional sectors.

μRate: An online dose rate calculator for trapped charge dating

AbstractIn this work, we present a new online service for dose rate calculations in trapped charge dating called “μRate”. The app provides a graphical user interface, convenient cloud storage of data, and the ability to exchange data between users. The data records are organised into projects, which can be easily recalculated with modified parameters. Calculations can be carried out for a wide variety of input data originating from different instruments. Radionuclide concentrations can be supplied in several formats and units. The calculations' results can be easily exported. The tool has been created specifically to maximise the flexibility of use and provide a stringent uncertainty estimation using the Monte Carlo method. In addition, μRate can perform a Sobol sensitivity analysis that can help assess the significance and risks associated with each parameter used in calculations. In addition, the app allows for temporal variability in cosmic radiation intensity, which may be of significance in low dose rate samples. The app's results are compared with other dose rate calculation methods, namely Dose4Win, DRAC, and dose rate R scripts, all used in the Leibniz Institute for Applied Geophysics, indicating good agreement with other calculation methods.

Inaugural Camp for Applied Geophysics Excellence (CAGE)

Inaugural Camp for Applied Geophysics Excellence (CAGE)

Applied Geophysics for Managed Aquifer Recharge.

Increasing water stress and decreasing supplies caused by growth and climate variability have expanded demand for managed aquifer recharge (MAR) projects to provide water supply resilience. Some of the most important factors in determining the performance of a MAR project include site selection, subsurface hydrogeologic characteristics and associated properties of the storage zone. Costs for invasive subsurface investigations to address these factors have slowly increased over the past two decades, with drilling costs increasing dramatically by as much as 30% or more since COVID-19 hit, a result of supply chain issues, steel prices, and manpower challenges. This paper provides a high-level review of major geophysical methods that have become more mainstream over the past decade or two to supplement invasive subsurface investigations and are very cost effective when compared to drilling boreholes and installing wells, which provide only point data. The more commonly used surface geophysical methods include ground-based and airborne time-domain electromagnetic methods (TEM), electrical resistivity, and seismic reflection. Airborne TEM methods (AEM) collect data very quickly, avoiding ground-based access constraints, and land-based methods are especially efficient using towed arrays. Electrical resistivity measurements provide resolution comparable to TEM but require more time than towed methods. Seismic reflection surveys are more expensive than other methods but typically have a much greater depth of penetration and can provide high resolution information on aquifer geometry, geology, and faults. Borehole geophysics is one of the more common methods used in MAR, providing near hole formation data and ground truths surface geophysics.

ЛАБОРАТОРНЫЙ ЭКСПЕРИМЕНТ ПО ИССЛЕДОВАНИЮ ВОЗДЕЙСТВИЯ ИОННОГО ВЕТРА КОРОННОГО РАЗРЯДА НА ТЕПЛЫЙ ТУМАН В ЗАМКНУТОМ ОБЪЕМЕ

The ion wind ability to initiate motions in the originally motionless warm fog inside an enclosed volume is studied. The objective of the study is the experimental check of the possibility to exploit corona discharges for the warm fog modification. The experiment was carried out in a specialized laboratory unit in the Fedorov Institute of Applied Geophysics. The possibility of using the unit to explore the effect of corona discharges on warm fogs is clearly demonstrated.

A High-Precision Elastic Reverse-Time Migration for Complex Geologic Structure Imaging in Applied Geophysics

High-precision elastic reverse-time migration (ERTM) imaging has always been one of the trends in the development of geophysics. However, current wavefield simulations using time-domain finite-difference (FD) approaches in ERTM have second-order temporal accuracy, resulting in travel time changes and waveform distortion in wavefield propagation with large time steps, i.e., temporal dispersion. Errors caused by the temporal dispersion can lead to erroneous imaging locations and out-of-focus diffraction events. A new ERTM and its workflow are established here using temporal and spatial high-order FD accuracy wavefields and the vector-based imaging condition. Our method computes elastic vector-based wavefields by solving a P- and S-wave decomposition form of a quasi-stress–velocity equation. An advanced finite-difference scheme is employed in the wavefield solution to achieve simulation with temporal fourth-order accuracy and spatial arbitrary even-order accuracy. The normalized dot-product imaging condition of the source and receiver P/S wavefields is then applied to generate high-quality images. The elastic wavefield simulation and ERTM numerical examples presented here reveal that the anti-dispersion workflow can improve modeling and imaging accuracy. In addition, the field data application shows that our method can achieve reasonable and reliable ERTM images. This method can integrate the most advanced imaging techniques into this computational framework to improve imaging accuracy.

Hydrological and Meteorological Variability in the Volga River Basin under Global Warming by 1.5 and 2 Degrees

The idea of the research to assess the impact of 1.5 °C and 2 °C global warming in the 21st century on the runoff formation in the Volga basin corresponds to the Paris agreement on climate change 2016 with the main goal to keep the global air temperature rise to below 2 °C relative to the pre-industrial level and to take measures to limit warming to 1.5 °C by the end of the 21st century. The purpose of this study was to obtain physically based results of changes in the water regime of the Volga basin rivers under global warming by 1.5 °C and 2 °C relative to pre-industrial values. The physical and mathematical model of runoff generation ECOMAG (ECOlogical Model for Applied Geophysics) was applied in calculations using data from global climate models (GCMs). The estimation of flow anomalies of the Volga River and its major tributaries showed a decrease in annual runoff by 10–11% relative to the period from 1970 to 1999. The largest relative decrease in runoff by 17–20% was noted for the Oka and Upper Volga rivers, while the Kama River had only a 1–5% decrease. The Volga winter runoff increased by 17% and 28% under global warming by 1.5 °C and 2 °C, respectively, and negative runoff anomalies during the spring flood and the summer–autumn period turned out to be in the range of 21 to 23%. Despite the increase in precipitation, the role of evaporation in the water balance of the Volga basin will only increase.

