Aplikasi Metode Geolistrik dan Analisis X-Ray Diffraction (XRD) untuk Investigasi Longsor di Pidada, Kecamatan Panjang, Bandar Lampung

ABSTRAK. Bandar Lampung merupakan wilayah perkotaan padat penduduk yang terdiri atas daratan dan perairan dengan beberapa dataran tinggi dan pegunungan yang terbentang di wilayah ini. Untuk mendukung pembangunan yang berkelanjutan di sebuah kawasan kota diperlukan konsep penataan wilayah yang mempertimbangkan segala aspek, salah satunya adalah aspek potensi bencana. Salah satu bencana yang berpotensi terjadi di Bandar Lampung, khususnya di Kecamatan Panjang, adalah gerakan massa/longsoran. Berdasarkan penelitian sebelumnya, daerah ini terekam memiliki beberapa titik sejarah longsor tetapi belum ada mitigasi/penanggulangan yang diaplikasikan khusus untuk jenis bencana tersebut. Tujuan dari penelitian ini adalah untuk mengetahui susunan batuan yang berada pada zona rawan longsor Kecamatan Panjang menggunakan metode geolistrik resistivitas serta untuk mengetahui hasil penilaian keteknikan tanah yang diperoleh dari hasil analisis litologi menggunakan X-Ray Diffraction (XRD). Hasil analisis dua lintasan geolistrik mengindikasikan adanya tiga lapisan litologi pada daerah penelitian, yaitu sedimen tuf dengan nilai resistivitas dan kedalaman antara (1–40 Ωm; 0,4–4 m), zona kontak atau bidang gelincir (40–120 Ωm; 2–4 m), dan breksi padu dengan komponen batuan beku (> 120 Ωm; 2–22 m). Selanjutnya berdasarkan hasil analisis penilaian keteknikan tanah, sedimen tuf sebagai lapisan permukaan yang mengalami longsoran diidentifikasi memiliki sifat keteknikan litologi yang rentan karena telah mengalami oksidasi dan pelapukan yang cukup intensif. Data yang diperoleh ini diharapkan dapat dimanfaatkan sebagai data dukung penataan wilayah berbasis potensi bencana.ABSTRACT. Bandar Lampung is a densely populated urban area consisting of land and water with several plateaus and mountains that stretch across this region. To support sustainable development in a city area, it is necessary to have a regional arrangement concept that considers all aspects, one of which is the potential disaster aspect. One of the potential disasters in Bandar Lampung, especially in Panjang District is a mass movement/landslide. Based on previous research, this area has been recorded as having several historical points of landslides, but there is no mitigation/response specifically for this type of disaster. The purpose of this study was to determine the arrangement of rocks that are in the landslide-prone zone in Panjang District using the geoelectric resistivity method and to analyze the soil engineering assessment obtained from the results of lithological analysis using X-Ray Diffraction (XRD). The results of the geoelectric analysis indicate that there are three lithological layers in the study area; namely tuff sediments with resistivity values and depths between (1–40 Ωm; 0.4–4 m), clay sand (40–120 Ωm; 2–4 m), and solid breccias with igneous rock components (>120 Ωm; 2–22 m). Furthermore, based on the results of the analysis of soil engineering assessments, tuff sediment as a surface layer that has experienced landslides has been identified as having susceptible lithological engineering properties because it has undergone quite intensive oxidation and weathering. The data obtained is expected to be used as supporting data for disaster potential-based regional planning.

Pendugaan sebaran intrusi air laut melalui sungai di desa Ujungmanik kecamatan Kawunganten kabupaten Cilacap menggunakan metode geolistrik resistivitas konfigurasi Wenner

