Geoelectrical Resistivity Research Articles

Subsurface Profile Analysis for Aquifer Layer Identification

Bungaiya village is a village located in Gowa Regency which has volcanic rock lithology with one of the problems faced in volcanic rocks is that the rock porosity is small so that this layer cannot be an aquifer zone. But the water needs needed by the community for agriculture are very large. Geoelectric is a geophysical method that can be used to describe subsurface profiles, especially aquifer layers. The purpose of this study is to interpret using the geoelectric resistivity method, is the Wenner configuration method as many as 2 lines with a length of 470 m and a space of 10 m. The interpretation results on Line 1, there are 3 layers, are volcanic breccia with resistivity values ​​of 85.6 – 2.2013.19 Ωm and depths between 1.2 – 68 m, layer 2 of tuff with resistivity values ​​of 9.82 – 59.68 Ωm, depth of 12 – 76 m and the third layer is a volcanic breccia, resistivity value is 85.6 – 176 Ωm. Line 2 has 2 layers, are the first layer with a depth of 1.2 – 42 m with a resistivity value of 93 – 490.41 Ωm which is a volcanic breccia. The second layer at a depth of 1.2 – 78.8 m with a resistivity value of 30.9 – 77, 67 Ωm is tuff. Layers 1 and 2 show a similar subsurface profile. Based on these results, it can be concluded that the layer that functions as a water-carrying layer is tuff with a resistivity value of 9.82 – 77.67 Ωm.

Groundwater Survey Using Resistivity Method for Drought Mitigation in Bima Regency, West Nusa Tenggara

Groundwater Survey in Bolo District, Palibelo District, Woha District, Langgudu District, Wawo District, Sape District, Wera District, Bima Regency, and West Nusa Tenggara for drought mitigation has been implemented. The study area is located in the majority of hilly areas with soil vulnerable to drought. Water is abundant during the rainy season. However, during the dry season, the ground surface is cracked, and there needs to be more clean water. This situation is troubling the community and the Regional Government of Bima Regency. The study was conducted using the Schlumberger resistivity geoelectric configuration method. The measurement point is in seven sub-districts, with a total of 18 measurement points. Research location at 118,6305833 SL; -8,3008888889 EL up to 119,01925 SL; -8,704638889 EL or covers an area of ± 1,961 km2. The length of the path used is a maximum of 400 meters. Based on the results of geoelectric resistivity data, two types of aquifers are found, open aquifers with depths ranging from 1 m to 26 m and aquifers depressed with depths ranging from 70 to 115 m. In addition to geoelectric information data, drilling data is also used at points that can be reached by heavy equipment in Lanta Barat Village, Lambu District. At the drilling point, the presence of an aquifer layer is obtained at a depth of about 80 meters. Residents then use the discovery of the wellbore to meet their need for clean water.

How to Identify the Subsurface Layer of Bangkam Hill - Mempawah Regency? Application of the Geoelectrical Resistivity Method

Mapping the subsurface is essential in rock exploration for construction to minimize costs and guide adequate mining planning. This study aims to identify the subsurface layer of Bangkam Hill, a depot of various rocks for construction materials located in Sungai Kunyit District, Mempawah Regency. A resistivity method was applied to map the sub-surface using the Wenner-Schlumberger configuration. Data acquisition was performed at six measurement lines to cover the hill. The results show that the subsurface layers of the hill from the ground to 40 m in depth are composed of sand, laterite soil, gravel, and igneous rock, with resistivity varying from about 30 to 693,055 Ωm. Using the subsurface map, the stakeholder can assess shallow rock reserves in the study area and create a proper mining strategy.

Identification of Potential Waste Fluid Contamination with Geoelectric Method in Tebing Tinggi Subdistrict, West Tanjung Jabung Regency, Jambi

