? On June 17, a magnitude 6 earthquake occurred in Changning County, Yibin City, Sichuan Province. This earthquake, let many people surprised earthquake warning countdown. After the earthquake, many places, including the main city of Chengdu, issued earthquake warnings in advance and reminded the public through television, loudspeakers and other ways to avoid danger in a timely manner, in order to fight for the people to avoid the precious time. Earthquake warning is not the same as earthquake forecasting, "earthquake warning" means "after a major earthquake occurs". When an earthquake is detected in the vicinity of an earthquake, an alert is immediately issued: "I have an earthquake here!" allowing places far from the earthquake to take shelter and escape before the destructive seismic waves arrive. ? When an earthquake occurs, it starts with small-amplitude P-waves that go up and down, followed by large-amplitude S-waves. Transverse waves meet transverse waves to form destructive surface waves, commonly known as seismic waves. Earthquake warning is a race against seismic waves at 300,000 kilometers per second. Typically, the duration of the warning is related to the distance of the warning source. ? Does earthquake warning reduce casualties? The role of earthquake early warning in disaster reduction was theoretically investigated. The results show that a warning time of 3 seconds can reduce the casualty rate by 14%; a warning time of 10 seconds can reduce the casualty rate by 39%; a warning time of 20 seconds can reduce the casualty rate by 63%. Therefore, earthquake early warning can effectively reduce casualties. For the public, according to the warning time, combined with the location, take reasonable risk avoidance measures for effective and rapid evacuation. For this project, emergency response can be carried out according to the warning time. ? Is there a blind spot in the earthquake warning? There is a blind spot in the earthquake warning system. A 21-kilometer radius from the epicenter of the earthquake is a blind spot in the warning system. People in the blind zone will first feel the shaking and then hear the warning sirens. The effective range of earthquake warning is 21 kilometers - 200 kilometers, but beyond 200 kilometers there is almost no tremor.