Earthquakes and Volcanoes

Earthquakes

• Earthquakes are vibrations in the Earth’s crust. They are caused by plate movement along fault lines.

• A fault is a very deep crack or break in the Earth’s crust.

• The place inside the Earth where the earthquake starts is the focus. Directly above the focus is the epicenter.

• There are 3 types of earthquakes:– Shallow focus (strongest because it is closest

to the surface). – Intermediate focus– Deep focus

Types of Faults

• Divergent – the ground moves apart– An example of this is the Sierra Nevada Mts.

• Convergent – the ground moves together– An example of this is Himalayan Mountains

• Transform – the ground moves side to side– An example of this is the San Andreas Fault

Measuring Earthquakes

• Magnitude – how strong an earthquake is. • The Richter Scale measures magnitude.

This scale goes from 1 to 10. • Each number is 10 times worse than the

number before it. For example, a 5 on the Richter Scale is 10x worse than a 4.

Ring of Fire

• The Ring of Fire is a major earthquake and volcano zone. It is where 2 major plates meet. This is in Asia and North and South America.

Volcanoes

• Volcanoes result from a lot of pressure inside the Earth. Magma rises up out of the Earth and becomes lava. This can result in the formation of new land. An example of land created from a volcano is the Hawaiian islands.

Types of Volcanoes

• Shield– Quiet eruptions– Thin lava– Dome Shaped

• Cinder Cone– Violent eruptions– Volcano is not very high, but is steep

• Composite– Combination of quiet and loud eruptions– Steep