Alarm of the Nature - Earth Sound

　　Sounds may come out from the earth minutes, hours or days before an earthquake. These sounds are often called “earthquake sounds”. 
　
　　According to our investigation, within the area of 100 km from the epicenter of the scale 7.8 earthquake happened in Tangshan（1976）, 95% of the people who did not fall asleep heard the sound of the earthquake. The earliest earth sound before the earthquake occurred at 23 on July 27, but the sound was quite low and deep. Many people in Zunhua county and Lulong county heard the rumbling sounds in the distance； the sound was rather dull and lasted for more than one hour. According to the recalling of the survivors, the sound was like the sound when a train rushed into the station, or like the howling of chained tractors. But it was different from any normal sound. 

　　Earth sound normally happened minutes, hours, days or dozens of days before the earthquake. As a matter of fact, more often than not, the earth sound occurred minutes before the earthquake. Earthquake sound is an accurate signal of an earthquake. Because the highlighting on earthquake sound in many earthquake areas, many people have survived earthquakes.

　　On June 12, 1830, an earthquake of 7.5 magnitudes occurred in Si County, Hebei Province. Before that, the people there heard the earthquake sound like the “rumbling of thunders”. Thus, people went out one by one to spacious places. Immediately after they were settled, the earthquake took place, which collapsed houses and buildings immediately.

　　Based on the characters of the earthquake sound, it is possible for people to judge the magnitude of the shock and the direction of the epicenter. Generally speaking, the louder and deeper the sound is, the more intense the earthquake would be； otherwise, the earthquake will be less strong. Whenever the earth sound is heard, it means the earthquake will come in a short period of time. Thus, the earth sound could be treated as an alarm. People should leave their houses as soon as they hear the earth sound and should take preventive measures to avoid loss of life and property.