Download What are Earthquakes

What are Earthquakes?
 Earthquakes are the Earth's
natural means of releasing
stress.
 When the Earth's plates move
against each other, stress is
put on the lithosphere.
 When this stress is great
enough, the lithosphere breaks
or shifts
Where do they occur most often?
 Within areas of the crust are
fractures, known as faults,
 One block may move up while
the other moves down, or one
may move horizontally in one
direction and the other in the
opposite direction.
 Geologists and seismologists
(scientists who study
earthquakes and the processes
that create them) have found
that earthquakes occur
repeatedly at faults, which are
zones of weakness in the
earth's crust.
Can Earthquakes Be Prevented?
There is no known way to prevent
earthquakes, but it is possible to
lessen the impact. The amount of
devastation from an earthquake can
be greatly diminished by building
structures using earthquake
resistant design, making the interiors
of buildings safe from falling
objects, and educating people about
earthquake safety.
Katie Sobolewski
The who, what,
when, and why of
Earthquakes!
What Was the Greatest Number of
People Killed in One Earthquake?
An earthquake in China in 1556 killed
approximately 830,000 people.
Effects of Earthquakes and
Volcanoes:

Volcanoes generate a wide variety of
phenomena that can alter the
Earth's surface and atmosphere and
endanger people and property. Small
events may pose hazards only within
a few miles of a volcano, while large
events can directly or indirectly
endanger people and property tens to
hundreds of miles away. First we'll
explore the origin of magma and then
we'll look at some eruptive types and
associated hazards.
Emergency Response Plan
During an Earthquake:
 Stay as safe as possible during
an earthquake. Be aware that
some earthquakes are actually
foreshocks and a larger
earthquake
might
occur.
Minimize your movements to a
few steps to a nearby safe
place and stay indoors until the
shaking has stopped and you
are sure exiting is safe.
 DROP to the ground; take
COVER by getting under a
sturdy table or other piece of
furniture; and HOLD ON on
until the shaking stops.
 Stay away from glass, windows,
outside doors and walls, and
anything that could fall, such
as lighting fixtures or
furniture.
Conclusions

Earthquakes can be categorized
according to their location (focus &
epicenter), intensity, magnitude, and
energy. Seismic waves are created by
the release of energy stored in
rocks.

The speed at which different types
of seismic waves travel can be used
to determine the epicenter of an
earthquake.
Volcanoes erupt as a result of highpressure gas and magma below the
surface of the Earth. The magma
forms through heating,
depressurizing, and water
introduction. Eruptions of volcanoes
produce pyroclastic flows, lava flows,
debris flows, and landslides.


Although these natural disasters
have been studied extensively and
their causes are well-understood,
predicting such events over short
time scales remains difficult.
After an Earthquake:




Expect aftershocks
Listen to a battery-operated
radio or television.
Be aware of possible tsunamis
if you live in coastal areas.
PLAN AHEAD FOR A DISASTER!