Download What Are Earthquakes? By Cindy Grigg 1 Caption: This picture

What Are Earthquakes?
By Cindy Grigg
Caption: This picture shows part
of the damage from a major
earthquake that struck San
Francisco, California, April 18, 1906.
1
The outside of the Earth is called
the crust. Just like the crust on a loaf
of bread, the Earth's crust has cracks
in it. The cracks are called faults.
The crust of the Earth isn't solid at all. It is made up of many
pieces called plates.
2
The plates of the Earth's crust fit together like a giant puzzle.
But unlike a puzzle, the plates of the Earth's crust are always
moving. The Earth's plates float on a layer of hot, melted rock.
This part of Earth is called the mantle.
3
Most earthquakes happen where two plates meet. The Earth's
plates don't always slide smoothly past each other. Their rocky
edges are jagged and rough. Sometimes they get stuck. The
force causing them to move builds up. Something has to give.
The plates may break apart with a huge jerk. Shock waves spread
out from the focus of the earthquake. The focus is the place
where an earthquake begins. Some of the shock waves travel to
the surface of the Earth where people are.
4
What is an earthquake like? The ground starts to rumble and
shake in an earthquake. It may crack open. Sometimes the
ground moves. It moves like ripples move across water. The
shaking may only last for a few seconds. But earthquakes can
cause awful damage.
5
In large earthquakes, buildings, roads, and bridges may give
way. Gas lines may break, causing fires. In mountain areas, an
earthquake can cause a landslide or mudslide. This happens
6
when giant amounts of rocks, dirt, and mud slide down the
mountain. An avalanche is when giant amounts of snow slide
suddenly down the mountain. When these things happen, they
can destroy buildings. They can cover large areas with mud, dirt,
or snow. Everything in their path is flattened. If an earthquake
happens under the ocean, it causes giant waves called tsunamis.
When a tsunami comes to land, the giant wave of water can
cause great damage.
Every year there are more than half a million earthquakes in
the world. Most of them are small. People don't even notice them.
Many others cause just a little damage. A few earthquakes are big
enough to cause much damage and many deaths. Our Earth is
dynamic. This means it is active, and it is always changing.
Earthquakes are one of the most powerful changes that happen
on Earth.
7
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What Are Earthquakes?
1. The place where an earthquake
begins is called the ______.
2. What is the Earth's mantle?
A layer of hot, melted rock
Pieces of the Earth's crust
The place where an earthquake
begins
3. Where do most earthquakes happen? 4. The Earth's crust is made up of
Under the ocean
______.
Where two plates meet
Hot, melted rock
On a mountain
Puzzle pieces
Many pieces called plates
5. If an earthquake happens under the
ocean, it causes giant waves called
______.
6. The word dynamic means ______.
Active and always changing
Having many pieces
Causing earthquakes
7. The Earth's crust is solid.
False
True
8. Earthquakes may cause ______.
No damage at all
Giant waves called tsunamis
Landslides or mudslides
All of the above
Type your answers here>>>>>
Vocabulary Exercise
Directions-Research the bold text words in the article. Go to dictionary.com to find the definitions.
1.