Jurnal Kumparan Fisika (Dec 2023)

Model 2D of Subsurface Structures in the Dempo Magnetic Area of Pagar Alam City Using Geomagnetic Method

  • Febri Adrianto Adrianto,
  • Refrizon,
  • Arif Ismul Hadi

DOI
https://doi.org/10.33369/jkf.6.3.167-176
Journal volume & issue
Vol. 6, no. 3

Abstract

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ABSTRAK Metode geomagnetik digunakan dalam penelitian ini untuk membuat model 2D struktur bawah permukaan di kawasan Dempo Magnet kota Pagar Alam berdasarkan sebaran anomali. Terdapat 48 titik pengukuran pada lokasi penelitian. Pengolahan data dilakukan dengan membuat peta anomali magnetik total. Koreksi diurnal dan koreksi international geomagnetic reference field (IGRF) dilakukan untuk mendapatkan nilai anomali magnetik total. Data magnetik tersebut kemudian diolah untuk memisahkan anomali regional dan anomali residual menggunakan bandpass filter, kemudian dilakukan transformasi reduksi ke kutub, dan pemodelan 2D menggunakan metode forward modeling. Hasil analisis kisaran nilai anomali magnet di kawasan magnet Dempo kota Pagar Alam diperoleh nilai anomali magnet tertinggi sebesar 781,8 nT, sedangkan anomali magnet terendah sebesar -796,6 nt. Hasil pemodelan 2D pada data magnetik diperoleh 4 lapisan batuan bawah permukaan dengan kedalaman sekitar 165 meter, dimana lapisan batuan pertama berupa breksi gunung api, lapisan batuan kedua berupa endapan piroklastik, lapisan batuan ketiga berupa basal, dan lapisan batuan terakhir. adalah gabro. Kata Kunci: Metode Magnetik, Intensitas Anomali Medan, Pemodelan 2D, Struktur Bawah Permukaan ABSTRACT The geomagnetic method was used in this research to create a 2D model of subsurface structures in the Dempo Magnet area of ​​Pagar Alam city based on the distribution of anomalies. There were 48 measurement points at the researched location. Data processing was carried out by creating a total magnetic anomaly map. Diurnal correction and international geomagnetic reference field (IGRF) correction were carried out to obtain total magnetic anomaly values. The magnetic data was then processed to separate regional anomalies and residual anomalies used a bandpass filter, then a reduction transformation to the poles was carried out, and 2D modeling used the forward modeling method. The results of the analysis of the range of magnetic anomaly values ​​in the Dempo magnet area of ​​Pagar Alam city obtained the highest magnetic anomaly valued of 781, 8 nT, while the lowest magnetic anomaly was -796, 6 nt. The results of 2D modeling on magnetic data obtained 4 subsurface rock layers with a depth of around 165 meters, where the first rock layer was volcanic breccia, the second rock layer was pyroclastic sediment, the third rock layer was basalt, and the last rock layer was gabbro. Keywords: Magnetic method, Field anomaly intensity, 2D modeling, Subsurface structures

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