A strong undersea earthquake has struck off eastern Indonesia, but there are no immediate reports of injuries or damage.

The U.S. Geological Survey said the quake with a magnitude of 6.6 struck 136 kilometers (85 miles) northwest of Ternate, the capital of North Maluku province. It had a depth of 41 kilometers (25 miles).

Indonesia is prone to earthquakes due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines in the Pacific Basin.

In December 2004, a massive magnitude-9.1 earthquake off Sumatra triggered a tsunami that killed 230,000 people in a dozen countries.