MOSCOW, October 1 (RIA Novosti) - A second powerful quake, measuring 6.8 on the Richter scale has been registered near the Indonesian island of Sumatra, the U.S. Geological Survey said on its website on Thursday.

The quake was registered at 9:31 local time (1:31 GMT) some 225 km (140 miles) southeast of the Indonesian city of Padang, hit by a powerful quake on September 30.

The death toll from Wednesday's 7.6 magnitude earthquake is likely to rise as thousands of people are believed trapped under rubble in the city, capital of the Indonesian region of West Sumatra. According to recent reports, at least 200 people were killed.

An official with the country's health ministry earlier told Reuters that "thousands" of people could be killed in the quake.

The quake is the latest in a series of natural disasters to rock Indonesia. Part of the Pacific's Ring of Fire, Indonesia is in the world's most seismically active region, registering 6,000-7,000 earthquakes with a magnitude of 4.0 or above annually.

Earlier on Wednesday, an earthquake thousands of kilometers to the west caused several tsunamis, which hit the Pacific island nations of American and Western Samoa, and Tonga killing hundreds of people.