The strongest registered a magnitude of 7.1 before dawn on Thursday, jolting people from their beds and sending them fleeing to higher ground by car and on foot.
Indonesia’s Meteorological and Geophysics Agency briefly issued a tsunami warning for the southwestern coast of Sumatra, but no rise in sea level was detected.
The agency said the quake was a part of a series of aftershocks that have kept the region on edge since an 8.4 magnitude quake killed 23 people and destroyed thousands of buildings on September 12.
A magnitude 9 "megathrust" earthquake off the coast of Sumatra on Dec. 26, 2004, triggered a tsunami that killed more than 230,000 people in a dozen countries, more than two-thirds of them in Indonesia.