Abnormity of some chemical substances is related to aftershocks of the earthquake, said sources with the Ministry of Land and Resources on Monday.

According to an official in charge of the Wenchuan Fault Scientific Drilling Program (WFSD), experts found after monitoring more than 3,000 aftershocks that changes of helium, methane and niton were closely related.

This discovery provided a chance for people to understand the relationship between earthquake and abnormity of chemical substances, he said.

WFSD, started on November 6 last year, is China's first drilling research program after an earthquake to study the mechanism of earthquake. It is recognized as world's fastest response to an earthquake.

The program was conducted between the worst-hit Beichuan county and Yingxiu township. The deepest well has reached 741.5 meters by Sunday.

By drilling experts also found more than 20 zones of fracture left by previous earthquakes in history, which could provide evidence for studies in quake cycles.

In Beijing, a 245-page map of earthquake disaster in Wenchuan was published, which is the last one of the five-book series on assessment and analysis of the Wenchuan earthquake that jolted southwest China last May 12.

(Xinhua News Agency May 11, 2009)