The quake was centered about 155 km (95 miles) south of the Sumatran port city of Padang at a depth of about 50 km (30 miles), the USGS said. It had originally been reported with a magnitude of 6.2.
There were no immediate reports of damage or injury.
In December 2004, a massive 9.15 magnitude undersea quake triggered an Indian Ocean tsunami that killed more than 200,000 people in a dozen countries. Most of those killed were in the province of Aceh on Sumatra’s northwest tip.
Indonesia straddles the so-called “Pacific Ring of Fire”, a highly seismically active zone, where different plates on the earth’s crust meet and create a large number of earthquakes and volcanoes. (Courtesy Reuters)