PERBANDINGAN KONFIGURASI ELEKTRODA METODE GEOLISTRIK RESISTIVITAS UNTUK IDENTIFIKASI LITOLOGI DAN BIDANG GELINCIR DI KELURAHAN PIDADA BANDAR LAMPUNG

Longsoran merupakan bencana yang terjadi dipengaruhi oleh faktor morfologi, litologi, struktur geologi, hidrogeologi dan penggunaan lahan. Kelurahan Pidada, Kecamatan Panjang, Bandar Lampung merupakan daerah yang kondisi morfologinya berupa perbukitan dengan kelerengan yang curam. Berdasarkan data dari Pusat Vulkanologi dan Mitigasi Bencana (PVMBG) pada bulan Januari-Oktober 2019, daerah penelitian yang berada di Kecamatan Panjang memiliki potensi gerakan tanah menengah-tinggi. Kriteria terjadinya longsoran adalah kelerengan yang cukup curam, terdapatnya bidang gelincir di bawah permukaan tanah yang jenuh air dan banyaknya kandungan air yang berasal dari air hujan yang meresap ke dalam tanah. Salah satu metode geofisika yang dapat mendeteksi litologi dan bidang gelincir adalah metode Geolistrik Resistivitas. Melalui metode ini diketahui daerah yang memiliki kandungan air tinggi yang ditunjukkan dengan nilai resistivitas yang rendah. Pada penelitian ini, dilakukan identifikasi litologi dan bidang gelincir di kawasan rawan longsor dengan menggunakan metode geolistrik resistivitas konfigurasi Wenner-Schlumberger dan Wenner-Alpha. Konfigurasi Wenner-Schlumberger mempunyai penetrasi pengukuran yang lebih dalam tetapi gambaran penampang bawah permukaan beresolusi rendah, sedangkan konfigurasi Wenner-Alpha mempunyai penetrasi pengukuran yang tidak terlalu dalam tetapi gambaran penampang bawah permukaan beresolusi relatif tinggi. Penggunaan kedua konfigurasi ini untuk memanfaatkan kelebihan dan mengurangi kelemahan dari masing-masing konfigurasi pada analisis kelongsoran. Setelah dilakukan pengukuran terhadap 2 lintasan, diidentifikasi litologi dan bidang gelincir daerah penelitian. Berdasarkan hasil pengukuran, konfigurasi Wenner-Schlumberger mempunyai gambaran penampang bawah permukaan yang lebih detail dan penetrasi yang lebih dalam untuk identifikasi litologi perlapisan dan bidang gelincir dibandingkan konfigurasi Wenner-Alpha

2D Gravity Qualitative Modeling to Identify Bedrock and Volcanic Rocks in South Lampung Region

Gravity measurement has been conducted in South Lampung area to study the characteristics of the distribution of bedrock and igneous rocks, especially those that can be utilized for development in the National Strategic Area of the Sunda Strait. This study uses a 2D qualitative modeling method and utilizing spectrum analysis of complete Bouguer anomaly data. Based on the result of modeling of residual gravity anomaly, it was found that the intrusion pattern on Sulan granitoid pluton and surrounding plutons showed a significant intrusion of the body and scattered in some Tarahan area. 2D qualitative modeling shows Paleozoic metamorphic rocks are responsible as bedding rocks, and the spread was identified scattered throughout the study area, although it cannot be ascertained whether the bedrock in the Bakauheni area is precisely the same rock as the bedrock in Tarahan area. Meanwhile, Quaternary volcanic rocks are still dominated by tuffaceous sandstone and breccia. This method also confirms that andesite lava is commonly found as a product of the eruption of Mount Rajabasa and Pre-Rajabasa in the Bakauheni region. Nevertheless, some potential of basaltic andesite rocks can be obtained in monogenetic volcanic zones exposed around the foot of Mount Rajabasa

Seismic Vulnerability Evaluation in Western Bandar Lampung's Quarter Formation using the ERT Technique

Western Bandar Lampung is rapidly evolving into a sought-after residential locale and a scenic mountainous tourist spot. Notably, this region sits atop multiple fault structures, signaling potential seismic threats. This study aims to gauge the susceptibility of superficial layers by analyzing the resistivity properties of the underlying rock. Using the ERT geoelectric method across three lines, following the Wenner-Schlumberger configuration, a length of 140 m was mapped with electrodes spaced at intervals of 5 m. The subsurface materials in the examined area displayed a resistivity range between 4 and 1050 Ohm m, characterized by a blend of weathered constituents and igneous lenses. The dominant presence of extensively weathered material, especially given its thickness, highlights possible seismic dangers, including amplification, liquefaction, and potential landslides. To mitigate the repercussions of seismic hazards stemming from these fault lines, there is an imperative need for stringent adherence to construction guidelines tailored for seismically active regions.Top of For

