Pemetaan Aliran Sungai Bawah Permukaan Menggunakan Metode Mikrotremor Studi Kasus Luweng Dawung Luweng Musuk Pacitan

Setiawan, Diki (2020) Pemetaan Aliran Sungai Bawah Permukaan Menggunakan Metode Mikrotremor Studi Kasus Luweng Dawung Luweng Musuk Pacitan. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kawasan karst Donorojo, Pacitan merupakan daerah dengan bentang alam yang khas. Hal ini dibuktikan dengan adanya gua atau luweng di sekitar kecamatan Donorojo. Keberadaan luweng-luweng ini dapat diindikasikan adanya goa yang saling terhubung sehingga membentuk satu sistem sungai bawah permukaan. Penelitian ini bertujuan untuk mengidentifikasi sistem aliran sungai bawah permukaan yang bermanfaat untuk memetakan potensi sumber air di daerah Pacitan. Salah satu metode geofisika yang dapat digunakan untuk penelitian sungai bawah permukaan adalah metode mikrotremor. Data mikrotremor tersebut diolah menggunakan tiga metode yaitu Horizintal to Vertical Spectral Ratio (HVSR) , Particle Motion, dan Time Frequency Analysis. Berdasarkan interpretasi data tersebut, dapat digunakan untuk mengidentifikasi sungai bawah permukaan. Berdasarkan analisis nilai frekuensi dominan (f0), terdapat dua zona karakter yaitu zona f0 yang bernilai rendah dengan rentang f0 < 10 dan dan zona f0 yang bernilai tinggi dengan rentang f0 > 10Hz, berdasarkan analisa particle motion pada lokasi penelitian menunjukkan karakter pola aliran sungai yang memiliki orientasi arah Timur Laut-Barat Daya (NE-SW), dan berdasarkan analisis Time Frequency Analysis (TFA) terdapat kontinuitas amplitudo di daerah yang dialiri sungai dengan nilai amplitudo 2.000 -20.000 dB dengan rentang frekuensi 4-5 Hz pada komponen Z (Vertikal). Hasil analisa dan menunjukkan bahwa arah aliran sungai bawah permukaan pada lokasi penelitian dikontrol oleh Sesar Grindulu yang berada dekat dengan daerah penelitian.
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The karst area of Donorojo, Pacitan is an area with a unique landscape. This can be proven by the existence of caves or luweng around the Donorojo sub-district. The existence of these luweng can be indicated by the existence of interconnected caves that form a subsurface river system. This study aims to identify an underground river flow system that is useful for mapping potential water sources in the Pacitan area. One of the geophysical method that can be used for subsurface river research is the microtremor method. The microtremor data is processed using three methods namely Horizontal to Vertical Spectral Ratio (HVSR), Particle Motion, and Time Frequency Analysis. Based on the interpretation of the data, it can be used to identify subsurface streams. Based on the analysis of the dominant frequency value (f0), there are two character zones, namely the low value f0 zone with a range of f0 <10 and the high value f0 zone with a range of f0 > 10Hz, based on particle motion analysis at the research location showing the character of river flow patterns that have orientation of the Northeast-Southwest direction (NE-SW), and based on the analysis of Time Frequency Analysis (TFA) there is continuity of amplitude in the area flowed by the river with an amplitude value of 2,000 -20,000 dB with a frequency range of 4-5 Hz in the Z component (Vertical) . The results of the analysis and reference of the study showed that the direction of the subsurface river at the study site was controlled by the Grindulu Fault which was close to the study area.

Item Type: Thesis (Undergraduate)
Additional Information: RSGf 551.49 Set p-1 • Setiawan, Diki
Uncontrolled Keywords: karst, HVSR, Particle Motion, Time Frequency Analysis, Karst, HVSR, Particle Motion, Time Frequency Analysis
Subjects: Q Science > QE Geology > QE538.8 Earthquakes. Seismology
Divisions: Faculty of Civil Engineering and Planning > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User: Diki Setiawan
Date Deposited: 24 Aug 2020 08:01
Last Modified: 25 Oct 2020 11:54
URI: http://repository.its.ac.id/id/eprint/79811

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