Transcript What is an Earthquake??

What is an Earthquake??
An earthquake is caused
by the release of stored
energy in Earth’s outer
layer. This causes sudden
shift of rocks.
An earthquake generates
movements and vibrations
that travel through the
earth
Defining Earthquakes
• Shaking and trembling of the
earth’s crust.
• The waves travel in all
directions
• More than 1,000,000 occur a
year or one every 30 seconds
• Faulting is the most common
cause
• Earthquakes continue until all
the energy is used up
• TSUNAMIS- earthquake on
the ocean floor: causing waves
to become greater than 20
meters high
Although the ground we walk on seems solid, the earth is actually
made up of huge pieces of flat rock called tectonic plates.
These move very slowly, and where they meet is called a fault.
When the plates rub together, the movement forces waves of energy
to come to the earth's surface.
This causes tremors and shakes - and this is what causes
earthquakes.
Seismic Waves
• FAULT- the break
• FOCUS-place where
movement begins
• As rocks move,
energy is released by
vibrations or seismic
waves
• The three main types
of seismic waves are:
P waves, S waves,
and L waves
P Waves
• Primary waves
• Fastest seismic
waves
• First to arrive at a
distant point
• Can travel through
solids, liquids, and
gases
• They are push-pull
waves
S Waves
• Secondary waves
• Slower than P waves
and arrive later at a
distant point
• Can travel through
solids, but NOT
through liquids and
gases
• Move in up-down
motion
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Link 2
L Waves
• Surface waves
• Slowest moving
seismic waves
• Travel on top of
Earth’s surface
• Cause most of
damage to Earth,
because they move
the ground up and
down, side by side
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John Milne- 1893
• Seismograph-measures and
detects seismic waves
• Seismogram- Paper record
of waves
• Seismologist- scientist who
study earthquakes
• Richter Scale- a scale that
allows scientists to determine
earthquake strength based
on many readings
• 1-10 levels at which an
earthquake is measured on
amount of damage caused;
Above a 6 is very destructive
seismograph
The “EARTHQUAKE GAME” – 1988
During the 1988 Auburn-LSU football
game LSU scored a late and winning
touchdown. The crowd cheered so
loudly that the “earthquake game”
made local history because the
ground motion appeared on the LSU
seismograph.
http://www.classzone.com/books/earth_sci
ence/terc/content/visualizations/es1009/es
1009page01.cfm
Eddie Fuller
catches Tommy
Hodson’s fourthdown pass in the
end zone to tie the
score 6-6 with
Auburn in 1988 with
1:47 remaining in
the game. The
crowd’s reaction
registered on the
seismograph in
LSU’s HoweRussell Geoscience
Complex.