Mikrozonasi Berdasarkan Data Mikrotremor dan Kecepatan Gelombang Geser di Kotamadya Yogyakarta

Gempabumi Yogyakarta dengan magnitude 6,3 Skala Richter yang terjadi pada tahun 2006 menyebabkan kerusakan bangunan di Kota Yogyakarta dan sekitarnya. Kerusakan banyak terjadi di daerah sedimen Yogyakarta daripada di perbukitan Wonosari yang memiliki lapisan lebih keras. Kerusakan ini mengindikasikan adanya kontrol efek tapak lokal. Penelitian ini bertujuan untuk memetakan daerah rawan kerusakan gempabumi di Kotamadya Yogyakarta berdasarkan analisis kurva Horizontal-to-Vertical Spectral Ratio (HVSR) dan mengetahui litologi bawah permukaan berdasarkan ground profiles kecepatan gelombang geser (Vs) dengan metode inversi kurva HVSR. Penelitian dilakukan di Kotamadya Yogyakarta dan sekitarnya yang dibatasi pada koordinat 7o45’58.09’’- 7o50’59.01’’ Lintang Selatan dan 110o19’7.87’’-110o24’35.43’’ Bujur Timur. Data mikrotremor sebanyak 280 diolah menggunakan metode HVSR. Proses inversi HVSR juga dilakukan untuk memperkirakan model perlapisan tanah. Hasil dari penelitian menunjukkan bahwa nilai frekuensi dominan (fo) di Kotamadya Yogyakarta dan sekitarnya berkisar antara 1,1-5,8 Hz, nilai amplifikasi (A0) berkisar antara 1-21, nilai Vs30 berkisar antara 210-376 m/s. Hasil inversi menunjukkan bahwa ketebalan lapisan sedimen di Kotamadya Yogyakarta dan sekitarnya berkisar antara 104 meter hingga 262 meter. Persebaran daerah lebih rentan secara seismik terdapat pada nilai amplifikasi tinggi sebesar 9-21 dengan rentang frekuensi 1,1-2,3 Hz yaitu di Kecamatan Sewon, Banguntapan dan Umbulharjo. Sebaran lokasi kejadian likuifaksi bersesuaian dengan nilai kecepatan gelombang geser rendah dengan rentang 210-262 m/s dengan jenis tanah sedang (SD) yaitu di Kecamatan Sewon, Banguntapan dan Umbulharjo

X-ray Absorption Near Edge Structure (XANES) Spectrum Interpretation for LiFePO4-Silicon Doped Cathode Material

LiFePO4-Silicon doped has been widely developed as a battery cathode material. Due to the doping of silicon atoms, this study aims to determine the peak energy (E0), oxidation state and percentage of component composition for Fe K-edge. The experimental sample used are LFP Si-0%, LFP Si-1%, LFP Si-3% and LFP Si-6%. These samples were characterized using XAS (X-ray Absorption Spectroscopy). XANES spectrum showed the peak energy of Pre-edge area is 7113.08 – 7114.49 eV. The oxidation state of Fe atoms were increased and tend to be Fe3+ than Fe2+. Moreover, Linear Combination Fitting (LCF) used to determine the ratio composition FeO/Fe2O3 in experimental samples. The ratio composition indicated Fe atom is multivalent, when the percentage of silicon-doped increases, the ratio of Fe3+ increased.It has been found that the presence of silicon atoms in the LiFePO4 structure has an effect in electronic structure

Analisis Pergerakan Partikel terhadap Rekaman Mikrotremor di Permukaan Sungai Bawah Tanah Bribin, Kawasan Karst Gunung Sewu

Microtremor has been widely used to determine soil characteristics and dynamics. In this research, particle motion analysis was conducted on 15 microtremor data recordings around the surface of the Bribin Underground River in the Gunungsewu Karst Area. Spectrum analysis was conducted as a basis for determining the frequency range for the particle motion analysis process. Particle motion analysis was only carried out on the horizontal component of the microtremor signal which is expected to provide a representation of the river flow path. The results of particle motion analysis of microtremor recordings in the surface area of the Bribin Underground River show that there are only two points that have a motion-resultant oriented to certain direction, which is perpendicular to the river channel.The points are A4 and B4 which are located in the eastern part of the river flow path