Earthquakes are caused by the movement of tectonic plates in the earth's crust. When the plates move and build up stress, they suddenly break, causing seismic waves that create shaking at the earth's surface. Scientists study plate tectonics and faults to better understand earthquake mechanisms. Safety tips during quakes include dropping under sturdy furniture, covering your head, and holding on until shaking stops. Earthquakes can trigger dangerous tsunamis by displacing large volumes of water.

1. Earthquake

2. ⦿Earthquakes are the shaking, rolling or
sudden shock of the earth’s surface.
⦿They are the Earth's natural means of
releasing stress.
⦿Earthquakes can be felt over large areas
although they usually last less than one
minute.
⦿Earthquakes cannot be predicted, although
scientists are working on it.

3. ⦿There are about 20 plates along the surface of
the earth that move continuously and slowly
past each other. When the plates squeeze or
stretch, huge rocks form at their edges and the
rocks shift with great force, causing an
earthquake.
⦿Ex: pencil test

4. ⦿As the plates move they put forces on
themselves and each other. When the
force is large enough, the crust is forced
to break. When the break occurs, the
stress is released as energy, which moves
through the Earth in the form of
waves, which we feel and call an
earthquake.

5. What is a fault?
⦿A fault is an area of stress in the earth where
broken rocks slide past each other, causing a
crack in the Earth's surface.
⦿ There are 4 major types of faults which are as
follows: dip-slip normal, dip-slip reverse,strike-
slip,and oblique-slip.

6. 4 Major Types of Fault
Dip-Slip
Normal Fault

7. Dip-Slip Reverse Fault

8. Strike - Slip Fault

9. Oblique - Slip Fault

10. What areplatetectonics?
⦿ The plate tectonic theory is
supported by a wide range
of evidence that considers
the earth's crust and upper
mantle to be composed of
several large, thin, relatively
rigid plates that move
relative to one another.

11. ⦿ The plates are all moving in different
directions and at different speeds.
Sometimes the plates crash together, pull
apart or sideswipe each other. When this
happens, it commonly results in
earthquakes.

12. ⦿A seismograph is an
instrument used for
recording the intensity
and duration of an
earthquake.

13. What is a tsunami?
⦿A tsunami is a large ocean wave usually caused by
an underwater earthquake or a volcanic
explosion.
⦿Tsunamis are NOT tidal waves.
⦿ Tidal waves are caused by the forces of the
moon, sun, and planets upon the tides, as well as
the wind as it moves over the water.
⦿With typical waves, water flows in circles, but
with a tsunami, water flows straight. This is why
tsunamis cause so much damage.

14. Tidal waves vs.
Tsunamis
tidal waves
tsunamis

15. Important Terminologies:
⦿EPICENTER
-The point on the earth's surface directly above
the source of the earthquake.
⦿SEISMIC WAVES
-The energy created by the quake that travels in
waves from the epicenter, where they are the
strongest.

16. ⦿RICHTER SCALE
- A measurement of an earthquake's intensity.
-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.

17. Richter Scale
⦿ 4 - Minor Earthquake
⦿ 5 - Moderate Earthquake
⦿ 6 - Strong Earthquake
⦿ 7 - Major Earthquake
⦿ 8 - Great Earthquake

18. Earthquake Safety Tips
⦿BEFORE AN EARTHQUAKE:
 Choose a safe place in every room such as under a sturdy piece
of furniture like a table or a desk where nothing can fall on you.
 Practice DROP, COVER AND HOLD ON!
- Drop under something sturdy, hold on, and protect your eyes
by pressing your face against your arm.
 Prepare a disaster supplies kit for your home and car. Include a
first aid kit, canned food and a can opener, bottled water,
battery-operated radio, flashlight, protective clothing and
written instructions on how to turn off electricity, gas, and
water.

19. ⦿ DURING AN EARTHQUAKE:
 DROP, COVER AND HOLD ON!
 Stay indoors until the shaking stops.
 Stay away from windows.
 If you’re in bed, hold on and stay there, protecting your
head with a pillow.
 If you’re outdoors, find a clear spot away from
buildings, trees and power lines. Then, 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.

20. ⦿AFTER THE SHAKING STOPS:
 Check for injuries.
 Inspect your home for damage.
 Eliminate fire hazards, so turn off the gas if you think its
leaking.
 Expect aftershocks.
 Each time you feel one, DROP, COVER AND HOLD ON.

21. T
H
A NK YOU FOR
LISENT ING!
DON’T FORGET TO
DROP, COVER AND
HOLD-ON! ☺