Gravity Forward and Inversion Modelling in Improving the Geology Model of the Flank Volcanic Structure Agus Laesanpura(1), Benyamin Oozatulo Telaumbanua,(2) Toni Rahadinata(3), Gestin Mey Ekawati(2), Asep Suginato(3)
1) Institut Teknologi Bandung, JL. Ganesha 10 Bandung
2) Institut Teknologi Sumatera, JL. Terusan Ryacudu, Lampung
3) PSDMBP - ESDM, Jl. Soekarno Hatta No. 444
Bandung - 40254
Abstract
Cross-sections of volcanic structures are usually constructing based on existing data on surface rocks. The detailed subsurface structure is inaccessible due to a limitation of general principles- hence, the accuracy is less accurate. The geophysical data obtained through surface gravity measurements will improve this phenomenon based on the response of density changes to the forward or reverse modelling of underground structures. Joint interpretation will improve the subsurface model and apply to the subsurface phenomena in volcano deposits experiencing downdraft fault. Gravity data acquire is 286 points in 16 x 24 square km area. An anomaly study will focus on near surface phenomena, where modelling show needs an improvement for inversion through refining the grid. Furthermore, forward modelling makes the model more realistic. Result show, the fault as volcanic fault, geology throws reach 0.5 km not seen in geology section, and density variation show 0.3 gr/cc from the surrounding. This variation of density is due to the varying of pyroclastic rock. Fumaroles in the surface may interpreting as the pathway of water percolation from the peak through flank structure. Water is flowing inside volcanic deposits and fault line is the end points of meteoric water reaching to surface.
