4-5 Faults and Volcanoes

The great cracks in the earth's crust are called faults.  Very often earthquakes occur next to these faults.  A very famous fault is the San Andreas Fault.  It is located near the city of San Francisco.  Another fault runs along the bottom of the Pacific Ocean near Japan.  When an earthquake occurs near an underwater fault it is called a tsunami.  It is called a tsunami because a huge wave usually occurs.  Tsunami is a Japanese word that means, "harbor wave."  Tsunamis can reach heights of two hundred feet.

Volcanoes are located above a pool of magma; the melted rock that comes from the earth's mantle.  Find the magma pool in the drawing below.

If the pressure under the earth's crust builds up due to heat and gases generated in the magma pools, the magma shoots to the surface through a thin spot in the earth's crust.  This is called a volcano.  Geologists call the magma that reaches the surface of the earth lava.  Ash, steam, and other gases shoot into the air.  Lava flows down the sides of the mountain.  Everything in its path is burned.  Once the lava hits the air it begins to cool, becomes solid, and eventually stops flowing.

Directions: Answer the following questions about earthquakes and volcanoes.

1. The large cracks in the earth's crust are called .

2. is the melted rock that comes from the earth's mantle.

3. The San Andres fault is located near the city of .

4. An underwater earthquake is called a .

5. Magma that reaches the surface of the earth is called .

6. Tsunamis can reach heights of

three hundred feet
two hundred feet
two hundred yards

7. The Japanese word that means, "harbor wave" is .

8. Volcanoes are formed from pools of .