In the study area of Tebing Tinggi Subdistrict, Tanjung Jabung Barat Regency, Jambi Province, there are several companies engaged in the manufacturing, agriculture, and plantation industries. This company uses the Pengabuan river for transportation. Therefore, the study area has the potential to be contaminated by the waste fluid produced by the company. In this study, the geoelectric resistivity method was used because it is good for identifying potential contamination at the subsurface. The Wenner array was used because it is good in a study with shallow surfaces, so it is good at identifying contamination. Data processing is done by inversion process using Res2Dinv software to get 2D modeling and Voxler to get 3D modeling. Based on the 2D modeling, it is identified that the contamination is on lines 1, 2, and 4 with a resistivity range of ±0.059-2 Ωm. Also, in the study area, it is identified that there are alternating tuffaceous claystone, claystone, tuffaceous sandstone, sandstone, and shallow aquifer. Based on the 3D modeling, it is identified that there is a potential continuity of contamination between line 3 and line 4, which is at a distance of 0-8 m from line 4 to line 3.Keywords: Contamination, Geoelectric Resistivity Method, Res2Dinv, Voxler, Wenner Array

Identification of Characteristics and Distribution of Subsurface Coal Using the 2D Geoelectric Method in Tanjung Palas Timur District, North Kalimantan

Based on regional geology, Tanjung Palas Timur Subdistrict is included in the only formation, which includes coal seams. The depletion of oil and gas energy sources in Indonesia results in the need for other alternative energy sources, one of which is coal. This study aims to determine the characteristics of coal in the study area. This research was conducted in Tanjung Palas Timur Subdistrict, North Kalimantan using the geoelectric resistivity method with a pole-pole configuration and 8 tracks which are divided into 2 track blocks. The resistivity geoelectric method is used because it is very suitable for mining exploration. Data processing was done in 2D using Res2dinv software and 3D using Rockworks15 software. The results of the geoelectric data processing of line 1 to 8 show that the coal seam in the study area has a resistivity of 10-30 Ωm with a thickness varying from 17.22 m - 60 m as a type of lignite coal. In addition, the research area is also dominated by layers of clay and sandstones. The continuity of the coal seam is also seen in block 1 from line 3 in the southwest direction to line 1 in the northeast direction.

KAJIAN POTENSI LONGSOR LERENG GALIAN CURAM DI KELURAHAN KALUMATA KOTA TERNATE MENGGUNAKAN GEOLISTRIK

The study of the potential for landslides on steep excavation slopes in Kalumata Village, Ternate City using geoelectricity is important to do. The location of the sirtu mining excavation which tends to be steep and close to residential areas is urgent to know the type of lithology so as to facilitate recommendations for handling to be carried out. The purpose of this study was to determine the lithological composition of the material from tracks 1, 2, and 3 along the steep excavation slope using the geoelectric resistivity Sclumberger configuration method. In addition, knowing the potential for landslides that will occur if there is no handling of steep slopes. This research is a quantitative type of field research. The research location is in the formation of lahar deposits (Gtla) and pyroclastic debris (pr) deposits. Trajectory 1 dominant lithology is 17.52 m of sand, andesite rock as an interlude and on the bedrock it is characterized by large resistivity (3241 m) while the top layer is clay type overburden. The 2 lithological paths consist of overburden, sand (7.82 m), silt (10.5 m), and andesite bedrock (resistivity 2811 m). The lithology of track 3 consists of overburden, andesite, sand (16.9 m), and andesite bedrock (4575 m). Lithology that tends to landslide in the field is overburden filled with sedimentary material in the form of clay, silt, and sandy silt (resistivity 1.5-114 m). Sand lithology with a resistivity of 479-855 m is very susceptible to landslides. Another factor causing landslides is the slope of the excavation which tends to be steep (> 60o). Keywords: Kalumata Village, Sclumberger configuration, lithology, landslide, sand

Geoelectrical resistivity mapping and characterization of bituminous sands at some parts of Eastern Dahomey Basin, SW Nigeria

Predicting the variability and subsurface distribution of bituminous sand deposits rely significantly on integrating geophysical techniques such as electrical resistivity mapping with borehole information. While several studies have been conducted to characterize the bitumen-rich sequence of the sedimentary terrain of the study area, there are no or few studies documenting the subsurface architecture of bituminous sands in the transition zones in the study area. This study utilized the integration of 2D electrical resistivity mapping and borehole lithology logs to delineate and characterize bituminous sands in the study area to provide insights into the electrical resistivity signature of bituminous sand deposits within the transition zone in Ondo state, SW Nigeria. Two boreholes (BHI and BH2) and 2D electrical resistivity mapping using dipole–dipole array along five traverses were used for the investigation. A systematic and data-based approach was employed for the mapping of the deposits. The 2D electrical resistivity survey acquisition was carried out on traverses oriented north–south in the direction perpendicular to the sedimentary strike to effectively map the bituminous deposits. The results obtained from the approach employed indicated a maximum of three to four geoelectric layers delineated within the study area. This includes the topsoil, the upper X-horizon, mudstone, and lower Y-horizon. The upper/shallow bituminous sands in the X-horizon, as well as the deeper bituminous sands in the Y-horizon sands, are characterized by a very high resistivity range of about 1000 to about 100,000 Ωm. Findings from this study reveal that the resistivity of bituminous sands in the area is generally high in contrast to the low resistivity signature observed in the sedimentary parts of the area. The results obtained from this study would serve as a means to guide future exploration studies within transition zones in Eastern Dahomey Basin, SW Nigeria.

