Subduction structure and its influence on geological hazards at the Java Plate margin in the eastern Indian Ocean

As an active convergent margin, the Sunda Arc is renowned for its intense seismic activity, tsunamis, and volcanic eruptions, and yet relatively less attention has been paid to its eastern segment. This study describes the along-strike variations of the subducting oceanic crust, trench, and accretionary wedge from eastern Java to Sumbawa Island. It investigates the control of subducting plate topography on the deformation of the overriding plate and reveals the influence of subduction on shallow geological hazards. The results show significant segmentation of the subduction structure in the study area, with the western and eastern parts controlled by the subduction of the Roo Rise and the Argo Abyssal Plain, respectively. The seafloor topography and structures of the subducting plate lead to distinct variations of trench and forearc deformation: the subduction of the Roo Rise results in prominent erosion and the development of a narrow and steeply inclined accretionary wedge, while that of the abyssal plain results in a broad and gently sloping accretionary wedge. Both seamount/rise subduction and normal faulting generated by plate bending may trigger geological hazards. These findings provide a theoretical basis for understanding accretion processes of subduction zones, as well as earthquake and tsunami hazards.