Bentiring Subdistrict is dominated by alluvial rock with a low water table depth, causing several roads and houses to experience subsidence and tilting, which may indicate the presence of a weak zone. The purpose of this study was to identify the presence of a weak zone based on resistivity values using the electrical resistivity imaging (ERI) method. This study utilised the ERI method with a Wenner Schlumberger configuration. The results showed that there was a weak zone on track 1 at a depth of 10.3-78.8 metres, with resistivity values of 12.3-28.2 Ωm. On track 2, subsidence was suspected at a depth of 3-39.6 metres, on track 3, the subsidence is located at a depth of 2.50-57.3 and 2.50-45.5 metres, on track 4, the subsidence is located at a depth of 10.8-67.3 meters, and on track 5, the subsidence is located at a depth of 10.3-57.3 metres. Weak zones are found on track 1 at a depth of 10.3-78.8 metres, where the constituent rock layer is sandy claystone. On tracks 2, 3, 4, and 5, there are subsidence areas with varying resistivity values ranging from 8.78 to 96 Ωm at depths ranging from 2.7 to 78.8 meters.
Adrian Daniel, Halauddin Halauddin, Suhendra Suhendra et al.· Jurnal Fisika Unand· 0 citations
Landslides are a common natural disaster in Indonesia, particularly in areas with steep slopes and high rainfall intensity. They can cause significant damage to property, loss of life, and disrupt the daily lives of affected communities. Bantul Regency is especially susceptible to landslides due to its geological structure and the tectonic activity resulting from the convergence of three major tectonic plates in the region. This research aimed to identify subsurface lithology and slip surface in the landslide-prone area of Selopamioro Village, Imogiri District, Bantul Regency, using the Wenner configuration resistivity geophysical method. Four measurement lines were conducted, each with a length of 225–240 meters and an electrode spacing of 15 meters. Data processing was performed using the Res2Dinv application to produce a two-dimensional resistivity model and RockWorks 17 for three-dimensional visualization. The modeling results revealed resistivity values ranging from 0.11 to 779 Ω·m, which were classified as sandy clay (0.11–44 Ω·m) and breccia (>44 Ω·m). The low resistivity zone indicated the presence of a wet sandy clay layer. The slip surface is estimated to be located at a depth of 20–30 meters below the surface, marked by a resistivity contrast boundary between the sandy clay layer and the fractured breccia. Local geological conditions, including volcanic breccia, rock fractures, and high rainfall infiltration, exacerbate the potential for slope instability.
H. Lutfiana, Uli Ulfa, K. N. Aziz et al.· IOP Conference Series: Earth...· 0 citations
Mapping of competent soil layers is a critical aspect of geotechnical site investigation for engineering construction, foundation investigation and design. The study employed six traverse lines of 2D electrical resistivity tomography (ERT) technique to delineate the subsurface conditions, and determine the thickness and depth to competent soil layers within the construction site at Amansea, Anambra State. The data was acquired using multi-electrode resistivity machine with Wenner array of equal electrode spacing of α = 3. The acquired apparent resistivity data were processed and inverted using RES2DINV software to generate 2D inverse resistivity sections of the studied areas. The interpreted resistivity sections revealed variations in subsurface lithology, including topsoil, sand clay and highly saturated zones and competent zones characterized by relatively high resistivity values. The top soil have low-resistivity values between 3.21 Ωm and 438 Ωm indicating weak, clayey, or highly weathered materials with depth range of 0 – 5 m. The intermediate layer varied across the site with resistivity range of ~ 247 - 2854 Ωm at 5 – 12 m depth, reflecting lateral heterogeneity in subsurface conditions. This transitional unit exhibits mixed sand and clay composition, providing moderate geotechnical competence. A laterally persistent, high-resistivity sandstone body (3580 – 109,354 Ωm) that thickens toward the central and eastern parts of the site at ~ 8 – 18 m depth. Information obtained from these electrical resistivity model correlated effectively with the information from the borehole log drilled around the study area. The geological model indicates that the near-surface clay-rich horizons possess poor geotechnical properties, whereas the underlying sandstone forms a competent bearing layer suitable for deep foundations. The study demonstrates that the 2D ERT technique is an effective, fast, and non-invasive tool for delineating competent foundation materials and provides valuable information for engineering site assessment and foundation planning.
