Download Earthquakes

Earthquakes
(Earthquakes are not associated with
weather, but instead are natural disasters.)
What is an earthquake?
Earthquakes are the shaking, rolling or
sudden shock of the earth’s surface. They
are the Earth's natural means of releasing
stress. More than a million earthquakes
rattle the world each year. The West Coast
is most at risk of having an earthquake, but
earthquakes can happen in the Midwest and
along the East Coast. Earthquakes can be
felt over large areas although they usually
last less than one minute. Earthquakes cannot
be predicted - although scientists are
working on it!
Click Here to learn more about earthquakes
from USGS.
What causes an earthquake?
There are about 20 plates along the surface
of the earth that move continuously and
slowly past each other. When the plates
squeeze or stretch, huge rocks form at their
edges and the rocks shift with great force,
causing an earthquake. Think of it this way:
Imagine holding a pencil horizontally. If you
were to apply a force to both ends of the
pencil by pushing down on them, you would
see the pencil bend. After enough force was
applied, the pencil would break in the middle,
releasing the stress you have put on it. The
Earth's crust acts in the same way. As the
plates move they put forces on themselves
and each other. When the force is large
enough, the crust is forced to break. When
the break occurs, the stress is released as
energy which moves through the Earth in the
form of waves, which we feel and call an
earthquake. (Graphic Credit: Wheeling Jesuit
University/NASA Classroom of the Future)
Click Here to see an animation of an
earthquake. It's great for kids, because they
get to see how it actually happens!
What is a fault?
A fault is an area of stress in the earth
where broken rocks slide past each other,
causing a crack in the Earth's surface. There
are the major types of faults: dip-slip
normal, dip-slip reverse, strike-slip, and
oblique-slip.
What are plate tectonics?
The theory of plate tectonics is a interesting
story of continents drifting from place to
place breaking apart, colliding, and grinding
against each other. The plate tectonic theory
is supported by a wide range of evidence that
considers the earth's crust and upper mantle
to be composed of several large, thin,
relatively rigid plates that move relative to
one another. (See plate tectonic graphic
above.) The plates are all moving in different
directions and at different speeds.
Sometimes the plates crash together, pull
apart or sideswipe each other. When this
happens, it commonly results in earthquakes.
Continental Drift: To see this animation
again, just refresh this page!This animation
shows you what our planet looked like millions
of years ago and what it looks like now!
(Graphic Credit: Geology Department at
University of California, Berkeley)
Click Here to learn more about plate
tectonics and the drifting of our continents.
What is a seismograph?
A seismograph is an instrument used for
recording the intensity and duration of an
earthquake.
Click Here to calculate the strength of
earthquakes!
What is a tsunami?
A tsunami is a large ocean wave usually
caused by an underwater earthquake or a
volcanic explosion. Tsunamis are NOT tidal
waves. Tidal waves are caused by the forces
of the moon, sun, and planets upon the tides,
as well as the wind as it moves over the
water. With typical waves, water flows in
circles, but with a tsunami, water flows
straight. This is why tsunamis cause so much
damage!
Click Here to see an animation of an
earthquake and the resulting tsunami. It's
great for kids, because they get to see how
it actually happens!
Click Here to get the latest tsunami warning
information from the NWS.
Click Here for tsunami safety information.
Know the Lingo
EPICENTER - The point on the earth's
surface directly above the source of the
earthquake.
SEISMIC WAVES - The energy created by
the quake travels in waves from the
epicenter, where they are the strongest. The
waves shake buildings, structures and the
earth vertically, causing them to move
horizontally!
RICHTER SCALE - A measurement of an
earthquake's intensity. Each one-point
increase on the scale indicates ten times the
amount of shaking and 33 times the amount
of energy. The energy released by a large
earthquake may be equal to 10,000 times the
energy of the first atomic bomb.
Click Here to see if there has been any
recent earthquake activity across the U.S.
Richter Scale
4
Minor Earthquake
5
Moderate Earthquake
6
Strong Earthquake
7
Major Earthquake
8
Great Earthquake
Click Here to learn about cool earthquake
facts!
Earthquake Safety Tips
BEFORE AN EARTHQUAKE: Have a
disaster plan. Emergency preparednesscan
save lives. Choose a safe place in every room.
It’s best to get under a sturdy piece of
furniture like a table or a desk where nothing
can fall on you. Practice DROP, COVER AND
HOLD ON! Drop under something sturdy,
hold on, and protect your eyes by pressing
your face against your arm. If you live in an
earthquake prone area, bolt tall furniture to
the wall and install strong latches to
cupboards. Prepare a first aid kit for your
home. By taking special precautions and
checking for hazards before a disaster
strikes, you will be much more likely to stay
safe.
DURING AN EARTHQUAKE: DROP, COVER
AND HOLD ON! Stay indoors until the
shaking stops. Stay away from windows. If
you’re in bed, hold on and stay there,
protecting your head with a pillow. If you’re
outdoors, find a clear spot away from
buildings, trees and power lines. Then, drop
to the ground. If you’re in a car, slow down
and drive to a safe place. Stay in the car
until the shaking stops.
AFTER THE SHAKING STOPS: Check for
injuries. Inspect your home for damage.
Eliminate fire hazards, so turn off the gas if
you think its leaking. Expect aftershocks.
Each time you feel one, DROP, COVER AND
HOLD ON.
Earthquake Activities
Lesson Plan: Here is a great lesson plan on
learning about how thrust faults are
responsible for the uplift of many mountain
ranges across the world, including the Los
Angeles Basin. This is a great lesson plan for
middle and high school students.
Lesson Plan: Here is a great lesson plan
keeping track of earthquakes around the
world. In this activity, kids keep a record of
the location of earthquakes for a week and
learn about plate tectonics.
Earthquake Experiment: Here is a great
experiment that explains how to prepare for
an earthquake.
Science Fair Ideas: Here is a list of science
fair project ideas that deal with
earthquakes.
Science Fair Project Ideas: Here is a
complete list of science fair project ideas.
Discover the science behind the weather
that impacts us every day.
Volcanoes:
http://ict.sopac.org/VirLib/EI0013.pdf
Tropical Cyclones/Hurricanes:
http://ict.sopac.org/VirLib/EI0009.pdf
Tsunami:
http://ict.sopac.org/VirLib/EI0011.pdf
Earthquakes:
http://ict.sopac.org/VirLib/EI0010.pdf