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NAME: ___________________
1, 2016
Test is on Monday, February
Date: ____________________
Chapter 6 Study Guide: Earthquakes
1. Focus vs. epicenter.
 Focus is beneath the Earth’s surface and it shows the exact location of
where the earthquake started. The epicenter is on top of Earth’s surface,
right above the focus.
2. Which one is the fastest seismic wave? Which one is the slowest?
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Fastest seismic wave: Primary Waves
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Slowest seismic wave: Surface Waves
3. Tsunamis are only a few feet high in __deep / shallow__ water.
4. What are the warning signs of tsunamis? What happens to the water?
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The shoreline goes back into the water. There are always big waves that rise
up. The waves at the shoreline move back and forth.
5. Name which type of stress is related to each type of wave.
a. Primary wave: Compressional stress.
b. Secondary wave: Shearing stress.
c. Surface wave: Tension stress.
6. In CA, which Fault, or fault zone, is the one we expect to see the most
damage on or around?
- San Andreas Fault
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7. What are seismic waves?
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Waves of energy produced at the focus of an earthquake as strain energy is
released.
8. What are tsunamis caused by? What are the steps of a tsunami?
- Tsunamis are caused by earthquakes on the ocean floor.
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Sudden movement along an underwater fault causes powerful waves that are
transferred to and spread across the water surface. When it reaches the
shoreline, friction slows it down. This causes a wall of water to build up in
the ocean.
9. What are Primary waves? Give 3-4 facts about them.
- They are the fastest waves and they cause the least destruction.
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They travel through solids and fluids.
The first wave to reach the surface.
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Compressional wave.
Rock particles move parallel to wave direction.
10. The modified Mercali scale measures the ___INTENSITY__ of an
earthquake.
11. The Richter scales is based on measurements of the __AMPLITUDE__ of
seismic waves.
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Amplitude: the maximum extent of a vibration, measured from the position of equilibrium.
12. What are earthquakes? What is it caused by?
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Earthquakes are rupture and sudden movement of rocks along faults. They
are caused by the release of elastic strain energy.
13. What happens to the plates at each plate boundary?
a. Divergent: Rocks break under tension stress forming normal faults.
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b. Convergent: Rocks break under compression stress forming reverse
faults.
c. Transform: Rocks slip horizontally past one another, forming strike
slip fault.
14. If the focus is close to the surface, the earthquake will be
___STRONGER__.
15. Which type of seismic wave can travel through solids, but not liquids?
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Secondary Waves.
16. Which type of seismic wave travels at the surface level of the crust?
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Surface Waves.
17. Indicate where the arrival of each type of wave is on this seismogram.
18. Where is the epicenter on this following figure?
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19. What are surface waves? Give 3-4 Facts about them.
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Slowest wave.
Cause the most destruction/damage.
Travel in the surface of Earth/get stuck in there.
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The rocks move side to side and up and down.
20. What are S-Waves? Give 3-4 points about them.
- 60% as fast as the P-waves.
- They only travel through solids.
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Rocks move perpendicular to wave direction.
21. The difference between the arrival time of __PRIMARY_ waves and
_SECONDARY_ waves at a recording station helps scientists determine the
distance from the epicenter of an earthquake.
22. What is a seismograph? How does it work?
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It is an instrument used to measure movements of the ground caused by
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earthquakes.
When seismic waves shake the ground, the heavy pendulum and the pen
remain still. But, the drum moves. As the ground shakes, the pen records the
motion of the paper wrapped around the drum.
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23. Explain what a seismogram is and what it displays.
- The record of seismic waves. It displays the ground motion in two
orientations.
24. What is elastic strain energy? What role does it play with earthquakes?
- The energy stored in an object that had changed shape. They are related to
earthquakes because the rocks involved in earthquakes, at faults, have this
certain type of energy. When the energy is released, the rocks change,
break, or rupture.
25. Who is a seismologist? What do they study?
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A person who studies seismic waves, the movement of earthquakes, and work
with seismographs and seismograms.
26. What is a landslide? How does it occur?
- A sudden movement of rock and soil down a slope. They occur when there are
earthquakes in places with steep slopes.
27. Is the San Andreas Fault one fault or a zone with many faults?
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The San Andreas Fault is a zone or area with many faults.
28. What happens to the energy of the seismic waves as the waves move farther
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from the focus?
As the seismic waves move farther away from the focus, their energy
decreases and they become weaker.
29. What are the steps you should take if you are caught in an earthquake?
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When you start feeling the shaking, you should first go under a table or a
desk and take cover. When it stops, you should go to a place with an open
area, so that items will not fall or hurt you.
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30. Compare and contrast the three types of seismic waves. You should indicate
3-4 facts about each one.
Primary wave:
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They are the fastest waves
They cause the least amount of destruction
They travel through solids and liquids
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They are the first waves to hit the surface.
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They are compressional waves.
Secondary waves:
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They are 60% as fast as P-waves
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They are the middle of speed and destruction.
They travel only through solids.
Rocks move perpendicular to waves.
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Shear stress is related to it.
Surface Waves:
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They are the slowest and most destructive.
The rocks move side to side and up and down.
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They move in the surface of earth, and get stuck in there.
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Good Luck!
Ms. Rozi 