JAKARTA -- A 5.7-magnitude earthquake struck off the west coast of Indonesia's Sumatra island Saturday but there was no threat of a tsunami and no immediate reports of damage, geologists said.

The epicenter of the tremor, which was 10 kilometers (6.2 miles) deep and struck at 10:53 am (0353 GMT), was 53 kilometers southeast of Mukomuko city, according to meteorology and geophysics agency.

The tremor was felt in Padang, about 244 kilometers northwest of the epicenter, the agency's geologist Anas Fauzi told Agence France-Presse.

The US Geological Survey also clocked the quake at 5.7.

Indonesia was the nation worst hit by the quake-triggered Asian tsunami in December 2004, which killed some 168,000 people in the country's Aceh province alone.

The Indonesian archipelago sits on the so-called Pacific Ring of Fire where continental plates meet and cause frequent seismic and volcanic activity.