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Applied Geophysics, 2 nd Edition
... Metode gravitasi merupakan metode geofisika yang melibatkan pengukuran variasi medan gravitasi bumi yang disebabkan oleh perbedaan densitas batuan bawah permukaan (Reynolds, 1998). Dasar dari metode gravitasi adalah hukum Newton yang menyatakan bahwa gaya tarik menarik antara dua buah benda bermassa m1 dan m2 adalah sebanding dengan massa kedua benda tersebut dan berbanding terbalik dengan kuadrat jaraknya (Telford, Geldart, & Sheriff, 1990) yang dapat dituliskan sebagai: G= Konstanta gravitasi (6.672 x 10 -11 m 3 / kg s 2 ) 1 dan 2 = massa objek (kg) r = jarak antara m1 dan m2 (meter) Meskipun disebut sebagai metode "gravitasi", pada kenyataannya yang diukur oleh metode ini adalah percepatan gravitasi (Reynolds, 1998). ...
... ( (Telford, Geldart, & Sheriff, 1990). ...
... Setelah regional terrain correction grid didapatkan maka terrain correction dapat dijalankan. Hasil terrain correction kemudian digunakan untuk mendapat densitas batuan rata-rata dengan metode Parasnis yaitu berdasarkan rumus (Telford, Geldart, & Sheriff, 1990): ...
In this modern era, technology is needed to conduct geothermal surveys that are efficient but still accurate. One method that is being developed to survey geothermal potential is remote sensing. In this study, the application of remote sensing methods namely Fault and Fracture Density (FFD) is used to evaluate permeable zones by evaluating areas that have high faults and joints structures. However, not all of lineament presence caused by fault activities, so digital signals processing need to be carried out. This research used Landsat 8 imagery which is done through dimension reduction using Principal Component Analysis and the filtering process such as Sobel, Line Detection, Prewitt, and Laplacian convolution filters to improve image quality. Lineament extraction from Landsat 8 images is performed automatically using Edge Detection while lineament from IFSAR image extracted manually. The extracted lineaments then compared in the form of FFD maps. To prove the effectiveness of this method, gravity data are also used to confirm the fault presence geophysically. The results of these data which integrated with other supporting data showed the suitability of covering permeable zones which can be most effective drill point areas are near the manifestations of APKK and APSE.
... For seismic attributes to have geological significance, they should have a physical basis for their correlation with properties measured at the wells". Sheriff, (1980) identified "amplitude, phase, frequency, polarity, and velocity as attributes useful as hydrocarbon indicators, whereas acoustic impedance, reflectivity and transmissivity are useful for boundary conditions, hardness, and nature of surfaces". Anomalies due to variations in seismic attributes often appear in sections as bright spots, flat spots, and velocity sags. ...
... Anomalies due to variations in seismic attributes often appear in sections as bright spots, flat spots, and velocity sags. Sheriff (1980), Chambers & Yarus (2002), and Schlumberger, (2009) highlighted "the geological significance of seismic attributes as useful in defining lithological contrast, bedding continuity, bed spacing and thickness, depositional environment, geologic structures, gross porosity, fluid content, abnormal pressure, temperature, and polarity of seismic. While the structural attributes can help in picking horizons and faults, seismic attributes relating to log and rock properties help in defining a better petrophysical and facies model, thus reducing uncertainty". ...
A seismic attribute is any measure of seismic data that helps us better visualize or quantify features of interpretation of interest. It could be described as a powerful aid to improve the accuracy of interpretations and predictions in hydrocarbon exploration and development. A qualitative seismic attributes analysis was carried out for the evaluation of subsurface geological features and hydrocarbon potential of an oil field in Niger Delta Basin. The Interpretation using geophysical software on the 3D seismic data presents a great opportunity for reservoir characterization, enhanced with attributes from seismic signal processing, complex seismic trace attributes, structural attributes, stratigraphic attributes and surface attributes. The seismic 3D cube data was investigated for potential structural and stratigraphic controls within the study area with surface attributes. Seismic attributes including reflection intensity, RMS amplitude, Time gain, Trace AGC, Sweetness, Envelope, Instantaneous Frequency, Instantaneous Phase, Quadrature amplitude, Ant tracking, Dip deviation, Gradient Magnitude, Local Structural dip, Chaos, Iso-Frequency, Local flatness were used for the interpretation of the 3D seismic cube, time and depth surface maps generated. The result shows moderate to high sweetness region (sweet spots) within the zone of interest, Envelope attribute results show acoustic impedance contrasts indicating discontinuities, lithology changes, possible presence of hydrocarbon (bright spots), Variance, Dip deviation, Gradient magnitude and Ant tracking attributes enhanced the signals to map out discontinuities caused by faults and fractures signature which enabled the delineation of the zone of interest. This study on the qualitative interpretation of seismic attribute validates the lithology discrimination using elastic rock properties from well logs and shows the effectiveness of the use of seismic attributes for the optimizing, understanding, improving, identifying, and unmasking hidden features of the reservoirs in the field. For successful exploration and production of hydrocarbons, it is imperative to characterize the hydrocarbon reservoir accurately in terms of its fluid properties and lithology using attributes extracted from seismic.
... The inversion method considers the geological parameters of the field conditions through regional geological data. These (Gercek, 2007) (Table 3), density (Telford et al., 1990) ( Amalina et al. (2022) show that the research area consists of four lithological layers: sand, coarse sand-gravel, siltclay, and breccia. This study compares the inversion model results based on the number of layers from the N-SPT drill test with the inversion model results based on the number of lithologies only. ...
... BS-1 also appears to have a high amplification value, after reviewing the lithology of the SPT drill test shows that this area consists of clay and sand lithologies in sequence and has a tighter layer thickness than other drill test points. This is due to the difference in density values based on Telford et al. (1990), clay lithology has a density value of 2.21 g/cm 2 while sand lithology has a density value of 2 g/cm 2 . So that the difference in density value will result in an increase in amplification value due to the difference in density of the two deposits. ...
The 2006 Yogyakarta earthquake was caused by the tectonic movement of the Opak Fault, which is located near the Opak River. This research conducts microtremor data processing and analysis using the Horizontal Vertical Spectral Ratio (HVSR) method and the Inversion method to determine dominant frequency (fo), amplification (Ao), and shear wave velocity to a depth of 30 meters (Vs30) in Opak River area as an effort in earthquake disaster mitigation. The purpose of this research is to compare the Vs30 value of the inversion method using layer parameters according to Standard Penetration Test (SPT) data from previous research and layer parameters according to the number of lithologies. The result presents that the Vs30 values around Opak River are in the range of 183 - 301 m/s and belong to the stiff soil site classification. The comparison shows that the Vs30 values in the two different layer parameters are both still in the stiff soil site classification and have a slight difference in Vs30 values. Thus, the use of microseismic data to determine the Vs30 value is a fast and efficient way to determine the subsurface geology of the study area.
... The Wenner-Schlumberger configuration is one of the configurations usually used for 2D resistivity measurements (Amir et al., 2022). The advantage of the Wenner-Schlumberger configuration is that it can describe lateral and vertical variations in resistivity values and its depth penetration is 10% greater than the Wenner configuration (Telford et al., 1990;Hati et al., 2022). The signal strength of the Wenner-Schlumberger configuration is lower than the Wenner configuration, but higher than the Dipoledipole configuration (Hermawan & Putra, 2016). ...
... Table 1. Resistivity values of earth materials (Telford et al., 1990;Pratama et al., 2019b). ...
Ultramafic rocks are the main source of nickel laterite deposits. One of the areas that has an ultramafic complex is located in Muara Lapao Pao Village, Kolaka Regency. The research was conducted in the mining area of PT Tri mitra Babarina Putra using the resistivity geoelectric method of the Wenner - Schlumberger configuration, In the area it is not yet known exactly how much peridotite bedrock is present in the subsurface. Therefore, it is necessary to conduct a geophysical survey in identifying the occurrence of peridotite bedrock, and can determine the depth and thickness of peridotite bedrock in the research area. the occurrence of peridotite bedrock in the mining area of PT Tri Mitra Babarina Putra has a resistivity value between 3000 – 17984 Ohm-meters. Peridotite bedrock in the research area on all four tracks has a depth and thickness that is almost uniform. lines 1 and 2 and 4 are at a depth of 34.5 - 39.6 meters with a thickness of up to 5.1 meters. and line 3 peridotite bedrock is at a depth of 40 m to more. There are 3 layers in the study area, namely, soil/overburden layer with a resistivity value of 16.5 – 122 Ohm-meters, serpentinite rock layer with a resistivity value of 200 – 2438 Ohm-meters and peridotite bedrock layer with a resistivity value of 3000 – 17984 Ohm-meters.
... Electrolytic conduction occurs in rocks or minerals that are porous and the pores are filled with an electrolyte solution that allows electric current to flow due to being carried by the ions of the electrolyte solution. While dielectric conduction occurs in rocks that are dielectric, namely rocks that have few or no electrons [9]. ...
... According to Telford et al. [9], based on their resistivity values, rocks and minerals on Earth can be grouped into three categories, namely: Every rock has its characteristics, including its electrical properties. The nature of the rock is its specific resistance which describes the ability of the material to conduct electric current. ...
