An Earthquake of 6.4 magnitude has struck off the coast of Indonesia's Sumatra island, with no reports of damage and there was no warning alert.
"The epicentre is in the sea and there is no tsunami warning because at less than 7.0 magnitude it is still considered moderate,'' said Arif Nurahim, an official at Indonesia's Meteorology and Geophysics Agency.
The quake on Sunday hit 640 kilometres southwest of Aceh province, which was shook on Wednesday by two massive earthquakes that triggered a tsunami alert.
At a magnitude of 8.6, the first of the two quakes was the strongest to hit since the 2004 Indian Ocean tsunami that killed 170,000 in Aceh. No major damage was reported.
The Sunday's aftershock was not felt in Aceh, unlike the quakes last week which sent panicky residents who flees their homes for a safety.