Aftershocks as strong as 5 on the Richter scale were felt in the provincial capital of Xining, about 70 miles northeast of Hainan Prefecture, and in Lanzhou, a city 180 miles the east.
An official at the bureau, contacted by telephone, said there was no information about damage or injuries and efforts were being made to contact the seismological bureau in Xining, the Qinghai capital.