Early warning system succeeds in catching quake

Scientists in Sichuan province successfully managed to send an early earthquake warning in Wenchuan county, site of a disastrous earthquake four years ago.

Though the warning was only for an earthquake of magnitude 1.3 that took place on Monday in Qingchuan, the northernmost county in Sichuan, an announcement reading "A minor quake is taking place in Qingchuan county, and the tremor won't be felt in Wenchuan" appeared on TV nine seconds after the quake.

Had it been more powerful, the shockwaves would have arrived in Wenchuan about 40 seconds after the event.

"It is believed to be the first time that a television station in China has provided an early earthquake warning," said Chen Huizhong, research fellow with the Institute of Geophysics of China Earthquake Administration.

The warning was sent from the Wenchuan county anti-earthquake and disaster reduction bureau and the Institute of Care-Life, an organization that does earthquake studies in Chengdu, Sichuan province.

"A magnitude 1.3 earthquake is minor, and I didn't flee the house. If it had been a major earthquake, the warning would have saved lots of lives," said Yang Chao, a resident in Wenchuan, the epicenter of the magnitute 8 earthquake on May 12, 2008, which killed about 90,000.

The technology for the early earthquake warning system was provided by the Institute of Care-Life.

Its founder Wang Dun, a native of Dazhou in eastern Sichuan, received his doctoral degree in theoretical physics from the University of Connecticut in the United States. Before his return to Sichuan in 2008, he was a post-doctoral fellow of theoretical physics with the Austrian Academy of Sciences.

The real-time earthquake warning system is possible thanks to the difference in speed between seismic and radio waves.

"Radio waves travel 300,000 kilometers per second, while seismic waves travel between 3 and 6 kilometers per second," Chen said.

Wang's institute has monitored more than 200 aftershocks in the Sichuan quake zone and has succeeded in giving early warnings for some 130 aftershocks, he said.

His system now covers more than 20,000 square kilometers of the Sichuan quake zone, including Wenchuan, Maoxian, Lixian and Qingchuan counties, and Shifang city, all of which were hit hard in the Wenchuan earthquake.

China only started stressing early earthquake warnings after the Wenchuan earthquake, while many countries, such as Japan, Mexico and Turkey, started much earlier, Chen said.

Wang's system is deployed in the quake zone, where there are aftershocks.

If it were in an area never hit by an earthquake, the situation would be more difficult, Chen said.

"First, the system has to detect whether it is an earthquake," said Chen, noting that Wang's system mistook the sound of firecrackers for a quake during the Spring Festival this year, a mistake that has since been corrected.

According to the China Earthquake Administration, a national earthquake warning system is under construction, but there is no deadline for completion of the system.

Wang Qian in Beijing contributed to this story.

You can contact the reporter at huangzhiling@chinadaily.com.cn