Subsurface Resistivity Modeling of the Lembang Fault Western Segment Using 2D Geoelectrical Method in Parongpong, West Bandung
Indriyati(1*), M Zulfansyah Saepul Mutaqin(1) , Ihyaudin Hasbillah(1), Dini Fitriani(2) , Randi Rusdiana(1)

(1)Earth Physics and Complex Systems Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132, Indonesia
*E-mail: indriyati89[at]gmail.com
(2)Department of Geophysics, Faculty of Mathematics and Natural Sciences, University of Padjadjaran, Bandung 45363, Indonesia

Abstract

The Lembang Fault is an active fault in West Java located 15 km north of Bandung City, generally divided into the East and West segments. This study applies the 2D Geoelectric method to model the subsurface resistivity of the western segment in Parongpong, identified by BMKG as an active zone. Data were acquired along a 675-meter North-South transect using 28 electrodes with 25-meter spacing, employing Schlumberger and Wenner configurations. Inversion results reveal a strong correlation between both configurations, with error rates of 8.9% and 9.5%. Both configurations identify three low resistivity anomalies below 20 ohm m at approximately 180 m, 300 m, and 425 m along the survey line. These anomalies spatially coincide with three mapped fault traces and are interpreted as fault-related deformation zones characterized by fractured volcanic rocks and possible fluid accumulation. Higher resistivity units above 40 ohm m are interpreted as relatively less deformed volcanic deposits, including tuff and sandy tuff that dominate the study area.

Keywords: Lembang Fault, 2D Geoelectrical Method, Subsurface Resistivity, Schlumberger Configuration, Wenner Configuration, Inversion Modeling

Topic: Earth Physics and Space Science