It is impossible to predict the specific occurrence time, but it can only be monitored when it occurs, but it is not completely unpredictable. It can be predicted according to some abnormal phenomena before the earthquake, such as abnormal behavior of animals and groundwater level. There was an earthquake in another place, and the Seismological Bureau there monitored the earthquake. Because seismic wave propagation takes a certain time, this time can be used as an early warning time for surrounding areas, but it will not be too long. This is the way to prevent the earthquake along the coast of Mexico City, and the predicted time is about 1 min.