Gravity Survey in Pandan Mountain - East Java, Indonesia

Pandan Mountain is volcanic area located near Kendeng Zone in East Java, Indonesia. Pandan Mountain area, that becomes one of geothermal prospect in East Java, was impacted an earthquake event with 4.2 Richter's scale on 25th June 2015 (10:35 AM local time). In this study, we conducted gravity survey in Pandan Mountain area to understand density subsurface. Data acquisition and processing are describe in detail to provide gravity anomaly map in this study area. The gravity anomaly then transformed into frequency domain to provide depth estimation of subsurface sources. We conducted subsurface modeling to find the interface density between hot-volcanic intrusion (modeled with low density) and background rock of pyroclastic layer (modeled with high density). The preliminary results of 2.5-D gravity inverse modeling shows that trend of low density distribution in the subsurface found in the deeper depth for Northern part of study area. Subsurface model of study area provide asimmetric shape of hot magma intrusion. The model solution of interface density suggest the possibility of magma source from from Southern part of study area. (paper)