Identification of Subsurface Materials in Landslide-Susceptible Areas in the Pacet-Trawas Road Corridor Using the Geoelectrical Resistivity Method

Landslides are caused by changes in the structure of subsurface materials on steep slopes due to weathered rock conditions and soil pores in saturated conditions. This study used the geoelectric resistivity method to identify the type and structure of subsurface materials in landslide-susceptible areas in the Pacet-Trawas road corridor, in Pacet District, Mojokerto Regency. The research location was an area with undulating to mountainous morphology. The geoelectrical resistivity configuration used was dipole-dipole with a measuring path length of 100 meters at three measurement points. The measurement location was based on geological formations and the distribution of landslide points along the Pacet-Trawas road corridor. The three 2D models produced showed resistivity values between 8.11 Ohm.m to 390 Ohm.m. The subsurface materials consisted of groundwater, volcanic breccia, lava rock, tuffaceous breccia, conglomerate, and andesite-basaltic at a depth of 1.5 meters to 25 meters below the ground surface. The research area was dominated by the parent rock structure of lava, volcanic breccia, basalt, and andesite. Locations with a high landslide threat were located at points two and three with subsurface materials of the conglomerate type and volcanic breccia.
 Keywords: geoelectrical resistivity, dipole-dipole, subsurface material

Landslide Analysis in Brau-Batu, East Java, Indonesia Based on Geoelectrical Resistivity Data

The Brau landslide area is about 40Ha. The Brau landslide area is administratively located in the hamlet of Brau, Gunungsari village, Bumiaji sub-district, Batu city, East Java. Hamlet of Brau is famous as a tourism area and because of dairy farm in Batu city. Topographically, this area is located in a hilly area with a range of topographical heights between 1067m to 1202m or has a topographical elevation difference of 135m. With such topography, it is not surprising that this area has a potential vulnerability to landslide geological disasters. As a precaution against further landslides, residents are planned to relocate to other safer places. However, considering that the Brau area is a source of economic livelihood for local residents, residents want to stay there. To convince and ensure the vulnerability of this area, a study related to landslide variables is needed. One thing that can be done is to apply technology that can provide subsurface information on this disaster risk area. Therefore, in this study, geophysical research was carried out using the geoelectrical resistivity method to obtain information on the subsurface conditions of the landslide field in this area. The research was conducted to obtain information on the stability of the subsurface landslide field. From 60 VES data arranged in 12 cross sections, information is obtained that 6 cross sections or 50% cross sections are in stable condition. The location with the stable condition of the landslide field is then recommended as a location for the construction of a relocation site in the landslide area of Brau.

Identification of Landslide Area Using Geoelectrical Resistivity Method as Disaster Mitigation Strategy

Extreme weather triggers high-intensity rainfall, and it triggers land movement that eventually becomes landslides. The water of rain will enter to the ground through the rock gaps and accumulate along the landslide area to reduce effective stress and reduce the shear strength of the soil. Morphologically, Sukaresmi Village, Cisaat Sub-District, Sukabumi Regency is located at the foot of Mount Gede with a bumpy surface relief. This condition is one factor that triggers landslides because the soil is prone to movement. This research aims to identify the field slope zone for landslide prediction in the Sukaresmi village, hoping that the surrounding community could anticipate further landslides. The research was carried out using the Geoelectrical Resistivity method of the Schlumberger configuration as many as eight measuring points with 1 m electrode spacing. This research indicates that the subsurface conditions are divided into three constituent rocks: Clay, Tuff, and Volcanic Breccia. The field slide zone is located between the Tuff rock and turf layer at a depth of 4-7. 5 m long, 82 m (Line 1), and 40 m (Line 2), with a resistivity value range of 56-158 Ωm. The efforts that the local government can make to anticipate the condition of the building to remain safe include analyzing soil stability, strengthening slopes, and making retaining walls to increase the value of the safety factor.

