Fida, Fachri Almawali Abil (2022) Aplikasi Filter Emd Dan Na-Memd Untuk Pengolahan Data Vlf Di Daerah Karst Pacitan (Studi Kasus Identifikasi Kepenerusan Sungai Bawah Permukaan). Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Kondisi geologi di wilayah penelitian (Pacitan) termasuk dalam morfologi karst. Morfologi karst pada daerah Pacitan memiliki struktur geologi yang kompleks dikarenakan berada pada daerah tropis yang membuat proses karstifikasi semakin cepat sehingga membuat banyak terbentuknya sungai bawah permukaan dan manifestasi seperti goa vertikal, dan doline. Salah satu metode geofisika yang dapat digunakan dalam pemetaan sungai Bawah permukaan adalah Very Low Frequency Method – Electromagnetic (VLF – EM). Daerah karst yang kompleks membuat munculnya ambiguitas yang tinggi. Penggunaan filter dalam pengolahan dapat membantu mengurangi ambiguitas tersebut. Pada penelitian ini digunakan filter Empirical Mode Decomposition (EMD) dan Noise Assisted – Multivariate Empirical Mode Decomposition (NA – MEMD) untuk membantu dalam pengolahan dan interpretasi. Tujuan dari penelitian ini adalah untuk mengetahui karateristik filter EMD dan NA – MEMD dengan menggunakan data tilt dan elips dari metode VLF – EM untuk mengidentifikasi pola aliran sungai bawah permukaan. Akuisisi dilakukan dengan 4 lintasan, dengan lintasan 1 dan 2 berada pada Desa Cemeng. Lintasan 3 dan 4 berada pada Desa Klepu. Pengolahan data dilakukan secara kualitatif dengan menggunakan filter Fraser dan Karous – Hjelt yang menghasilkan grafik tilt dan fraser derivative serta penampang rapat arus ekuivalen. Hasil dari pengolahan tersebut selanjutnya dikorelasikan dengan penampang geolistrik agar interpretasi pola arah aliran sungai bawah permukaan lebih akurat. Didapati penggunaan filter (EMD) dan (NA – MEMD) dapat membantu interpretasi VLF - EMD. Filter EMD dan NAMEMD diketahui memiliki perbedaan. Diperoleh hasil dugaan pola arah aliran sungai Bawah permukaan pada desa Cemeng cenderung menuju kearah Selatan dengan azimuth sekitar N 178o E – N 185o E dari Luweng Cemeng. Pada Desa Klepu diduga pola arah aliran sungai bawah permukaan cenderung menuju kearah Selatan dengan azimuth sekitar N 200o E – 180o E dari Telaga K06.
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The geological conditions in the study area (Pacitan) area are belong to the karst morphology. The karst morphology in the Pacitan area has a complex geological structure because it is located in the tropics which makes the karstification process faster, resulting in the formation of many subsurface rivers and manifestations such as vertical caves and dolines. One of the geophysical methods that can be used in mapping underground rivers is Very Low Frequency Method – Electromagnetic (VLF – EM). Complex karst areas create a high level of ambiguity. The use of filters can help to reduce this ambiguity. In this study, Empirical Mode Decomposition (EMD) and Noise Assisted – Multivariate Empirical Mode Decomposition (NA – MEMD) filters were used to assist in processing and interpretation. The purpose of this study was to determine the characteristics of the EMD and NA – MEMD filters using tilt and ellipse data from the VLF – EM method to identify the underground rivers flow patterns. The acquisition was carried out in 4 lines, with line 1 and line 2 located in Cemeng Village. Line 3 and line 4 are located in Klepu Village. Data processing was carried out qualitatively using the Fraser and Karous – Hjelt filters wich result in tilt and fraser derivative graph and equivalent current density cross section. The data processing result is then correlated with a geoelectrical cross section so that the interpretation of the underground river flow direction pattern become more accurate. It was found that the use of EMD and NA - MEMD filters can assist the interpretation of VLF - EMD. EMD and NA-MEMD filters are known to have differences. It was suspected that the pattern of underground river flow direction in Cemeng village tends to be towards the south with an azimuth of about N 178o E – N 185o E from Luweng Cemeng. In Klepu Village, it is suspected that the subsurface flow direction pattern tends to be towards the south with an azimuth of about N 200o E – N 180o E from Lake K06.
| Item Type: | Thesis (Other) |
|---|---|
| Additional Information: | RSGf 551.49 Fid a-1 2022 |
| Uncontrolled Keywords: | Filter EMD, Filter NA-MEMD, Karst, Sungai Bawah Permukaan, VLF – EM. EMD Filter, Karst, NA-MEMD Filter, Underground River, VLF – EM. |
| Subjects: | G Geography. Anthropology. Recreation > GB Physical geography > GB1003.2 Groundwater. |
| Divisions: | Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis |
| Depositing User: | Mr. Marsudiyana - |
| Date Deposited: | 21 May 2026 07:33 |
| Last Modified: | 21 May 2026 07:33 |
| URI: | http://repository.its.ac.id/id/eprint/133317 |
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