An earthquake occurs when energy is rapidly released along a fault line. The point where the rock breaks is called the focus, and the point directly above it on the earth's surface is the epicenter. Seismic waves carry energy away from the focus, including P waves and S waves. P waves are compressional and can travel through all material, arriving first, while S waves are transverse and can only travel through solids, arriving second. Locating an earthquake's epicenter requires detecting the seismic waves with seismographs at three different recording stations and finding the point where the circles around each station intersect. Underwater earthquakes can create massive tsunamis by displacing large volumes of water.

1. Earthquake
Epicenter

2. Mystery Words
Volcanism
Epicenter

3. • An Earthquake occurs when energy is released
through rapid movement along a fault.
• An EARTHQUAKES are natural geological
phenomena caused by the sudden and rapid
movement of large volume of rocks.

4. Focus
• That is the point along the fault line where the
rock under stress breaks.

5. Epicenter
• Is the point on the earth’s surface directly above
the Focus.

6. Focal Depth
• This is the distance between the Focus and the
Epicenter.

7. Seismic Waves
• Energy from an Earthquake is carried away
from the focus as Seismic Waves.
• There are many different types of waves.
• We will concentrate on the two most
prominent.

8. Primary Waves
• P Waves
• The fastest seismic wave.
• Arrives at recording stations first (Primary).

9. Primary Waves
• P waves are compressional waves.
• The energy travels in the same direction as the
wave travels.

10. Primary Waves
• P waves can travel through solids, liquids or
gases.

11. Secondary Waves
• S Waves
• Arrives at recording stations second
(secondary).

12. Secondary Waves
• S waves are transverse waves.
• Another term is shear waves.
• The energy is perpendicular to the direction of
wave travel.

13. Secondary Waves
• S Waves can only travel through solids.

14. Surface Waves
• Waves like L waves
and R waves travel
slightly slower then S
waves but do
tremendous damage.

15. • https://www.youtube.co
m/watch?v=yOGoKCK17a4

16. Seismograph
• Instruments that detect and measure seismic waves
are called Seismographs.
• They originally were a weight and pen suspended
over a moving drum.

17. Seismograph
• The tracing on the drum is called a seismogram.
• The different types of waves make different
tracings on the seismogram.

21. • https://www.youtube.co
m/watch?v=VSgB1IWr6O4

22. History of Earthquakes
Largest In Magnitude
• Date Location Magnitude
• May 22nd, 1960 Chile 9.5
• March 28th, 1964 Alaska 9.2
• December 26th, 2004 Sumatra (Ocean) 9.1
• March 11th, 2011 Japan (Ocean) 9.0
• February 27th, 2010 Chile 8.8
Largest In Destruction
• Date Location Deaths Magnitude
• Jan 25th, 1556 China 830,000 8
• July 27th, 1976 China 655,000 7.5
• Aug. 9th, 1138 Syria 230,000 Unknown
• Dec. 26th, 2004 Sumatra 227,898 9.1
• Jan. 12th, 2010 Haiti 222,570 7.0

23. Locating an Earthquake Epicenter…
• To find where the an
Earthquake originates you
need wave data from 3
recording stations.
• Circles are drawn around
these stations.
• Where the 3 circles
connect is where the
earthquake originated.

25. Underwater E-quake
• Fault movement along the ocean floor moves
the water up and down which can create a
massive wave called a “Tsunami”.

26. Tsunami

27. • https://www.youtube.com/watch?annotation_
id=annotation_1885845763&feature=iv&index=
2&list=PLNspHwmzscYE2-
cUkOfHo92ATHZUqqsPH&src_vid=j0YOXVlPUu4
&v=pTtneXyhoPA