
Officials at Jakarta's Meteorology and Geophysics Agency (BMG) said another 6.7-magnitude aftershock rattled Sumatra shortly before 9 am (0200 GMT), after an earlier 7.8-magnitude quake struck at 6:49 am (2349 GMT Wednesday).
Both aftershocks triggered government authorities to issue tsunami warnings, but they were lifted after no waves materialized, officials said.
The USGS said the first new quake on Thursday was centered about 200 kilometres from Bengkulu, a city on Sumatra. It occurred at a shallow depth of about 10 kilometres.
The Pacific Tsunami Warning Centre in Hawaii warned Thursday's quake had the potential to generate a destructive regional tsunami along coasts within 600 miles of the epicentre. It advised authorities to take immediate action to evacuate coastal areas.
Thursday's quake caused extensive damage in Padang, a local official said.
"Many buildings collapsed after this morning's quake," Fauzi Bahar, the mayor, told El Shinta radio. "We're still trying to find out about victims.
On Wednesday, a powerful 8.2-magnitude earthquake shook South-East Asia, collapsing buildings, killing at least five people and injuring dozens in Indonesia. That tremor triggered a small non-destructive tsunami off the coastal city of Padang on Sumatra, the Indonesian island ravaged by the 2004 tsunami disaster.
A tsunami warning was issued for wide areas of the region and nations as far away as Sri Lanka.
Officials said at least three people were killed in Bengkulu provincial capital from Wednesday's powerful quake, while more than a dozen were injured.
Deutsche Presse-Agentur