Instrumental Determination of the Earth\u2019s South Magnetic Pole Position During the Round-the-World Antarctic Expedition on Board the Russian Navy ORV Admiral Vladimirsky

—The round-the-world Antarctic expedition of the Russian Navy that took place from December 2019 to June 2020 on board the Russian Navy oceanographic research vessel (ORV) Admiral Vladimirsky was supported by the Russian Geographical Society and was dedicated to the 200th anniversary of the discovery of Antarctica and the 250th birthday anniversary of Admiral Ivan Kruzenshtern. One of the expedition’s main objectives was to instrumentally determine the position of the South Magnetic Pole (SMP) whose latest location had been measured more than twenty years before. Planning of magnetometric research, its monitoring and processing of obtained data were carried out by members of the Chair of Geophysical Methods of the Earth’s Crust Study of the MSU Department of Geology and the Fedorov Institute of Applied Geophysics. Based on a set of instrumental determinations (modular proton-precession differential magnetometers, vector three-component flux-gate magnetometers, the ship compass), the SMP position was measured to a precision of ±5 km. Proceeding from the 1980 and 2000 instrumental SMP determinations, it is proven that over the past 40 years, the SMP has been shifting at a consistent velocity in the same direction.

Geophysical and Geotechnical Investigations for Subsoil Competence at a Proposed Hostel Site at Oba Nla, Akure Southwestern Nigeria

Geophysical and Geotechnical Investigations for Subsoil Competence at a Proposed Hostel Site at Oba Nla, Akure Southwestern Nigeria by Festus Olusola Eebo * , Abidakun Bayode Samuel , Gbenga Moses Olayanju Department of Applied Geophysics, Federal University of Technology, Akure, Nigeria * Author to whom correspondence should be addressed. Journal of Engineering Research and Sciences,

Can high-school students contribute to seismic risk mitigation? Lessons learned from the development of a crowd-sourced exposure database

On a global scale, one out of three people is exposed to earthquakes, and most injuries and deaths in case of seismic events are caused by the damage or collapse of residential buildings. Knowing the type and distribution of exposed assets, in particular buildings, is thus paramount for effective mitigation of disasters. Citizens' involvement in disaster risk reduction activities is constantly increasing by means of crowdsourced data collection, education/training and citizen science activities. In particular, schools have a central role in engaging young students and increasing risk awareness and preparedness. In this work, we explored whether students’ participation in this kind of activities can lead to the improvement of current exposure datasets, while increasing citizens' risk-related understanding. In 2021, due to the restrictions imposed by the COVID-19 pandemic, the National Institute of Oceanography and Applied Geophysics - OGS started a new project to be deployed in fully remote mode, named “CEDAS: building CEnsus for seismic Damage ASsessment”. The project consists in the collection and elaboration of crowdsourced data on main residential buildings typologies of northeastern Italy, a seismically active area which suffered consequences from strong past earthquakes. During the project, 170 high school students collected reports on more than 3200 buildings, performing a statistical analysis of theing results. The CEDAS project makes a first step beyond crowdsourcing activities and applies citizen science to exposure development. Results allow identifying the most common building typologies in the region and the challenges and opportunities associated with data collection and analysis. The experience collected during the CEDAS project shows that crowdsourcing and citizen science activities can contribute to both enhancing the exposure data available for the scientific community and increasing risk awareness among young students in the region.

Process-Based Modeling of the High Flow of a Semi-Mountain River under Current and Future Climatic Conditions: A Case Study of the Iya River (Eastern Siberia)

The purpose of the study was to analyze the formation conditions of catastrophic floods in the Iya River basin over the observation period, as well as a long-term forecast of the impacts of future climate change on the characteristics of the high flow in the 21st century. The semi-distributed process-based Ecological Model for Applied Geophysics (ECOMAG) was applied to the Iya River basin. Successful model testing results were obtained for daily discharge, annual peak discharge, and discharges exceeding the critical water level threshold over the multiyear period of 1970–2019. Modeling of the high flow of the Iya River was carried out according to a Kling–Gupta efficiency (KGE) of 0.91, a percent bias (PBIAS) of −1%, and a ratio of the root mean square error to the standard deviation of measured data (RSR) of 0.41. The preflood coefficient of water-saturated soil and the runoff coefficient of flood-forming precipitation in the Iya River basin were calculated in 1980, 1984, 2006, and 2019. Possible changes in the characteristics of high flow over summers in the 21st century were calculated using the atmosphere–ocean general circulation model (AOGCM) and the Hadley Centre Global Environment Model version 2-Earth System (HadGEM2-ES) as the boundary conditions in the runoff generation model. Anomalies in values were estimated for the middle and end of the current century relative to the observed runoff over the period 1990–2019. According to various Representative Concentration Pathways (RCP-scenarios) of the future climate in the Iya River basin, there will be less change in the annual peak discharge or precipitation and more change in the hazardous flow and its duration, exceeding the critical water level threshold, at which residential buildings are flooded.