It is located in a chain of islands parallel to the west coast of Sumatra; Simeulue is about 140 km (87 mi) northwest, and the Batu Islands are located about 80 km (50 mi) southeast. This chain, which resurfaces in Nusa Tenggara in the mountainous islands of Sumba and Timor, is the forearc of the South Sumatra Basin along the Sunda Trench subduction zone.
At Nias the oceanic plate is being obliquely subducted under the Asian Plate at the rapid rate of 52 mm (2.0 in) a year (Milsom)
