URUMQI - A 7.3-magnitude earthquake that struck China's far-western region of Xinjiang on Wednesday afternoon has affected more than 7,800 people, while no casualties have been reported.

The epicenter, in a sparsely populated area with an average altitude of 5,000 meters, is more than 50 km from the nearest settlement, Aqqan Township in Yutian County, Hotan Prefecture.

By 11 a.m. on Thursday, 7,838 residents in six counties of Hotan had been affected by the tremor, with 982 relocated to safety, said a statement from the regional civil affairs department.

The jolt also toppled 157 houses and damaged 3,297 others to varying degrees, inflicting direct economic losses of about 41.65 million yuan ($6.82 million), according to the statement.

As of 1 p.m. on Thursday, a total of 811 aftershocks had been monitored in Yutian, with the biggest measuring 5.7-magnitude at 5:24 pm on Wednesday and 12 measuring between 4 and 4.9-magnitude.

Two local rescue teams have arrived in Pixka and Pulu villages of Aqqan to check on the damage. Rescuers said aftershocks and poor conditions on rugged mountain roads were hindering disaster relief efforts.

Dispatched by the regional health department, 14 medical workers have reached quake-hit areas. The department has ordered its local branches to monitor water quality and prevent diseases.

By 10 am on Thursday, hard-hit villages had set up tents to accommodate the relocated, supplying them with blankets, overcoats and food, said the civil affairs department's statement.

Among the most heavily hit regions, the old town of Yutian's county seat saw 260 houses damaged in the jolt, including 25 that almost collapsed, said Kurbanjan, Party chief of the old town's Ostangbexi Community. He added that 50 tents had been erected to house the evacuated households.

"Yesterday's tremor was strong, but less destructive than we expected. And I'm grateful to see many people outside Xinjiang, not only the government, are concerned about our safety," said an old town resident while breakfasting at an eatery.

Xinjiang started a quake-resistant housing project in 2004.

The vast majority of rural residents in Hotan, including Aqqan, are living in quake-resistant buildings, said Zhang Zhide, director of the prefecture's seismological bureau.

"Mountainous areas located near an active fault zone were given priority in our construction plan years ago," Zhang said.

In Pixka Village, 181 out of 183 households are living in quake-proof buildings, which remained almost completely intact in the jolt.

Experts said the area shares the same tectonic plate with Wenchuan in southwest China's Sichuan Province and Yushu in northwest China's Qinghai Province.

Wenchuan was devastated by an 8.0-magnitude quake in 2008, and Yushu was hit by a 7.1-magnitude quake in 2010.

Sun Shihong, a researcher with the China Earthquake Networks Center, said Wednesday's earthquake signaled the beginning of a seismically active period for the Earth.

Since records began in 1900, areas within 100 km of the epicenter of Wednesday's quake have been hit by 13 earlier earthquakes with a magnitude of five or above, according to monitoring data.

The largest two quakes, both measuring 7.3-magnitude, struck Minfeng county in 1924 and an uninhabited area in Yutian county in 2008.