Urban construction authorities should be on guard against geological disasters in China's urbanization process, a disaster control expert has warned.

Landslides, mud-rock flows, ground subsidence and crevices can all be destructive to small, outlying counties and towns, a large number of which are being transformed into cities these days, said Wang Zhirong, an expert on geological disaster control with the Gansu Provincial Academy of Sciences in northwest China.

"Such disasters might affect every corner of a small town, while in large and medium-sized cities, it's much easier to localize the impact and divert the crowds to safer regions," Wang said in an interview with Xinhua on Monday.

He said some Chinese counties are constantly in danger of geological disasters because they were built in disaster-prone areas without a necessary geological survey in the first place to ensure safety. Improper irrigation, excavation and other human activities have even increased such risks, he said.

In 1998, Wang's academy carried out a survey on the geological disasters of 81 counties and towns in Gansu Province. They found that 48 of them, or 59.3 percent of all that surveyed, suffered mud-rock flows.

Meanwhile, incomplete statistics indicate the northwestern province reported at least 1,515 deaths in 188 landslides and mud- rock flows between 1950 and 1998, with a direct economic loss of 1. 3 billion yuan (US$157 million).

The hillside Lijie township in Zhouqu county, for example, suffers two to three disastrous mud-rock flows each year that destroy its roads and cut off the villagers from the outside world for two to three months.

When the pivotal Liujiaxia Reservoir was built in the 1960s, the northwestern province relocated many peasants to plateau forms on either banks of the Yellow River that are prone to landslides and ground subsidence. The Yanguoxia township of Yongjing County, for example, reports four to five landslides each year and the situation has been worsening since the 1980s.

"Prior to a massive urban construction project, it's crucial to carry out geological surveys and assess the risks for geological disasters, so as to avoid building on disaster-prone regions," said Wang.

(Xinhua News Agency January 11, 2005)