DC Resistivity Survey Research Articles

Joint Electromagnetic-Terrain Conductivity and DC-Resistivity Survey for Bedrock and Groundwater Characterization at the New Al-Obour City, Egypt

A multi-spacing electromagnetic–terrain conductivity survey profile and vertical electrical resistivity soundings were carried out at New Al-Obour City, Northeastern Cairo. The chief purpose of this survey was to characterize the bedrock, and groundwater occurrence, and hence to image both the surface and subsurface structures. The water is used mainly to meet the demands of the agricultural sector in the area. Accordingly, a set of sixteen Multi Spacing Electromagnetic Terrian Conductivity profiles and 11 vertical electrical soundings were done from September 2018 to March 2019. The data sets were transformed–inverted comprehensively with regard to stitched one-dimensional (1D) electrical resistivity smoothed-earth models. These sets were used efficiently in the interpretation of the geologic sequence of bedrock through successive conductive anomalies and electrically resistive. Remarkably, the obtained subsurface electrical resistivity structures are coincident with the mapped field geologic faults. The current study proved that a comprehensive Multi Spacing Electromagnetic Terrian Conductivity and vertical electrical sounding resistivity survey could help optimize geotechnical exploratory work. The results of the interpretation of geoelectrical data indicate that the elevation of the top of the groundwater aquifer ranges from 60-70 m above sea level.

Subsurface Structure Analysis of Landslide Potential Areas Based on Electrical and Physical Properties of Soil

Indonesia is a tropical region with a high level of rainfall in November-December for the 2020-2021 period, especially in the West Java region. Jayagiri is one of the villages in Lembang district, West Bandung regency, which experienced landslides due to heavy rainfall. High and constant rainfall causes the soil layer to become saturated and unable to withstand the water, so soil movement occurs. Identification of landslide slip field identification can be analyzed by the geoelectric method and some soil samples for laboratory tests. Four lines of DC resistivity surveys were carried out in the research area using a multichannel instrument. The result of two-dimensional modelling resistivity shows a wide zone of saturation online JG-1 to a depth of around 10 m. Based on the laboratory soil test, permeable soil with a high porosity dominated the area. Low resistivity variation values ranging from 3.79 - 93 Ωm correspond to the low saturation zones. The constituent rocks of the saturation zone are clay, loam, and sand.

Integrated geophysical investigation for understanding agriculturally induced landslides in southern Peru

We conducted near-surface geophysical surveys in and around the Majes I agricultural development (60 km west of Arequipa, Peru), where the nexus of geology and agriculture has increased landslide activity along the Majes–Siguas River Valley. Through DC resistivity, transient electromagnetics (TEM), and seismic surveys, we refined the understanding of local geology, characterized the agricultural impact on the local water table, and updated landslide modeling to help inform discussions on landslide mitigation strategies at Majes I and landslide prevention at the planned Majes II site. At the Majes I development, we identified an increase in water table and water saturation due to irrigation. At the planned Majes II site, which shares similar geology to Majes I, we interpret the regional water table that has yet to be affected by significant human development. We integrated these results into updated landslide modeling. Our modeling for Majes I suggests stable conditions prior to irrigation; as the water table rose from irrigation, landsliding began and evolved as a retrogressive failure that is now focused along the headscarp near critical infrastructure including the Carretera Panamericana (Pan-American Highway). Majes II is currently stable and irrigation management, such as drip versus flood techniques, must be supported. Soil ameliorants such as polymers and/or biochar should be encouraged to hold water near the roots to reduce the risk of landslide initiation. Combined this work shows the value of integrated hydrological and geophysical research for landslide management and optimized irrigation.

Resistivity structure deduced from the developed marine vertical DC resistivity survey system around a hydrothermal deposit area

Resistivity structure deduced from the developed marine vertical DC resistivity survey system around a hydrothermal deposit area

Multi-Scale Geophysical Methodologies Applied to Image Archaeological Ruins at Various Depths in Highly Terraneous Sites

