A strong earthquake shook central Indonesia on Tuesday, causing tall buildings in the capital to sway and briefly prompting a tsunami alert, authorities and witnesses said.

The quake with a preliminary magnitude of 6.6 struck at a depth of roughly 12 miles in the Sunda Strait, around 155 miles northeast of Jakarta, said Fauzi, a government geologist who goes by one name.

The Indonesian Meteorological and Geophysics Agency issued a tsunami alert, but there were no immediate signs of large waves and it was revoked within 30 minutes.

There were no immediate reports of damage or injuries.

The U.S. Geological Survey put the magnitude at a preliminary 5.8 at depth of 27 miles.

Indonesia, a vast island archipelago, straddles continental plates and is prone to seismic and volcanic activity along what is known as the Pacific Ring of Fire.

A giant quake off Aceh spawned the December 2004 Indian Ocean tsunami that killed more than 130,000 people in Indonesia alone.