Identification of Subsurface Structure Derived from Gravity Data in the Mud Volcano Area of Sangiran, Central Java, Indonesia
Cahyo Aji Hapsoro(a*), Mariyanto(b), Eleonora Agustine(c), Mimin Iryanti(d), Rina Dwi Indriana(e), Mochamad Khoirul Rifai(a)(f), and Alpan Ibrahim(a)

(a) Department of Physics, Faculty of Mathematics and Natural Science, Universitas Negeri Malang, Malang, 65416, Indonesia.
(b) Department of Geophysical Engineering, Faculty of Civil, Planning and Geo Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia.
(c) Department of Geophysics, Faculty of Mathematics and Natural Science, Universitas Padjadjaran, Bandung, 45363, Indonesia.
(d) Department of Physics, Faculty of Education of Mathematics and Natural Science, Universitas Pendidikan Indonesia, Bandung, 40154, Indonesia.
(e) Department of Physics, Faculty of Science and Mathematics, Universitas Diponegoro, Semarang, 50275, Indonesia.
(f) Junior High School of Darul Faqih Indonesia, Malang, 65158, Indonesia.

*Corresponding Author: cahyo.ajihapsoro.fmipa[at]um.ac.id

Abstract

Java Island, Indonesia, contains a variety of mud volcanoes. They are mainly located along the northern line of the island of Java. Each mud volcano has its characteristics and uniqueness. However, research on various mud volcanoes in Java Island still needs to be completed. This study uses gravity data to identify the surface structure of one of the mud volcanoes in the Sangiran area, Central Java. The study area measures 400 x 400 meters. Measurement of gravity method data with 81 points spaces 50 meters to determine the value of rock density and subsurface structure of Sangiran mud volcano area. Based on the data obtained, data processing is carried out to obtain a map of the distribution of regional and residual gravity anomaly values. 3D inversion was used to create a subsurface structural map from the anomaly data. The 3D gravity inversion modeling results indicate that a high-density rock block is interpreted as a basin containing the mud volcanos reservoir. The presence of mud content contributes to the distribution of low density on the surface and around the mudflow of the Sangiran mud volcano. A fault zone could exist in the west-to-east direction from the research region.

Keywords: Sangiran- Mud volcano- Subsurface structure- Inversion- Gravity method

Topic: EARTH, ATMOSPHERIC, AND SPACE SCIENCE