Electronic Theses and Dissertation

Telah dilakukan identifikasi struktur bawah permukaan daerah rawan longsor dengan menggunakan metode magnetic di Desa Ginting, Gayo Lues. Pengukuran dilakukan dengan menggunakan tiga lintasan pada area perbukitan yang berpotensi longsor. Masing-masing lintasan memiliki panjang 200 m, 300 m dan 320 m dengan jarak antar titik sebesar 10 m. Data hasil pengukuran lapangan kemudian dikoreksi melalui koreksi harian dan koreksi IGRF serta melalui filter Upward Continuation dan Reduksi ke Equator sehingga didapatkan nilai anomali medan magnetik total yang merefleksikan variasi nilai suseptibilitas di bawah permukaan. Nilai anomali medan magnetik total kemudian dimodelkan secara forward modelling untuk mengetahui jenis perlapisan batuan yang ada dibawah permukaan sehingga dihasilkan model suseptibilitas bawah permukaan. Hasil pemodelan suseptibilitas kemudian diinterpretasikan dengan menjumlahkan nilai suseptibilitas tiap lapisan terhadap nilai suseptibiltas rata-rata lokasi penelitian sehingga didapatkan jenis-jenis lapisan dibawah permukaan. Didapatkan hasil yang menunjukkan adanya lapisan sedimen yang berpotensi menjadi bidang gelincir diatas lapisan bedrock. Lapisan sedimen tersebut terdiri dari lapisan topsoil (k=0,0179 cgs), clay (k=0,0172 cgs) dan gravel (k=0,0162 cgs). Sedangkan lapisan bedrock terdiri dari lapisan arenit. Pada kondisi curah hujan tinggi, kandungan air yang ada didalam lapisan sedimen dapat mengurangi kompaksi lapisan batuan yang menyebabkan lapisan berpotensi menyebabkan longsor.
Kata kunci: Longsor, Medote Magnetik, Suseptibilitas

Identification of subsurface structures prone to landslides using the magnetic method has been carried out in Ginting Village, Gayo Lues. Measurements were carried out using three tracks in hilly areas that have the potential for landslides. Each track had a length of 200 m, 300 m, and 320 m with a distance between points of 10 m. The data from the field measurements were then corrected through daily corrections and IGRF corrections as well as through Upward Continuation and Reduction to the Equator filters. As a result, the total magnetic field anomaly value was obtained which reflects the variation in the subsurface susceptibility value. Total magnetic field anomaly value was then modeled by forward modeling to determine the type of rock layers that exist below the surface so that a subsurface susceptibility model was produced. The results of the susceptibility modeling were then interpreted by adding up the susceptibility value of each layer to the average susceptibility value of the research location to find the types of layers below the surface. The results indicate the presence of a sedimentary layer that has the potential to become a slip plane above the bedrock layer. The sediment layer consists of a layer of topsoil (k=0.0179 cgs), clay (k=0.0172 cgs) and gravel (k=0.0162 cgs). Meanwhile, the bedrock layer consists of a layer of arenite. In conditions of high rainfall, the water content in the sediment layer can reduce the compaction of rock layers, which causes the layer to have the potential for landslides. Keywords: Landslide, Magnetic Method, Susceptibility