A major earthquake struck western China early Friday, but there were no initial reports of casualties.

The 7.2 magnitude quake hit at 6:33 a.m. (6:33 p.m. EDT Thursday), about 140 miles southeast of the city of Hotan in Xinjiang province, the U.S. Geological Survey reported.

A spokesman for China's Earthquake Administration said it was a 7.3 magnitude quake. There were no immediate reports of injuries, he said, and the area is sparsely populated.

Dale Grant, a USGS geophysicist, described the area as "very seismically active" but said Friday's temblor was the biggest there on record.

Xinjiang is a predominantly Muslim region with a culture that is distinctly different from that of China's ethnic Han majority.