Microplastic has attracted the attention of the scientific community since the last 3 years due to its effects and damages to the environment. Microplastics are defined as tiny solid plastics generally ranging from 20 µm to 5 mm in diameter. They are roughly classified into small (20 µm–1 mm) and large (1–5 mm) microplastics. In this study two preparation methods to analyze the presence of microplastics in bottled drinking water are developed. Microplastic in drinking water is isolated by direct filtration and drying methods. By drying method, the isolated material is then analyzed using Fourier‐transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) instrument. Since the isolated material from filtration method is observed by digital microscope and further analyzed using FTIR microscope. FTIR microscope has been used to identify the type of plastic material. The small size of a particle starting at 20 microns can be identified using this instrument. Microplastics, high density polyethylene, and polyethylene terephthalate, size 20–200 µm are spiked in drinking water as control. The observation of the filtrates shows that microplastic only appeared in drinking water that has been spiked with microplastic. Further plastic identification using FTIR spectroscopy, DSC, and TGA needs microplastic in large amount.

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ABSTRAK.Kompleks prisma akresi memiliki karakteristik morfologi yang unik sebagai hasil dari proses deformasi dan sedimentasi yang berkembang di daerah tersebut. Pulau Simeulue merupakan salah satu contoh pulau yang terbentuk pada prisma akresi. Studi geologi dilakukan untuk menggambarkan keadaan struktur geologi yang terbentuk di Pulau Simeulue yang berhubungan dengan mekanisme pembentukan sesar-sesar anjak pada prisma akresi, pembentukan kompleks batuan bancuh dan mekanisme kubah lumpur. Morfologi dan struktur geologi Pulau Simeulue dipetakan melalui interpretasi citra dan survey lapangan. Citra yang digunakan dalam studi ini adalah citra Landsat TM5, Landsat 8 dan Aster-GDEM. Tumbukan di bagian muka deformasi mengakibatkan berkembangnya struktur berupa sesar-sesar naik dan anjak dimana di bagian utara-timurlaut cenderung lebih naik daripada bagian selatan-baratdaya. Berdasarkan hasil interpretasi citra, sesar-sesar yang berkembang tersebut umumnya merupakan sesar-sesar anjak berarah palung (trenchward-vergence thrusts). Berdasarkan hasil pengukuran fitur struktur di lapangan dan rekonstruksi lipatan di Pulau Simeulue, perkembangan struktur anjak juga terjadi secara out-of-sequence yang mengakibatkan teraktifkannya sesar anjak berarah busur (arcward-vergence thrusts). Sesar anjak berarah palung dapat diinterpretasikan sebagai backthrust fault dari sebuah mekanisme backstop di bagian belakang prisma akresi. Sesar-sesar anjak ini dapat dikaitkan dengan keberadaan kubah lumpur (mud diapir) yang jejaknya juga ditemukan di beberapa lokasi di Pulau Simeulue. Hal-hal tersebut mendukung teori bahwa kompleks batuan mélange di Pulau Simeulue terbentuk melalui proses mud diapirism yang muncul melalui sesar-sesar anjak.Kata kunci: Pulau Simeulue, kompleks mélange, prisma akresi, sesar anjak, mud diapir, kompleks subduksi. ABSTRACT. The accretionary prism complex

A b s t r a c tWe analyzed receiver function of teleseismic events recorded at twelve Indonesian-GEOFON (IA-GE) broadband stations using nonlinear Neighbourhood Algorithm (NA) inversion and H-k stacking methods to estimate crustal thickness, Vp/Vs ratios and S-wave velocity structure along Sunda-Banda arc transition zone. We observed crustal thickness of 34-37 km in Timor Island, which is consistent with the previous works. The thick crust (> 30 km) is also found beneath Sumba and Flores Islands, which might be related to the arc-continent collision causing the thickened crust. In Timor and Sumba Islands, we observed high Vp/Vs ratio (> 1.84) with low velocity zone that might be associated with the presence of mafic and ultramafic materials and fluid filled fracture zone. The high Vp/Vs ratio observed at Sumbawa and Flores volcanic Islands might be an indication of partial melt related to the upwelling of hot asthenosphere material through the subducted slab.