Transcript Formation of the Earth: Earthquakes presentation

EARTHQUAKES
Formation of
the Earth
WHAT IS AN EARTHQUAKE
 An earthquake is a natural hazard caused by the
sudden and rapid movement of a large volume of
rock
 Earthquakes are a way for the earth to release stress
 More than a million earthquakes occur every year
 Earthquakes can happen all over the nation, but are
most likely to occur along the West Coast
 Earthquakes usually last less than one minute
 Earthquakes cannot be predicted!
THE CAUSES OF AN EARTHQUAKE
 There are about 20 plates that are constantly moving
along the surface of the earth
 As the plates move, they put forces on themselves
and each other
 When enough force is added, the earth’s crust snaps
 When the snap occurs, stress is released as energy
which moves through the earth in the form of waves
 A fault is the area of stress in the earth where
broken rocks slide past each other causing a crack in
the earth’s surface
PARTS OF AN EARTHQUAKE
 The epicenter is the point at the surface directly
above the focus
 The focus is the location where the earthquake
begins
 The hypocenter is the point within the earth where
the earthquake rupture starts
 Seismic Waves are waves of energy that travel
through the earth’s layers as a result of an
earthquake
THE PARTS OF THE EARTHQUAKE
SEISMIC WAVES
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Surface waves: travel along the earth’s surface
Body waves: travel through the interior of the earth
Primary waves: compressed, longitudinal waves
Secondary waves: transverse waves
HOW TO MEASURE AN EARTHQUAKE
 Scientists use the Richter Scale to measure the intensity of
an earthquake
 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.
 4 Minor Earthquake
 5 Moderate Earthquake
 6 Strong Earthquake
 7 Major Earthquake
 8 Great Earthquake
EARTHQUAKE SAFET Y
 DROP, COVER AND HOLD ON!
 During an earthquake it is important to stay indoors
until the shaking stops
 Stay away from windows
 If you’re outdoors, find a clear spot away from
buildings, trees and power lines.
 Always 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.