The 6.8 magnitude quake Thursday hit South Sumatra at 8:52 a.m. local time (9:52 p.m. Wednesday ET), about 89 miles (143 kilometers) from Bengkulu, the Pacific Tsunami Warning Center said. The earlier quake Wednesday was 7.6 magnitude.
At least 529 people were dead and more than 500 were injured, said Tugiyo Bisri, spokesman for the Indonesian Social Affairs Ministry's Crisis Center said Thursday. The worst hit was the West Sumatra capital of Padang, where 376 people perished, he said.
Officials had little information on those who were missing and feared the death toll would climb into the thousands. Rustam Pakaya, the head of the Ministry of Health's crisis center said that thousands of people may be trapped by collapsed buildings and houses.
Officials were expecting casualties to surpass those of the massive Yogyakarta earthquake three years ago, given the intensity and the spread of the damage this week. The second temblor Thursday only magnified the scope of the disaster.
The second quake was on a smaller scale than the first, said meteorology official Fauzi, who uses only one name. There were no damage reports yet.