Introduction: Aquifer layers have been identified in the oil palm plantation area of PT Unggul Widya Teknologi Lestari Pasangkayu Regency. This study aims to determine the lithology of subsurface rocks and the depth of the aquifer layer as a source of clean water in the study area. Method: This study uses the geoelectric method of type resistance with Wenner configuration, with the number of electrodes 24 rods and a spacing of 10 meters. 2D cross-sectional model using Res2Dinv software program. Results and Discussion: Based on the value of the type resistance of the subsurface constituent rock lithology at the research site is interpreted to consist of three layers, namely clay with a specific resistance value < 29.15 Ωm, sand and sandy clay with a specific resistance value of 29.15 Ωm to 72.89 Ωm, and conglomerate with a specific resistance value > 72.89 Ωm. The aquifer layer is interpreted with a specific resistance value of 29.15 Ωm to 72.89 Ωm. The aquifer layer is detected to spread from the northeast to the southwest of the research site with a depth of ±25-39 m. Conclusion: In the oil palm plantation of PT Unggul Widya Teknologi Lestari, the subsurface layer consists of clay (1.98 Ωm - 29.15 Ωm), sand and passive clay (29.15 Ωm - 72.89 Ωm), and conglomerate (72.89 Ωm - 1120.5 Ωm). Thin aquifers, with a thickness of 5-10 m and depth of 25-39 m, are detected in the sand and sandy clay layers.
... Terget kedalaman yang mampu dicapai metode ini adalah 2/a. Dalam akuisisi data lapangan susunan elektroda arus dan potensial diletakkan simetri dengan titik sounding (Telford et al., 1990). Dalam konfigurasi wenner terdiri atas dua elektroda arus dan dua elektroda potensial. ...
... Gambar 4. Tetapan nilai resistivitas batuan (Telford et al., 1990). ...
Wiayah Kabupaten Batanghari sebagian besar berada pada Daerah Aliran Sungai (DAS) sungai Batanghari. Kelurahan Terusan merupakan salah satu desa di Kecamatan Maro Sebo Ilir, Kabupaten Batanghari, Jambi yang terletak di sepanjang aliran sungai Batanghari tersebut. Keberadaan infrastruktur pada Kelurahan Terusan banyak yang terdapat di sepanjang aliran, sehingga menyebabkan pembebanan terhadap kondisi bawah permukaan yang tersusun oleh litologi sedimen-sedimen lepas yang saling menyisip pada lapisan diatas maupun dibawahnya. Hal tersebut menyebabkan berkurangnya daya dukung tanah dan berakibat terbentuknya zona lemah. Penelitian ini bertujuan untuk mengetahui struktur bawah permukaan serta mengidentifikasi lokasi zona lemah daerah penelitian. Akuisisi data dalam mengidentifikasi zona lemah menggunakan metode geolistrik konfigurasi wenner sebanyak 3 lintasan. Hasil penelitian berdasarkan pengolahan menggunakan software Res2dinv, berupa penampang 2D bawah permukaan. Hasil penelitian diperoleh litologi penyusun bawah permukaan terdiri dari endapan pasirhalus, lanaupasiran serta kerikil. Keberadaan lokasi zona lemah tersebar pada setiap lintasan. Berdasarkan hasil penampnag 2D bawah permukaan zona lemah terdapat pada nilai resistivitas 4,06-17,04 Ωm, yang didominasi oleh pasirhalus. Kata Kunci: Geolistrik, Konfigurasi Wenner, Zona Lemah, Amblesan
... The principle of ERT measurement involves injecting direct current into the ground through 2 current electrodes, while the resulting voltage response is measured using 2 potential electrodes [28]. The data obtained in Electrical Resistivity Tomography (ERT) measurements are the apparent resistivity values. ...
... Resistivity value of fracture and lithology[4,28,32]. ...
Fracture is an early symptom of ground movement related to the physical properties of soil, including permeability, porosity, density, cohesion and internal friction angle, where these physical properties affect the stability of the soil. This research aims to identify soil fracture in landslide-prone areas using the values of water saturation and soil pressure based on electrical resistivity tomography (ERT) data. Water saturation values are obtained using the Waxman-Smits model based on the relationship between porosity and resistivity. The advantage of this model is its ability to apply correction due to clay-containing soil layers found in the research area. Another parameter used to determine soil fracture is the soil stress value. In this study, the Rankine method is used to calculate soil stress, and this method can be applied to the soil conditions that experienced deformation, caused by weathering of breccia and tuff rocks, allowing water to penetrate the rock medium. Consequently, the weathered layers of breccia and tuff act as slip planes. The presence of water on the slip planes leads to soil movement. Based on the analysis results, soil fractures are correlated with low water saturation values and contrast in soil stress values. A profound contrast in water saturation and soil stress values appears only at fractured slopes. Based on our analysis, soil fractures correlate with low water saturation values (5 - 15 %) accompanied by apparent contrast of soil stress values, i.e. the fractured soil is having lower soil stress (< 15 KN/m2) in comparison to the surrounding. Such a contrast was not found in slopes without fractures. HIGHLIGHTS The electrical resistivity parameter can be related to other physics parameters such as water saturation and soil stress to identify soil fractures Soil fractures can be identified through water saturation profiles using Waxman-Smits model based on data from water resistivity measurements (Rw), resistivity obtained from inversion modeling (Rt), porosity (∅). The additional data was obtained from literature, such as clay conductivity (B), cation exchange capacity (Qv) and the constant to characterize cementation (m) Soil fractures can also be identified from the soil stress values/soil stress profile GRAPHICAL ABSTRACT
... dengan I adalah arus listrik (Ampere), ΔV merupakan beda potensial terukur (Volt), dan K adalah faktor geometri yang disesuaikan dengan konfigurasi elektroda. Adapun nilai resistivitas dari beberapa material di bawah permukaan dapat dilihat pada Tabel 1. Tabel 1. Nilai resistivitas batuan dan mineral di bawah permukaan bumi (Legowo dkk., 2022) dalam (Sheriff, 2001 Dalam konfigurasi dipole-dipole pada Gambar 2, jarak elektroda arus dan potensial dipisahkan sejauh "na" sedangkan jarak antar masing-masing elektroda arus dan potensial dibuat sama yaitu sebesar "a". Target kedalaman dapat dengan mudah didapatkan dengan konfigurasi ini yaitu jika nilai "n" diperbesar maka kedalaman target semakin bertambah (Rachmawati dkk., 2018). ...
... Gambar 2. Konfigurasi dipole-dipole modifikasi dari(Sheriff, 2001). ...
Identifikasi bidang gelincir telah dilakukan di Batu Koneng, Kota Ambon dengan menggunakan metode geolistrik konfigurasi dipole-dipole. Tujuan dilakukan penelitian ini yaitu untuk menginterpretasi lapisan batuan bawah permukaan di area penelitian melalui nilai resistivitas guna mengetahui adanya potensi bidang gelincir yang menyebabkan longsor. Data pengukuran dilakukan sebanyak 4 lintasan dengan panjang 110 m yang pengolahan datanya menggunakan software Res2Dinv. Hasil interpretasi menunjukkan bahwa di lokasi penelitian terdeteksi litologi lempung dengan variasi nilai resistivitas 8,77-24,9 Ωm. Sedangkan lapisan lain diduga sebagai batu gamping dengan variasi nilai resistivitas 23,0-70,1 Ωm. Bidang gelincir diduga berupa lapisan lempung yang terdeteksi pada semua penampang lintasan, untuk penampang 1 ditemukan pada kedalaman 1,25 m hingga 6,76 m, untuk penampang 2 ditemukan pada kedalaman 1,25 m hingga 8 m. Sedangkan pada penampang 3 pada kedalaman 1,25 m hingga 11 m dan penampang 4 menjadi lapisan yang paling dalam yaitu 1,25 m hingga 24 m.
... The values of the analytical signal amplitude ranges from 0.001 to 0.047 nT/m. According to Telford et al. (1990), rocks that are rich in ferromagnesian and minor felsic minerals, are usually associated with areas of high magnetic fields. The areas with high analytical signal amplitude from the map with a value of about 0.010 to 0.047 nT/m are related to ophiolotic serpentine, ophioliticmeta gabbro and gabbro rocks as these rocks contain ferromagnesian in large quantities and equally has large amount of felsic minerals. ...
... The areas with high analytical signal amplitude from the map with a value of about 0.010 to 0.047 nT/m are related to ophiolotic serpentine, ophioliticmeta gabbro and gabbro rocks as these rocks contain ferromagnesian in large quantities and equally has large amount of felsic minerals. While the areas with low analytical signal amplitude with value range of about 0.001 to 0.006 amplitude (nT/m) are associated with granite, metasediments and clastic sediments as these rocks has quartz that is greater than 60% (Okonkwo et al., 2021;Telford et al., 1990). Figure 6 shows the first vertical derivative map of the study area. ...
... The interpretation of seismic data is the final step of a seismic exploration investigation. The result of seismic work is seismic interpretation; hence the accuracy of earlier work affects the accuracy of the interpretation stage (Telford et al., 1990). The interface at which the seismic wave is reflected is typically represented by the reflectors. ...
The study was conducted in Al-Fao area southeastern Iraq, which is about 20
km away from Basra city, using two-dimensional seismic data. The purpose of
the study to describe the structural and stratigraphy of Yamama Formation and
identify hydrocarbon indicators using reflection seismic data. The seismic lines
were divided into three surveys (F, Kl, and Sa). Al-Fao is an exploratory area
that does not contain any wells; the well information was based on Sb-2 well in
Siba field, located north of the study area. Two reflectors, top and base Yamama
Formation are defined using a synthetic seismogram and checkshot in the time
domain for Sb-2 well.
The results showed that the strata tended to slope from the south and
southwest to the north and northeast, and Al-Fao area is structurally higher than its
surrounding areas. Siba field is an elongated fold whose axis extends northeast- southwest; it consists of a structural nose and northeastern dome.
