A 7.9 magnitude earthquake has struck off the coast of western Indonesia, the US Geological Survey (USGS) reports.
There have been no immediate reports of damage.
The USGS said the earthquake struck at 19:49 local time (12:49 GMT). It said the epicentre was 808km (502 miles) southwest of the city of Padang, and 10km deep.
Indonesian officials issused a tsunami warning for the regions of West Sumatra, North Sumatra and Aceh.
Australia also issued a tsunami warning for Cocos Island and Christmas Island, in the Pacific.
In 2004 an 8.9 magnitude earthquake triggered the world's deadliest ever tsunami, killing more than 200,000 people.
After that disaster, a more effective tsunami monitoring system was put in place. Warnings are now issued more frequently after earthquakes in the area.(BBC)