The tsunami Indonesian officials feared would follow Wednesday's two massive earthquakes never materialized.
The 8.6 magnitude quake, which was soon followed by a 8.2 aftershock, was centered a little more than 300 miles from Banda Aceh.
The larger temblor sent people racing from their homes. Many screamed as they jumped into cars and motorcycles, headed to higher ground.
"I was in the shower on the fifth floor of my hotel," Timbang Pangaribuan told El Shinta radio from the city of Medan. "We all ran out. ... We're all standing outside now."
The quake was felt in Singapore, Thailand, Bangladesh, Malaysia, and India.
A tsunami watch was issued for Indonesia, India, Sri Lanka, and Australia.
"Our warning system is working well, and I have ordered the national relief team to fly immediately to Aceh to ensure the situation is under control and to take any necessary action," President Susilo Bambang Yudhoyono told reporters Wednesday.