Electronic Theses and Dissertation

Sebagian besar wilayah Aceh Selatan pada tahun 2004 tidak mengalami bencana tsunami, namun demikian bukan berarti daerah Aceh Selatan aman dari bencana tsunami. Pada penelitian ini dilakukan kajian mengenai sejarah tsunami pada masa lalu (paleotsunami). Desa Ladang Tuha, Kecamatan Meukek, Kabupaten Aceh Selatan merupakan salah satu lokasi yang potensial diteliti berdasarkan morfologi pantai dan kajian pengangkatan dan penurunan tanah akibat aktivitas tektonik sebelum dan setelah kejadian gempa bumi pada daerah tersebut. Data sedimen di bawah permukaan diambil menggunakan Hand Auger pada 8 titik yang membentuk lintasan yang tegak lurus dengan garis pantai. Analisis sedimen dilakukan berdasarkan klasifikasi Troel-Smith, sedimen tsunami biasanya terdapat di antara dua endapan tanah organik akibat adanya aktivitas tektonik, ukuran butir sampel juga dipilah dengan menggunakan saringan mesh untuk membedakan butir antar lempung, lanau dan pasir. Data hasil analisis berupa ukuran butir dan warna dari masing-masing lapisan disajikan dalam bentuk Spider webs. Berdasarkan klasifikasi tersebut endapan sedimen tsunami umumnya ditandai oleh dominasi kandungan pasir dan organik. Hasil penelitian menunjukkan ada 2 lapisan tsunami purba di Desa Ladang Tuha pada kedalaman sekitar 188-200 cm dan 340-372 cm.

Kata Kunci : Paleotsunami, Gempa Bumi, Analisis Troel-Smith, Sedimen, Aceh Selatan.

Most of the parts of Aceh Selatan, the southern part of Aceh, were not hit by the 2004 tsunami. However, such a condition does not guarantee that Aceh Selatan is safe from a tsunami. This present study examines the history of previous tsunamis (paleo-tsunami). Ladang Tuha, situated in Meukek Subdistrict, Aceh Selatan Regency, is a potential research location based on the morphology of its coastal area and the presence of evidence of land subsidence caused by tectonic activities measured before and after the event of the earthquake. The sediment under the surface was taken using Hand Auger in 8 points in a shape of a vertical line with the shoreline. The analysis of sediment was performed through Troel-Smith's classification. The sediment of tsunamis usually is apparent between two layers of organic soil sediment caused by tectonic activities. The particle size of the sample was also sorted using a mesh filter to distinguish clay, silt, and sand. The data from the analysis results were presented in Spider Webs, consisting of the size of particles and colors of each layer. Based on this classification, the sediment of the tsunami can be recognized through the dominant presence of sand and organic content. The research results revealed that there were two layers of paleo-tsunami that hit Ladang Tuha coast with the depth of 188-200 cm and 340-372 cm. Keywords: Paleotsunami, Earthquake, Analisis Troel-Smith's, Sediment, Aceh Selatan.