1. EARTHQUAKES

2. A. Definition-
a sudden vibration or trembling in
the Earth’s crust.

3. B. Causes
1. Earthquake motion is caused by
the quick release of stored
potential energy into the kinetic
energy of motion.
2. Most earthquakes are produced
along faults, tectonic plate
boundary zones, or along the
mid-oceanic ridges.

4. C. Features of an Earthquake
1. Focus
- a point in the earth’s crust
where the earthquake
originates.

5. 2. Epicenter
-point on the earth’s
surface directly above
the focus.

6. D. Earthquake Waves
Primary Waves or P-Waves
(Compressional Waves)
Travel through solids, liquids and gases.
b. They cause rock particles to
vibrate in the same direction as the
wave is traveling.
c. They are the fastest traveling EQ
waves.

7. P-Waves

8. 2. Secondary Waves or S-Waves
Shear Waves
a. Travel through solids, only.
b. They cause rock particles to
vibrate at right angles to the
direction of travel of the wave.
c. They travel slower than P-waves.

9. S-Waves

10. II. Locating Earthquakes
A. Seismographs
-detect and record
the magnitude of an
earthquake.

11. B. Seismograms
-a recording of P, S and L
waves and their time of
arrival.

13. Triangulation

14. Epicenter and Focus Seismic waves do not travel in straight lines.
The waves are bent as
they move from a
medium of one density
into a medium of a
different density

15. E. Shadow Zone-
An angular distance from an
earthquake where P-waves are bent or refracted and S-waves are stopped by the liquid outer core.

16. F. Velocity and Density-the denser the
material, the faster
the waves move.

17. C. Earthquake Intensity
Richter Scale-measures the magnitude of
Earthquakes.
Richter scale no. No. of Typical effects of this magnitude
EQ’s /yr.
< Detected only by seismometers
Just about noticeable indoors
Most people notice them, windows rattle.
Everyone notices them, dishes may break, open doors swing.
Slight damage to buildings, plaster cracks, bricks fall.
Much damage to buildings: chimneys fall, houses move on foundations.
Serious damage: bridges twist, walls fracture, buildings may collapse.
Great damage, most buildings collapse.
> One every Total damage, surface waves seen, objects thrown to 10 years in the air.

18. 2. Modified Mercalli Intensity Scale

19. III. Emergency Preparedness-
A. Before an Earthquake Strikes
1. Develop an evacuation plan.
2. Know the safe spots in each room:
under sturdy tables, desks, or
against inside walls.
3. Conduct practice drills.
4. Learn how to shut off gas, water
and electricity in case the lines
are damaged.

20. B. During and Earthquake
DROP, COVER, HOLD
1. Duck or drop down to
the floor.
2. Take cover under a sturdy desk, table or
other furniture.
3. If outdoors, stay away from trees
and power lines.

21. 4. If you take cover under a sturdy piece of
furniture, hold on to it and be prepared to
move with it. HOLD the position until the
ground stops shaking and it is safe to move.

22. C. After an Earthquake Strikes
1. Check for injuries, render first aid.
2. Check utilities; because of possible gas
leak, do not light matches.
3. Use radio and listen for emergency
reports.

23. D. Tsunami Preparedness
Tsunami-means ‘harbor wave’, a huge
wave created by an EQ in the ocean crust.

24. 1. Move inland to higher ground.
2. Stay away from the beach.
3. Generally there is a noticeable
recession of the water away from
the shoreline, move away quickly.