ANALISA RESISTIVITAS TANAH TERHADAP PREDIKSI KOROSI PADA PIPA DISTRIBUSI AIR BERSIH DI KAMPUS UNIMAL BUKIT INDAH

This study aims to predict corrosion in water distribution pipes at the Bukit Indah Unimal campus. Corrosion is the damage to chemical elements in a metal that changes the original properties of the metal. There are four kinds of processes for corrosion, namely, one anode loses electrons, two cathodes accept electrons, three liquids and four metals connect the cathode and anode. The geoelectric resistivity method is used to determine the soil resistance properties of the subsurface layer. The wenner 4 pin method is a geoelectric data retrieval that is often used with the same pin spacing arrangement. Res2Dinv is software that is on a computer to generate 2-dimensional images from the resistivity data obtained and determine the layer below the surface. From the inverse results, the smallest error value can be obtained when iterating up to 4 times, namely Java Road 45.3%, Sulawesi Road 49.6%, Kalimantan Road 30.6%, Sumatra II Road 46.1%, Main Gate 41.1% Sumatra I 23.4%. Based on the data, the measurable results below the surface range from 0.05 m to 5 m.

Assessment of seawater ingress in the coastal aquifers of south Andaman Island, India

Seawater ingress is a widespread environmental issue posing threat to the fresh groundwater reserves of the coastal aquifers of Andaman and Nicobar Islands (ANI) particularly after the great Indian Ocean Tsunami 2004, and the comprehensive investigations of seawater ingress in this region are relatively uncommon. In this context, the spatial distribution and vertical movement of seawater ingress in the coastal and catchment areas were mapped using geo-spatial techniques and the extensive geoelectrical resistivity surveys (96 vertical electric soundings (VES) and profiling) along and across the identified and affected coastlines. The geoelectrical surveys unravels very low resistivity formations (≤10 Ω m) at varying depths interpreted as the lateral and vertical intrusion of seawater. The hydro-chemical and other physical analyses of groundwater samples reveal critical concentrations of the different major elements and other physical parameters like TDS, pH as well the EC above its permissible limit for drinking water standards. The integrated approach allows to delineate the site specific hydrogeological setting including the saline/fresh aquifer geometry (transition zone) and stratigraphic−geomorphological reconstruction of coastal aquifers. Further, various assessment parameters including very low formation resistivity, surface manifestation of salt tolerant plants, high chloride concentration, low formation factor and high ionic strength were employed to infer the various levels of contamination. The present study show that impact of seawater intrusion is intense in sedimentary formations than Ophiolite suite and needs site specific mitigation measure to prevent further deterioration of aquifer health.

Geoelectrical subsurface characterization: A case study of saltwater intrusion in Kudat, Sabah

Saltwater intrusion is one of the primary sources of groundwater contamination, especially near the coastal line, and it is crucial to monitor saltwater intrusion to protect fresh groundwater. Due to the proximity of the coastal line, the area within Kudat Peninsula that was formed by the ophiolite basement, Kudat Formation Chert-Spilite Formation, and alluvium deposit is susceptible to saltwater intrusion. In this study, two survey lines of geoelectrical resistivity and induced polarization imaging survey with a total length of 200 m were carried out. The Wenner configuration was used to characterize the subsurface of the Kudat Peninsula. The interpolation between geoelectrical resistivity and chargeability profiles provided better interpretations of the subsurface environment. The saltwater intrusion zone displays a resistivity value between 0 – 5.0 Ωm and a chargeability value between 0 – 3.0 ms. The results showed that saltwater intrusion was detected at depths as shallow as 1.25 m to 36.90 m and intruded as far as 218.00 m into the mainland, from the coastline.

