An expert warned that frequent aftershocks will likely occur in earthquake-hit areas following a 6.6-magnitude quake that jolted northwest China's Gansu Province on Monday.

A series of aftershocks are likely to follow in the next week, said Liu Jie, an official with the China Earthquake Networks Center.

There is also a strong possibility of landslides triggered by the quake in mountainous areas, Liu said, adding that serious damage will likely occur, as construction quality in the region is poor.

The quake is located in the same seismic belt as the 8.0-magnitude earthquake that hit Wenchuan County in southwest China's Sichuan Province on May 12, 2008, although the two belong to different fault zones, Liu said.

"The Wenchuan quake unleashed tremendous energy that triggered the movement of fault zones in the same seismic belt," said Liu, adding that fault zones tend to be unstable.

At least 75 people had been killed in the quake as of Monday evening, according to the provincial earthquake emergency response center.

More than 400 aftershocks have been recorded so far, with the strongest showing a magnitude of 5.6, the China Earthquake Administration said.