Early warning system alerts people before quake in N China

At 1:21 a.m. on March 26, a magnitude-4.2 earthquake struck Yongqing County in Langfang City, north China's Hebei Province, at a depth of 20 kilometers. Many residents in the Beijing-Tianjin-Hebei region reported feeling the tremor.

Following the earthquake, a level-III emergency response was launched. Working teams have been dispatched to the affected areas to support local governments in emergency response efforts.

The China Earthquake Networks Center (CENC) and local seismic agencies closely monitored the situation. No casualties were reported so far, but the tremor raised public awareness of earthquake early warning (EEW) systems, and their integration with smartphones and other electronic devices.

China's EEW system provides real-time alerts through various digital platforms. During the Langfang earthquake, nearly 300,000 people received advance warnings on their smartphones and other connected devices.

Users can enable earthquake alerts by following CENC's official Weixin account. Huawei smartphones offer built-in EEW functionality in "settings – security – emergency warnings," while Apple users can also receive alerts through China's emergency notification system if enabled in settings.

Warnings were also sent via television, emergency radio and network push notifications. These alerts help residents take immediate protective actions.

Zou Wenwei, director of the Science Popularization Committee of the China Society for Disaster Prevention, notes that the EEW system allows critical infrastructure, such as high-speed railways and nuclear power plants, to take preventive measures and gives the public time to react.

However, he states that EEW is most effective within 50 to 200 kilometers of the epicenter. Closer than 50 km, warnings may come too late; beyond 200 km, seismic waves are weakened. Despite its limitations, EEW remains a vital tool for disaster mitigation.

By 2021, the Beijing-Tianjin-Hebei region had made significant strides in developing its earthquake early warning system, deploying 1,653 monitoring stations spaced an average of 11 km apart, with denser coverage in key urban areas.

Three regional EEW centers in Beijing, Tianjin and Hebei can issue alerts within seconds of detection, strengthening the region's earthquake preparedness.

(With input from Xinhua)

(Cover via VCG)