Rapid urbanization forces observatory relocation

Updated: 2011-12-07 07:49

By Wang Qian (China Daily)

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TIANSHUI, Gansu - The little white building looks somewhat out of place, with a line-up of cranes in front, a logistic hub on its right and a school on its left.

It is the geomagnetic principal station under the Tianshui central seismological observatory. Set up in 1970, it was moved about 170 meters south to the current location, to keep pace with fast urbanization.

"After a negotiation, we moved the station and shifted the measuring tools underground," Wu Ying, director of the observatory, told China Daily.

This way the monitored data won't be easily influenced by constructions happening overhead.

Seismic stations should ideally be built in remote places, having certain geological features, so that data related to earthquake waves, resistance and radioelement could be recorded accurately without being disturbed by human activities.

The data on Earth waves collected by a seismic station could get distorted even by the impact of a truck running tens of miles away from the station.

But the use of underground monitoring technologies lessens the conflicts between fast urbanization and earthquake monitoring.

He Songyi, a 59-year-old worker in the observatory, said the new technology has largely reduced his work. Earlier, he had to climb telegraph poles to check information.

"The change of location and monitoring technologies have had a slight impact on the data collected, but with scientific calculation it is possible to connect the current figures with previous ones," Wu said.

The technological upgrade has reduced the number of staff from 18 to three.

Many similar seismic observatories in Gansu are also planning to monitor geological data through digging wells for underground information, to avoid disturbances from increasing human activities.

It's a typical case, as some of China's roughly 1,000 seismic stations, built in the 1960s and 1970s, faced growing difficulties caused by increased human activities, experts said.

Most of these were built 40 or 50 years ago, some in remote areas that were no longer remote and hence unsuitable for seismic monitoring.

But not all observatories could be shifted to a more suitable location like the one in Tianshui.

The search for a suitable location for the 37-year-old Hanwang seismic station in Longnan, Gansu province, is on for at least two years.

Some of China's first seismic stations were built in Longnan, which has seven of these.

"Fast urbanization, coupled with a boom in infrastructure construction, has disturbed data collected by about 80 percent of seismic stations in Longnan," Su Yonggang, director of the Longnan Seismological Station, told China Daily.

"Most seismic stations across the province are facing similar difficulties," said Yang Liming, vice-director of the Lanzhou institute of seismology. "But with new laws coming into effect and a close communication between earthquake administrations and local bureaus, things are looking up."

The Law on Earthquake Prevention and Disaster Reduction, implemented in May 2009, stipulated that major infrastructure projects should avoid disturbing seismic stations and that local authorities should ask for local earthquake bureaus' opinions in planning.

China has been hit by several massive earthquakes in recent years, including the 8.0-magnitude Wenchuan quake in 2008 and the 7.1-magnitude Yushu quake last year.

On average, four earthquakes with a magnitude of above 6.0 hit China every year, Xinhua News Agency quoted Zhao Xiaodong, vice-director of the China Earthquake Networks Center, as saying.