Numerous aftershocks were reported off the Andaman Islands, the Nicobar Islands and the region of the original epicentre in the hours and days that followed. The magnitude 8.7 2005 Nias–Simeulue earthquake, which originated off the coast of the Sumatran island of Nias, is not considered an aftershock, despite its proximity to the epicentre, and was most likely triggered by stress changes associated with the 2004 event. The earthquake produced its own aftershocks (some registering a magnitude of as high as 6.1) and presently ranks as the third-largest earthquake ever recorded on the moment magnitude or Richter magnitude scale.