Electronic Theses and Dissertation

Telah dilakukan penelitian dengan menggunakan metode gravitasi di daerah jantho sampai leungah untuk mengidentifikasi sesar sumatra segmen seulimeum bagian utara. distribusi percepatan gravitasi telah diukur dengan menggunakan instrumen gravitimeter scintrex cg-5. data percepatan gravitasi yang terukur sebanyak 39 titik dengan total panjang lintasan 39 km. untuk mendapatkan nilai anomali bouguer lengkap, beberapa standar koreksi data diterapkan termasuk koreksi drift, koreksi pasang surut, koreksi lintang, koreksi udara bebas, koreksi bouguer, dan koreksi medan. data nilai anomali bouguer lengkap sepanjang profil digunakan untuk pemodelan maju (forward modeling) 2d menggunakan software grav2dc. hasil model menunjukkan bahwa struktur bawah permukaan daerah penelitian terdiri dari tiga lapisan dengan formasi batuan dan densitas yang berbeda-beda. lapisan pertama terdapat batu pasir tufaan (=2.90 g/cm3), batuan vulkanik: andesit, tufa (=2.75 g/cm3), batuan aluvium (=1.70 g/cm3). lapisan kedua terdapat batu gamping kurang (=2.48 g/cm3), batuan vulkanik: andesit, tufa (=2.75 g/cm3). lapisan ketiga terdapat batuan gunung api andesit (=2.69 g/cm3) dan batu gamping kurang (=2.48 g/cm3). hasil interpretasi kuantitatif di kawasan penelitian pada segmen seulimeum diindikasikan adanya sesar mendatar yang tidak murni atau disebut sesar oblique yaitu kombinasi antara sesar mendatar dan sesar normal. struktur sesar berada di sekitar lon baroh sampai lamtamot. kata kunci: metode gravitasi, densitas, grav2dc, sesar sumatra

A study using gravity method has been conducted from Jantho until Leungah in order to identify the northern Seulimeum Segment of the Sumatra Fault. The gravity acceleration distribution was measured using a Gravitimeter Scintrex CG-5 instrument. The measured data of gravity acceleration are 39 points with a total track length of 39 km. In order to obtain a complete Bouguer anomaly value, some standard data corrections were applied, including drift correction, tidal correction, latitude correction, free air correction, Bouguer correction, and terrain correction. Complete Bouguer anomaly value data along the profile was used for 2D forward modeling by using Grav2DC software. The models showed that the subsurface structure of the area consists of three layers with different rock formations and densities. The first layer is tuffaceous sandstone (=2.90 g/cm3), volcanic rocks: andesite, tuff (=2.75 g/cm3), alluvium rocks (=1.70 g/cm3). The second layer is contains less limestone (=2.48 g/cm3), volcanic rocks: andesite, tuff (=2.75 g/cm3). The third layer andesitic volcanic rock (=2.69 g/cm3) and contains less limestone (=2.48 g/cm3).The results of quantitative interpretation in the research area of Selimeum Segment indicated a impure strike slip faults, which also called as oblique faults, a combination of strike slip faults and normal faults. The fault structure is around Lon Baroh until Lamtamot. Keywords: Gravity Method, Density, Grav2DC, Sumatra Fault