Analisis Suseptibilitas Magnetik Tanah Permukaan sebagai Indikator Longsor di Bukit Karan Padang
DOI:
https://doi.org/10.25077/jfu.9.4.472-478.2020Abstract
Penelitian mengenai analisis nilai suseptibilitas magnetik tanah permukaan daerah potensi longsor di Bukit Karan Padang telah dilakukan. Pengambilan sampel dilakukan pada sisi Bukit Karan yang berada di Kelurahan Rawang Kecamatan Padang Selatan dengan berjarak 10 m dari pemukiman penduduk. Sampel diambil pada empat lintasan yaitu lintasan A, B, C, dan D dengan jarak antar lintasan 20 m. Setiap lintasan terdiri dari 10 titik dengan jarak antar titik yaitu 10 m, sehingga membentuk grid yang terdiri dari 40 titik. Pengukuran suseptibilitas magnetik menggunakan MS2B Bartington Susceptibility Meter dengan dua frekuensi, yaitu frekuensi rendah (0,47 kHz) dan frekuensi tinggi (4,7 kHz). Hasil penelitian menunjukkan bahwa keseluruhan sampel memiliki nilai suseptibilitas magnetik pada frekuensi rendah (χLF) berkisar antara 120,2×10-8 m3/kg dan 458,5×10-8m3/kg dengan rata-rata 208,2x10-8m3/kg. Dari hasil tersebut diperkirakan bahwa mineral magnetik yang terkandung dalam sampel bersifat Paramagnetik dan Ferimagnetik dan jenis mineralnya diperkirakan mineral Hematit (Fe2O3). Hasil menunjukkan bahwa 87,5% sampel memiliki nilai χFD (%) antara 2,00% - 10,0%. Hal ini menunjukkan bahwa lokasi penelitian memiliki kandungan bulir superparamagnetik yang tinggi sehingga sampel-sampel tersebut bersifat halus dan mudah untuk menyerap air sehingga potensi longsor pada daerah tersebut cukup tinggi.
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Research on the analysis of the magnetic susceptibility value of surface soil in landslide potential areas in Bukit Karan Padang has been done. Soil samples were collected from the hillside in Rawang Village South Padang 10 m away from the residential area. Samples were taken on four paths, namely lines A, B, C, dan D, with a distance between the path is 20 m. Each path consists of 10 points with a distance between the point is 10 m. Magnetic susceptibility measured using Bartington Susceptibility Meter MS2B with two frequencies, namely low frequency (0.47 kHz) dan high frequency (4.7 kHz). The results show that all samples have the value of low frequency magnetic susceptibility (χLF) ranged from 120.2×10-8 m3/kgand 458.5×10-8m3/kg and average of 208.2x10-8m3/kg. From these results it is estimated that the magnetic minerals contained in the sample are Paramagnetic and Ferimagnetic and the mineral type is estimated to be the Hematite (Fe2O3). The result showed that 87.5% samples have a value of χFD (%) between 2.00% - 10.0%. The result indicates that the research location has a high Superparamagnetic grain content so that the samples are fine and easy to absorb water so have enough potential for landslides.
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