Electronic Theses and Dissertation

ABSTRAK


Survei metode gravitasi telah dilakukan pada kawasan panas bumi Seulawah Agam untuk memprediksi struktur bawah permukaan gunungapi Seulawah Agam, Aceh Besar, Provinsi Aceh. Data percepatan gravitasi diukur menggunakan alat gravitimeter CG-5 AutoGrav Scientrex. Pengukuran data dilakukan pada 2 lintasan dengan lintasan 1 dari Selatan ke Utara panjang lintasan 12 km dan lintasan 2 dari Utara ke Baratlaut dengan panjang 6 km. Untuk mendapatkan anomali, data gravitasi telah dilakukan koreksi lintang, koreksi udara bebas, koreksi Bouguer, dan koreksi terrain, sedangkan koreksi pasang surut dan koreksi kelelahan alat sudah dilakukan secara otomatis pada alat gravitimeter CG-5 AutoGrav Scientrex. Data hasil koreksi atau anomali Bouguer lengkap digunakan untuk pemodelan 2D dengan menggunakan software Grav2DC. Hasil pemodelan didapatkan struktur bawah permukaan dari kawasan panas bumi berdasarkan variasi densitasnya dengan 4 lapisan yaitu, ?=1,76 gr/cm3 sebagai tufa pasiran, ?=2,4 gr/cm3diduga batuan lempung pasiran, ?=2,72 gr/cm3 sebagai batuan breksi tufa terlempungkan diduga sebagai lapisan penutup, dan ?=2,99 gr/cm3 sebagai batuan breksi vulkanik diduga lapisan reservoir.

Kata Kunci : Metode Gravity, Densitas Batuan, Panas Bumi, Pemodelan 2D, Gunungapi Seulawah Agam.


ABSTRACT

Survey of Gravity Method has been done at Seulawah Agam volcano. The study is aimed to predict the subsurface structure of geothermal field in the area. Data of gravitational acceleration were measured using Scientrex CG-5 AutoGrav gravimeter. The measurements were done on two profiles. Profile 1 was measured from South to North direction and 12 kilometers long while profile 2 was from North to Northwest direction and 6 kilometers long. The tide and drift corrections were done automatically by the equipment. A series of corrections such as latitude, free air, Bouguer, and terrain corrections have been conducted in order to draw a clear anomalies from the data. The complete Bouguer anomalies data were used for 2D forward modeling using Grav2DC software. The results show that the studied area is consist of 4 layers of subsurface structures based on its densities. The first layer is predicted as sandyceous tuffastones (? = 1,76 gr/cm3), the second layer is predicted as sandyceous argillastones (? = 2,4 gr/cm3), the third layer is the cap rocks consist of argillaceous tuffastones (? = 2,7 gr/cm3), and the fourth layer is the reservoir consist of vulvanic breccias (? = 2,99 gr/cm3).

Keywords : Method of Gravity, Density, Geothermal, 2D Model, Seulawah
Agam vulcano.

Tidak Tersedia Deskripsi