The Interpretation of Subsurface Structure Beneath Banda Api Volcano Inferred from Gravity Data

Indonesia has 127 active volcanoes along subduction zone, one of them is Mount Banda Api. As active volcano which is surrounded by the sea, volcanic eruption may trigger destructive tsunami in the adjacent coastline. Several geological studies had been conducted to understand the history of volcanic eruption based on the surface mapping. However, in order to further interpretation regarding subsurface activity of the volcano geophysical data is needed. Therefore, the purpose of this study was to understand the subsurface structure of Mount Banda Api based on the interpretation of gravity data. The Complete Bouguer anomaly are acquired by PSDMBP in 2016. The complete Bouguer anomaly range is 130-200 mgal with low values located on the Banda Api volcano and high anomalies on Neira Island and Lonthoir Island. Then 2D spectral analysis is conducted to estimate the depth of regional dan residual anomaly and determine the optimal Moving Average (MA) windows to conduct regional-residual separation. Furthermore, the residual anomaly and background density of 2.63 g/cc was used to interpret the subsurface structure beneath the volcano by conducting forward modelling 2,5 D. The resulting model shows that the low anomaly in the study is estimated as a response to the presence of magma at the bottom of Mount Banda Api-Neira.