The island of Sumatra in Indonesia is located on the Sunda shelf, which is part of the Eurasian plate. The Sunda shelf is bordered by two major tectonic plates: the Eurasian plate to the north and the Indo-Australian plate to the south. The Indo-Australian plate is in turn subdivided into the Indian and Australian plates. The Indian plate is pushing northward into the Eurasian plate, and this collision is the reason for the active volcanism and seismic activity in Sumatra.…