Identifikasi Kondisi Bawah Permukaan Menggunakan Metode Audio Magnetotelurik Studi Kasus Mata Air Umbulan, Kabupaten Pasuruan

Adausy, Thufeil Amr (2020) Identifikasi Kondisi Bawah Permukaan Menggunakan Metode Audio Magnetotelurik Studi Kasus Mata Air Umbulan, Kabupaten Pasuruan. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kondisi geologi bawah permukaan dari suatu mata air merupakan faktor utama besarnya debit air yang dikeluarkannya. Mata air Umbulan, dengan debit yang mencapai 3500 liter/detik merupakan salah satu mata air terbesar di Indonesia. Penelitian terdahulu di kawasan mata air Umbulan menggunakan metode geolistrik membuahkan kesimpulan bahwa munculnya mata air Umbulan akibat kontak antara akuifer bebas dengan lapisan kedap di bawahnya yang memotong permukaan. Hasil penampang resistivitas dari penelitian yang sama juga mendapati anomali resistivitas tinggi di bawah mata air umbulan. Namun peneliti terdahulu tidak menjelaskan lebih detail pola persebaran anomali resistivitas tinggi tersebut dikarenakan batasan penetrasi kedalaman. Metode audio magnetotelurik menjawab permasalahan tersebut dengan memodelkan resistivitas bawah permukaan yang lebih dalam yang selanjutnya diinterpretasi menjadi model geologi. Hasil pemodelan menunjukkan ditemukannya intrusi yang diindikasikan dengan zona resistivitas lebih dari 200 ohm.m dengan pola yang relatif vertikal memotong perlapisan. Puncak dari intrusi diduga berada 50 meter dari mata air Umbulan ke arah barat laut yang ditemukan pada elevasi -75 meter. Tubuh intrusi memiliki pola persebaran ke arah barat laut dengan lebar hingga lebih dari 200 meter di elevasi -300 meter. =================================================================================================== The subsurface geological condition of a spring is a major factor in the amount of water it releases. Umbulan spring, with a discharge that reaches 3500 liters / second is one largest spring in Indonesia.. Previous research in the Umbulan spring area using geoelectric methods led to the conclusion that the appearance of the Umbulan spring due to contact between the unconfined aquifer and the impermeable layer beneath it cut through the surface. The results of the resistivity cross section from the same study also found high resistivity anomalies under the spring water. However, previous researchers did not explain in more detail the pattern of high resistivity anomaly distribution due to the depth penetration limit. The audio magnetoteluric method solves this problem by modeling deeper subsurface resistivity which is then interpreted as a geological model. Modeling results indicate the discovery of intrusion indicated by a resistivity zone of more than 200 ohms with a relatively vertical pattern of cutting bedding. The peak of intrusion is thought to be 50 meters from the Umbulan spring to the northwest which was found at an elevation of -75 meters. The intrusion body has a northwestward distribution pattern with a width of more than 200 meters at an elevation of -300 meters.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: Audio magnetotelluric, Umbulan spring, resistivity model, Audio magnetotelurik, mata air Umbulan, model resistivitas
Subjects: Q Science > QE Geology > QE601 Geology, Structural
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: Thufeil Amr Adausy
Date Deposited: 28 Aug 2020 06:32
Last Modified: 28 Aug 2020 06:32
URI: https://repository.its.ac.id/id/eprint/77272

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