Pemodelan 2D Data Magnetotelurik (MT) Berdasarkan Analisis Koherensi di Zona Prospek Geotermal Bonjol, Kabupaten Pasaman, Sumatra Barat

Putra, Rheza Marchellino (2023) Pemodelan 2D Data Magnetotelurik (MT) Berdasarkan Analisis Koherensi di Zona Prospek Geotermal Bonjol, Kabupaten Pasaman, Sumatra Barat. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Metode Magnetotelurik (MT) atau dikenal dengan MT merupakan metode geofisika pasif yang mengukur variasi medan elektromagnetik alami bumi untuk menyelediki struktur bawah permukaan bumi dengan penetrasi yang cukup tinggi berdasarkan sifat resistivitas bawah permukaan. Kualitas data merupakan suatu kunci untuk mendapatkan hasil interpretasi yang baik. Permasalahan utama dari data magnetotelurik adalah pengaruh noise reguler yang dapat mempengaruhi signal to noise ratio. Pada pengolahan data MT, untuk mendapatkan kualitas data yang baik maka dapat dilihat dari salah satu parameternya, yakni nilai koherensi. Sinyal koherensi MT merupakan medan listrik dan medan magnetik dari hasil pengukuran dimana asumsi kedua medan memiliki nilai yang sama pada tiap komponen data (Ex, Ey, Hx, Hy dan Hz). Kualitas data MT dapat dioptimalkan dengan pemrosesan robust menggunakan variasi pembobotan rho variance dan ordinary coherency. Nilai koherensi rata-rata raw data (robust processing variasi No Weight yang awalnya 0.85362) meningkat setelah dilakukan robust processing variasi Ordinary Coherency menjadi 0.86691 dan setelah dilakukan robust processing variasi Rho Variance menjadi 0.86269, sedangkan nilai koherensi rata-rata setelah seleksi crosspower meingkat sebesar 0.0134 untuk No Weight, 0.01013 untuk Ordinary Coherency dan 0.00865 untuk Rho Variance. Penampang hasil inversi robust processing variasi No Weight memiliki nilai koherensi paling rendah serta tidak mencerminkan penampang yang mendekati dengan keadaan geologi sebenarnya, variasi Rho Variance memiliki nilai koherensi yang lebih rendah dari Ordinary Coherency serta tidak mencerminkan penampang yang mendekati dengan keadaan geologi sebenarnya, variasi Ordinary Coherency memiliki nilai koherensi yang paling tinggi dan merupakan hasil inversi terbaik yang paling mendekati dengan kondisi geologi sebenarnya.
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The Magnetotelluric (MT) method, also known as MT, is a passive geophysical method that measures variations in the earth's natural electromagnetic field to investigate subsurface structures with high penetration based on the resistivity properties of the subsurface. Data quality is a key to get good interpretation results. The main problem with the magnetotelluric data is the influence of regular noise which can affect the signal to noise ratio. In MT data processing, to get good data quality, it can be seen from one of the parameters, namely the coherence value. The MT coherence signal is the electric field and magnetic field from the measurement results where it is assumed that the two fields have the same value in each data component (Ex, Ey, Hx, Hy and Hz). MT data quality can be optimized by robust processing using weighted variations of rho variance and ordinary coherency. The average coherence value of raw data (robust processing of No Weight variation which was originally 0.85362) increased after robust processing of Ordinary Coherency variation to 0.86691 and after robust processing of Rho Variance variation to 0.86269, while the average coherence value after crosspower selection increased by 0.0134 for No Weight, 0.01013 for Ordinary Coherency and 0.00865 for Rho Variance. The cross-section of the results of the inversion of robust processing of No Weight variations has the lowest coherence value and does not reflect a cross-section that is close to the actual geological conditions, the Rho Variance variation has a lower coherence value than Ordinary Coherency and does not reflect a cross-section that is close to the actual geological conditions, the Ordinary Coherency variation has the highest coherence value and is the best inversion result that is closest to the conditions actual geology.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Koherensi, MT, Noise, Pemrosesan Robust, Time Series, Coherence, MT, Noise, Robust Processing, Time Series
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK1318 Geothermal Power Plants
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Rheza Marchellino Putra
Date Deposited:	08 Aug 2023 14:03
Last Modified:	08 Aug 2023 14:03
URI:	http://repository.its.ac.id/id/eprint/103273

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