The quake, the second off Sumatra in 12 hours, struck at 1:06 am (1806 GMT) at a depth of 35 kilometres (22 miles), 164 kilometres southwest of Sumatra's Padang, the survey said.

The Hawaii-based Pacific Tsunami Warning Center issued the tsunami alert 11 minutes after the quake.

Indonesia's geophysics and meteorology office (BMG) put the quake at 6.3 and put it at a depth of 25 kilometres. They did not issue any local tsunami warning.

"Most probably it's an aftershock following the quake today (Monday)," BMG official based in Jakarta, Benny, told AFP.

On Monday afternoon 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.

There were no initial reports of damage or injuries from the latest quake.

A policeman in Padang who gave his name as Kalinggin told AFP that the latest quake was felt quite strongly and residents rushed outside to ensure their safety, but there was no panic "as people have got used to quakes."

"There were no immediate reports of damage," he added.

Last Wednesday, a strong 7.5-magnitude quake also 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.

Related Links
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest

Memory Foam Mattress Review

SPACE MEDIA NETWORK PROMOTIONS Solar Energy Solutions Tempur-Pedic Mattress Comparison ... Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News