The estimation of the distribution of the sea water intrusion through the rivers in Ujungmanik Village, Kawunganten District, Cilacap Regency has been carried out using the Wenner configuration resistivity geoelectric. This research aims to estimate the distribution of sea water intrusion through rivers in Ujungmanik Village, Kawunganten District, Cilacap Regency based on geoelectric resistivity and conductivity data of groundwater. The geoelectric data acquisition was carried out on four lines. They were Wen1 Line, Wen2 Line, Wen3 Line, and Wen4 Line. Each line had a range of 200 meters. The results of geoelectric data processing showed that the subsurface rock structure consisted of sand, clay, sandy loam, and sandy clay. The Seawater intrusion shown by the sand layer occurred in all trajectories which had a range of resistivity value of 0.20 - 2.79 Ωm. Groundwater samples was carried out at fifteen points with the conductivity value varies between 1363 - 4145 µS / cm so that they can be classified that the water was fresh and brackish due to the sampling done in the rainy season. From this research it can be implied that the entire Ujungmanik area is evenly intruded by the sea water at the coordinates 7º38ꞌ15.62ꞌꞌLS 108°57ꞌ20.89ꞌꞌBT to 7º39ꞌ22.86ꞌꞌLS 108º56ꞌ35.33ꞌꞌBT.

Analisa Model Struktur Geologi Untuk Menduga Air Tanah Dengan Menggunakan Metode Geolistrik

Gondanglegi Kulon Village is located in Gondanglegi District, Malang Regency, the research location is in the Muhammadiyah Entrepreneur Islamic Boarding School area. From the results of information from local villagers, it was explained that in the study area there was no shallow groundwater found. This is also reinforced by the fact that there are no wells in the settlements of the residents around the Entrepreneur Muhammadiyah Islamic Boarding School, so that practically no residents use wells to fulfill clean water, they still depend on river water or PDAM services which are relatively expensive and continuous. still below expectations. As a center for religious education, Islamic boarding schools continue to develop supporting facilities. One of the most needed facilities is the availability of clean water. Quantitatively, the supply from the PDAM is not sufficient and the operational costs borne by the manager are too high. The use of groundwater is a solution that can be used to meet the needs of clean water at the research location. Therefore we need a technology to identify the point of exploration, the technology used in this research is geoelectric resistivity. By using the resistivity geoelectric method, it is expected to know the rock structure at the research location and see the potential for deep groundwater. Thus, the hope that in the future the Entrepreneur Muhammadiyah Islamic Boarding School (PPEM) will no longer depend on water raw materials from the PDAM, so the hope is that daily operational costs related to clean water needs can be minimized. From the results of the analysis and discussion, 2 (two) points of drilling recommendations were obtained, but with technical and non-technical considerations, exploration was suggested at point 3 with a potential of 4.2423 L / sec. Where at this location is a rock lithological arrangement consisting of a top soil layer, a clay layer, a tuff layer, a sandy silt layer, a sand layer and a gravel layer.

Resistivitas Batuan Berdasarkan Metode Geolistrik Konfigurasi Schlumberger untuk Menentukan Potensi Air Tanah Sebagai Acuan Sumur Bor

The purpose of this study is to analyze rock resistivity based on the geoelectric method of the Schlumberger configuration to determine the potential for groundwater as a reference for boreholes. The method used in this research is the geoelectric resistivity method with a Schlumberger configuration. Data acquisition modeling was analyzed using Progress Version 3.0 to describe the subsurface based on measurement sounding points in the field. The main targets for these measurements are confined aquifer traps and sandstone stratigraphy. Field measurement points are at coordinates S 030 43 '52.2 "and E 1020 19' 27.1". The results of this study indicate that the layer that is thought to be the groundwater carrier layer is found at a depth of about 64.99 meters to 150.86 meters with a layer thickness of 85.87 meters, which is in the form of sandstone density with a resistivity value of 5.39 ohm meters. The iteration error scale value in this study is, 5.05% RMS. In conclusion, the results obtained can provide specific information for groundwater drilling actors in the research location. Keywords: Groundwater, Geoelectricity, Resistivity, Schlumberger

Estimation Of Mangaan Carrier Rock Volume Using Geoelectric Method In Empol Sub-Village, West Lombok Regency

The research has been done using geoelectric resistivity method to estimate the volume of Manganese (Mn) carrier rock in Empol sub-village, Central Sekotong Village, West Lombok NTB. Measurements was conducted with the Wenner configuration using a Resistivity Meter G-Sound GL - 4100. Data was modeled and calculated using three software, there are Res2Dinv 3.5, Surfer 10, and Rockwork 15. The rocks that regarded as carrier mangaan is pyrolusite manganese (Mn02). The description and distribution of MnO2 can be determined from the results of 2-dimension modeling using Res2Dinv. Mn02 was detected in almost all resistivity line with value around 0,023 m up to 9,8 m. From the 3-dimension visualization processed using RockWorks 15 software, we obtained volume of pirolusit about 38,199 m3 of area 160,000 m2 and 100 m of thickness.

