JAKARTA, Indonesia — A powerful earthquake struck waters off eastern Indonesia early today, briefly generating tsunami warnings for coastlines within 600 miles of the epicenter.

Residents in nearby coastal towns fled their homes in panic, but there were no immediate reports of damage or injuries.

The U.S. Geological Survey put the quake's preliminary magnitude at 7.5 and said it struck 54 miles from Gorantalo, a coastal town on Sulawesi island. It was centered 13 miles beneath the sea.

The temblor was followed by a strong aftershock.

The Pacific Tsunami Warning Center said the quake had the potential to generate a destructive tsunami along coasts within 600 miles of the epicenter.

But Fauzi, an official with Indonesia's geological agency, later said the threat had passed. Like many Indonesians, he goes by only one name.