Analisis Nilai Suseptibilitas Magnetik Tanah Permukaan Daerah Potensi Longsor di Bukit Gado-Gado Padang
DOI:
https://doi.org/10.25077/jfu.9.2.209-216.2020Abstract
Telah dilakukan penelitian mengenai analisis nilai suseptibilitas magnetik tanah permukaan daerah potensi longsor di Bukit Gado-Gado Padang. Pengambilan sampel dilakukan pada lokasi perbukitan yang pernah terjadi longsor dengan jarak 15 m dari pemukiman penduduk. Sampel diambil pada empat lintasan dengan jarak 10,0 m dan luas 100 m2, sehingga diperoleh 40 titik sampel. Pengukuran suseptibilitas magnetik menggunakan MS2B Bartington Susceptibility Meter dengan dua frekuensi, yaitu 0,47 kHz lowfrequency (LF) dan 4,7 kHz highfrequency (HF). Hasil penelitian menunjukkan bahwa nilai suseptibilitas magnetik pada frekuensi rendah (χLF) berkisar antara 120,2×10-8 m3kg-1 dan 458,5×10-8m3kg-1 dengan rata-rata 209,86×10-8m3kg-1. Dari range nilai χLF tersebut diperkirakan bahwa mineral magnetik yang terkandung dalam sampel bersifat Paramagnetik dan Ferimagnetik dan jenis mineralnya diperkirakan adalah Hematit (Fe2O3). Grafik hubungan antara nilai suseptibilitas magnetik terhadap χFD (%) menunjukkan bahwa hampir keseluruhan sampel memiliki nilai χFD(%) di atas 2,00 %. Hal ini menunjukkan bahwa lokasi penelitian memiliki kandungan bulir superparamagnetik yang tinggi sehingga sampel-sampel tersebut bersifat halus dan mudah untuk menyerap air sehingga lebih besar kemungkinan terjadinya longsor.
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A research on the analysis of the magnetic susceptibility of surface soil in the landslide potential area in Gado-Gado Hill Padang has been conducted. Sampling was carried out at 40 points in the location of the hills that had occurred landslides with a distance of 15 m from residential areas. Samples were taken of four trajectories on a 10.0 m space with an area of 100 m2. Magnetic susceptibility measured using Bartington Susceptibility Meter MS2B with two frequencies, namely 0.47 kHz low frequency (LF) and 4.7 kHz high frequency (HF). The results show that the magnetic susceptibility value at low frequency (χLF) ranged from 120.2×10-8 m3kg-1 dan 458.5×10-8m3kg-1 with an average of 209.86×10-8m3kg-1. The range of χLF values indicated that the sampel contain Paramagnetic and Ferrimagnetic and the mineral type is estimated to be Hematite (Fe2O3). χFD (%) of almost all samples are above 2.00 %. This shows that the location of the study has a high Superparamagnetic grain content so that the sample are smooth and easy to absorb water so there is a greater chance of landslides.Â
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