3D Modelling of Geoelectrical Resistivity Data to Determine the Direction of Landslides in Kastoba Lake, Bawean Island, Indonesia

Landslides are one of the factors caused by subsurface structures that are not compact, and have low density or resistivity values due to changes in groundwater. Rainwater that infiltrates into the ground will reach to an impermeable layer which is identified as a slip plane. This research was conducted in the Kastoba Lake area, Bawean Island, Indonesia. The purpose of this study is to determine the slip plane and the direction of the landslide in the studied area. Data acquisition was carried out based on a preliminary study of residual anomaly contour analysis from gravity data, then geoelectric data acquisition was carried out in the studied area. The results of lithological analysis on 3D geoelectric resistivity modeling in this study obtained three layers of subsurface structures, namely topsoil, clay, and lavas. The slip plane of the study area is above the clay layer (7.25 meters depth). The results of the 3D interpretation indicated that the direction of the landslide was towards the north, as evidenced by the existence of public information that the area studied had landslides with the avalanche direction towards the north. For further analysis, a factor of safety analysis is needed based on the analysis of the bore hole drilling method in the studied area

Use of geoelectrical resistivity method for detecting near-surface groundwater potential zones at Riyadh city, Saudi Arabia

Six profiles of the two-dimensional multi-channel electrical resistivity tomography (ERT) were conducted at the northwest part of Riyadh city using the SYSCAL Pro system with a dipole–dipole configuration to detect the near-surface water-bearing potential zones. The ERT field measurements use a series of regularly placed electrodes to measure the electrical resistivity along the profile. The results of the inverse models are displayed as cross-sections of the true resistivity distribution of the subsurface with depth along with each profile. The two-dimensional (2-D) inversion results of the electrical resistivity data indicate three geoelectric zones; 1st zone of low resistivity values (<100 Ω.m), representing two groundwater-bearing potential zones from top to bottom as follows; the 1st one extends downwards to 10- and 15-meters depth, while the 2nd zone spreads between 15- and 30-meters depth, 2nd zone with resistivities ranging from 100 to 1000 Ω.m, which represent the highly fractures limestone; the 3rd zone with resistivities greater than 1000 Ω.m reflecting compacted limestone rocks. It is noticed also some of the low resistivity pockets are isolated through the subsurface geoelectrical cross-section indicating the presence of voids and/or cavities. Based on these results, the investigated area is considered as one of the promising zones for groundwater supply in Riyadh city and its future urbanization expansion projects. This can be accessed by drilling wells down to a depth of 50 m for groundwater extraction.

Depicting of groundwater potential in hard rocks of southwestern Saudi Arabia using the vertical electrical sounding approach

In the hard rock terrains of southwestern Saudi Arabia, vertical electrical soundings (VES) were used to demarcate groundwater potential zones. To map the groundwater potential zones, 16 VES were done using a Schlumberger electrode array arrangement. Zond-IP computer software was used to analyze and interpret field measurements. The pseudo and resistivity cross-sections have been processed. The evaluation of the 1D geoelectrical curves revealed that the area is characterized by three geoelectrical resistivity layers. The topmost layer of unconsolidated alluvium deposits, which has a wide range of resistivities (42.28 to 297.97 Ω·m) and a thickness of up to 6 m, is the first of these layers. This range of resistivity is linked to changes in the layer's lithology and humidity. The second layer's resistivity values range from 372 to 3625 Ω·m, while the third layer's resistivity values range from 1015.37 to 21113 Ω·m. The second layer's resistivity implies fractured and weathered/jointed basement rocks, and the third layer's resistivity indicates broken to huge basement rocks. According to the findings, the worn and fractured horizons of basement rocks found in the vicinity are acceptable groundwater potential aquifers. The degree of weathering and fracture of the foundation rocks, and thus their water saturation, can be linked to vertical and horizontal variations in resistivity.

Pelatihan Akuisisi Data Geolistrik Dalam Identifikasi Subsurface di SMK Penerbangan Techno Terapan

School partners indicated that there were several problems, namely that there were still students who did not understand how to interpret resistivity geoelectrical data. This is due to the limited facilities and infrastructure as well as teaching staff in supporting the learning process in schools. The purpose of this PkM is to prepare students' abilities as early as possible so that they can understand how to interpret resistivity geoelectrical data before entering the world of work in geology and mining. Another thing is that school partners can more easily and effectively teach the interpretation of resistivity data using the geoelectric method in the teaching and learning process in schools.. The method used in achieving the objectives is a questionnaire (pretest and posttest) with descriptive statistical analysis, lectures (presentations) and discussions as well as field practice. The results of the analysis showed an increase in students' ability in the acquisition of geoelectric resistivity data after attending the training. Prior to participating in the training, 70% of students had the ability to acquire geoelectric resistivity data in the Poor category. However, after participating in the training, the students' abilities increased to Excellent (55%).

