The epicenters were near where a destructive magnitude 9.1 quake generated a towering ocean-wide tsunami that killed 170,000 people in Sumatra alone on Dec. 26, 2004.
While the resulting ground motions on Wednesday caused panic as far away as southern India, there were no reports of significant damage, injuries or widespread changes in sea level.
One wave less than 30 inches in height did roll onto the Sumatran coast shortly after residents had fled to higher ground.
The initial quake registered a magnitude of 8.6 when it hit at 2:38 p.m. local time. Tremors were felt in neighboring Malaysia, where high-rise buildings shook.
Singapore, Thailand, Bangladesh and India also were shaken.
An 8.2 aftershock struck at 5:43 p.m., sparking another tsunami alert.
But seismologists said the latest quakes were characterized by side-to-side movement rather than the upward thrust generated by the massive 2004 seismic event.