Geological Structure Identification inGeothermal Manifestation of LamonganVolcano Complex: A Magnetic DataAnalysis Approach

Abstract

Tiris area in Lamongan Volcano Complex, Probolinggo, East Java, is estimated to be an area with geothermal potential in Indonesia. There are several hot springs along the Tancak River that form a continuous line with a distance of about 20–50 meters between hot springs. One of the hydrothermal manifestations that can indicate the existence of geothermal potential in this location is the Segaran Hot Springs. The identification of geothermal manifestations in this location is limited, so it still needs to be developed using magnetic methods to identify subsurface geological structures. Some previous research has shown the existence of subsurface geological structures around Segaran hot springs in a northwest-southeast direction. Magnetic data collection was taken by following the contours of the research area, so the interval between data points varied greatly, with a total of 117 data points. First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) analyses were carried out to delineate the boundaries of the magnetic anomaly. To determine the depth of the magnetic anomaly, Euler Deconvolution analysis was performed and overlaid with derivative analysis. The integration of the three analyses on the magnetic data is sufficient to interpret the presence and direction of subsurface structures in the research area. The result shows the presence of lineaments in the Lamongan Volcano Complex through Segaran hot springs with a northwest-southeast orientation. This result corresponds with the dominant orientation from the density lineaments analysis performed based on DEMNAS. The existence of geological structures associated with Segaran hot springs can enhance the indication of geothermal potential in Lamongan Volcano Complex, especially in Tiris area.