Unit 2E B Plates of Earth

4. Earthquakes

A shaking of the surface of Earth when the plates of Earth move About one million earthquakes happen every year Vocabulary earthquake A shaking of the surface of Earth when the plates of Earth move

Most earthquakes happen under the ocean or are too small to notice

In a strong earthquake the ground can shake violently and even split open

Remember: a fault is the place where two plates meet Most earthquakes are caused by the sudden movement of plates along a fault Romania Jan 30 2000 Remember: a fault is the place where two plates meet

Rocks in the crust break and move apart at a point called the focus When the plates move, the crust near the fault is squeezed and stretched Click image for focus points Rocks in the crust break and move apart at a point called the focus

Vocabulary focus The point where rocks in the crust break and move apart during an earthquake

The focus is usually less than 25 miles below the surface of Earth

Near epicenter of an earthquake is where the most damage occurs Vocabulary: epicenter The place on the surface of Earth directly above the focus of an earthquake

If the focus of an earthquake is under the ocean floor, a tsunami is produced Vocabulary: tsunami A giant wave produced when the focus of an earthquake is under the ocean floor

This huge wall of water moves across the ocean at high speed It causes great damage when it reaches land

Many earthquakes take place in an area known as the Ring of Fire Volcanoes are also common in this area

This chain of earthquake zones and volcanoes circles the Pacific Plate