Engel’s earth science on a shoestring™
Name ______________________ Date _____________ Hour_____
Earthquakes happen
when crustal plates slip
on each other. The
energy is given off in
waves much
like when
you drop a
stone into a
pond. Two
types of
earthquake waves are P
or Primary and “S” or secondary. The Richter scale measures earthquake
magnitude using the amplitude (height) of the S wave recorded on a
seismogram.
Open the following link and answer the questions that follow.
http://www.classzone.com/books/earth_science/terc/content/visualizations/es1002/es1002page01.cfm?chapter_no=visualization
1. P or Primary waves move _________________.
2. S or secondary waves move ___________________.
Open the following link and answer the questions that follow.
Earthquakes
How and why the earth moves, and different types of quake
Go through the 13 slides and answer the following questions.
3. Most earthquakes occur at the___________________.
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Tsunami
How earthquakes at sea can trigger devastating waves
Go through the 7 slides and answer the following questions.
4. ___________________ are caused by earthquakes at sea.
5. When the waves are slowed by the sea bottom, the waves grow in
_______________.
http://www.indiana.edu/~geol116/week8/earthquakeloc.swf
Open the following link and answer the questions that follow.
http://www.nationalgeographic.com/forcesofnature/interactive/index.html
Choose the tab at the top of the window labeled “Earthquakes”
Tab 1- Worldwide there are about
____________earthquakes.
Tab 2 - _______% of all earthquakes
occur around the ring of fire.
Tab 3-When plates crash together
and shift suddenly it is called an _________________.
Tab 4-Then click next to see the four faults. Click on each one to see how
they are different.
Tab 5-The Hypocenter is directly below the ____________________ center.
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Tab 5-The P waves are ____________ than the S waves.
Tab 6- Earthquakes are triangulated using the time delay between the P
waves and the _____ waves.
Open the following link and answer the questions that follow.
http://www.geology.sdsu.edu/visualgeology/geology101/geo100/earthquakes2.htm
Click through the following buttons on each page to learn about
earthquakes.
For each page on the bottom right, run the slider to the right to see the
animation and answer the following questions.
3. Love waves travel in a __________ like pattern.
4. The P waves always arrive before the _________ waves.
5. On page 11, follow the directions and click
1.8 minutes, the epicenter is ________ miles away.
3.2 minutes the epicenter is ________ miles away.
4.8 minutes the epicenter is ________ miles away.
6. On page 12, Station A is _______ miles away.
7. Station B is ________ miles away.
8. Station C is _______________ away.
Open the following link and answer the questions that follow.
http://www.sciencecourseware.org/VirtualEarthquake/VQuakeExecute.html
Select “Japan Region” then click through the following buttons on each
page to learn about earthquakes. The actual distance to
9. Pusan 56 sec ________ km.
10. Tokyo 44 sec ________km.
11. Akita 71 sec ________km.
Now complete Richter scale!
12. The Magnitude of the quake was ___________.
Background Information
When an earthquake occurs, shock waves spread out in all directions. Different types of
earthquake waves travel through rocky material at different speeds. The earthquake shock waves
that travel fastest are known as P, or primary, waves. P waves are also sometimes called push-pull or
compression waves. Slower waves are S, or secondary, waves. S waves, also known as shear waves,
are the type that causes rock particles to vibrate from side to side. The underground point where the
slip happens is called hypocenter. The point on the land surface directly above the focus is known as
the epicenter.
Seismograph can detect even very weak earthquake shock waves. From the information
recorded by a seismograph, scientists are able to determine the exact arrival times of both P and S
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waves. Since P waves travel faster than S waves, you can determine how far away you are from the
earthquake’s epicenter if you know the difference in the arrival time of the two types of waves. When
information from at least three stations in different locations can be compared, the precise location of
the epicenter can be located.
In this investigation you will duplicate this procedure in a model situation.
Materials (per group) drawing compass with pencil. the graph below, the map of the United States
Procedure
1. Carefully observe Figure 1, which shows a comparison of the difference in arrival time between
P and S waves and distance to the epicenter of an earthquake. Note that the two quantities
are directly related; that is, the greater the difference in arrival time, the greater the distance
to the epicenter.
2. Before going further in this investigation, you will need to become familiar with the graph. Use
the graph to answer the questions.
City
Difference in P and
S Wave Arrival
Time
Denver, Colorado
2 min 30 sec
Houston, Texas
4 min 10 sec
Miami, Florida
5 min 40 sec
Distance
(km)
3. Now that you know how to read the graph, see if you can put it to use. Assume that an
earthquake has occurred and that the times of arrival of the P and S waves from it have
been detected and recorded by seismographs located at the three cities listed in the Data
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Table. Note that the difference in P and S wave arrival times has been included in the
table.
4. Using Figure 1, determine each city’s distance form the earthquake epicenter. Enter your
figures in the Data Table.
5. Use the map scale to set your compass at a radius equal to the distance from Denver to the
earthquake epicenter.
