Structural Framework of the Nyi Sindurejo Geothermal System Revealed by Gravity Data Analysis, East Java, Indonesia

The “Nyi Sindurejo” geothermal manifestation in Batu City, East Java, is an atypical geothermal feature. It is located in the central part of Batu City, relatively distant from the active volcanic center. Although it is close to the Kasinan and Songgoriti geothermal systems, no previous specific geoscientific study has evaluated its structural framework and geothermal potential. This study aims to analyze the structural controls of Nyi Sindurejo and assess its possible relationship with adjacent geothermal systems. We utilized Digital Elevation Model (DEM) data to extract geomorphological lineaments and GGMplus data to examine anomaly contrasts. Lineaments were identified and mapped based on topographic features. The gravity data were analyzed to delineate subsurface density differences. Geomorphological lineament analysis reveals a dominant N-S trend with a secondary NNW-SSE orientation. No structural trends appear to connect Nyi Sindurejo with the Kasinan-Songgoriti geothermal systems. The residual Bouguer anomaly indicates local variations in subsurface density without significant continuity toward adjacent geothermal areas It represents a local system rather than being connected to the nearby Songgoriti-Kasinan geothermal areas.