The tremor was registered at 22:01 GMT on Wednesday, 14 kilometers (8.7 miles) northeast of the city of Harnai. The epicentre was located at a depth of 20.8 kilometres.
According to reports, tremors were felt in Quetta, Sibi, Pishin, Chaman and a number of other cities in Balochistan, a province in western Pakistan.
The authorities are assessing the damage caused by the natural disaster. The provincial administrative buildings were reported to have been destroyed.
Pakistan lies along the border between the Eurasian tectonic plate and the Indian plate. The latter has been moving to the north for some 100 million years, colliding with the Eurasian plate. This colossal geological process, which resulted in the formation of the Himalayas and other nearby mountain ranges, causes powerful earthquakes.