题目内容：

The Science of Earthquakes

1.

The surface of the earth is divided into different pieces. These are called tectonic plates (构造板块). When two plates suddenly slip past one another, an earthquake happens. This shakes the ground and everything on it.

What cause earthquakes and where do they happen?

2.They are inner core, outer core, mantle (地幔) and the earth’s crust (地壳). The crust and the top of the mantle make up a think skin on the surface of the planet. But this skin is not all in one piece. It is actually made up of many tectonic plate. They are like puzzle pieces. These pieces are always sliding around and bumping into each other. Sometimes their edges get stuck together. When this happens, the rest of the plate keeps moving. Eventually the edges come unstuck. 3..

Why does the earth shake when there is an earthquake?

Earthquakes send out waves in all directions. When they reach the earth’s surface, they shake the ground. 4.The P wave squeezes and stretches the earth. The S wave shake it up and down.

5.

Scientists use special tools to record and measure earthquakes. These tools are called seismographs. Recordings from seismographs tell scientists when and where an earthquake took place. They can also tell scientists the size of an earthquake.

A. How are earthquakes recorded?

B. That is when an earthquake happens.

C. There are different types of earthquake waves.

D. What is an earthquake?

E. The earth has four main layers (层).

F. Can scientists predict earthquakes?

G. Scientists can tell where an earthquake took place by studying the P and S waves.