About 2,000 people were safely evacuated from their homes after a 6.8-magnitude earthquake hit southwest China's Tibet Autonomous Region late on Monday.

Authorities on Tuesday were assessing the impact of the quake, which struck at 9:22 p.m. with the epicenter about 10 km underground at 31 degrees north and 83.6 degrees east in Zhongba County, Xigaze Prefecture.

Three townships in the county felt the tremor, but no casualties have been reported.

But cracks appeared in 42 residential buildings, said Tan Yungao, the regional civil affairs department's deputy director. The quake also damaged 54 rooms in primary and middle schools.

The official said the affected area was in urgent need of tents and quilts. Some 400 tents, 3,500 quilts and clothing were being transported to the area.

Gerze and Coqen counties in Ali Prefecture also felt the quake, but the county seats sustained no damage, said the regional earthquake bureau.

A regional flood control and drought relief official said a local hydropower station was slightly damaged. The damage included the flood control levee shifting 5 m from its original location and cracks in workshop walls.

The plant maintained normal power generation.

Zhu Quan, the regional earthquake bureau chief, said the tremor would have no effect on the Qinghai-Tibet railway, which was several hundred kilometers from the quake zone.

Zhongba, in the west of Xigaze with a population of 18,000 and covering 43,594 square kilometers, experiences frequent quakes. It is 4,700 meters above sea level.

A 6.7-magnitude quake occurred in the same area in 2004, followed by a 6.5-magnitude quake on April 8, 2005, but neither caused casualties, according to the regional earthquake bureau.

(Xinhua News Agency August 27, 2008)