The USGS said there was little chance of serious economic losses or fatalities.
Indonesia, a vast archipelago of more than 270 million people, is frequently hit by earthquakes and volcanic eruptions because of its location on the “Ring of Fire,” an arc of volcanoes and fault lines in the Pacific Basin.
In October, a magnitude 5.1 earthquake hit Sibolga, a coastal city in North Sumatra province, killing at least one person, injuring 11 and damaging more than a dozen buildings. In February, a magnitude 6.2 earthquake killed at least 25 people and injured more than 460 in West Sumatra province.
A powerful Indian Ocean earthquake and tsunami in 2004 killed nearly 230,000 people in a dozen countries, most of them in Indonesia.