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Warning system boosts quake defenses

Li Hongyang
Updated: August 9, 2021 09:15    China Daily

A nationwide earthquake early warning network will begin operating by the end of next year.

The network, which has been under development by the China Earthquake Administration since 2018, will alert people more than 20 kilometers from a quake's epicenter a few seconds before the destructive seismic waves arrive, the administration said at a news conference last month.

The administration has built more than 15,000 monitoring stations across the country, and warning signals will cover more than 3,000 schools, dozens of railways and other vital spots.

"Earthquake early warning signals play an important role in disaster reduction. Within a few seconds, residents in places kilometers away from the epicenter can avoid danger and evacuate to safe places," Yin Chaomin, deputy head of the administration, told the conference.

The warning system detects the first waves of an earthquake-which are weak and cause little destruction-and then sends out a warning several seconds before the second waves, which can forcefully shake the ground but arrive later.

"Earthquake warnings and forecasting are different. The forecast is carried out before an earthquake's occurrence and remains a worldwide challenge. However, warning technology is developing rapidly and works effectively in reducing disasters' impact," the administration said.

In response to alerts, authorities will deal with major infrastructure, engineering projects and important facilities.

The responses include emergency braking of high-speed trains and the rapid closure of gas pipelines.

In the past three years, the administration has piloted monitoring stations in Beijing and Tianjin and the provinces of Hebei, Sichuan, Yunnan and Fujian.
The construction of monitoring stations has been completed in all six regions, and they have been put into trial operation.

Residents in those places can receive early warning messages via television and apps on their phones.

Warnings sent out by the system for three quakes in Yunnan this year helped with disaster prevention. They were a 6.4 magnitude earthquake in Yangbi, a 5.1 magnitude one in Shuangbai and a 5.0 magnitude one in Yingjiang.

Wang Bin, head of the Yunnan Provincial Earthquake Bureau, said about 14,000 residences received alerts on television seven seconds after the first tremors in Yangbi on May 21.

"The warning reduced fear among the public and, facilitated by the warning, we were able to instantly launch an earthquake emergency response," he said.

Wang Tun, head of the administration's earthquake early warning technology research center in Chengdu, capital of Sichuan province, said that the warning system needs to act quickly and accurately. Otherwise, it will not aid disaster response.

"After years of efforts, China has managed to lead in the technology worldwide," he said.

Huang Jiantao, head of the Shenzhen Academy of Disaster Prevention and Reduction in Guangdong province, said that in some areas, China has set up monitoring stations at an average of every 12 km, which can warn people 20-plus km from the epicenter within six seconds of an earthquake's first tremors.
"The period of time in which the system can warn in advance is among the best in the worldwide warning system," Huang said.