After 5.12 earthquake struck sichuan province since 2008, we, I was so frightened by an earthquake, I felt the earthquake many houses will be apart, can let many people lost their lives, is one of the world's most terrible disaster. Today I saw "China children's encyclopedia, really know anything about earthquake.

　　It turns out that the earthquake happened all of a sudden the vibration phenomenon, like the wind, rain, is a kind of common natural phenomena. Vibrations in the earth, in fact, very frequently, probably every 30 seconds there will be time, but most of them are very ease, people did not feel. We can feel the earthquake is due to the relative movement between earth's tectonic plates, rock is squeezed, produce a huge amount of energy to make rock failure in an instant, or make originally the already existing fracture activity, suddenly release a large amount of energy, and some of the energy to the earth's surface, make the earth trembling violently, causing strong earthquake. Started happening earthquake site is called the source, the source above the ground is called the epicenter, the ground of the devastating earthquake is the most strong place is called the magistoseismic area, while the magistoseismic area often is the place where the epicenter. When the earthquake occurred, the source of shock wave in the earth's crust to all directions called seismic waves. Seismic waves hit the ground, the result will be a disaster.

　　We Chinese people are very smart, as early as the eastern han dynasty, there is a man named zhang heng scientists invented to measure the earthquake Hou Feng seismograph, and our modern scientists are generally measured the spread of seismic wave speed with the help of a seismograph, the place and time of the earthquake.

　　Know the earthquake knowledge, learning even before the earthquake early warning and self protection method, I think, to know that knowledge is very useful for our own.

　　自从2008年我们四川发生5.12大地震之后，我就特别害怕地震，我觉得地震会震垮很多房屋，会让许多人失去生命，是世界上最可怕的灾难。今天我看了《中国少年儿童百科全书》后，才真正知道地震是怎么回事。

　　原来，地震是突然间发生的大地震动现象，就像刮风、下雨一样，是一种很普遍的自然现象。地球上的震动实际上非常频繁，大概每30秒种就会有一次，但大多数都非常缓和，人们都没有感觉。我们能感觉到的地震是由于地球板块之间产生相对运动，岩石层受到严重挤压，产生巨大的能量使岩石在瞬间发生断裂，或者使原来已经存在的断裂突然活动，释放出大量能量，而其中一部分能量传到地球表面，使大地剧烈地颤动，从而引起强烈地震。地震开始发生的地点称为震源，震源上方的地面称为震中，破坏性地震的地面最烈处称为极震区，而极震区往往就是震中所在的地方。地震发生时，震源发出的在地壳中传向四面八方的冲击波称为地震波。地震波冲击到地面，就会引发灾难。

　　我们中国人非常聪明，早在东汉时期，就有一位叫张衡的科学家发明了用来观测地震的侯风地动仪，而我们现代的科学家也一般都借助地震仪来测量地震波的传播速度，判断地震发生的地点和时间。

　　知道了地震知识以后，还要学习地震发生前的提前预警和自我保护方法，我想，了解到这些知识对我们自己是非常有用的。