一、地声现象所谓地声,就是地面振动耦合(或透射)到空气中的一种可听声。地声有三种:震前声、震时声和震后声。所谓震时声,就是从震源方向传来的一种低频闷雷声,几秒钟以后,大地开始振动。由于时间短促这种地声没有任何预报价值。但是,如果应用得当,也可免遭于难。例如,1830年河北磁县7.5级大震前,人们听到震源方向传来如“雷吼”、如“千军涌溃,万马奔腾”的地声,于是“争先恐后,扶老携幼,走避空旷之处”,紧接着“屋宇倾 First, the phenomenon of ground sound The so-called ground sound, is the ground vibration coupled (or transmitted) into the air of an audible sound. There are three kinds of earth tones: pre-earthquake sound, earthquake noise and post-earthquake sound. The so-called earthquake-time sound, which is from the source direction came a low-frequency bored thunder, a few seconds later, the earth began to vibrate. Due to a short period of time this kind of voice has no predictive value. However, if applied properly, it can be avoided. For example, before the great earthquake of magnitude 7.5 in Cixian County in Hebei Province in 1830, people heard the sound of thunderstorms such as Thunderclap, Walk away from open space “, followed by” house dumping