1. Earthquakes & Seismic Waves

2. An Earthquake occurs when energy is released through rapid movement along a fault.
A fault is a crack in the Earth’s outer Crust.
Most faults are located along Earth’s plate boundaries.
Plate boundaries can be Divergent, Convergent, or Transform.
Most E-quakes are not felt because they occur under the ocean water.

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

6. Tsunami

8. Current Earthquake Data…..

9. Parts of an Earthquake: Focus
That is the point along the fault line where the rock under stress breaks.

10. Parts of an Earthquake: Epicenter
Is the point on the earth’s surface directly above the Focus.

11. Parts of an Earthquake: Focal Depth
This is the distance between the Focus and the Epicenter.
The smaller the depth, the more damage an Earthquake can have.

12. Parts of an Earthquake: 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.

13. Parts of an Earthquake: Primary Waves
P Waves
The fastest seismic wave.
Arrives at recording stations first (Primary).
P waves can travel through solids, liquids or gases. (all layers of the Earth)

14. Secondary Waves S Waves
Arrives at recording stations second (secondary).
S Waves can only travel through solids

18. Seismograph
Instruments that detect and measure seismic waves are called Seismographs.

19. Seismogram The tracing on the drum is called a seismogram.
The different types of waves make different tracings on the seismogram.
Seismographs are buried under ground so they can feel the vibrations of the waves.

24. History of Earthquakes
Largest In Magnitude
Date Location Magnitude
May 22nd, Chile 9.5
March 28th, Alaska 9.2
December 26th, Sumatra (Ocean) 9.1
March 11th, Japan (Ocean) 9.0
February 27th, Chile 8.8
Largest In Destruction
Date Location Deaths Magnitude
Jan 25th, China 830,000 8
July 27th, China 655,
Aug. 9th, Syria 230,000 Unknown
Dec. 26th, Sumatra 227,
Jan. 12th, Haiti 222,

25. 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.