The two-way time (TWT) maps showed higher values in the southeast and
east, indicating sloping reflectors in those directions. The time in TWT map of
top Yamama Formation ranged from 1870 to 2319 ms, and 2144 to 2524 ms in
the TWT map of base Yamam Formation. The depth maps of Yamama
Formation showed the deepest part in the southeast and east, suggesting a
plunging structure in those directions. The depth of top Yamama ranged between
3438 to 4300 m, and 3622 to 4621 m in base Yamama.
Average velocity maps for top and base Yamama Formation were created
using regional velocity from well velocity surveys, both maps show a gradual
increase in velocity values from the northeast to the southwest, this increase is associated with the changes in the thickness of sedimentary cover in the study
area. The average velocity for the top Yamama Formation ranges from 3660 to
3765 m/s, while the average velocity for the base Yamama Formation ranges
from 3665 to 3800 m/s.
The isopach map showed that the thickness values range between 175m to
530m with an increase along an axis extending from Al-Fao area to Siba field in
the southeast-northwest, and it decreases on both sides of this axis, which represents the shoal carbonate buildup.
... Furthermore, the integration of regional seismic reflection data with well information has led to more precise depth conversions and improved geological interpretations (Yilmaz, 2001). The regional seismic section provides valuable information about the subsurface geology structures to help the geoscientist in visualizing and interpreting the distribution of rock layers, faults, and oil exploration (Telford et al., 1990). The regional seismic section is important in geophysical and geological applications (Sheriff, 1991). ...
... This RMS is the difference between the calculated and observed field values and in this inversion model, the RMS value is less than 5% and this helped to get an improved result and match between the observed and calculated field. (Telford et al., 1990). ...
The aeromagnetic survey of Isi-Uzo was conducted by Nigeria Geological Survey Agency. 305,669 numeric data points make up the entire amount of Isi-Uzo data points. These data points were digitally captured (X, Y, Z text file) following the removal of the geomagnetic slope from the initial data set using the International Geomagnetic Reference Field (IGRF). Through the use of source parameter imaging, that was examined using Oasis montaj software, the depths of the magnetic source body were determined. The research area's magnetic intensity varies between-74.72 to 147.24 nT, at its lowest and maximum levels, respectively. There could be a dip or plunge, change in lithology, change in depth, variation in magnetic susceptibility, or angle of strike causing this fluctuation in magnetic strength. The SPI depth value varies with a minimum of 151.6 m for shallow depth magnetic bodies to a maximum of 3082.7 m for deep lying magnetic things. Thick sedimentation for hydrocarbon formation and mineral deposit is seen at depths ranging from 1200 m to 3082.7 m whereas shallow depths of 35 m to 150 m which are evident of excellent prospective sources of water. This work gives information that will be very important in mineral exploration and management for economic growth in the area.
... In the field, the procedure is to determine a fixed point or centre and the spreading distance and electrode configuration to be used, this is to allow for equal spread on the survey area. The greater the electrode spacing, the deeper the current will penetrate into an inhomogeneous earth and the resistivity so measured does not represent the true resistivity of the subsurface, it is the apparent resistivity because of the inhomogeneity of the subsurface [8]. ...
Characterization of aquifer using Geo-electrical techniques in Kaani, Khana Local Government Area of Rivers State, Nigeria was carried out using Schlumberger electrode configuration of Vertical Electrical Sounding (VES) technique. The field data were obtained using Herojat resistivity meter which was applied on ten VES stations. A maximum distance of 150m and 7m were used for current electrode spacing and potential electrode spacing respectively. Data obtained from the field were analyzed using IPI2WIN computer software. The results reveal resistivity value ranges from 61.7Ωm to 7487Ωm, thickness ranges from 0.883m to 55.85m and depth value ranges from 0.883m to 105m which implies that the study area has a shallow aquifer and moderate thickness with potential for groundwater exploration. The results also reveal seven curve types KK, AH, HK, KKH, HK, QKK and QKAK in the study area. The results from the study area will be useful in well construction to reduce the high level of borehole failure and groundwater contamination due to high longitudinal conductance value of the aquifer in the study area.
... The apparent electrical resistivities are then calculated from the measured data and these are used to determine the geoelectric datas. These geoelectric parameters are then interpreted to determine subsurface resistivity anomalies, depths and thicknesses [27,28]. ...
Groundwater is an important source for Nigerian water balance. Therefore assessing its experimental evidence supporting saltwater intrusion is necessary before initiating developmental plans using this resources. In this research, the extent of saltwater intrusion, physiochemical properties of groundwater samples and suitability was experimented in the study areas. Geophysical and geochemical techniques were employed in a research study to investigate saltwater intrusion in freshwater aquifers in coastal areas of Delta State, Nigeria. The resistivity data from fifty Vertical Electrical Soundings (VES) in the aquifer layers revealed high water content and saline intrusion, with resistivity ranging from 0.4 to 769.9 Ωm. The hydraulic resistance values ranged from 2.877m-1 to 27.2831m-1, determining the Aquifer Vulnerability Index (AVI). The findings from the Groundwater Occurrence and Depth (GOD) index classified the study area into low and moderate vulnerability classes, with values ranging from 0.168 to 0.420. Groundwater analysis indicated elevated levels of electrical conductivity, salinity, and total dissolved solids, exceeding WHO standards. Moreover, high concentrations of chloride, sodium, and potassium confirmed saltwater intrusion.
... Nilai resistivitas yang terukur bukan merupakan nilai reistivitas untuk satu lapisan saja, hal ini terutama untuk spasi elektroda yang lebar. Menurut Telford (1990), berilut adalah persamaan untuk menentukan resistivitas semu. ...
The resistivity geoelectric method is very suitable for determining the condition of the earth's subsurface by studying the properties of the electric current contained in a rock. Seawater intrusion can occur naturally to a certain degree in most coastal aquifers, due to the hydraulic relationship between groundwater and seawater. This study was conducted by collecting subsurface data by measuring the resistivity value of the rock. In addition, surface observations were made directly by observing the condition of the groundwater level in the wells of the community in coastal areas. This study is directed at providing recommendations for the use of clean water for everyday life. Based on the resistivity value of the modeling results, it can be seen that seawater has intruded the research area. This is indicated by the very small resistivity value (0.168-0.469 Ωm) shown in the deep blue area in the modelings, and the depth of 3-9 meters below the earth surface. Keywords: aquifer, resistivity, seawater intrusion, Manggar Baru
... In typical surface resistivity survey, artificially generated direct current (DC), or very low alternating current (AC) (I) are introduced into the ground using two current-electrodes (C A , C B ) and the resulting potential differences (∆V) are measured between them using two potential-electrodes (P M , P N ). Most commonly used four-electrode configurations are Schlumberger, Wenner, Lee, half-Schlumberger, dipoledipole, pole-dipole, gradient and square arrays (Parasnis, 1997;Griffiths andKing, 1981, Robinson andCourth, 1988;Telford et al., 1990;Keary and Brooks, 1991;Reynolds, 1997;Milsom, 2003). ...
... The curve ρ a = f (AB / 2) is obtained by plotting the apparent resistivity values ρ a against AB/2 (half spacing of the current electrodes, which can reach up to 10 (km) in a bi-logarithmic scale (Telford et al., 2012). ...
One of the world's most pressing needs today is access to groundwater. Although hydrological parameters can generally be estimated using underground studies, these methods are time-consuming and expensive. By taking the direct relationship of these parameters with electrical resistivity and measuring it with a cheaper and faster geoelectric method, a qualitative estimate of these parameters will be obtained. The electrical resistivity method is one of the most widely used methods to probe aquifers. The main objective of this paper is to show how, by interpreting and modeling the data of this exploratory method along with other geological information, the hydrogeological modeling of groundwater reservoirs can be done, and then, with an informed vision, the wells can be drilled for exploitation. For this purpose, the electrical resistivity data at 189 points and 9 profiles in the Shahroud region with Schlumberger array, after reviewing and making some modifications, were subjected to one-dimensional inverse modeling. According to the peripheral vision, the electrode distance was considered to be 50 meters and the length of the profiles is different. The longest profile was 1000 meter and related to profile 3. Then, using the results of modeling along with other available information, the hydrogeological models of the area were prepared in the form of iso-resistivity contour map and interpreted in terms of resistivity and thickness of subsurface layer using computer software Geographic Information System (GIS). Similarly, the thickness map of the aquifer unit (s) was also prepared to classify the good and poor zones. Using the prepared models and also considering the direction and piezometric of the groundwater flow inside the aquifer, suitable places were identified and suggested for future exploitation.
... All measurement stations were georeferenced. Details of the principles and procedures of the electrical resistivity survey are contained in standard geophysical textbooks such as Kearey et al. (2002) and Telford et al. (1991). ...
We present an integrated site investigation of a proposed estate with a view to generating baseline data required for safe design and construction of structures and groundwater schemes, installation and protection of utilities, and post-construction environmental issues. An electrical resistivity survey involving 1D and 2D imaging techniques was involved. The 1D resistivity imaging involved the Schlumberger Vertical Electrical Sounding (VES) with half current electrode spacing of 1–125 m, whose data were interpreted for layer resistivities and thicknesses using segment-by-segment curve matching and 1D forward modeling with W-Geosoft/WinSev 5.1 code. The 2D dipole-dipole resistivity imaging utilized 20 m dipole length and an expansion factor (n) ranging from 1 to 5. The 2D data were inverted to 2D resistivity images with DIPRO software. The 1D and 2D interpretation models delineated five subsurface layers comprising topsoil, fill, laterite, weathered basement, and fresh basement. The weathered basement is the main aquifer with thicknesses ranging from 11.9 to 64.4 m with prospect for groundwater development. The essentially lateritic subsoils in the upper 10 m with resistivity values generally > 450 Ωm are adjudged moderately to highly competent. The low-porosity/permeability lateritic layer overlying the weathered layer aquifer constitutes a sealant against infiltrating pollutant with the groundwater significantly protected. Except within the stream channel, the soils/subsoils are practically non-corrosive.
