An earthquake measuring 6.4 on the Richter scale struck remote Qinghai Province in northwest China at 9:52 a.m. Friday, the China Earthquake Administration said, but no casualties have been reported.

A total of 128 aftershocks had been registered by 11 a.m. near the epicenter in the Da Qaidam (also known as Dachaidan) district in the Mongolian-Tibetan Autonomous Prefecture of Haixi, with the strongest measuring 5.3 magnitude that struck at 10:14, according to the Qinghai Provincial Seismological Network.

"Frequent aftershocks can still be felt here, but we have not received any reports of casualties," Li Daqing, deputy director of the Haixi Seismological Bureau, told Xinhua at about 3 p.m. at the Da Qaidam Township where the Da Qaidam District Administrative Committee seats.

"The township is safe and sound, except for cracks in the walls of some old houses," he said.

A deserted coal mine in a mountain near the epicenter and about 30 old houses in its compound collapsed during the quake. A Xinhua reporter saw that landslides triggered by the quake and aftershocks had blocked roads in the mine Friday afternoon.

The epicenter, at 37.6 degrees north and 95.8 east, was about 140 km away from Delingha City, the capital of the Haixi prefecture, and about 160 km away from Golmud, another major city in Haixi, according to the China Earthquake Administration.

The quake was strongly felt in both cities, the administration said.

The local government, the China Earthquake Administration, the National Disaster Reduction Committee and the Ministry of Civil Affairs have all sent staff to the quake-hit region to investigate and direct relief work.

Da Qaidam is a sparsely populated district with an average altitude of 4,000 meters and about 16,000 people, including Mongolians, Tibetans, Muslim Hui and Han. The district covers 34,000 square km and administers three townships. The population of farmers and herdsmen is less than 1,000 and they all live in the three towns.

Da Qaidam, which literally means "a big salt lake" in Mongolian, is rich in mineral resources, with one of the largest lead-zinc mines in western China and several coal mines.

On Nov. 10 last year, a 6.3-magnitude quake struck Da Qaidam, in which three people were injured, more than 11,000 were forced to be evacuated and more than 10,000 houses collapsed or were seriously damaged.

In April 2003, a 6.6-magnitude quake hit the same region but did not cause casualties, either, and only damaged old buildings.

(Xinhua News Agency August 28, 2009)