Seismic Waves and Earthquake Hazards
Goals:
-Explore the properties of the different kinds of waves.
-Examine the impact of the different types of waves.
-Look at some local, regional and global seismic hazards
-Examine what we can do to be earthquake aware.
Introduction
Since we have already talked about earthquakes, what causes them, the waves they produce and the processes associated with those waves, I am going to keep the introduction short. There are a few web links that contain some fun animations that help clarify the concepts associated with earthquakes and seismic waves. Just check them out quickly before you get started!
Part I: Properties of waves.
(For some this may be review, but is is always good to review!)
We are going to use the Allen Jones Seismic Wave simulation to explore properties of seismic waves. Open the Seismic Wave simulation by going to the Program Menu and clicking first on the "Seismology" folder and then opening "Seismic Waves." Once the program is open
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button.Questions:
1. Draw the path of the first P-wave through the earth. At each boundary (between layers of the earth) describe why the wave path changes. What properties of the P-waves make it behave the way it does?
2. Draw the path of the first S-wave through the earth. At each boundary (between layers of the earth) describe why the wave path changed. What properties of the S-waves make it behave the way it does?
3. How much delay (in minutes) is there between the arrival of the P-wave and S-wave? The S-wave and Surface waves? This delay will tell you how far away the seismic station is from the epicenter. We won't calculate that now, but we will explore it a bit later in the lab.
4. Judging (just do a qualitative assessment) by the amplitude of the P-waves, S-waves and Surface waves, do you think people in France (the first seismic station) were able to feel this earthquake?
5. Do a Google search on the Izmit, Turkey (1999) earthquake. How far away was the earthquake felt? Using images you found, what was the Mercalli Intensity of the Izmit earthquake? Which waves did the most damage?
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6. Imagine you are standing at the College Outpost, Alaska seismic station. Describe what the ground (how might the different waves look as they moved through the ground) would look like in the first 5 minutes of the quake.
7. Do another Google search on the Denal Fault Earthquake. How is this earthquake similar or different from the Izmit earthquake?
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8. Notice the depth of the Bolivian earthquake! You will also notice a lack of surface waves because of the great depth of the quake. At what kind of plate boundary do you suspect this earthquake occurred?
Part II: Virtual Seismologist
California State University at Los Angeles has designed a "Virtual Earthquake" Web site which talks you through how earthquakes are located in 2 dimensions. Access the site and click on the
to get started. Follow the instructions to become a virtual seismologist!
Note: There are no questions associated with this section. Make a note of what earthquake you used and how the process went!
Part III: Is my home earthquake safe?
So we all agree that Bozeman is located in reasonably seismically active region. If you don't believe me just check out the data! The Federal Emergency Management Agency has a checklist for homeowners to help them avoid earthquake damage.
9. Go through you house or dorm room and assess as many questions as possible.
10. Are your living quarters "safe" according to FEMA's checklist?
11. What could you do to be better prepared if/when the "big one" hits Bozeman?
| L.B. Cantwell 1/29/04 | Return to Class Homepage |
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