... Electrical resistivity is a volumetric property of a material that describes its resistance to electrical current flow (Rucker et al., 2009;Telford et al., 1990). For this study, we acquired ERT data using a combination of Schlumberger, Wenner and Dipole-Dipole electrode arrays to obtain good lateral and vertical resolution of the nearsurface along the survey traverse. ...
Understanding near-surface groundwater storage, flow patterns, surface and groundwater interactions in mining areas can assist in making mining more efficient and profitable. This is especially important in opencast mines affected by water inflows that may negatively affect production and increase mining costs. We map and characterize the near-surface aquifer zones at the opencast site of Tharisa Minerals, located in the southwestern region of the Bushveld Complex (South Africa). The main goal is to infer pit water inflow at the mine site and determine how it may be better controlled. The Bushveld Complex hosts partially connected and unconfined alluvial, shallow-weathered and crystalline bedrock aquifers, which are often connected by small-scale permeable zones. Seismic refraction tomography, multichannel analysis of surface waves, electrical resistivity tomography and borehole data are used to map and understand the different aquifer zones in the vicinity of the mine, as well as infer their relation to water inflow in the mine pits. The geophysical surveys map the overburden, weathered bedrock aquifer zone, and the top of the crystalline aquifer rock zone reasonably well. They reveal extensive and deep weathering, and possible high hydraulic conductivity in the vicinity of the mine. The results provide a better understanding of the mine's near-surface environment, which could be used to implement effective and targeted dewatering techniques, thus enabling better pit inflow water control to improve mine working conditions and production.
... Pada software Surfer pengolahan ini dilakukan menggunakan fitur "Math" dengan memilih fungsi A-B, Dimana A mewakili SBA dan B mewakili anomali regional. Kedua anomali tersebut digunakan untuk menggambarkan anomali bawah permukaan yang lebih jelas berdasarkan kedalaman dari anomali densitas tersebut (Telford, 1991). Pemisahan anomali bawah permukaan diperlukan karena dalam analisis turunan menggunakan metode SVD sensitif terhadap anomali dan untuk menemukan struktur sesuai kedalaman yang dimiliki (Tsuboi dkk, 1952;Alhassan dkk, 2022 ). ...
Pulau Jawa dan Madura merupakan pulau yang memiliki aktivitas tektonik yang aktif akibat adanya keberadaan sesar-sesar aktif. Sesar aktif tersebut perlu dipetakan, salah satu yang perlu dipetakan lebih lanjut adalah Sesar Rembang-Madura-Kangean-Sakala (RMKS). Metode yang digunakan dalam pemetaan Sesar RMKS adalah metode gaya berat yang diperoleh dari laman Murray GGMPlus. Dalam pengolahan data gaya berat tersebut ada beberapa langkah yang harus dilakukan seperti penentuan nilai densitas rata-rata dengan metode Nettleton, penentuan nilai Simple Bouger Anomaly (SBA), pemisahan anomali regional dan residual, analisis turunan nilai anomali regional dengan metode FHD (First Horizontal Derivative) dan SVD (Second Vertical Derivative). Nilai densitas rata-rata yang digunakan dalam penelitian ini sebesar 2,6 gr/cm 3. Nilai tersebut digunakan dalam tahapan selanjutnya. Hasil dari peneltian ini, menunjukkan bahwa Sesar RMKS memiliki mekanisme berupa sesar normal. Namun, menimbang beberapa sumber lain yang menyebutkan Sesar RMKS memiliki mekanisme berupa sesar geser mengiri, maka dapat disimpulkan bahwa Sesar RMKS memiliki mekanisme oblique dengan pengaruh sesar normal.
... Magnetic survey is widely used in mineral prospecting for regional-scale resource mapping and for detailed characterization of mineral ore deposits at site-scale (Telford et al., 1990;Silva, 1999;Nabighian et al., 2005). Iron ore deposits are well-defined targets for magnetic methods, as ores rich in magnetite and hematite are easily identified by their high magnetic contrast to host rocks. ...
Wadi Um Nar area acquired its importance since the discovery of banded iron formations (BIFs), and is one of the largest iron formation occurrences in the Eastern Desert of Egypt. Therefore, the recorded aeromagnetic data were processed, using a combination of edge enhancement filters, to identify major structures and recognize the lateral and vertical distribution of BIFs, as well as to determine the locations of buried magnetite ore bodies in this area. The obtained results from the application of these techniques revealed that the NW–SE, NE–SW and N–S directions are the common tectonic trends in the region. These trends could be faults or shear zones that have acted as good pathway or channels for hydrothermal fluids. Estimating the basement depth using source parameter imaging (SPI) showed that the BIFs depths varied from the surface down to about 450 m. Additionally, the orthogonal derivative maps of Wadi Um Nar BIFs showed an E–W trend, which corresponds exactly to the maximum magnetic intensity belt and their anomalies are characterized by a distinct dipole nature. These maps also revealed the extent and continuity of the main ore body of BIFs and showed that, they were mainly produced from magnetite mineral, formed in regions of structurally-controlled fluid flow.
... Where K is the geometric factor of the Schlumberger configuration, a is the current electrode distance, b is the potential electrode distance, ρ is the resistivity, ∆V is the potential difference, and I is the current (Telford et al., 1990). ...
Research on groundwater aquifers using the geoelectric method has been carried out in the Sukadanaham area, Tanjung Karang Barat District, Bandar Lampung City. This Research Objectives This research aims to identify the lithology and depth of groundwater aquifer zones based on resistivity values and geological literature. Data acquisition was carried out using the Schlumberger configuration of 3 points in the young Betung volcanic formation (Qhvb). The data used is the resistivity value. Resistivity value data is modeled vertically with inverted results. The resistivity value of each point is adjusted and interpolated based on the literature on rock resistivity values. Based on the identification results, 4 types of subsurface rock lithology were found, namely top soil, tuff, breccia, and andesite. The lithology of the layers at point 1, point 2 and point 3 is dominated by tuff and breccia layers. The resistivity value of the andesite layer obtained has a high value, which is > 300 Ωm. The resistivity value of the tuff layer for the waterproof layer has a value of 200-250 Ωm. The breccia layer acts as a groundwater aquifer zone with a low resistivity value of 15-60 Ωm. The rock resistivity value with the lowest value is at a depth of 40-95 m which is a compressed aquifer layer with andesite and tuff layers as a waterproof layer above and below.
... The contrasts in electrical properties that exist between the host rocks and subsurface geologic structures are advantageous for the applicability of the ER method. This contrast allows for the detection of electrically conductive materials such as leachates and native groundwater (Telford et al., 1990;Keary et al., 2002;Oni et al., 2020;Salako et al., 2020;Song et al., 2022;Zhang et al., 2022). In this research, two traverses, ranging from 1 to 5. The inversion of the dipole-dipole data was performed to retrieve a two-dimensional subsurface structure with the aid of the DIPRO inversion tool. ...
In this study, we investigated the implications of a leachate plume within an aquifer system, unravelling the intricate dynamics that govern contaminant transport and dispersion. An integrated approach of geophysical investigations is used to establish the impact of an open-waste disposal site around Aromed, in a part of Akure, in the Precambrian Basement Complex of Southwestern Nigeria. Investigations using eight (8) Vertical Electrical Sounding (VES) and Double-Dipole Resistivity Tomography (ERT) along two (2) traverses were conducted. The geoelectric interpretation and the inverted two-dimensional electrical resistivity tomography (ERT) images provided insights into the underlying geological composition, identifying three distinct units: the topsoil, the weathered column, and the fractured Basement/fresh Basement bedrock. The geoelectric tomography structures in the 2-D interpretation reveal that the dumpsite area exhibits low apparent resistivity estimated to be between 12 to 71 ohm-m in both the topsoil and the weathered column aquiferous zone. These values closely agree with results from the geoelectric sections, which range between 11 - 68 ohm-m, respectively. The relatively low apparent resistivity results are suggestive to be due to the presence of leachate’s chemical composition from the open waste disposal sites, which are suspected to be generated from the dissolution of ions of iron and other conductive minerals producing the leachate plume. The probable leachate depth of migration as revealed by the 2-D tomography structures varies from about <1 – > 14 m beneath the dumpsites. The leachate migration, which is structurally controlled, has a southward flow, majorly in the orientation with the observed structures. The subsurface depression-relief is also attributed to influence the direction of leachate flow. In conclusion, it is suggested that groundwater in the aquiferous zones in the vicinity of the dumpsites have entered a significant pollution level; hence water in the aquifer is not safe for consumption.
... Metode gravitasi sendiri didasarkan pada pengukuran perubahan medan gravitasi bumi. Dalam metode ini, untuk menyelidiki perubahan medan gravitasi akibat perubahan kerapatan batuan di bawah permukaan, digunakan teori Hukum Newton mengenai gaya tarik-menarik antara dua materi bermassa m1 dan m2 yang terpisah dengan jarak r (Telford, 1990) (persamaan 1). ...