E. Onyebueke, S. C. Obiadazie, O. Ben-Owope et al.· International Journal of Glo...· 0 citations
To address the growing challenges of water resource management in coastal karst areas, this study investigated subsurface lithological characteristics and evaluated aquifer potential in Mon Ikeun Village, Aceh Besar. The research integrated Electrical Resistivity Tomography (ERT) and grain size gradation analysis to provide a scientific basis for sustainable groundwater exploration. Resistivity data were collected along three survey lines, each 420 m long, using the Wenner-Schlumberger configuration. The 2D inversion results identified conductive zones with resistivity values below 454 Ωm, interpreted as alluvium comprising sand, silt, and gravel. These high-porosity, permeable layers extend to depths of approximately 25 m, indicating significant aquifer potential. In contrast, resistive zones above 454 Ωm were interpreted as limestone bedrock, representing impermeable layers with very low porosity. Laboratory grain size analysis using the hydrometer method revealed sand-dominated samples with high porosity (25-50%) and moderate permeability (2.5-45 m/day), while gravel-sand mixtures displayed moderate porosity (25-40%) and high permeability (150-450 m/day). The strong correlation between resistivity data and grain size distribution confirms the consistency of the lithological interpretation. This integrated approach offers an effective framework for securing freshwater resources in regions with complex geological settings and high vulnerability to water scarcity.
Muhammad Syukri, Adila Latifa, D. Sugiyanto et al.· IOP Conference Series: Earth...· 0 citations
This study presents a geophysical investigation of the foundation conditions at a proposed construction site in Agbura Town, Bayelsa State, Nigeria, using the electrical resistivity method. The research is motivated by the increasing incidence of building failures in Nigeria, often attributed to inadequate understanding of subsurface conditions and neglect of pre-construction site investigations. The study area lies within the Niger Delta, characterized by soft, water-saturated, and compressible alluvial deposits that pose significant challenges to foundation stability. Vertical Electrical Sounding (VES) employing the Schlumberger array configuration was used to acquire subsurface resistivity data at selected locations. For interpretation, the IPI2Win software was employed. The data were processed and interpreted to delineate subsurface lithology, identify stratification, and determine the depth to competent layers suitable for foundation placement. The results enabled the identification of geoelectric layers, including topsoil, clayey formations, and more competent sandy strata at depth. Findings reveal the presence of weak, low-resistivity clayey and water-saturated zones in the near surface, which are unsuitable for supporting heavy structures due to their high compressibility and low bearing capacity. Conversely, relatively higher resistivity zones corresponding to sandy materials were identified at greater depths, indicating more competent layers for foundation support. The interpreted VES results revealed resistivity values ranging from 1.61 to 22,430 Ωm, indicating a subsurface sequence composed of conductive clayey materials, sandy/lateritic topsoil, weathered or fractured basement, and fresh basement rock. The low-resistivity zones, ranging from 1.61 to 15.3 Ωm, were interpreted as clayey or saturated clayey layers, while the higher-resistivity sandy/lateritic materials ranged from 99.4 to 575 Ωm. Fresh basement was identified by very high resistivity values between 6,133 and 22,430 Ωm. The study demonstrates that electrical resistivity methods provide a reliable, cost-effective, and non-invasive approach for evaluating subsurface conditions. It emphasizes the importance of integrating geophysical investigations into engineering site assessments to mitigate risks of structural failure. The results offer valuable insights for safe and sustainable foundation design in flood-prone and geologically complex environments like Agbura. It is recommended that geophysical investigations be integrated into pre-construction planning to minimize structural failure risks in the Niger Delta region.
ThankGod Arekumo, Baridamue Raymond Osih· International journal of re...· 0 citations
Way Ratai Road in Pesawaran Regency, Lampung Province, is characterized by hilly morphology with steep slopes, rendering the area susceptible to mass movement. To date, no geophysical studies have specifically identified the slip surface zone along this road corridor, making this research essential as a basis for landslide disaster mitigation. This study aims to identify the slip surface with criteria encompassing subsurface layer structure and weak zone depth estimation. Data acquisition was conducted using the dipole-dipole configuration resistivity geoelectrical method with a traverse length of 128 m, employing 33 electrodes at 4 m spacing. Resistivity data inversion modeling was performed using Res2Dinv software. The interpretation results indicate that the subsurface structure of the study area comprises five lithological units, namely clay, gravel, tuff, basite, and quartzite. The slip surface was identified at a depth of 6–21 m, located at the contact zone between the tuff and basalt units, which exhibits significant resistivity contrast. The estimated volume of potential landslide material reaches 34,560 m³. The findings of this research can serve as a reference for structural and non-structural mitigation planning to minimize landslide risk in the Way Ratai Road area.
Sofiana Herman, I. Permanasari, Tia Anisa et al.· Jurnal Geosaintek· 0 citations
