Transcript Earthquakes - Cloudfront.net

October 07, 2014
Agenda
1. Roll
2. Pass out Notes for
Chapter 7 Section 1
3. Start PowerPoint
Chapter 7 Section 1
4. Possible Video
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Subject Areas: Earthquakes
EQ: What are Earthquakes?
Questions:
1. Where do earthquakes come from and
what causes them?
2. What are the different types of
earthquakes?
3. How do earthquakes travel through
the Earth?
What are Earthquakes?
A person who studies earthquakes is called
a seismologist.
Earthquakes are complex and present many
questions for seismologists. There is much
that is unknown about earthquakes.
Where do Earthquakes Occur?
Most earthquakes occur near
the edges of tectonic
plates. Tectonic plates
move in different
directions
Partner Share:
and at different
speeds.
As
Where do earthquakes occur?
a result of these
The place where earthquakes occur is …
movements faults are
formed. A fault is a break in
the Earth’s crust along
which blocks of crust slide
against each other.
What Causes Earthquakes?
As tectonic plates push, pull, or scrape
against each other they build up stress.
This stress causes the rock in the plates to
deform. Deformation is the change in the
shape of rock in response to stress.
What Causes Earthquakes?
Elastic Deformation is where rock will stretch
to a point and then break. Like a rubber
band it can be stretched to a point before it
will break. When it breaks energy is
released. The rock in the Earth will stretch
and break, resulting in an earthquake.
What Causes Earthquakes?
Elastic Rebound is the sudden return of elastically
deformed rock to its undeformed shape.
This occurs
when more
stress is
applied to rock
than the rock
can withstand.
Are all Earthquakes the Same?
Plate Motion
Prominent fault type
Earthquake characteristics
Transform
strike-slip fault
moderate, shallow
Convergent reverse fault
Divergent
normal fault
strong, deep
weak, shallow
This is found on
page 168 in your
textbook!!!!!
Movie
Are all Earthquakes the Same?
Transform motion occurs where two plates
slip past each other. Transform motion
creates strike-slip faults. Blocks of crust
slide past each other along strike-slip
faults. This motion produces moderate,
shallow earthquakes.
Are all Earthquakes the Same?
Convergent motion occurs where two plates
push together. Convergent motion creates
reverse faults. Blocks of crust are pushed
together slide vertically along reverse
faults. This motion produces strong deep
earthquakes.
Are all Earthquakes the Same?
Divergent motion occurs where two plates
pull away from each other. Divergent
motion causes normal faults. Blocks of
crust are pulled away from each other and
slide vertically along normal faults. This
motion produces weak, shallow
earthquakes.
Partner Share:
What are three plate motions that cause earthquakes?
The three plate motions that cause earthquakes are …
Plate Motion
Prominent fault type
Earthquake characteristics
Transform
strike-slip fault
moderate, shallow
Convergent reverse fault
Divergent
normal fault
strong, deep
weak, shallow
Partner Share:
What plate motion causes the weakest earthquakes ?
The plate motion that causes the weakest earthquakes is…
Partner Share:
What plate motion causes the strongest earthquakes ?
The plate motion that causes the strongest earthquakes is…
How do Earthquakes Travel?
The energy released when a rock springs
back is called Seismic waves. Seismic
waves are waves of energy that travel
through the Earth.
Link>>
Link>>
Body Waves
Waves that travel
through the
Earth’s interior
are called body
waves. There
are two types of
body waves; P
waves and S
waves.
Surface Waves
Waves that travel
along the Earth’s
surface are called
Surface waves.
These waves will
travel at different
speeds and move
the material that
they move through
differently.
How do Earthquakes Travel?
P is for primary. P waves travel through solids,
liquids, and gasses and are the fastest
seismic waves. These are body waves. They
are so fast they can travel through any part of
the earth. They are also the first waves to be
detected.
How do Earthquakes Travel?
S is for secondary. S
waves are the second
fastest waves and can
shear rock back and
forth. These are also
body waves. They
cannot travel through
liquid. They are slower
and arrive after the P
waves.
How do Earthquakes Travel?
Surface waves move the ground up and
down in circles as the wave travels along
the surface. Surface waves move more
slowly than body waves but are more
destructive. People have reported feeling
like they are on a roller coaster when an
earthquake occurs. More damage occurs
from surface waves.
Forces in the Environment
Questions for your
Science Notebook
Engineering Earthquakes
What did you know?
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What did you learn?
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What do you want to know?
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