Ketergantungan pada energi fosil terus meningkat seiring dengan meningkatnya tuntutan kehidupan. Oleh karena itu, ketergantungan kita pada energi fosil perlu dialihkan dengan menggunakan energi panasbumi. Salah satu daerah prospek panasbumi di Kabupaten Dompu, Provinsi Nusa Tenggara Barat adalah Hu’u Daha 35 km di sebelah timur Kabupaten Dompu memiliki potensi terduga ±69 MW. Penelitian lebih lanjut dilakukan pada sistem panasbumi Hu’u Daha melalui korelasi analisis peta Land Surface Temperature (LST), analisis derivative, dan pemodelan inversi 3D sehingga dapat diketahui dugaan keterdapatan lapisan reservoir berupa batuan lava dan breksi berkomposisi andesit dan basalt serta sisipan batuan tufa dengan rerata kedalaman 633 – 1500 m dengan nilai densitas 3,4 - 3,33 gr/cm3 yang dilingkupi oleh lapisan cap rock berupa batuan lava hasil erupsi dengan kedalaman rata-rata 0 – 633 m dengan nilai densitas 3,51 – 3,44 gr/cm3, serta terdapat 11 patahan yang mengontrol sistem panasbumi berupa 2 strike-slip fault, 7 normal fault, dan 2 reverse fault. Berdasarkan analisis peta Land Surface Temperature (LST) yang di overlay dengan peta geologi dapat diketahui pula persebaran suhu permukaan daerah Hu’u Daha berkisar antara 26°C – 28,4°C.
... Percepatan gravitasi bervariasi dari tempat ke tempat karena bumi mempunyai bentuk mendekati bentuk spheroid, relief permukaannya tidak rata, berotasi, berevolusi dalam sistem matahari serta tidak homogen, sehingga variasi gravitasi disetiap titik dipermukaan bumi dipengaruhi oleh berbagai faktor seperti lintang, ketinggian, topografi, pasang surut, dan variasi rapat massa bawah permukaan (Telford, 1990). Jadi, hasil data survei gravitasi perlu dikoreksi untuk mendapatkan data yang hanya dipengaruhi oleh variasi rapat massa bawah permukaan (Rezki Amaliah, 2014) Teknik pengolahan data dalam penelitian ini dimulai dengan melakukan perhitungan koreksi terhadap data yang sudah didapat. ...
Geothermal manifestation area around Tampusu Mountain is an area surrounded by highlands and lowlands. The existence of the highlands and lowlands allows the fault in the Geothermal Manifestation area around Mount Tampusu. The purpose of this study was to determine the presence of faults in the geothermal manifestation area around Tampusu Mountain based on the Gravity Method. From the results of the study, high bouguer anomaly values are located in the southeast of Tampusu Mountain, with a distribution value of 152.4 - 164.4 mGal (0,001524 – 0,001644 m/s2). Whereas for areas with low bouguer anomaly values are in the southwestern part of Mount Tampusu with values 126 - 136 mGal (0,00126 – 0,00136 m/s2). This anomaly variation is probably caused by differences in the density of rocks scattered in the Geothermal Manifestation Area around Tampusu Mountain. Through Bouger Anomaly Value Mapping, it is estimated that the fault in the Geothermal Manifestation area around Mount Tampusu is in the southeastern part of Mount Tampusu which leads to the Northeast, based on the drastic increase in the value of the bouguer anomaly. Fault that is in the Geothermal Manifestation area around Mount Tampusu is classified as a normal fault or fault down.
... It is essential to understand the subsurface geology to identify the locations of oil and gas accumulations, and this includes mapping the subsurface structure to detect structures that could trap oil and gas or faults that might block oil flow in a production field (Bacon et al., 2003). The interpretation of seismic data is the final step of a seismic exploration investigation; hence, the accuracy of earlier work affects the accuracy of the interpretation stage (Telford et al., 1990). The interpretation sequence is a series of processes that carry out an interpretation in a form similar to that typically used to process seismic data. ...
A structural study was conducted in Al-Fao area, southeastern Iraq using two-dimensional seismic data. The seismic lines were divided into three surveys (F, Kl, and Sa). Al-Fao is an exploratory area that does not contain any wells; the well information was based on Siba field, located north of the study area. The primary reservoir target in the lower Cretaceous was Yamama Formation. Two reflectors,top and base Yamama Formation are defined using synthetic seismogram in the time domain for Sb well. A top Yamama Formation was defined as Z-crossing, and a base Yamama Formation as S-crossing. The results showed that the strata tended to slope from the south and southwest to the north and northeast, and the area was affected by multiple structural orogenies. Siba field is an elongated fold whose axis extends northeast-southwest; it consists of a structural nose and northeastern dome. The Two-Way Travel Time map showed higher values in the southeast and east, indicating sloping reflectors in those directions. The depth maps of Yamama Formation showed the deepest part in the southeast and east, suggesting a plunging structure in those directions. The study also revealed the presence of numerous closures as structural noses, which could serve as potential structural traps.
... Setelah itu perhitungan faktor geometri (Ks) dan resistivitas semu (ρsemu) lintasan pengukuran 1 seperti ditampilkan pada Tabel 1. Berdasarkan Tabel 3 dan Gambar 3 terkait pengukuran pada lintasan 1, terlihat bahwa resistivitas batuan di lokasi pengukuran berkisar 0,668-2477 Ωm dengan kedalaman pengukuran hingga 50,1 m serta terdapat 6 perlapisan. Berdasarkan tabel resistivity dari Telford dkk (1990) keberadaan air tanah (groundwater) resistivitas batuannya antara 0,5-300 Ωm [10]. Berdasarkan peta geologi lembar Ternate, lokasi penelitian lintasan 1 berada pada formasi Gunungapi Gamalama Muda (Gm)-Breksi Letusan Gunung dan Percikan (Gmlp), yaitu sebagian besar berupa bom percikan lava dan bom kerakroti andesit kadang-kadang tuff kuning kecoklatan teralterasi, terbentuk sekitar lubang erupsi pada 1763 [11]. ...
Kelurahan Sasa bagian puncak kesulitan air khususnya di musim kemarau karena tidak ada sumur bor atau sumur gali. Kendala muka air tanah yang tidak diketahui dengan pasti sehingga sulit untuk memastikan kedalaman pengeboran dan biaya investasinya. Deteksi muka air tanah menggunakan metode geolistrik resistivitas konfigurasi Sclumberger di Kelurahan Sasa Kecamatan Ternate Selatan Kota Ternate menjadi penting dilakukan. Penelitian ini termasuk jenis penelitian lapangan (field research), dimana dilakukan pengukuran menggunakan metode geolistrik untuk 2 lintasan dengan panjang masing-masing lintasan 200 meter yang mengarah selatan-utara, dengan elevasi antara 47-86 mdpl. Lintasan 1 tidak ditemukan potensi akuifer, batuannya didominasi andesit dengan resistivitas 553-2477 Ωm. Lintasan 2 ditemukan potensi akuifer dengan kedalaman 28,9-50,1 m ketebalan 21,2 m dengan resistivitas 125 Ωm. Lapisan ini diinterpretasikan sebagai breksi vulkanik dengan matriks berupa tuff. Pada kedalaman 8,53-28,9 m (resistivitas 4,24 Ωm) lapisan ini disusun oleh tuff halus dan tuff lapili. Lapisan ini diduga aquiklud, yaitu media berpori yang dapat menyimpan air tetapi tidak dapat mengalirkan air tanah yang dapat terisi oleh air pada musim hujan, namun pada musim kemarau tidak mengandung air. Tingkat kesiapan teknologi (TKT) penelitian ini adalah TKT 3 yang merupakan pembuktian konsep (proof of concept) serta hasil penelitian menjadi rekomendasi kepada pemerintah khususnya PDAM Kota Ternate.Â
... The application of 2D time-lapse electrical resistivity tomography (ERT) has the major advantage of being non-destructive and minimuminvasive when measuring the electrical resistivity targeting the air/soil/ rock-filled volumes and water-filled voids in highly heterogeneous aquifers to analyze changes in groundwater characteristics (Samouëlian et al., 2005;Vanderborght et al., 2005;Al Hagrey, 2007;Brunet et al., 2010;Binley et al., 2015;Watlet et al., 2018). Several parameters contribute to variations in ERT measurements, including subsurface composition, moisture content, temperature, porosity, permeability, mineralization, instrumentation, noise, and survey configuration (Telford et al., 1990). ERT monitoring is an extremely efficient method for some hydro-geophysics studies (Kuras et al., 2009;Coscia et al., 2012;Revil et al., 2012;Uhlemann et al., 2016Uhlemann et al., , 2017, including investigations of heterogeneous aquifers (Chen et al., 2018;Torrese, 2020;Yan et al., 2023), characterization of water storage zones (Pope et al., 2023;Delgado-Gonzalez et al., 2023;Kadam et al., 2023), and preferential flow studies (De Carlo et al., 2021;Song et al., 2023). ...
The hydrodynamics of karst terrain are highly complex due to the diverse fractures and reservoirs within limestone
formations. The time delay between rainfall events and subsequent flow into reservoirs exhibits significant
variability. However, these hydrological processes are not easily visualized in karst topography. Subsurface geophysics,
specifically 2D time-lapse electrical resistivity tomography (ERT), provides an effective method for
studying the relationships between hydrological and geophysical features. In our research, we adopted ERT in
the Karst Critical Zone (KCZ) to visualize specific karstic zones, including cave galleries, water storage reservoirs,
wetting fronts, soil layers, and potential preferential flow paths down to a depth of 20 m. To capture spatial and
seasonal variations in resistivity, we presented a comprehensive approach by combining sixteen inversion models
obtained between February 2020 and September 2022 above the Villars Cave in SW-France—a well-known
prehistoric cave. We used a multi-dimensional statistical technique called Hierarchical Agglomerative Clustering
(HAC) to create a composite model that divided the synthetic ERT image into eight clusters representing different
karst critical zones. The ERT image clearly visualized the cave gallery with high resistivity values that remained
consistent throughout the seasons. Our analysis revealed a close seasonal relationship between water excess and
resistivity variations in most infiltration zones, with time delays increasing with depth. The karst reservoirs, located
at significant depths compared to other clusters, displayed sensitivity to changes in water excess but were
primarily affected by fluctuations in water conductivity, particularly during summer or dry periods. These findings
have significant implications for predicting rainwater infiltration pathways into caves, thereby assisting in
the conservation and preservation of prehistoric caves and their cultural heritage.
