HONG KONG -?A Hong Kong-based earth system science expert on Friday warned against possibility of more earthquakes along a major fault line on China's mainland since the deadly quake in Northwest China had recorded more aftershocks than the Wenchuan earthquake in May 2008.

Zhang Yuanzhi, with the Institute of Space and Earth Information Science under the Chinese University of Hong Kong, said both the Tibetan Autonomous Prefecture of Yushu in Qinghai Province, which was hit by a 7.1-magnitude quake on Wednesday, and Wenchuan lie on the major fault line called Bayan Har.

Historical data indicated Bayan Har massif had been prone to major earthquakes, he said. Five quakes measuring 7.0 or above on the Richter scale were recorded in this massif between 1996 and 2008.

According to Zhang, the 7.1-magnitude quake in Yushu on early Wednesday came right after a moderate earthquake measuring 4.7 on the Richter scale. Following the Yushu quake were several strong aftershocks, which showed even more active earth movement this time than after the 8.0-magnitude quake in Wenchuan in 2008.

Therefore it was necessary to guard against more earthquakes that might be triggered by the Yushu earthquake, he added.

The 7.1-magnitude quake in Yushu has so far left at least 791 people dead, 11,486 others injured, and 294 missing. On May 12, 2008, the 8-magnitude earthquake hit Wenchuan in Southwest China's Sichuan Province, leaving more than 86,600 people dead or missing.