The whole of Indonesia except Borneo , Bangka Belitung , Riau Islands and Timor is situated within a zone of high seismic activity known as the Pacific Ring of Fire . Along the Sunda megathrust , the Indo-Australian Plate is being subducted beneath the Eurasian plate . The subduction creates regular earthquakes , many of them of megathrust type . Specifically the Sumatran segment is currently experiencing a period of increased activity that began with the catastrophic 2004 Indian Ocean earthquake . Each earthquake of the sequence adds additional stresses to segments of the plate boundary that have not moved recently
2004 Indian Ocean earthquake
2004 Indian Ocean earthquake and tsunami
2009 Sumatra earthquakes