The geography of Sumatra is dominated by a mountain range called Bukit Barisan (lit: "a row of hills"). The mountain range spans nearly from the north to the south of the island, and it was formed by movement of the Australian tectonic plate. The plate moves with a convergence rate of 5.5 cm/year which has created major earthquakes on the western side of Sumatra including the 2004 Sumatra–Andaman earthquake. The tectonic movement has been responsible not only for earthquakes, but also for the formation of magma chambers beneath the island.