Among all geophysical techniques, electrical resistivity and magnetic surveying as an integrative approach has been used widely for archaeological prospection at different scales of investigations. In this study, DC resistivity (1D vertical sounding and/2D/3D ERT) and magnetic surveys (total and gradient) as a multi-scale approach was applied in a highly terraneous archaeological site (Tell) with a case study to characterize and image the various archaeological assets at different depths with different spatial resolutions. Four critical zones of great interest within the considered Tell were surveyed. At the heart of the study area, three layers were depicted clearly from 1D resistivity sounding. A thick conductive zone of mostly clay is sandwiched between two resistive layers. The topmost layer contains construction debris (dated back to the Islamic Era), whereas the deeper layer could be related to Gezira sand on which the probable Pharaonic temple was constructed. A long 2D ERT profile using Wenner Beta (WB) and Dipole–Dipole (DD) arrays with a 5-m electrode spacing identified shallow high resistivity anomalies that could be related to construction ruins from fired bricks. Additionally, it succeeded in imaging the turtleback-shaped deeper resistive layer of mostly sand. At an elevated rim to the east and west of the Tell, total and vertical magnetic gradient maps clearly delineated different archaeological structures: the walls of the rooms of ancient Islamic settlers and the walls of water tanks from the Byzantine Era. Magnetic modeling assuming 2.5-dimensional magnetic models constrained by the 2D ERT inversion models could be used to create a realistic representation of the buried structures. Toward the northern part of the Tell, the joint application of the quasi-3D ERT inversion scheme and the magnetic survey revealed an anomaly of a well-defined geometric shape of an archaeological interest thought to be a crypt or water cistern based on nearby archaeological evidence. The overall results of the geophysical survey integrated with the image of some partially excavated parts provided the archaeologists with a comprehensive and realistic view of the subsurface antiquities at the study area.

Imaging ahead of a tunnel boring machine with DC resistivity: A laboratory and numerical study

Tunnel Boring Machines (TBMs) are used for tunneling and underground construction, by excavating material and subsequently installing a segmental concrete tunnel liner for support. However, unknown ground conditions pose a significant risk to tunneling operations and any damage to the machine can be disastrous to a project. There is a need for tools which look ahead of the TBM for potential hazards during tunneling, such as water saturated zones, faults, boulders and metal pipes. Geophysical methods offer the capability to image unexcavated material in order to avoid such hazards and thus improve tunneling operations. In particular, the DC resistivity method is useful because it is sensitive to a large range of conductivity variations in geological and man-made materials.The research presented in our paper consists of three parts: (1) a laboratory study of a DC resistivity system mounted on a scale model TBM within a simulated tunneling environment, (2) a series of forward models studying different DC resistivity survey designs, and (3) the inversion and imaging of synthetic DC resistivity data under different constraints. We introduce several new survey designs that attach electrodes on a probe (or probes), which are then pushed into the earth in front of the machine each time excavation stops. Our laboratory data and forward modeling results show that using probes reduces interference caused by the metallic TBM body, and increases the distance ahead of the machine at which a target may be detected. The TBM influence on the data is significantly reduced once the probe is pushed 25% of the TBM diameter ahead of the machine and negligible once the probes are pushed 50% ahead of the machine. Depending on the specific survey design, targets can be detected from up to 70% of the TBM diameter away. Finally, we invert synthetic data to produce ahead-of-tunneling images using different amounts of prior information (e.g. TBM geometry and host resistivity) and also study time-lapse inversion. Numerical results show the target can be imaged with these methods from distances up to 45% TBM diameter.

Marine DC resistivity and self-potential survey in the hydrothermal deposit areas using multiple AUVs and ASV

Marine DC resistivity and self-potential survey in the hydrothermal deposit areas using multiple AUVs and ASV

DC Resistivity Survey Design for Deep Magma in Mt. Baekdu Using Distributed Acquisition System

DC Resistivity Survey Design for Deep Magma in Mt. Baekdu Using Distributed Acquisition System

Development and Field Test of a Distributed Acquisition System for High Efficiency Deep DC Resistivity Surveys

Recently, the necessity of a DC resistivity survey for deeper parts has increased for the purpose of locating mineral resources and investigating earthquakes and volcanic activities. Accordingly, we developed and verified a distributed acquisition system to implement efficient deep DC resistivity surveys. The main features of our system adopting state of the art of electric and electronic technologies are described as follows: 1) high-power transmission and high-precision measurement is possible; 2) broad functional implementation by firmware programming guarantees the scalability and applicability for various geophysical high-precision measurements; and 3) it has high efficiency and maintainability in field operations due to its small size, light weight, modular design, and low power consumption. The system was verified through comparison with a commercial system under the same conditions along the 480-m survey line. After the verification, a large-scale survey was successfully carried out along the 4-km survey line at Mt. Taebaek.