Identifikasi Bidang Gelincir Zona Rawan Longsor Menggunakan Metode Geolistrik Di Ruas Jalan Toraja – Mamasa

Abstrak. Metode geolistrik tahanan jenis merupakan salah satu dari metode geofisika yang dapat mendeteksi aliran listrik di bawah permukaan bumi. Salah satu aplikasi metode geolistrik tahanan jenis adalah dapat mengidentifikasi bidang gelincir pada daerah rawan longsor. Penelitian ini bertujuan untuk mengetahui bidang gelincir pada daerah rawan lonsor di ruas jalan Toraja – Mamasa. Hasil dari pengukuran geolistrik tahanan jenis dipadukan dengan hasil pengeboran di beberapa titik agar tidak terjadi kesalahan dalam proses interpretasi batuan yang diduga sebagai penyebab terjadinya tanah longsor. Informasi tentang perlapisan tanah tersebut digunakan untuk mengetahui batas-batas ketidakstabilan pada lapisan tanah yang dapat menjadi acuan dalam pengembangan wilayah, khususnya ruas jalan Toraja - Mamasa. Dalam penelitian ini diperoleh nilai resistivitas yang berbeda-beda untuk setiap batuan. Variasi resistivitas yang diperoleh dimulai dari 0 – 978 Ωm. Nilai resistivitas batuan pada bidang gelincir di lokasi penelitian berada pada bidang batas 50-300 Ωm. Batuan penyusunnya berupa batupasir lempung, lava andesit dan basalt. Abstract The resistivity geoelectric method is one of the geophysical methods that can detect the flow of electricity below the earth's surface. One application of the resistivity geoelectric method is to identify the slip field in landslide prone areas. The research aimed to discover slip area of landslide prone zone at the segment road of Toraja-Mamasa. The results of the geoelectric resistivity measurements are combined with the results of drilling at several points so that there are no errors in the process of rock interpretation which are thought to be the cause of landslides. Information about the soil layers is used to determine the boundaries of instability in the soil layer which can be used as a reference in regional development, especially the Toraja - Mamasa road segment. In this research, it was obtained different resistivity values for each rock. The resistivity variation obtained started from 0 - 978 Ωm. The rock resistivity value in the slip plane at the research location is in the 50-300 Ωm boundary fields. The rocks lithologies are clay sandstones, andesite lava and basalt.

Identification of Aquifer in the MIPA Faculty - University of Jember Using 1D Geoelectrical Resistivity Method with Schlumberger Array

Faculty of Mathematics and Natural Sciences University of Jember located in Sumbersari District with lithological conditions in the form of volcanic rocks, lithosol soils, and regosol soils that are capable of absorbing water and potentially as aquifers. In point of fact, in the campus zona of the University of Jember including in the Faculty of Mathematics and Natural Sciences, there is always a shortage of freshwater for various academic and non-academic activities. Therefore, research needs to be conducted to assess the lithology of subsurface structures in the FMIPA zone so that the depth of groundwater layers and aquifer layers can be determined. The study was conducted using the Schlumberger array geoelectric resistivity method at 5 VES points. The results obtained in the form of resistivity log curves can be seen that at the five points VES has lithology in the form of clay, gravel, sandstone, and groundwater layer. Each VES point was identified the groundwater layer and some of them were identified as aquifers. The aquifer with the greatest thickness is found at point VES 2, which is to the west of the Baitul Ilmi Mosque, so it is recommended as the location of a new well.Keywords: lithology, aquifers, geoelectric resistivity method, groundwater.