Download Earthquakes

Nature’s Forces
What does this sound like?
Has anyone ever experienced an
earthquake?
Why do you think an earthquake makes
those sounds?
Objectives
Understand how an earthquake
happens
 Plan the best and safest way to
survive an earthquake
 Create own mini earthquake to see
how shock waves can be so
damaging

Question
If you find yourself indoors during an
earthquake, is it better to rush
outside or to take cover inside?
It’s better to Stay Inside!!
Many people are injured by falling debris just
outside buildings. Usually it's better to stay
inside, if you are already inside, and to stay
outside if you are already outside. Inside, try
taking cover underneath something sturdy like
a desk, and avoid windows, mirrors, and heavy
furniture that might fall such as overloaded
bookshelves. Outside, avoid walls, chimneys,
and electrical power lines. Try not to look up,
however: because it's important to protect your
head!!
How do earthquakes
happen?
Earthquakes are usually caused when rock
underground suddenly breaks along a fault.
This sudden release of energy causes the
seismic waves that make the ground shake.
When two blocks of rock or two plates are rubbing
against each other, they stick a little. They don't
just slide smoothly; the rocks catch on each
other. The rocks are still pushing against each
other, but not moving.
After a while, the rocks break because of all the
pressure that's built up. When the rocks break,
the earthquake occurs. During the earthquake
and afterward, the plates or blocks of rock start
moving, and they continue to move until they
get stuck again.
The spot underground where the rock breaks is
called the focus of the earthquake. The place
right above the focus (on top of the ground) is
called the epicenter of the earthquake.
Different Types Of Earthquakes
There are many different types of earthquakes: tectonic, volcanic,
and explosion. The type of earthquake depends on the region
where it occurs and the geological make-up of that region.
Tectonic earthquakes are the most common. These occur when
rocks in the earth's crust break due to geological forces created
by movement of tectonic plates.
Volcanic earthquakes occur in conjunction with volcanic activity.
Collapse earthquakes are small earthquakes in underground
caverns and mines.
Explosion earthquakes result from the explosion of nuclear and
chemical devices. We can measure motion from large tectonic
earthquakes using GPS because rocks on either side of a fault
are offset during this type of earthquake.
The most recent
earthquake happened…
In New York City on.
Saturday, October 27th.
What Happened?
It was very minor, and people were just slightly shaken
up, but there was no damage done to the city.
What might people have mistaken it for?
Terrorist attacks………This is why we need to prepare….
How to prepare for an
earthquake:




Prepare an emergency plan for your family and
household.
Take a first aid course, including cardiopulmonary resuscitation (CPR).
Know the safe places to be - and where not to be
- in your home during an earthquake. Practice
taking cover in the safe places.
Safe places under heavy tables or desks; inside
hallways; corners of rooms or strong archways.




Dangerous places: near windows or mirrors; under any
heavy objects that can fall; the kitchen where the stove,
refrigerator or contents of cupboards may fall on you;
doorways where the shaking may slam the door on you.
Chances of survival are improved if emergency plans are
prepared and practiced together with your family. Start by
discussing what could happen and what you should do at
home, at school or at work if an earthquake strikes.
Prepare a list of what needs to be done ahead of time.
Divide up tasks so that everyone involved in the plan
participates as much as possible.
Write down and exercise your plan. Make sure everybody
has a copy and keeps it close at hand.
Hands-On Activity
Earthquake and Shock Waves
Materials:
Plastic Table
Three cups of sand
Rubber Mallet.
Procedure:
1. Pour three cups of sand on the top of a plastic table near
the edge.
2. Tap the table lightly with the rubber mallet. You will see
the sand "jump" into the air.
As rocks snap and break at the focus of an earthquake
shock waves are sent out in all directions. The "jumping
sand" represents the release of the energy from the
hammer through the plastic table.
3. Move the sand farther away from the point of
contact and see what happens.
The farther away the sand is from the source of
energy (tapping of rubber mallet) the less the
sand jumps. This represents the fact that the
farther you are from
the epicenter the less you will feel the
earthquakes shock waves.
.
4. Move the sand to the opposite side of the table
and tap lightly. You should observe a very small
movement of the sand.
Closure
When you go home today, talk with
your family about how to prepare
for an earthquake, and share with
them what you have learned.