Evidence of geoelectrical resistivity values on groundwater conditions in Wadi El Natrun and its vicinities, West Delta, Egypt (cases studies)

Recently, Wadi El Natrun and its surroundings have witnessed intensive investments in land reclamation, including the arbitrary drilling of hundreds of groundwater wells. Currently, serious hydrogeological and environmental problems have been addressed, such as groundwater quality degradation and water head drop. Electrical resistivity measurements were performed at six locations across the study area to assess its ability to reveal the heterogeneous subsurface stratigraphic and hydrogeological setting of groundwater aquifer(s). The geoelectrical results successfully reflect the current vulnerable hydrogeological setting of the study sites. The current study highlights the current practice in which farmers rely on isolated 1-dimensional vertical electrical sounding (1D VES), which is not the only exploration tool for such electrically conductive stratigraphic succession. One of the main findings is addressing the advantage of applying 2-dimensional electrical resistivity imaging (2D ERI), where it offers a more robust view of both vertical and lateral variation of the investigated subsurface section (Case 3). On the other hand, the Geographic Information System (GIS) could mirror the present groundwater potentiality status, where both GIS analysis and resistivity results coincide, and where the good potentiality zone is restricted to the west and southwest directions of the study area (area of interest (aoi)), where the resistivity values of water bearing are relatively high and lie on the main drainage (Cases 2, 5, and 6). On the contrary, poor potentiality zones are deemed because of their proximity to tiny attributers, and are characterized by low resistivity values (Cases 1, 3 & 4), Finally, the current research study demonstrates the significance of combining morphometrical analysis with geophysics techniques for such environmental problems, where groundwater is primarily controlled by geomorphological features and geological conditions, including lithology and geological structures.

PENDUGAAN POTENSI AIR TANAH BESERTA KEDALAMAMNYA DENGAN METODE RESISTIVITAS KONFIGURASI SHLUMBERGER DI NGLANGGERAN KULON KABUPATEN GUNUNG KIDUL

Research on the estimation of groundwater potential and its depth has been carried out in Nglanggeran Kulon which is the Nglanggeran Ancient Volcano Tourism Village in Gunung Kidul. The large number of tourists who visit makes the need for groundwater in this location also increases but has not been matched by its availability. This area is also a district that almost every dry season experiences a water crisis. The purpose of this study was to find out the potential presence of groundwater and its depth. This is related to the efforts of local residents who want to build new wells. The method used is the geoelectric resistivity method with the Shlumberger configuration. This method exploits the electrical properties of the rock beneath the surface. The physical parameter measured is the resistivity value to create a subsurface geological model in the form of a 1D model. The length of the stretch carried out is 125 m at two measurement points. The results of this study indicate that 1st point has two layers of rock and no groundwater potential is found. 2nd point has four layers of rock. Groundwater potential is found in 2nd layer because it has a low resistivity value of 9.89 ꭥm at depths ranging from 5-9 meters with a thickness of about 4 meters. So that the location of the 2nd point is more recommended for making new wells.

Geoelectrical resistivity survey to determine sliding surface of landslides prone area case study in Ponjong subdistrict Gunung Kidul regency Indonesia

The research area is located in Ponjong Subdistrict, Gunung Kidul Regency. Ponjong area specific at Tambakromo village is one of potential in landslides disaster since 2011. The outspread information about landslide and mitigation should be done in research area. The aim of this research is to get the subsurface condition and determine of landslide surface based on geoelectrical resistivity in Tambakromo area, Ponjong Subdistrict, Gunung Kidul regency. The method of this research is used geoelectrical survey by using Dipole - dipole configuration. The result of this research is the lithology of sliding surface is claystone – fine tuffaceous claystone with resistivity value of 29.9 ohmmeter based on Dipole – dipole subsurface cross section at Grogol village. The sliding surface could be found at 5 metres to 20 metres underground. At Sumberejo village, based on dipole-dipole subsurface the lithology of sliding surface is claystone – fine tuffaceous claystone with resistivity value of 6.18 to 29.9 ohmmeter at depth of 20 to 25 metres. Based on the regional stratigraphy correlation showed that the claystone or tuffaceous claystone is included in Semilir Formation. This research should be able to held for local government to proved landslide mitigation in research area.