BEIJING - An earthquake measuring 5.1 on the Richter scale jolted the junction area of Northwest China's Gansu and Qinghai provinces on Friday morning.

No casualties have been reported so far, according to local authorities.

A 5.1-magnitude earthquake hit a region between Sunan county, Gansu province, and Menyuan county, Qinghai province, at 5:37 a.m., the China Earthquake Networks Center said.

The epicenter, with a depth of seven km, was determined to be at 37.7 degrees north latitude and 101.5 degrees east longitude, the center said.

The quake was felt strongly in the county seat of Menyuan, said Feng Xiuying, vice director of publicity department of the Menyuan County.

Initial investigation showed no houses have been toppled in the county seat.

People have rushed to a square to take refuge. As the temperature is low, some people took their cars as temporary shelters to keep warm, Feng said.

The quake was also felt in the city of Xining, capital of Qinghai Province, which is about 150 km away from Menyuan county.

No casualties have been reported in the neighboring Gansu Province, said the emergency office of the province.

The quake lasted for a dozen seconds and was felt slightly in Sunan county when most local residents were asleep.

The county has launched an emergency plan and sent quake-relief teams to the affected areas.

Further verification of the impact of the quake is under way.