Secara umum bentang alam kelurahan Rajabasa Jaya didominasi oleh perbukitan dan rawa-rawa dengan pertumbuhan penduduk yang terus meningkat berimplikasi terhadap ketersediaan air di daerah ini. Berdasarkan wawancara dengan warga Rajabasa Jaya hingga tahun 2024, di Lingkungan II (LK I) RT. 08 Kelurahan Rajabasa Jaya sebagian besar mengeluhkan kondisi air sumur yang tidak layak konsumsi seperti bau dan keruh, terutama ketika musim hujan. Tujuan dari kegiatan pengabdian ini adalah untuk mengidentifikasi sumber air tanah dalam dan dangkal dengan teknologi geofisika dan menerapkan alat Filter Air Sederhana untuk mengolah air keruh sehingga layak digunakan untuk kebutuhan rumah tangga. Kegiatan pengabdian kepada masyarakat ini dilakukan dengan metode pemaparan materi dan diskusi. Materi yang disampaikan pada kegiatan pengabdian ini adalah materi pengenalan metode geofisika geolistrik untuk mendeteksi keberadaan air tanah dan materi mengenai air bersih dan teknik penyaringan air. Setelah kegiatan pemaparan materi dari narasumber, kegiatan pengabdian kepada masyarakat ini kemudian dilanjutkan dengan pembagian Filter Air kepada warga masyarakat RT08 Rajabasa Jaya Bandar Lampung. Warga masyarakat yang mengikuti kegiatan ini memberikan respon yang sangat positif terhadap terselenggaranya acara kegiatan pengabdian kepada masyarakat Unila karena sangat bermanfaat bagi warta RT08 Rajabasa Jaya untuk mendapatkan kualitas air yang lebih bersih.
Subsurface modeling based on density variations is currently developing very rapidly. This modeling can be achieved using a computational technique called inversion modeling for mathematical calculations on gravity data. The objectives of this research are to create a 2D sparse inversion algorithm for gravity data using SimPEG, which is then interpreted to analyze geothermal fields. The method research begins with a synthetic data study that includes spectrum analysis and synthetic data inversion using vertical, horizontal, and fracture block models. In terms of synthetic data inversion results, the sparse inversion algorithm is considered quite good, with an average root mean square error (RMSe) of 0.551 mGal and a correlation of 69.81%. Furthermore, the sparse inversion algorithm was used to invert the Ungaran Volcano field data, obtaining results with an RMSe value of 0.087 mGal. The model produced using the sparse inversion method was considered to correlate well with the geological information and models in previous research. In this paper, we present a new approach to inversion modeling techniques that are available in the SimPEG library with the Python programing language and can be applied to geothermal fields.
Keperluan air bersih cenderung melonjak bersamaan dengan perkembangan Masyarakat karena sumber daya air bersih semakin terbatas. Penelitian ini bertujuan untuk mengidentifkasi keberadaan lapisan akuifer dan potensi air tanah di daerah Megal, Blora, Jawa Tengah, menggunakan metode geolistrik resistivitas dengan konfigurasi Wenner dan Schlumberger. Pengukuran dilakukan dengan jarak antar elektroda 3 meter menggunakan alat SuperSting R8/IP, dan data diolah menggunakan perangkat lunak Res2DInv. Hasil analisis menunjukkan bahwa konfigurasi Wenner mendeteksi lapisan akuifer dengan nilai resistivitas rendah pada kedalaman 11.9–17.2 meter. Sedangkan konfigurasi Schlumberger menunjukkan kedalaman akuifer hingga 31,4 meter dengan resistivitas yang sesuai untuk mengalirkan air. Terutama pada kedalaman 20.3 – 31.4 m yang didominasi oleh lapisan batu pasir dengan porositas dan permeabilitas tinggi.
New roads are built to alleviate congestion that occurs in an area. Tembalang is one of the most densely populated areas in Semarang city. The research location is Tembalang-Jangli New Road. The construction of Jangli-Undip New Road aims to reduce congested vehicle traffic in Gombel and Meteseh, which causes frequent congestion. Therefore, subsurface identification using the resistivity geoelectric method of dipole-dipole configuration was carried out to know the cause of landslides at the research location. Data acquisition was carried out with 10 passes. The results obtained 5 (five) layers of subsurface constituent rocks on Undip-Jangli New Road based on their resistivity values, namely topsoil (0.105 - 1.0 Ωm), clay (1.11 - 6.29 Ωm), sandstone (8.52 - 20.0 Ωm), tuff (20.0 - 75.0 Ωm), and volcanic breccia (75.0 - 133 Ωm). The interpretation results show the sliding plane at a 6.76 - 24.8 m depth. The layer that acts as a slide plane is a clay layer. The existence of sliding planes detected in the trajectories A-A’, B-B’, C-C‘, D-D’, E-E‘, F-F’, G-G‘, H-H’, I-I‘, and J-J’ has great potential to cause soil movement or landslides with the type of sliding is rotation. Keywords: landslide, resistivity geoelectricity, dipole-dipole.
Air merupakan kebutuhan pokok manusia untuk melangsungkan kehidupan. Air permukaan dan air tanah merupakan sumber air utama yang digunakan masyarakat untuk memenuhi berbagai kebutuhan. Air tanah terdapat pada lapisan tanah yang mengandung air yang disebut akuifer. Sebelum pembangunan sarana air bersih dilaksanakan, terlebih dahulu dilakukan penyelidikan geologi dan hidrogeologi sebagai bagian kegiatan eksplorasi. Kedalaman air tanah di suatu daerah tidak sama dengan daerah lainnya, tergantung dari ketebalan lapisan penutup serta kedudukan akuifernya. Lokasi penyelidikan pengabdian mencari sumber air bersih ini berada di Makam Syiah Kuala, Banda Aceh, di mana pengaabdian ini juga bekerjasama dengan Tentara Nasional Indonesia Angkatan Darat (TNI AD) Komando Daerah Militer (Kodam) Iskandar Muda. Di lokasi ini dilakukan pengukuran geolistrik dengan permodelan data geolistrik 1D menggunakan Software Earthimager. Proses pengabdian kepada masyarakat untuk mencari lapisan akuifer yang mengandung air di dalam tanah ini dilakukan dengan metode pendugaan geolistrik yang bertujuan di antaranya untuk memperkirakan ada tidaknya lapisan pembawa air (akuifer) dan mencari/ mengetahui letak, posisi, ketebalan, kedalaman dan penyebaran lapisan pembawa air (akuifer) bawah permukaan. Dari hasil penyelidikan diketahui bahwa lapisan yang diduga sebagai akuifer tidak terdapat pada hasil pemodelan hingga kedalaman pengukuran.
Permeability is one of the key factors in a geothermal system that accommodated the geothermal fluid to flow in the reservoir through faults. The DB geothermal field has a geothermal system, as evidenced by the appearance of manifestations such as fumaroles, steaming grounds, and hot springs. The appearance of manifestations is influenced by weak zone or permeable zones associated with the main structures as a fluid conduit in the study area. This study was conducted to identify permeable zones using gravity data in the DB geothermal field. In detecting permeable zones associated with the presence of structures, advanced processing on gravity data can be used, namely from Complete Bouguer Anomaly (CBA), regional and residual anomalies, Horizontal Gradient Magnitude (HGM), Second Vertical Derivative (SVD) and Multi Scale-Second Vertical Derivative (MS-SVD) which is correlated with geological and geochemical data. The integrated analysis shows the contrast of gravity anomaly, the maximum value of HGM, and the zero value of SVD that forms alignment patterns in the NW-SE direction. The alignment pattern is associated with the geological structure developed in the study area, which is NW-SE oriented, and along the structure, there are manifestations of hot springs. Therefore, the results of this study can identify high permeability zones that can be used as drilling well targets and can develop the DB geothermal field in the future.
In this study, geophysical, hydrogeological and hydrochemical
investigations have been done in the Uplands of W.Rasyan, Taiz, Yemen. The study is aiming to explore water resources and to evaluate groundwater and environmental situation in the area. A total 38 vertical
electrical sounding are preformed at selected positions along 6 profiles and interpreted
into different geoelectrical and structural features. The hydrogeological information,
water levels measurements and pumping test data were analyzed; the groundwater
budget has been prepared for area. The water quality in the area has been evaluated
through conducting of field measurements, laboratory analysis for the collected water
samples, the main contaminant sources and their environmental impacts were
recognized.
The results indicated that the total exploitable groundwater in storage within the study area is estimated about 1029 MCM. The total annual recharge is estimated about 41.8 MCM and the total annual discharge is estimated about 58.3 MCM that gave an imbalance between the recharge and discharge for about 16.5 MCM/year.
Water quality evaluation indicted that the ion concentrations in the study area are
appreciably tends to increase with increasing distance from the recharging areas. High
salinity marks the main stream of wadiy Rasyan and the shallow alluvial aquifer in Taiz plain. Variations in natural and human activities reflect spatial variations in the contaminant indicators. The water quality in the most of the study area is good and
suitable for use in drinking and irrigation. Contaminated water (unsuitable for drinking
or irrigation) is concentrated below the waste water deposal sites in Burayhi, Hawgala,
Hawban and Hidran areas and along the main stream of W.Rasyan.
