Analisis Shear Wave Splitting Menggunakan Metode Cross-Correlation Berdasarkan Data Gempa Mikro

Setyawan, Roby Daris (2020) Analisis Shear Wave Splitting Menggunakan Metode Cross-Correlation Berdasarkan Data Gempa Mikro. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Dalam monitoring reservoir panas bumi diperlukan informasi tentang rekahan atau crack dibawah permukaan. Informasi tersebut dapat diperoleh dari data gempa mikro pada lapangan panas bumi. Analisis shear wave splitting bertujuan untuk mengetahui rekahan berdasarkan polarisasi gelombang S saat melewati medium anisotropi yang terekam oleh seismogram. Terdapat dua parameter yang berhubungan dengan shear wave splitting yaitu arah polarisasi dan waktu tunda. Penelitian ini menggunakan metode cross correlation untuk menganalisis parameter shear wave splitting tersebut. Metode cross-correlation mampu menunjukkan kemiripian dari dua gelombang S (fast dan slow) pada komponen horisontal N-S dan E-W berdasarkan nilai koefisien crosscorrelation. Setelah dicari nilai koefisien cross-correlation maksimum, maka diperoleh parameter waktu tunda dan arah polarisasi shear wave splitting. Hasil yang diperoleh adalah nilai waktu tunda shear wave splitting sebesar 0.11 – 0.32 detik. Besar kecilnya waktu tunda shear wave splitting ini bergantung pada panjang material dan intensitas dari rekahan pada medium anisotropi dibawah permukaan. Selanjutnya arah polarisasi yang diperoleh memiliki dua arah dominan yaitu barat laut – tenggara dan timur laut – barat daya. Hal ini diakibatkan oleh keberadaan patahan yang berada disekitar lokasi penelitian ini. ================================================================================================================== In monitoring geothermal reservoirs information is needed about fractures or cracks below the surface. This information can be obtained from microearthquake data on geothermal fields. Shear wave splitting analysis aims to determine the fracture based on the polarization of the S wave as it passes through the anisotropy medium recorded by the seismogram. There are two parameters related to shear wave splitting namely polarization direction and time delay. This study uses a cross-correlation method to analyze the parameters of the shear wave splitting. The cross-correlation method is able to show the similarity of two S waves (fast and slow) on the horizontal components N-S and E-W based on the value of the cross correlation coefficient. After searching for the maximum cross-correlation coefficient, the delay time parameters and the direction of the shear wave splitting polarization are obtained. The results obtained are shear wave splitting delay time values of 0.11 - 0.32 seconds. The size of the delay time shear wave splitting depends on the length of the material and the intensity of the fracture in the anisotropic medium below the surface. Furthermore, the polarization direction obtained has two dominant directions namely northwest - southeast and northeast - southwest. This is caused by the presence of faults that are located around the location of this study.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: Arah Polarisasi, Metode Cross-Correlation, Shear Wave Splitting, Waktu Tunda ========================================================= Cross-Correlation Method, Delay Time, Polarization Direction, Shear Wave Splitting
Subjects: T Technology > TN Mining engineering. Metallurgy > TN269 Prospecting--Geophysical methods
Divisions: Faculty of Civil, Environmental, and Geo Engineering > Geophysics Engineering > 33201-(S1) Undergraduate Theses
Depositing User: SETYAWAN ROBY DARIS
Date Deposited: 23 Aug 2020 05:12
Last Modified: 23 Aug 2020 05:12
URI: http://repository.its.ac.id/id/eprint/79930

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