Doug Stanglin

USA TODAY

A massive magnitude-7.8 earthquake struck off the southwest coast of Indonesia on Wednesday, the United States Geological Survey reported.

There were no immediate reports of injuries or damage from the quake, which hit 21 miles south of Gombangan, Indonesia.

An initial tsunami warning for West Sumatra, North Sumatra and Aceh was lifted by the Indonesian Meteorological Agency, according to the Associated Press.

The USGS, which initially reported the quake as a magnitude-7.9, said it occurred in an area southwest of Sumatra that is part of a long tectonic "collision zone" that extends over 4,900 miles from Papua, New Guinea, in the east to the Himalayan front in the west.

It said the quake is a result of a "strike-slip faulting" in an area where the India/Australia tectonic plates move north-northeast relative to the Sunda plate at a speed of about 55 mm per year.