The eastern flank of the Merapi volcano (Central Java, Indonesia): Architecture and implications of volcaniclastic deposits

In this study, we describe the specific deposits and subsequent alteration and removal processes. The stratigraphic analysis was performed with respect to the distinct phases of construction due to eruptions and dismantling of the volcano by erosion, gravitational collapse and the associated local to distal re-sedimentation. Based on GIS analysis and field surveys, a drainage network anomaly was detected in two main rivers, the Soka and the Brambang Rivers. We infer that an apex fan of volcaniclastic material was deposited into a central paleo-Pusur river and explains the abnormal divergence of the rivers. A new lithological 3D conceptual model is proposed based on the characterization of the lithological facies and their temporal and spatial evolution along the eastern flank of Merapi volcano.