China's national earthquake early warning project, the largest in the world, has officially entered full operation after five years of construction, making people in populous and quake-prone areas able to receive warnings in an average of just seven seconds after an earthquake occurs, officials said on Friday.

The system, fully known as the National Earthquake Intensity Rapid Reporting and Early Warning Project, allows people to receive alerts within a critical window of seconds to tens of seconds before destructive seismic waves arrive, Li Yonglin, director of the China Earthquake Networks Center, said at a news conference in Beijing.

The project was initiated in 2018, with pilot areas in the provinces of Yunnan, Sichuan and Fujian, as well as the Beijing-Tianjin-Hebei region, and began offering trial services to the public in 2021. It passed its final acceptance of construction on Thursday.

The warning network now covers the entire country, ensuring that the average time for people in key alert areas to receive their first warning is just 7 seconds after an earthquake occurs, while in general alert areas, this time ranges from 10 to 30 seconds, he said.

"Upon detecting an earthquake, the early warning system uses the information from the initial, less destructive primary waves to quickly estimate the earthquake's basic parameters and predict its impact on surrounding areas," Li said. "This information is then sent to potentially affected regions before the more destructive secondary waves arrive."

Key alert areas include 19 provincial or local areas in North China, the Southeast coastal regions, the country's north-south seismic zone, and the Xinjiang Uygur and Xizang autonomous regions.

Prior to this network, the public mostly relied on the China Earthquake Networks Center's rapid earthquake reports, which usually take two to three minutes to be released after an earthquake occurs, said Ma Qiang, the project's chief engineer.

These improvements in early warning capabilities are supported by a network of 15,899 monitoring stations across the country, according to the China Earthquake Administration.

Ma said that on a global scale, China is now among the few countries capable of large-scale earthquake early warnings.

"Our early warning network covers a larger area, offers more timely warnings, has greater stability, and serves a larger population compared to those in countries like Japan, Mexico and the United States," he said. "Overall, its functionality and performance have reached world-class levels."

Furthermore, the project has significantly enhanced the speed and accuracy of reporting on earthquake intensity, which is fundamental data for assessing the impact area after a quake, Li said.

"Before the completion of this project, the assessment of earthquake intensity largely relied on postquake field surveys by on-site personnel," he said.

"However, this project can produce intensity distribution maps within five to 10 minutes after an earthquake."

This capability provides the government with scientific data for deploying rescue efforts, assessing disaster losses and more, Li said.

After earthquakes like the 6.8-magnitude quake in Luding, Sichuan in 2022 and the 6.2-magnitude quake in Jishishan, Gansu in 2023, early warning information was transmitted to millions of users in affected areas within seconds, and rapid, accurate intensity reports were generated, providing technical support for emergency responses by the government, the public and various industries, said China Earthquake Administration deputy director Yin Chaomin.

jiangchenglong@chinadaily.com.cn