Analisis Suseptibilitas Magnetik Tanah Lapisan Atas sebagai Indikator Bencana Longsor di Bukit Sula Kecamatan Talawi Kota Sawahlunto

Authors

  • Febri Naldi Laboratorium Fisika Bumi, Jurusan Fisika Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Andalas
  • Arif Budiman Laboratorium Fisika Bumi, Jurusan Fisika Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Andalas

DOI:

https://doi.org/10.25077/jfu.7.2.110-116.2018

Abstract

Telah dilakukan penelitian mengenai analisis suseptibilitas magnetik tanah lapisan atas sebagai indikator bencana longsor di Bukit Sula Kecamatan Talawi Kota Sawahlunto. Sampel tanah diambil dari dua lokasi di Bukit Sula, yaitu lokasi bervegetasi (lokasi A) dan lokasi tanpa vegetasi (lokasi B). Pengambilan sampel dilakukan secara vertikal ke bawah masing-masing sepanjang 100 m dengan jarak spasi 5 m, sehingga diperoleh 21 titik pengambilan sampel pada masing-masing lokasi tersebut. Pengukuran nilai suseptibilitas magnetik menggunakan Bartington Magnetic Suseptibility Meter yang diukur pada dua frekuensi, yaitu low frequency 0,465 kHz (χLF) dan high frequency 4,65kHz (χHF). Pada lokasi A nilai χLF rata-rata yang diperoleh yaitu 804,05×10-8 m3kg-1, sedangkan nilai χHF rata-rata yaitu 804,25×10-8 m3kg-1. Pada lokasi B nilai χLF rata-rata yang diperoleh yaitu 9,85×10-8 m3kg-1, sedangkan nilai χHF rata-rata yaitu 9,64×10-8 m3kg-1. Hasil pengujian XRF menunjukkan bahwa mineral magnetik yang terdapat pada sampel di kedua lokasi yaitu hematit (Fe2O3). Berdasarkan perbandingan nilai suseptibilitas dan konsentrasi mineral hematit dan kuarsa antara sampel lokasi A dan lokasi B, dapat dikatakan bahwa lokasi B telah mengalami erosi. Berdasarkan keberadaan bulir superparamagnetik, sampel lokasi B memiliki butiran lebih halus dibandingkan sampel lokasi A. Hal ini disebabkan karena lokasi B merupakan daerah tanpa vegetasi, sehingga menyebabkan air hujan langsung masuk ke dalam tanah dan dapat menurunkan tingkat kelekatan butiran tanah. Oleh karena itu, lokasi B lebih besar kemungkinan terjadinya bencana longsor dibandingkan dengan lokasi A.

 

Kata kunci: bulir superparamagnetik, suseptibilitas magnetik, longsor, Kecamatan Talawi

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Published

2018-04-02

How to Cite

Naldi, F., & Budiman, A. (2018). Analisis Suseptibilitas Magnetik Tanah Lapisan Atas sebagai Indikator Bencana Longsor di Bukit Sula Kecamatan Talawi Kota Sawahlunto. Jurnal Fisika Unand, 7(2), 110–116. https://doi.org/10.25077/jfu.7.2.110-116.2018

Issue

Vol. 7 No. 2 (2018)

Section

Articles

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Copyright (c) 2018 Febri Naldi, Arif Budiman

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