1. earthquakes
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By Sharon and Rajat

2. What is an Earthquake?
Earthquakes: Vibrations (seismic waves)
Earthquakes
within Earth materials are produced by the rapid
release of energy
 Earth’s crust is in constant motion because of
tectonic forces
 Earth’s crust can store elastic energy
 When forces exceed the elastic limits and structural
strength of the rocks, the rocks will break and/or
move producing vibrations that travel outward in
all directions

3. Earthquakes
o The actual place underground where
the rocks break producing vibrations is
called the focus
o The place on the surface directly
above the focus is called the epicenter

4. What types of
forces are created?
Compression Force:
Force
 force pushing something together
 Makes a reverse fault

5. What types of
forces are created?
Tension Force:
Force
 stretching or pulling force
 Makes a normal fault

6. What types of
forces are created?
Shear Force:
Force
 a system of forces that operates
against a body from different sides
 Makes a strike-slip fault

7. http://www.geo.uib.no/jordskjelv/index.php?topic=earthquakes&lang=en

8. http://www.geo.uib.no/jordskjelv/index.php?topic=earthquakes&lang=en

10. What causes
Earthquakes? when the
 Movement along faults: occurs
energy exceeds the friction holding the sides of
the fault together and is suddenly released
 .Movement of magma (volcanic)
 Volcanic eruptions

11. Originate at the focus and travel outward in al
Seismic Waves
directions
 Foreshocks: small earthquakes that come
Foreshocks
before a major earthquake
 Aftershocks: Are adjustments in the crust
Aftershocks
after in earthquake
o Smaller than main earthquake, but can cause as
much or more damage. They can continue for
weeks to months. Not every earthquake
months
produces aftershocks

12. 3 Types of seismic Waves
 P waves (primary waves) Compressional wave
 Particles move back and forth in the same direction as the wave
 Travels the fastest
 Can pass through solids and liquids (gases also)
 Does not cause damage

13. Types of Waves
 S wave (secondary wave, shear wave)
 Particles move at right angles to the direction of the wave
 Travels slower than P waves
 Can pass through solids only
 Does not cause damage

14. Types of Waves
 L wave (long wave, surface wave, ground
wave)
 Particles move in elliptical orbit
 Originates on the surface after
the P and S waves go straight up
from the focus and reach the
surface
 The L wave causes the damage
and will be the strongest at the
epicenter
 Travels the slowest

15.  Earthquake Safety
Protect yourself from falling objects (GET
UNDER SOMETHING) or stand in a hallway
or doorway (watch out for a swinging door)
 Do not try to go outside during the earthquake
 After the earthquake and before the aftershocks,
go outside
 Do not return to the building until it has been
inspected

16. Why japan is still
alive after the massive
earthquake

17. Sharon and Rajat