Jakarta: A strong 6.7-magnitude earthquake struck off Indonesia s Sumatra island today, the US Geological Survey said, sparking a local tsunami alert.

The quake, the second off Sumatra in 12 hours, struck at 1:06 am (2336 IST) at a depth of 35 kilometres, 164 kilometres southwest of Sumatra's Padang, the survey said.

There were no initial reports of damage or injuries.

Earlier in the day, a 7.2-magnitude quake struck off the west coast of Sumatra, briefly triggering a tsunami alert, seismologists said, but there were no reports of damage.

Last Wednesday, a strong 7.5-magnitude quake rocked Indonesia s Aceh province, at the tip of Sumatra, killing three people and seriously injuring 25 others on remote Simeulue island.

The Indonesian archipelago sits on the Pacific Ring of Fire, where continental plates collide and cause frequent seismic and volcanic activity.

Indonesia was the nation worst hit by the earthquake-triggered Indian Ocean tsunami in December 2004, which killed some 168,000 people in Aceh.

Source : PTI