6. Draw a circle with the radius determined in step 5, using Denver as the center. Draw the
circle on the map in Figure 2.
7. Repeat steps 5 and 6 for Houston and Miami.
8. If you have worked carefully, the three circles should intersect at one point. This point
marks the epicenter of the earthquake.
Observations:
Data Table 1 Figure 2
13. If the difference in arrival time for P and S waves at a certain location is 3 min, how far
from that station is the epicenter? A. 430 km B. 1400 km C. 1800 km D. 2100 km
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14. If a seismograph shows that a P wave arrives 7 min 20 sec before an S wave, how far is it
to the earthquake’s epicenter?
15. If a recording station is known to be 4600 km from an earthquake epicenter, what is the
difference in arrival time between the P and S waves from that earthquake?
16. If a seismograph is located 2200 km from an earthquake epicenter, how great will be the
difference in arrival time between the P and S waves at this station?
Conclusions
17. A. Which city on the map is closest to the earthquake epicenter? __________
B. How far, in km, is this city from the epicenter? _______________
18. Which of the three cities listed in the Data Table would have become aware of the earthquake
first? ______________ Second? ____________________ Third? _____________________
19. Why was it necessary to know the distance from the epicenter for at least three recording
stations to be able to locate the epicenter? _______________
________________________________________________________
20. If the epicenter of this earthquake were located in San Francisco, how much earlier than the S
wave would the P wave arrive for an observer in New York
City?__________________________________________________
21. As the distance between and observer and an earthquake decreases, the difference in arrival
times of P and S waves
a. decreases
b. increases
c. remains the same.
Critical Thinking and Application
22. How far from an earthquake epicenter would an observer be if he or she measured a difference
of 8 minutes and 40 second between the arrival times of a P and S wave?
_________________________________________________________________
23. What kinds of landforms would you be most likely to find in an earthquake zone?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
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Open the following link and answer the questions that follow.
http://www.sciencecourseware.org/eec/Earthquake/
Go to “Demonstration”
Click the
button
“Travel
Time”
on your
screen.
Read the paragraphs and press the forward button to advance through the slides.
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Then Click “Epi and Mag
The rest of this lab is all extra, you are done!
Go put your answers into Moodle!
For hot shots honor links:
http://tlc.discovery.com/convergence/quakes/interactives/makeaquake.html
http://earthquake.usgs.gov/learning/kids/
http://www.pbs.org/wnet/savageearth/animations/earthquakes/index.html
http://earthquake.usgs.gov/learning/topics.php?topicID=55&topic=Instrumentation,%20seismographs,%20monitoring
http://www.data.scec.org/Module/s3act02b.html
http://dsc.discovery.com/guides/planetearth/earthquake/interactive/interactive.html
www.cas.muohio.edu/scienceforohio/Rocks/Rr.html
www.bedford.k12.ny.us/.../images/default.html
http://tlc.discovery.com/convergence/quakes/interactives/makeaquake.html
http://earthquake.usgs.gov/learning/topics.php?topicID=55&topic=Instrumentation,%20seismographs,%20monitoring
http://cse.ssl.berkeley.edu/lessons/indiv/davis/inprogress/Where.html
visualclutter.com/Links/Science/
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How Do Earthquakes Travel?
Seismic waves are waves that travel through the Earth by cause of explosion or an earthquake. The two types of
seismic waves are "body waves" and "surface waves".
Body Waves: waves that travel through the interior of the Earth
- P-Waves (primary waves) can travel through any material and travel twice as fast as S-Waves.
- S-waves (secondary waves) can only travel through solids. Liquids and gases cannot sustain the force.
Surface Waves: are similar to water waves. They travel slower than body waves and have a low frequency, long
duration, and large amplitude. These can be the most destructive.
- Rayleigh Waves (ground roll) travel in ripples similar to waves in a body of water.
- Love Waves (L waves) can cause circular shearing of the ground. Move faster than Rayleigh waves.
Click here to watch a video showing the characteristics of the waves described above Earthquake Waves Animation
Determining the Epicenter
To locate an earthquake's epicenter you must have 3 seismograms recorded from that earthquake. After finding the
arrival times of the primary and secondary waves you can calculate the time difference by subtracting the p-waves
arrival from the s-waves time. Then using a method involving a map and grid paper, you can estimate the location of
the earthquakes epicenter.
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Boundary Types
Divergent Boundaries occur when two tectonic plates move away from one another. This is an example of a reverse
thrust fault. These are most common between oceanic plates and also can form volcanic ridges.
Convergent Boundaries (a.k.a. destructive plate boundary) cause deformities where two tectonic plates come together
and collide. These kind of boundaries occur at a thrust fault. These are common sites for volcanic activity. There are
three types of convergent boundaries:
- Oceanic Continental
- Continental Continental
- Oceanic Oceanic
Transform Boundaries occur when two plates slide past each other. They
are mostly found on the ocean floor where they form spreading ridges in a
zig-zag pattern.
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