Transcript What is an Earthquake

What is an Earthquake?
An earthquake also known as a quake,
tremor or temblor is an unpredictable
event in which masses of rock shift below
Earth's surface, releasing enormous
amounts of energy and sending out shock
waves that sometimes cause the ground
to shake dramatically.
http://www.scienceclarified.com/Di-El/Earthquake.html
What causes Earthquakes?
Earthquakes are caused when tension is
released from the rocks in the Earth's crust
and upper mantle. This tension is due to
friction between what scientists believe are
large 'plates' floating on magma on the
Earth's surface. Sometimes earthquakes
happen when the rocks in the earth's crust
bend and break. This causes shock waves
to travel on the earth's surface, resulting in
widespread destruction.
http://library.thinkquest.org/10136/earthquk/earttq.htm#what
Where do earthquakes
occur?
Earthquakes usually occur in places where
two plates meet, called faults. They are
mostly generated deep within the earth's
crust, when the pressure between two
plates is too great for them to be held in
place. The underground rocks then snap,
sending shock waves out in all directions.
These are called seismic waves. The point
at which an earthquake originates on the
surface is called the epicenter.
http://library.thinkquest.org/10136/earthquk/earttq.htm#what
Types of Earthquakes
There are many different types of
earthquakes these are tectonic, volcanic,
collapse and explosion. The type of
earthquake depends on the region where
it occurs and the geological make-up of
that region.
http://scign.jpl.nasa.gov/learn/eq2.htm
Tectonic Earthquake: earthquake that
occurs when the earth's crust breaks due
to geological forces on rocks and adjoining
plates that cause physical and chemical
changes.
Volcanic Earthquakes: earthquakes that
result from tectonic forces which occur in
conjunction with volcanic activity.
http://scign.jpl.nasa.gov/learn/eq2.htm
Collapse Earthquakes: small earthquakes
in underground caverns and mines that
are caused by seismic waves produced
from the explosion of rock on the surface.
Explosion Earthquakes: earthquakes
which are the result of the detonation of
nuclear and chemical devices.
http://scign.jpl.nasa.gov/learn/eq2.htm
How are earthquakes
measured?
Earthquakes can be measured in several
ways. The first is to describe the
earthquake's intensity and the second type
of measurement is the magnitude of the
earthquake. Two scales are commonly
used to measure earthquakes: the Mercalli
Scale and the Richter scale.
http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx
The Richter Scale
The Richter Scale measures the
magnitude or amount of energy released
by the earthquake. Magnitude does not
depend on population and effects to
ground structures, but rather on wave
amplitude and distance. This is a measure
of size for earthquakes based on
recordings of ground motions by
instruments.
http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx
The Mercalli Scale
The Mercalli Scale measures the intensity of the
earthquake that is, the impact of a quake on
people and their property. This speaks to the
observed effects of an earthquake over a limited
geographical area. Intensity scales assign whole
numbers usually from 1 to 12 to describe these
observed levels of shaking. An intensity of 1
means the earthquake was not felt, while 12
means absolute and total destruction.
http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx
Earthquake preparedness
tips
Earthquakes can happen at anytime and
anywhere. There is a chance, when an
earthquake hits, that you may have a few
seconds between the realization that this
is an earthquake and the time when the
shaking stops. If you know what to expect
and what to do, you can make the right
decisions that may mean the difference
between injury, life or death.
http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/ProtectYourselfFromanEarthquake/tabid/258/Default.aspx#What_to_do_During_an
_Earthquake
Duck, Cover and Hold
Duck: get under a sturdy piece of furniture,
making yourself into a little ball (do not
duck under beds or other objects that
could collapse).
Cover: keep your head and eyes protected from
falling or flying objects. Cover your head with
one hand.
Hold: with your other hand, hold onto the piece of
furniture. If it moves, move with it. Stay under
shelter until you are sure the shaking has
stopped.
When in a HIGH-RISE BUILDING, move against
an interior wall if you are not near a desk
or table. Protect your head and neck with
your arms. Do not use the elevators.
When OUTDOORS, move to a clear area away
from trees, signs, buildings, or downed
electrical wires and poles.
When on a SIDEWALK NEAR BUILDINGS, duck
into a doorway to protect yourself from
falling bricks, glass, plaster and other
debris.
When DRIVING, pull over to the side of the road
and stop. Avoid overpasses and power lines.
Stay inside your vehicle until the shaking
stops.
When in a CROWDED OR PUBLIC PLACE, move
away from display shelves containing
objects that could fall. Do not rush for the
exit.
When in a STADIUM OR THEATER, stay in your
seat, get below the level of the back of the
seat and cover your head and neck with your
arms.
Aftermath of Haiti earthquake Jan 14, 2010
Aftermath of Haiti earthquake Jan 14, 2010
Chile quake February 27, 2010
quake February 27, 2010
When an earthquake strike: Be Bold, Drop,
Cover, Hold.