JAKARTA, Indonesia — A powerful earthquake struck off the western coast of Indonesia's Sumatra island today. Agencies briefly issued a tsunami warning, but no large waves were generated, and no injuries were immediately reported.

The quake, which had a preliminary magnitude of 7.2, was centered in the Indian Ocean around 96 miles from the coastal town of Bengkulu, Indonesia's geophysics agency said. It was a very shallow 6 miles below the surface.

The U.S. Geological Survey put the magnitude at 7.3.

Residents in Bengkulu and the nearby town of Mukomuko said they felt the quake strongly, but that it did not appear to have caused major damage in the region, which late Sunday was also hit by a strong tremblor.

The geophysics agency issued a tsunami bulletin, but canceled it after determining no large waves were generated.

Indonesia straddles a series of active fault lines and is prone to seismic and volcanic activity. A giant earthquake along the same coast spawned the tsunami that killed more than 230,000 people in several countries in December 2004.

Indonesia does not have equipment to measure changes in sea level that would indicate an actual tsunami was on its way. Agencies routinely issue warnings when shallow offshore quakes with a magnitude of 6.5 or above strike.