Identifikasi Struktur Geologi Sesar Menggunakan Metode Magnetotelurik Studi Kasus Lintasan Surabaya – Tulungagung, Jawa Timur

Bounigeta, Dinda Indiana (2019) Identifikasi Struktur Geologi Sesar Menggunakan Metode Magnetotelurik Studi Kasus Lintasan Surabaya – Tulungagung, Jawa Timur. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Letak Jawa Timur yang berada di wilayah tektonik aktif mengakibatkan terbentuknya struktur sesar yang tidak jarang menyebabkan gempa darat yang cukup merusak. Berdasarkan kondisi tersebut, perlu dilakukan penelitian untuk pendugaan keberadaan struktur sesar dan geometrinya di wilayah Jawa Timur bagian utara selatan. Struktur sesar dapat diidentifikasi menggunakan metode magnetotelurik melalui adanya discontinue electricity pada penampang resistivitas 2D MT. Penelitian ini menggunakan data magnetotelurik sebanyak 11 titik yang terbagi dalam 2 lintasan yang memiliki arah relatif baratdaya – timurlaut, yang mana kedua line tersebut melintasi memotong tegak lurus antiklin Guyangan. Identifikasi struktur sesar yang dilakukan selain berdasarkan penampang resistivitas 2D MT juga didukung dengan peta anomali gaya berat residual dan peta geologi wilayah pengukuran. Anomali residual yang digunakan
diperoleh berdasarkan pengolahan data anomali Bouguer dari topex. Berdasarkan hasil pengolahan metode magnetotelurik diperoleh hasil berupa munculnya anomali low resistivity di line 1 dan line 2 dengan nilai resitivitas 22 – 230 Ohm.m di bawah titik MT04, MT1-5, SBY15, SBY12 dan SBY08 yang diduga merupakan zona sesar. Hasil penampang anomali residual juga menunjukkan zona low density di bawah titik MT04, MT1-5, SBY15, SBY12 dan SBY08 dengan pola kontur fluktuasi high anomaly dan low anomaly berarah relatif barat – timur. Hasil overlay penampang metode MT dan penampang metode gaya berat menunjukkan kecocokan letak anomali dengan panjang anomali 10 km dan lebar anomali 4 km yang diduga sebagai struktur Sesar Kendeng dan juga sesar baru di zona Solo pada kedalaman 5 – 10 km di bawah MT04. Hasil yang diperoleh penelitian ini selanjutnya dapat dikaji lebih lanjut terkait slip rate dari struktur sesar yang terekam untuk mengetahui arah kemenerusan sesar dan seberapa aktif sesar tersebut.
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East Java is located in an active tectonic region, resulting in the formation of a fault structure which often causes earthquakes. According to that conditions, it is necessary to search the existance and estimate the geometry of the fault structure in northern – southern region of East Java. The faults can be identified through existence of discontinued resistivity value on 2D MT resistivity profile.
This research used magnetoteluric data in 11 spots, divided into 2 lines which had relatively southwest-northeast. Those two lines crossed vertically the Guyangan anticline. Further, identification of faults structure applied was based on the profile of the 2D MT resistivity and supported with map of residual gravity anomaly and geological map of measuring site. Residual anomaly was gained from processing Bouguer anomaly from topex. According to the result of
magnetotelluric method, it showed that existence of low resistivity anomaly in the Line 1 and Line 2 by resistivity value of 22-230 Ohm.m under the point of MT04, MT1-5, SBY15, SBY12 and SBY08, assumed as faults zone. In addition, the result of residual anomaly depicted that low density zone was under the point of MT04, MT1-5, SBY15, SBY12 and SBY08, where the pattern of fluctuate contour was high and low anomaly, relatively east-west. The result of overlay in
the profile of MT method and profile of gravity demonstrated suitability of anomaly site and anomaly continuity westward-eastward by anomaly’s length of 10 km and width of 4 km. Such anomaly was assumed as Kendeng Faults and new faults in Solo zone, 5 -10 km below MT04. The result of this research can be further investigated regarding the slip rate and dipping of the faults structure.

Item Type:	Thesis (Other)
Additional Information:	RSGf 538.3 Bou i-1 2019
Uncontrolled Keywords:	Jawa Timur, Magnetotelurik, Resistivitas, Sesar
Subjects:	Q Science > QE Geology > QE601 Geology, Structural
Divisions:	Faculty of Civil, Environmental, and Geo Engineering > Geophysics Engineering > 33201-(S1) Undergraduate Theses
Depositing User:	Dinda Indiana Bounigeta
Date Deposited:	25 May 2023 03:34
Last Modified:	25 May 2023 03:36
URI:	http://repository.its.ac.id/id/eprint/64778

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