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