The study concluded that the surface and groundwater water resources in the
uplands W.Rasyan are not managed in a sustainable way, the environmental protection
efforts are scare, and most of rainfall and floods are being ignored or poorly managed.
The study recommended that protection of the groundwater resources against unregulated drilling, over abstraction and environmental pollution is a vital important.
Increasing the public and national awareness of water resources management problems
is necessary.
As the technology development, there are more and more new innovations that utilize existing resources to support the energy needs and to fulfill the consumer needs. The energy source that is being discussed at this time is geothermal energy. Geothermal energy sources are considered effective because they are renewable and environmentally friendly when compared to other energies such as fossil energy. In Indonesia itself, geologically, it has a complex series of volcanoes that can be used as a heat source in this new energy innovation. One area that thought to have geothermal potential is the telomoyo mountain area, which is indicated by the manifestation of hot springs on the surface, precisely around Candi Umbul. However, it is necessary to conduct subsurface studies to identify the presence of subsurface structures such as faults or intrusions as heat sources, where this can be overcome using geophysical methods. This research was conducted using the integration of two geophysical methods, namely the geomagnetic method to determine the direction of the fault continuity and the gravity method to determine the regional heat source, and in the other side geological data as a reference for interpretation. From geomagnetic measurements, 163 rock magnetism data were obtained which indicated the existence of a fault continuity with northeast-southwest orientation in the direction of the river flow and cut the manifestation of hot springs. Meanwhile, from 176 gravity topex data, a high complete boguer anomaly value was obtained as an indication of an intrusion in the northeast that was cut by the fault recorded in the geomagnetic data. Based on geophysical data analysis and correlation with geological data from previous studies, it can be assumed that there is a geothermal system in the study area with andesitic intrusion as the heat source, fault structure with northeast-southwest orientation as a weak zone for meteoric water migration, andesite lava as caprock, unit tuff rock as a reservoir and the telomoyo plateau as a recharge area to supply meteoric water from the geothermal system.
Telah dilakukan upaya pencarian sumber air bawah permukaan menggunakan metode goefisika yakni metode resistivitas Schlumberger dengan memetakan sumberdaya air tanah. Penelitian ini bertujuan untuk menentukan keberadaan sumberdaya air tanah di wilayah Kabupaten Kolaka khususnya Desa Langori Kecamatan Baula. Pengambilan data dilakukan pada dua titik lokasi ukur dan diolah memakai software Progress. Hasilnya menunjukkan profil nilai resistivitas air tanah 3,32 Ωm – 48,96 Ωm yang berada pada kedalaman 4,92 m hingga 370 m. Dugaan keterdapatan lapisan air tanah untuk titik lokasi ukur 1 atau line 1 berada pada beberapa kedalaman yaitu kedalaman 8,57 m - 9,42 m, kedalaman 13,30 m - 27,22 m, kedalaman 166,28 m - 188,36 m, dan kedalaman 249,78 m - 370 m yang masing-masing memiliki nilai resistivitas 26,95 Ωm, 6,52 Ωm, 31,54 Ωm, dan 31,82 Ωm. Titik lokasi ukur 2 atau line 2, dugaan keterdapatan lapisan air tanah yaitu pada kedalaman 4,92 m - 8,55 m, kedalaman 20,53 m - 31,60 m, dan kedalaman 70,73m - 117,42 m yang masing-masing memiliki nilai resistivitas 41,91 Ωm, 3,32 Ωm, dan 32,11 Ω.
The need in technical groundwater exploration to construct a groundwater well for water supply of the rotation village of the mining and processing plant "Svetlovsky"in the Bodaibo district of the Irkutsk region. The electrical resistivity tomography is a common method for studying the upper part of a cross section and is widely used in mineral pro-specting, geological mapping, engineering surveys, hydrological and environmental studies. The application of electrical re-sistivity tomography in these conditions will allow substantiating the location of hydrogeological wells and boreholes.Aim.Assessment of the geological and hydrogeological conditions of the area of work for the prospect of extracting groundwater for technical water supply for the needs of the rotational camp.Objects.Bedrocks, which are characterized by high resistance values and are aquicludes; permeable low-resistance zones that are water-bearing rocks.Methods.Ground-based geophysi-cal surveys using electrical resistivity tomography; two-dimensional inversion of ERT data and their interpretation taking into account engineering and geological data of drilling and the GIS complex.As a result of the engineering and hydrogeologi-cal surveys performed using ground-based geophysical surveys by electrical resistivity tomography, it was established that the aquifer system of fissured rocks of the Imnyakh suite of the Proterozoic sediment complex (PR2-3im) is represented by fissured limestones of various colours from grey to blueish, with bands of mica schist. Analysis of the study results showed that the thickness of the exposed sediments is upto 50 m, the groundwater level of the operating horizon is opened at depths from 21 to 28 m. They are covered with a complex of low-permeabilitysediments of thickness from 5 to 11 m that are pre-sented by interbedding of dense grey limestones and black metasandstones.
Seismic method practicum has been carried out with the title "Interpretation of reflection seismic data: picking horizon and picking fault". The seismic method is a geophysical method that is often used in imaging the subsurface conditions of the earth. The purpose of this practicum is to find out how to do picking horizon and picking fault. Picking horizon and picking faults are done with petrel software. Picking Horizon is a method that is carried out by making a horizon line on a continuous layer on a seismic cross section. For picking horizon, petrel software is used. From these data it is known that there are 3 horizons (layers). Fault picking is carried out simultaneously with seismic horizon picking. Fault picking is carried out starting from a clear shift in the horizon and continuing to the vertical shift zone. For picking faults, petrel software is used. From these data it is known that there are 4 faults (faults).
This seismic method practicum meeting is expected that practitioners are able to meet the objectives of knowing the process of forming the T-X curve in refraction seismic. The practicum was held on Monday, December 5, 2022 at the Faculty of Science and Technology, Jambi University. Based on the T-X curve attached to T-X 1, the reverse direct will be inverted from the forward. This value will be searched for an equation to get the result of rock velocity based on forward and reverse waves. Velocity is the level of rock hardness that will determine the speed of a wave in a rock layer. For interpretation, it can be seen from the table of seismic wave propagation velocity in the rock above. Where for V1 of 333.3333 m/s is included in layered weathered rock. For V2 where the speed value is 1000 m/s is unsaturated sand and gravel. For V3 where the velocity value is 1666,67 m/s, it is sand and shale. The interpretation of these rocks actually requires information about the formation where the data was collected.
Daerah Ulujadi, Kota Palu, Provinsi Sulawesi Tengah sering mengalami gempabumi karena dilalui sesar aktif yaitu sesar Palu Koro. Hal tersebut mengakibatkan kerugian yang besar bagi penduduk setempat, sehingga diperlukan upaya mitigasi bencana gempabumi untuk masa yang akan datang. Sebagai bentuk dukungan untuk keberhasilan mitigasi tersebut dilakukanlah penelitian dengan tujuan untuk mengidentifikasi jenis lapisan batuan bawah permukaan dan menduga keberadaan zona sesar. Metode geofisika yang digunakan adalah metode Geolistrik 2D Konfigurasi Wenner sebanyak 3 lintasan. Berdasarkan hasil analisis pemodelan 2D terdapat 3 lapisan batuan bawah permukaan yang terdiri dari batupasir pada rentang 0,86 – 163 Ωm, batugamping pada rentang 164 -1.013 Ωm, dan batu konglomerat pada rentang 1.014 – 10.527 Ωm. Terdapat 3 terduga zona sesar pada lintasan 2 dan lintasan 3 yang tergolong pada sesar minor (patahan dangkal) yang termasuk jenis sesar normal dengan arah kemenerusan dominan timur laut-barat daya daerah penelitian. Hasil penelitian ini, diharapkan menambah informasi terkait zona sesar, agar upaya mitigasi bencana dapat diupayakan lebih baik.
Senawang District is an area in Sumbawa Province with a high level of drought. This study aims to provide additional information about groundwater to support the availability of clean water in Senawang District. The study used Geoelectric-Schlumberger Method as main method of subsurface identification. The acquisition was conducted with 10 points acquisition, with spacing between points is 200 m and the line stretch of 250 m. The results of data processing are a vertical resistivity variation in depth at each point measurement. This result will be interpreted into the type of rock and the presence of groundwater. The interpretation shows that the presence of groundwater aquifer with resistivity of 12.54 – 26.28 m, thickness 4.59 – 7.95 m, depth (upper part of the layer) 23.29 – 50.56 m. The type of groundwaters aquifer in the study area are confined aquifers.
Electrical Resistivity prospecting method was used in determining groundwater potential zone at SabonKaura village, Bauchi, Bauchi State using the vertical Electrical Sounding (VES) technique at points selected at convenience place away from contaminant sources), a total of eighteen (18) VES data using Schlumberger array with 300c model of ABEM Terrameter SAS was used in the survey. The VES data acquired were initially presented as field curves on a bi-log scale, and later refined by ID offix iterative inversion software program. The interpreted curves show H, and HA curves. The interpreted models indicate various layers that vary between three and four interpreted as topsoil, decomposed/weathered zone, slightly to a highly weathered basement and fresh basement. The first two lithologic units (topsoil and 1st aquifers) are overburden in origin and the 2nd aquifers are structurally controlled based on their resistivity value ranges and probable depth.
