양괄식 1

[최정빈]

Our topic of today is the interior of the earth.

The quistion is how can we know about its interior when can't go down very far inside.

So a lot of we know has come from monitoring ? waves or simplely like studying earthquakes.

?waves are waves of energy caused by sudden brake ? of rocks and they usually result from the earthquakes.

By utilizing insruments at various parts of the earth, in order to monitor ?waves, we have been able to study the behavior of the waves into gain an inside into the earth interior.

Two principle regarding ? waves proved to be very convenient.

For one, ? waves change direction when they come upon a sudden change in the density of material one moving to the earth.

In addition, they change volocity as well.

Traveling faster and ? materials and slower less ? materials.

Knowing these two characteristics, we can map out density patterns in the earth interior by noting the direction and volocity of ? waves.

From here, we'd do the layers of the earth. 

We will began from the outermost layer the ? .