Subsurface Structure around Mas Crater of Papandayan Volcano based on Magnetotelluric and Geomagnetic Data

Abstract

Papandayan is a hydrothermally active volcano in Indonesia. We revealed the subsurface structure around the Mas Crater area of Papandayan based on the magnetotelluric (MT) and geomagnetic (GM) method. For the MT method, 14 sounding stations were deployed and two of them are located close to the active fumaroles. We estimated the MT response functions using a remote reference and then modeled the data with the aid of a 1-D robust inversion. The resistivity structure can generally be divided into three layers, namely a thin resistive surface layer, a middle conductive layer, and a more resistive basement. We interpreted the middle layer to be the hydrothermal zone or clay mineral. For the GM method, we measured the total intensity at 19 data points. The IGRF and diurnal variation were subtracted from the raw data. We then obtained the 2-D magnetic susceptibility model of magnetic field anomaly using an Occam inversion. The model shows a significantly low susceptibility structure beneath the fumaroles which might correlate with thermally demagnetized rocks.

Analysis of Subsurface Resistivity Distribution of the Kelud Volcano Using Magnetotelluric Method

“…This indicates the presence of a clay layer at the range's boundary. The characteristics of a volcano with clay layers can be attributed to the graph that resembles the letter U [14].…”

“…Furthermore, several studies [9][10][11][12][13][14] use magnetotelluric techniques for fault identification and geothermal discovery. As a result, the magnetotelluric method used in this study is based on the ability to penetrate very deep subsurface layers while maintaining sufficient vertical resolution to describe the distribution of resistivity values beneath the earth's surface.…”

Resistivity Distribution of Lembang Fault Based on Magnetotelluric Data

“…The Lembang fault has been located in numerous researches using various geophysical techniques [10][11][12][13][14][15]. Additionally, several research employs magnetotelluric techniques such as volcanic mapping [16][17][18][19][20][21], fault identifying [22][23][24], and finding geothermal [25,26]. Therefore, the magnetotelluric method was used to identify the Lembang fault for this study.…”

Identification of Geological Structure Based on Gravity Method in Tangkuban Parahu Volcano, Bandung, Indonesia

“…The investigation of the faults and the volcano structure has been done using several methods, i.e., the Magnetotelluric method [6][7][8] [9][10] [11], the geomagnetic method [12], and the self-potential method [13]. The gravity method is a geophysical method often used for initial surveys because it can provide detailed information about geological structures from rock density contrasts.…”