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