Pemodelan 2D Data Magnetotelurik (MT) Berdasarkan Analisis Koherensi Di Zona Prospek Geotermal Cisolok, Kabupaten Sukabumi, Jawa Barat

Yulianita, Dina (2021) Pemodelan 2D Data Magnetotelurik (MT) Berdasarkan Analisis Koherensi Di Zona Prospek Geotermal Cisolok, Kabupaten Sukabumi, Jawa Barat. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Metode Magnetotelurik (MT) merupakan metode elektromagnetik pasif yang pada proses perekaman datanya dapat menghasilkan noise. Solusi untuk mereduksi noise tersebut dapat dilakukan saat pengolahan data magnetotelurik, yakni menggunakan metode pembobotan robust processing serta seleksi cross power. Parameter indikator untuk meninjau kualitas data magnetotelurik adalah koherensi. Parameter ini mengukur korelasi antara medan listrik dan medan magnet yang dihasilkan pada data magnetotelurik. Dilakukannya pembobotan robust processing (ordinary coherency dan rho variance) serta seleksi cross power pada penelitian ini menghasilkan peningkatan pada nilai koherensi. Nilai koherensi rata-rata no weight (raw data) sebesar 0,73; nilai koherensi rata-rata ordinary coherency sebesar 0,84 dan nilai koherensi rata-rata rho variance sebesar 0,81. Pemodelan inversi 2D yang sebelumnya dilakukan robust processing variasi pembobotan ordinary coherency memiliki nilai koherensi relatif lebih tinggi menghasilkan penampang resistivitas yang paling representatif terhadap kondisi geologi. Nilai koherensi variasi pembobotan ordinary coherency lebih tinggi dibandingkan dengan rho variance karena pada proses pembobotan data korelasi medan listrik dan medan magnet, data yang tidak memenuhi minimum (dianggap noise) akan direduksi sehingga meningkatkan rasio signal to noise, sedangkan penurunan bobot data resistivitas semu yang menyimpang (outlier) dapat menghilangkan data resistivitas semu sebenarnya. Sistem geotermal lokasi penelitian terdiri dari batuan penudung (batuan piroklastik) dengan nilai resistivitas 5-29 ohm m, reservoar (batu gamping) dengan nilai resistivitas 29-163 ohm m, sumber panas (intrusi batuan beku) dengan nilai resistivitas 163-1.314 ohm m dan aliran fluida yang dikontrol oleh sesar arah barat daya-timur laut, barat laut-tenggara dan utara-selatan.
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The Magnetotelluric (MT) method is a passive electromagnetic method which in the data recording process can produce noise. The solution to solve this problem is reducing noise in processing magnetotelluric data, robust processing using weighting variations (no weight, rho variance and ordinary coherency) and cross power selection. The parameter for indicating the quality of magnetotelluric data is coherence. This parameter measures the correlation between the electric and magnetic fields generated in the magnetotelluric data. The implementation of robust processing and cross power selection in this study resulted in an increase in the coherence value. The average coherence value of no weight is 0.73; the average coherency value of ordinary coherency is 0.84 and the average coherence value of rho variance is 0.81. The 2D inversion modeling previously carried out with robust processing of ordinary coherency weighting variations has a higher coherence value resulting the most representative of geological conditions. The ordinary coherency weighted variation coherence value is higher than the rho variance because in the process of decreasing the weight of the electric field and magnetic field correlation data, it will increase the signal to ratio, while decreasing the apparent resistivity data weights that deviate (outliers) will eliminate the actual apparent resistivity data. The geothermal system of the research site consists of cap rock (pyroclastic rock) that has a resistivity value 5-29 ohm m, reservoir (limestone) that has a resistivity value 29-163 ohm m, heat source (igneous intrusion) that has a resistivity 163-1,314 ohm m and fluid flow is controlled by faults in the southwest-northeast, northwest-southeast and north-south directions.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	Koherensi, Pemodelan, Robust Processing, 2D Inversion Modelling, Coherence
Subjects:	H Social Sciences > HA Statistics > HA31.7 Estimation Q Science > QE Geology > QE601 Geology, Structural T Technology > TJ Mechanical engineering and machinery > TJ808 Renewable energy sources. Energy harvesting. T Technology > TN Mining engineering. Metallurgy > TN269 Prospecting--Geophysical methods
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Dina Yulianita
Date Deposited:	25 Aug 2021 04:40
Last Modified:	25 Aug 2021 04:40
URI:	http://repository.its.ac.id/id/eprint/89456

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