1. EaRtHqUaKeS!!!

2. What do earthquakes feel like?
San Francisco Earthquake of 1989

3. Seismology: the study of earthquakes
Most earthquakes take place near the edges of tectonic plates (most active earthquakes occur along the plates surrounding the Pacific Ocean)
What else is The Ring of Fire known for?

4. What Causes Earthquakes?
As tectonic plates push, pull or scrape against each other, stress builds up along faults until the rocks finally move
A fault is a break in the Earth’s crust where plates slide, push or pull against each other

5. What Causes Earthquakes?
Deformation is the change in the shape of rock in response to stress.
Rock can deform in 2 ways: - plastic - elastic

6. ***Write this in your glossary!*** Plastic Deformation
Stress causes the crust on one side of a fault bend like clay
THIS DOES NOT LEAD to EARTHQUAKES!!!!

7. Elastic Deformation Rock can only stretch so far before it will break
Like a rubber band, when it breaks, energy is released and the broken pieces return to their unstretched shape causing energy to spread through the earth in waves.
THIS DOES LEAD to EARTHQUAKES!!!!

8. Are All Earthquakes the Same?
***Copy this chart in your notebook!***
No. Depending on the type of plate boundary, earthquakes can be strong or weak.
Plate Motion
Earthquake Characteristics
Transform
Moderate, shallow
Convergent
Strong, deep
Divergent
Weak, shallow

9. How Do Earthquakes Differ?
***Write down the part in red***
Not all earthquakes are the same.
The type of earthquake that occurs depends on the type of plate motion and fault type there is!

10. Transform = Strike-Slip
***Write the definition of strike slip in your glossary***
If two plates have a transform motion, they will probably have a strike-slip fault between them
A strike-slip fault is when two blocks of crust slide past each other horizontally
These types of earthquakes are moderate and shallow

11. Convergent = Reverse
***Write the definition of in your glossary***
If two plates have a convergent motion, they will probably have a reverse fault between them.
A reverse fault happens when two blocks of crust are pushed up against each other and they slide vertically.
These types of earthquakes are usually strong and deep.

12. Divergent = Normal ***Write the definition of in your glossary***
If two plates have a divergent motion, they will probably have a normal fault between them
A normal fault occurs when two blocks of crust are pulled away from each other and slide vertically
This type of earthquake is usually weak and shallow

13. Earth on the Move

14. Earthquake Waves All earthquakes release energy called seismic waves
Scientists measure seismic waves to determine the scale (how big or small) an earthquake is
Most people use the Richter scale to measure earthquake seismic waves

15. How Seismographs Work
the pendulum remains fixed as the ground moves beneath it

16. Typical Seismogram

17. How Are Earthquakes Measured?
This is a seismograph
It is an instrument located at or near the surface of the Earth that records seismic waves

18. What Scale is Used to Measure the Strength of an Earthquake?
The Richter Scale
Magnitude
Estimated Effects 2
Can only be detected by a seismograph 3
Can be felt at the epicenter* 4
Felt by most in the area 5
Causes damage at the epicenter 6
Causes widespread damage 7
Causes great, widespread damage
* Right where the earthquake begins

19. How are Earthquakes Measured? Richter Scale

20. Primary Waves (P Waves)
***Write the definition in your glossary***
A type of seismic wave that compresses and expands the ground. Primary waves are longitudinal waves. They can travel through liquids.
The first wave to arrive at an earthquake. P comes before S in the alphabet.

21. Secondary Waves (S Waves)
***Write the definition in your glossary***
A type of seismic wave that moves the ground up and down or side to side. These are transverse waves. They cannot go through liquids.
They are the second wave people feel. They are sometimes called the aftershock.

22. Comparing Seismic Waves

23. ***Write the definition in your glossary***
Surface Waves
***Write the definition in your glossary***
Move along the Earth’s surface
Produces motion in the upper crust
Motion can be up and down
Motion can be around
Motion can be back and forth
Travel more slowly than S and P waves
More destructive

24. How do scientists calculate how far a location is from the epicenter of an earthquake?
Scientists calculate the difference between arrival times of the P waves and S waves
The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

25. Scientists used what we know about S and P waves to figure out the layers of the Earth. What information may have helped them to determine which parts of the Earth are solid and which are liquid?

27. Locating Earthquakes

28. Locating Earthquakes

29. Locating Earthquakes

30. Focus –. point inside the Earth where an
Focus – point inside the Earth where an earthquake begins Epicenter – point on Earth’s surface above focus