Identification of the Semangko Fault in Sumatra, Indonesia, based on gradient gravity data analysis

The Semangko Fault (SF) is a major active fault that extends across from Aceh (in northern part) to Lampung Province (in southern part) of Sumatra Island, contributing to much deformation and high seismicity along the fault. The fault affects a pattern in the density of surrounding rocks and can be identified by the gravity method. This research aimed to determine the fault structure using gravity gradient analysis in the Lampung area. Bouguer anomalies were analyzed from satellite gravity data and gravity gradient calculation, for fault structure identification around SF. Based on the Bouguer anomalies and gravity gradient analysis (first and second-order horizontal derivatives), SF trends NW-SE. The SF is divided into two sides at the Suoh area, West and East SF sides across to Semangko Bay. That trend is confirmed with geological and topographical data analysis. These findings suggest that gravity anomaly data and horizontal gravity gradient analysis can be used to determine and identify the presence of the SF. The seismic hazard assessments can mitigate hazards to all people in the vicinity of the SF area

Studi Awal Prospek Bahan Tambang Berdasarkan Sebaran Alterasi Hidrotermal Menggunakan Komposit dan Density Slicing Citra Landsat 8 di Kabupaten Ulubongka, Sulawesi Tengah

Difficult access to the field in Central Sulawesi causes the process of identifying prospects for mining minerals requires a relatively large time and cost. Therefore, the remote sensing approach can be carried out as a preliminary study to determine the distribution of hydrothermal alterations that characterize the presence of mine minerals. This study utilizes Landsat 8 imagery to obtain the distribution of alteration minerals, especially the group of ferrous mineral oxide and hydroxide minerals, clay and carbonate minerals and Ferromagnesian minerals. The method used is composite (RGB) 4/2, 6/7, 5 and 4/2, 6/7, 10 to detect the distribution of alteration minerals. Whereas the Density Slicing method uses 4/2, 5/6 and 6/7 ratio images to detect Ferrugitation, Ferromagnesian, clay and carbonate minerals. The results of the analysis showed the distribution of iron oxide and hydroxide minerals (Ferrugination) dominated the area in alluvium and opiolite rocks. This alteration distribution is interpreted as a prospect of further studies of the presence of mining minerals such as nickel and iron. Whereas ferromagnesian minerals, clays and carbonates dominate in conglomerate and limestone rocks.Sulitnya akses ke lapangan di Sulawesi Tengah menyebabkan proses identifikasi prospek mineral tambang membutuhkan waktu dan biaya yang relatif besar. Oleh karena itu, pendekatan penginderaan jauh dapat dilakukan sebagai studi awal untuk mengetahui sebaran alterasi hidrotermal penciri kehadiran mineral tambang. Penelitian ini memanfaatkan citra Landsat 8 untuk mendapatkan sebaran mineral alterasi khususnya kelompok mineral oksida dan hidroksida besi (Ferrugination), mineral lempung dan karbonat serta mineral Ferromagnesian. Metode yang digunakan adalah komposit (RGB) 4/2,6/7,5 dan 4/2,6/7,10 untuk mendeteksi sebaran mineral alterasi. Sedangkan metode Density Slicing menggunakan citra rasio 4/2, 5/6 dan 6/7 untuk mendeteksi mineral Ferrugitation, Ferromagnesian, lempung dan karbonat. Hasil analisis menunjukkan sebaran mineral oksida dan hidroksida besi (Ferrugination) mendominasi area di batuan aluvium dan ofiolit. Sebaran alterasi ini diinterpretasikan sebagai prospek studi lanjut keberadaan mineral tambang seperti nikel dan besi. Sedangkan mineral ferromagnesian, lempung dan karbonat mendominasi di batuan konglomerat dan batugamping

Analisis anomali bouguer dan gradien horizontal untuk merekontruksi struktur bawah permukaan Lampung bagian Timur [Skripsi] /

Bibliografi hal. 81-82rnAda CD-nyaiv, 82 hlm. : il. ; 30 cm. . -- Lamp. (8 Lembar