Development of Data Acquisition Instrumentation and Inversion System for Earth Resistivity Survey in a Smart Integrated System

This research has developed an integrated system of data acquisition and inversion process for earth dc resistivity survey in smart and compact instrumentation. Data acquisition system was developed based on microcontroller which is embedded to a PC. The microcontroller will choose the appropriate electrode sensor by command of PC . The data of a measurement and it’s electrodes configuration will be saved in PC. Once the data acquisition process is complete, automatically the system will start the inversion process based on finite difference method. Finally, the result of survey process will be shown in a 2D cross section image.

Evaluations of effectiveness of marine deep-towed DC resistivity survey in investigation of seafloor massive sulfide deposits

Evaluations of effectiveness of marine deep-towed DC resistivity survey in investigation of seafloor massive sulfide deposits

Geothermal system boundary at the northern edge of Patuha Geothermal Field based on integrated study of volcanostratigraphy, geological field mapping, and cool springs contamination by thermal fluids

Patuha Geothermal System is a volcanic hydrothermal system. In this type of system, the boundary of the system is often determined by low resistivity (10 ohm.m) anomaly from Magnetotelluric (MT) or DC-Resistivity survey. On the contrary, during geothermal exploration, the system boundary often need to be determined as early as possible even prior of resistivity data available. Thus, a method that use early stage survey data must be developed properly to reduce the uncertainty of the geothermal area extent delineation at the time the geophysical data unavailable. Geological field mapping, volcanostratigraphy analysis and fluid chemistry of thermal water and cold water are the data available at the early stage of exploration. This study integrates this data to delineate the geothermal system boundary. The geological mapping and volcanostratigraphy are constructed to limit the extent of thermal and cold springs. It results that springs in the study area are controlled hydrologically by topography of Patuha Volcanic Crown (complex) or so called PVC, the current geothermal field and Masigit Volcanic Crown (complex) or so called MVC, the dormant volcano not associated with active geothermal system. Some of the cold springs at PVC are contaminated by subsurface steam heated outflow while others are not contaminated. The contaminated cold springs have several characteristics such as higher water temperature than ambient temperature at the time it was measured, higher total disolved solid (TDS), and lower pH. The soluble elements analysis support the early contamination indication by showing higher cation and anion, and positive oxygen shifting of stable isotope of these cool springs. Where as the uncontaminated spring shows similar characteristic with cool springs occur at MVC. The boundary of the system is delineated by an arbitrary line drawn between distal thermal springs from the upflow or contaminated cool springs with the cool uncontaminated springs. This boundary is more or less in agreement with low resisitivity boundary derived from MT and DC resistivity survey. The area defined as part of geothermal area from this method is also validate with drilling data that give high temperature gradient. It suggests that the method use in this study is applicable and reliable.

Possible mechanism of molten sulfur eruption: Implications from near-surface structures around of a crater on a flank of Mt. Shiretokoiozan, Hokkaido, Japan

Shiretokoiozan volcano in northern Japan is well known for its eruptions, which eject huge amounts of molten sulfur. Watanabe (1940) reported details of the 1936 eruption, but its mechanisms, and how and where the huge amount of sulfur is produced and pushed out remain unknown. The aim of this study is to elucidate the near-surface underground structure of this area and the mechanisms of the molten sulfur eruption. We implemented aerial photographic observations, geological surveys, hot spring analysis, Self-Potential survey and DC resistivity surveys at the western flank of Mt. Shiretokoiozan. The geology of this area is mostly composed of hydrothermally altered boulders, gravels, sand, and clay. Some areas of fumaroles are covered by sulfur cement. Chemical analyses revealed that SO42− and Cl− are rich in hot water, which imply an area with upwelling hot water/gas below the surface. Results of DC resistivity surveys conducted at several sites show extremely low resistivity, suggesting an aquifer several meters below the surface. Compiling this evidence, we infer a possible mechanism of molten sulfur eruption: the sulfur has been produced and stored in an aquifer located at the eastern hill from Crater I for several decades by chemical reactions of volcanic gases; it gushes out when volcanic activity becomes high.