Desa Sungai Duri merupakan salah satu desa di Kabupaten Bengkayang yang berada di daerah pesisir. Keberadaan air bersih masih menjadi masalah di daerah pesisir, karena sumur yang telah dibuat masih menghasilkan air payau hingga asin. Tujuan pada penelitian ini adalah untuk mengidentifikasi sebaran intrusi air laut di Pesisir Desa Sungai Duri, Kabupaten Bengkayang. Metode yang digunakan adalah metode geolistrik vertical electrical sounding (VES) di lima titik pengukuran dengan bentangan masing-masing 500 m. Intrusi air laut di lokasi penelitian tersebar hingga ±230 m dari garis pantai. Intrusi air laut juga teridentifikasi di titik 1 pada kedalaman 4.68 m – 11.8 m, titik 2 pada kedalaman 3.72 m – 9.81 m, titik 3 pada kedalaman 5.32 m – 9.92 m, dan titik 5 pada kedalaman 7.61 m- 18.3 m. Intrusi di daerah penelitian ini disebabkan karena kondisi litologi yang didominasi oleh material pasir.
Tersedianya informasi gravitasi di daerah Lembar Kota Agung pada kawasan yang memiliki potensi panas bumi memberikan peluang dilakukan pemodelan struktur bawah permukaan. Memanfaatkan data anomali percepatan gravitasi yang diperoleh dari Global Gravity Model plus (GGMplus) dengan spasi antar titik sejauh 220 m. Hasil penafsiran data gravitasi berupa Anoamli Bougeur Lengkap (ABL) pada daerah Lembar Kota Agung menunjukkan bahwa nilai anomali daerah ini dikelompokkan menjadi dua bagian, yaitu kelompok dengan nilai rendah dan nilai tinggi, yang masing-masing menggambarkan daerah busur vulkanik dan daerah lembah. Model gravitasi berbasis perhitungan dengan pemilihan nilai rapat massa dan geologi bawah permukaan menunjukkan bahwa struktur lapisan bawah permukaan di kawasan potensi panas bumi daerah Lembar Kota Agung berupa batuan pasir, batuan lempung, batuan andesit, batuan granit, dan untuk batuan breksi tersusun atas mineral penyusun berupa kuarsa dengan nilai densitas berkisar antara 2,314 g/cm3 hingga 2,782 g/cm3.Kata Kunci : Anomali Bougeur, GGMplus, Potensi Panas BumiTersedianya informasi gravitasi di daerah Lembar Kota Agung pada kawasan yang memiliki potensi panas bumi memberikan peluang dilakukan pemodelan struktur bawah permukaan. Memanfaatkan data anomali percepatan gravitasi yang diperoleh dari Global Gravity Model plus (GGMplus) dengan spasi antar titik sejauh 220 m. Hasil penafsiran data gravitasi berupa Anoamli Bougeur Lengkap (ABL) pada daerah Lembar Kota Agung menunjukkan bahwa nilai anomali daerah ini dikelompokkan menjadi dua bagian, yaitu kelompok dengan nilai rendah dan nilai tinggi, yang masing-masing menggambarkan daerah busur vulkanik dan daerah lembah. Model gravitasi berbasis perhitungan dengan pemilihan nilai rapat massa dan geologi bawah permukaan menunjukkan bahwa struktur lapisan bawah permukaan di kawasan potensi panas bumi daerah Lembar Kota Agung berupa batuan pasir, batuan lempung, batuan andesit, batuan granit, dan untuk batuan breksi tersusun atas mineral penyusun berupa kuarsa dengan nilai densitas berkisar antara 2,314 g/cm3 hingga 2,782 g/cm3.Kata Kunci : Anomali Bougeur, GGMplus, Potensi Panas Bumi
Abstrak: Metode geolistrik merupakan salah satu metode eksplorasi geofisika yang kompleks karena metode geolistrik digunakan untuk eksplorasi barang tambang, persediaan air, pendugaan di bawah permukaan dan panas bumi. Metode geolistrik dirancang untuk memberikan informasi dari formasi batuan yang mempunyai anomali konduktivitas listrik. Pada penelitian ini diukur lintasan 1 pada jalan lintas Matuting dan ditemukan terdapat 5 perlapisan dengan kedalaman mencapai 25 m. Jenis materialnya pada lapisan 1 terdapat pasir, lapisan 2 terdapat batupasir, lapisan 3 terdapat batugamping, lapisan 4 terdapat batulempung dan lapisan 5 terdapat lempung, dengan nilai resistivitas antara 0,203Ω-2.821Ω. Pada lintasan 2 terdapat 6 perlapisan dengan kedalaman mencapai 25 m, jenis materialnya pada lapisan 1 terdapat lempung, lapisan 2 terdapat napal, lapisan 3 terdapat lempung, lapisan 4 terdapat napal dan lapisan 5 terdapat batu lanau, di lapisan 6 terdapat batulempung, dengan nilai resistivitas antara 0,11Ω-65,9Ω. Dalam penelitian ini membuktikan bahwa kondisi perlapisan batuan di sekitar jalan lintas matuting-saketa atau lokasi kerja praktek harus dilakukan pengeboran pada titik pengukuran Kata kunci: geolistrik, jalan, lapisan, material, batuan. Abstract: The geoelectric method is a complex geophysical exploration method because the geoelectric method is used for mining exploration, water supply, subsurface, and geothermal estimation. The geoelectric process is designed to provide information from rock formations that have electrical conductivity anomalies. In this study, track 1 on the Matuting causeway was measured, and it was found that there were five layers with a depth of up to 25 m. The type of material in layer 1 is sand, layer 2 is sandstone, layer 3 is limestone, layer 4 is claystone, and layer 5 is clay, with a resistivity value between 0.203Ω-2.821Ω. On track 2, there are six layers with a depth of up to 25 m; the type of material in layer 1 is clay, layer 2 is marl, layer 3 is clay, layer 4 is marl, and layer 5 is siltstone, layer 6 is claystone, with a resistivity value between 0.11Ω-65.9Ω. This research proves that the condition of the rock layers around the Matuting-Saketa causeway or practical work location must be drilled at the measurement point. Keywords: geoelectricity, roads, layers, materials, rocks.
Penelitian yang dilakukan untuk mengidentifikasi potensi panas bumi di Desa Limang Kecamatan Tigabinanga Kabupaten Karo menggunakan citra satelit landsat 8 dan geolistrik resistivitas terletak pada koordinat 03o07’13” LU dan 98o14’08” BT yang berada 600-700 meter di atas permukaan laut. Penelitian ini bertujuan untuk mengetahui adanya anomali panas sebagai pendugaan terdapatnya potensi panas bumi di bawah permukaan daerah tersebut dengan menggunakan metode citra landsat 8 dan geolistrik resistivitas. Pengambilan data dilakukan dengan dua cara yaitu pengunduhan data citra landsat 8 yang telah disesuaikan pada laman USGS untuk metode penginderaan jauh dan melalukan penelitian di lapangan dengan alat geolistrik resistivitas (ARES-G4 v4,7 , SN: 0609135). Data yang telah diperoleh kemudian diolah untuk dianalis dan diinterpretasikan, pengolahan dan analisis data dilakukan dengan software Envi, ArcGIS, Res2dinv dan lainnya. Hasil penelitian citra landsat 8 menunjukkan korelasi NDVI dan LST dan korelasi LST dengan tutupan lahan dan elevasi yang menunjukkan adanya anomali yang kemudian disesuaikan dengan faktor penyebabnya. Metode geolistrik resistivitas menunjukkan nilai resistivitas pada daerah tersebut berkisar dari 0,904 Ωm sampai dengan 1,26 Ωm pada lintasan 1 dan 0,114 Ωm sampai dengan 9,93 Ωm pada lintasan 2 yang menginterpretasikan bahwa struktur lapisan bawah permukaan tersebut didominasi oleh air tanah yang terkontaminasi oleh air sungai yang mengalir di dekat daerah penelitian dan tanah lempung atau lanau, yang merupakan hasil pelapukan batuan yang mengandung silika oleh asam karbonat dan aktivitas panas di bawahnya dan mengakibatkan munculnya manifestasi air panas di atas permukaan di daerah tersebut.
Daerah Bengkulu merupakan daerah yang dilalui oleh jalur subduksi Indo-Australia dan Eurasia. Jalur subduksi dapat teridentifikasi dengan metode gravitasi yang dapat menggambarkan bentuk bawah permukaan berdasarkan variasi medan gravitasi yang dapat dilihat oleh perbedaan rapat masa anatar batuan. Penelitian ini bertujuan untuk mengidentifikasi karakteristik Sesar Segmen Ketahun dengan menggunakan data anomali gayaberat GGMplus. Wilayah penelitian adalah daratan Lebong-Rejang Lebong. Metode First Horizontal Derivative (FHD) dan Second Vertical Derivative (SVD) digunakan untuk melihat posisi dan karakteristik sesar. Dari analisis FHD dan SVD, daerah Sungai Lisai dan Ketenong merupakan sesar turun, sedangkan Pinang Berlapis, sekitar Pungguk Pedaro dan Rimbo Pengadang merupakan sesar naik. Talang Ulu dan sekitar Lubuk Pedaro merupakan sesar naik, Daerah Mangkorajo merupakan sesar geser, serta Danau Tapak Kaki merupakan sesar turun. Berdasarkan pemodelan data anomali diperoleh wilayah Kabupaten Lebong–Rejang Lebong memiliki sebaran densitas antara 1,97 gram/cm 3 -2,00 gram/cm 3 yang merupakan batuan sedimen (debu bersisipan pasir,bongkahan lepas, kerakal, gambut dan kaolinit).
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