Imaging of wastewater percolation in heterogeneous soil using electrical resistivity tomography (ERT): a case study at east of Tenth of Ramadan City, Egypt

The objective of this study is to evaluate the effectiveness of DC resistivity surveys for imaging the wastewater percolation around the stabilization ponds in the Tenth of Ramadan City, the desert fringes of East Nile Delta, Egypt. Detailed resistivity surveys, including DC soundings and electrical resistivity tomography (ERT), were carried out along several profiles. Furthermore, synthetic modeling of ERT was designed to optimize the survey configurations and interpretation of the results. A 2D modeling of smoothness-constrained least-squares inversion scheme was applied to delineate the possible wastewater infiltration zones from oxidation ponds. Because the geoelectrical interpretation has a degree of non-uniqueness, the resistivity inversion was constrained using borehole lithological information and soil sample laboratory measurements. The DC inversion results indicate decreasing resistivity down to a depth of 15 m around waste disposal sites. The inferred soil zone close to the oxidation ponds was a mixture of sand, silt and clay. Moreover, the clay minerals were characterized by moderate swelling that could have reduced the vertical infiltration speed, causing wastewater seepage, especially around unlined disposal sites and open surface drains. Accordingly, the medium-to-low resistivity values can be attributed to wastewater leakage in clayey sand soil. Because the area slopes generally toward the northeast, the surface seepage was dominant in the shallow impermeable sandy clay subsoil. Therefore, measuring soil parameters is a complementary method to optimize resistivity interpretation, with potential for mitigating environmental hazards from wastewater leakage around disposal ponds.

Mapping Buried Aquifers with HTEM in the Fort McMurray, Alberta Region

Heliborne time-domain electromagnetic systems (HTEM) have proven to be effective tools in mapping sub-surface resistivity. As these systems are able to measure increasingly earlier time channels after the waveform's turn-off, they improve their ability to resolve resistivity contrasts in near-surface geology. This is demonstrated with the VTEM system over the Aspen property, near Fort McMurray, Alberta. This area provides a useful setting in mapping near-surface resistivity variations, specifically the location and geometry of the Pemmican Valley aquifer. This begins with the a Tau constant analysis of the earliest time channels of the VTEM decay curve that laterally mapped the Pemmican Valley aquifer and the existence of a shallower, previously unmapped, east-west trending aquifer. This is confirmed through 1D inversions of the dataset. The 1D inversion models accurately resolve the main near-surface geo-electrical units within the Aspen property when compared to resistivity well logs and a ground DC resistivity survey. Analysis of the stitched 1D inversion section maps provides useful resistivity maps that reflect the geological model.

DC resistivity survey for the assessment of groundwater potential in Oba Akoko, Southwestern, Nigeria

A DC resistivity survey of Oba Akoko in southwestern Nigeria was carried out over the three major rock units of the Migmatites; granite, granite-gneiss and grey-gneiss underlying the study area. The objectives of the study included the delineation of the subsurface geological/geoelectrical sequences and aquifer unit(s) and types with a view to assessing prospective site for groundwater potential rating of the area. Fifty nine Schlumberger vertical electrical sounding data were acquired. The inter-electrode spacing (AB/2) varied from 1 to 100 m with maximum spread length of 200 m. The ground resistance measurements were made with ABEM SAS 1000 resistivity meter. Seven distinctive sounding curve types were obtained from the data inversion/interpretation techniques. These included H, A, HA, AA, HK, QH and AK curve types. Maximum of four geological/geoelectric layers were delineated; the top-soil, clay/clayey sand/sandy clay weathered basement, partly weathered/fractured basement and fresh basement with resistivity values that ranged from 20 - 360 Ωm, 25 - 850 Ωm, 476 - 979 Ωm and infinity ohm-m respectively, while the thickness values ranged from 0.4 - 3.8 m, 1 - 17 m, 4 - 17 m respectively, and depth to rock head of 24.9 m. Isopach maps of the weathered layer and overburden showed spatial distribution of the thickness with a relatively thick weathered/fractured basement not less than 10 m as basement depressions or pockets of closures. The thickness pattern showed uneven basement bedrock interface. It may, therefore, be concluded that groundwater potential of the study area is generally low arising from shallow depth to basement or thin regolith and few fracture density in places in the area. The localized fractured bedrocks and weathered basement columns/basement depressions arising from the deep weathering of the parent rocks may have constituted the main sustainable aquifer/groundwater storage units for consumption via borehole groundwater abstraction in the area. Keywords: Geology, Mapping, Geoelectrical, Resistance, Delineating

Data quality control methodologies for large, non-conventional DC resistivity datasets

With developments in instrumentation and computational resources, the collection of large, non-conventional DC resistivity datasets has become commonplace. While the increased data content of these large datasets can significantly improve the resolution of inverse models, these datasets also present challenges for standard data quality control (QC) methodologies. Standard QC methodologies for DC resistivity datasets typically rely on our ability to decompose the dataset into 2D lines and/or reciprocal measurements. Non-conventional electrode geometries and the cost of collecting a large number of reciprocal measurements can severely limit the applicability of standard DC resistivity QC methodologies.To address these limitations, we developed a more generalized data QC methodology which utilizes statistical analysis and classification tools. The merit of this methodology is illustrated using a field dataset collected in an underground potash mine and several synthetic examples. Results from these applications show that the methodology has the ability to identify and characterize highly noise-contaminated data from a number of different sources. The flexibility of the 4-stage methodology allows it be tailored to accommodate data from any type of DC resistivity survey and the use of statistical analysis and classification tools decreases the subjectivity of the process. Although this study focuses on the applicability of this methodology for DC resistivity data, it is potentially applicable to a variety of geophysical surveys.

Combined DC Resistivity Survey and Electric Conductivity- Dielectric Permittivity Measurement at Sag Pond near Lembang Fault, West Java, Indonesia

Lembang Fault is a normal fault situated at the southern flank of Tangkuban Parahu Volcano in West Java Indonesia. The fault's movement may have caused the formation of sag pond in the vicinity of its which is characterized by the soil layers of the sag pond. The characteristics of the soil can be examined based on its electrical properties such as conductivity (the inverse of resistivity) and dielectric permittivity. Direct field measurement was conducted using DC-resistivity Wenner-Schlumberger method on the sag pond as well as laboratory resistivity measurement of cores taken from the sag pond. Two resistivity crosssections were obtained after performing 2D inversion of the data which reveal that the resistivity distribution consist of a resistive layer (40-60 ohm.m) overlying a medium resistive layer (30-35 ohm.m). The third layer has relatively low resistivity of 16-25 ohm.m. At the intersection of these two lines we took coring samples down to depth of 5 m below surface and measured the electrical conductivity and dielectric permittivity for each 1 cm of sample using EM-50 data logger. Results from both field and laboratory measurement were analysed to get a better understanding of the sag pond.

Surface DC resistivity survey of contamination Beneath Ido-Osun dumpsite, southwestern Nigeria

Surface DC resistivity techniques have been used to investigate the subsoil characteristics around an abandoned dumpsite in Ido Osun, Southwestern Nigeria. The aim was to delineate groundwater contamination, identify lithologic layers, locate possible leachate plumes, and assess the risk of groundwater pollution. Schlumberger vertical electrical sounding (VES) and Dipole-dipole resistivity profiling data were acquired at 20 m and 10 m intervals respectively along three northwest-southeast geophysical traverses. The geoelectric sections revealed four probable subsurface geoelectric layers which were considered to be topsoil, laterite, weathered/fractured bedrock and competent/fresh bedrock based on previous works. The weathered/fractured bedrock forms the groundwater reservoir in the area as interpreted from the over 98% occurrence of H, KH geoelectric curve types. The dipole-dipole sections showed several distinct low resistivity zones which extends into the weathered/fractured bedrock. These were interpreted as probable contamination plumes beneath the dumpsite.

Surface DC resistivity survey of contamination Beneath Ido-Osun dumpsite, southwestern Nigeria

DC resistividad superficial las tecnicas se han utilizado para investigar las caracteristicas del subsuelo torno un abandonado vertedero en Ido-Osun, suroeste de Nigeria. El objetivo es delinear contaminacion de las aguas subterraneas, identificar las capas litologicas, localizar posibles lixiviados penachos de humo y evaluar el riesgo de contaminacion de las aguas subterraneas. Sondeo electrico vertical Schlumberger (VES) y dipolo-dipolo resistividad perfiles de datos fueron adquiridos en 20 m y 10 m, respectivamente a lo largo de tres intervalos noroeste-sureste geofisicos recorre. La geoeli secciones revelo cuatro probables las capas subsuperficiales geoelectricos que se consideraban de superior del suelo, laterita, capeado y roca fracturada y competente/roca con base en trabajos previos. La roca fracturada constituye la reserva de agua subterranea en la zona interpretado a partir del mas del 98% de H, KH geoeli tipos de curva. El dipolo-dipolo secciones mostro zonas de baja resistividad que se extiende en el capeado/roca fracturada. Estos fueron interpretados como probable contaminante plume por debajo del vertedero