Name: _______________________
Period: ______ Date: ___________
VIRTUAL EARTHQUAKE
An Activity on the World Wide Web
Directions: In this activity you will try to predict the origin of an earthquake by interpreting seismograph
readings recorded at three seismic stations. The computer will let you know how you have done and show you
where the epicenter really was located. The data used in the simulation is from real earthquakes that have
occurred.
Let’s get rockin! Go to google and type in: Virtual Earthquake. Click on the choice with the following ULR
or type it into your browser:
http://www.sciencecourseware.com/VirtualEarthquake/VQuakeExecute.html
Step #1- Read the introduction page and answer the following questions. Some of the material will be a review
of what we learned in class and some of it will be new.
1. What is the point of origin of an earthquake called? (be careful)
2. What are the 2 types of waves that interest us most when studying the origin of an earthquake?
3. What type of matter can P-waves travel through?
4. What type of matter can S-waves travel through?
5. What is a seismogram?
6. What does the S-P interval refer to?
7. How many recording stations are needed to find the epicenter of an earthquake? Why?
Step #2- You will be completing 2 of the 4 earthquake simulations. Everyone will be doing San Fransisco and
one of your own choice. As you work through the simulations, please record all of your data from the computer
on the following worksheet in pencil. Make sure to record all your data under the proper earthquake.
Click on San Fransisco to begin your simulation. Click on, Submit Your Choice.
Read the paragraph on measuring S-P interval. You will want to be very accurate, so make sure you look at the
way the seconds were calculated on the sample (Remember that each blue vertical line represents 2 seconds).
Click on, View Seismograms, and record the data in the appropriate space for the earthquake you are doing.
Earthquake Name:
San Fransisco
S. California
Japan
Mexico
Location #1
S-P Time (Seconds):
Location #2
S-P Time (Seconds):
Location #3
S-P Time (Seconds):
Step #3- Click on, Convert S-P Interval. According to the sample graph, how long does it take a P-wave to
travel 200 km? A P-wave 200 km?
P-wave = __________
S-wave = __________
Scroll down to the larger graph that shows only the S-P interval curve. Record your epicentral distances.
Epicentral Distances:
San Fransisco
S. California
Japan
Mexico
Seismograph #1
Seismograph #2
Seismograph #3
After you have entered the distances into the corresponding boxes, click on, Find Epicenter. You will receive
one of the following messages:
If your screen says “OOOPS” this means you have probably made a mistake in your calculations. In
this case, click on, Remeasure S-P Interval, and try again. (This is why you should use pencil).
If your screen says, Very Close, this means your three epicentral distances are very close to
intersecting at one point. You do not have to remeasure your S-P interval, click on View True
Epicenter to see how close you are. Once you find the true epicenter, click on Compute Richter
Magnitude.
If your screen says “Excellent Work” this means that you found the true epicenter of the earthquake.
Click on Compute Richter Magnitude.
Answer the questions about Richter Magnitude, based on the information in the Magnitude Explained section.
1. What does the richter scale measure?
2. What is the magnitude of an earthquake?
Look at the example of the Amplitude Measurement in the given seismograph. Again, you will need to be as
accurate as possible, so take note of the example measurement. Remember, each horizontal blue line represents
10 millimeters. Click on Go To Next Page.
According to the Richter Nomogram, if we change one unit of magnitude, the maximum amplitude increases by
what factor?
Click on, Go To Next Page. Record your Amplitudes under the correct earthquake location.
Amplitude:
San Fransisco
S. California
Japan
Mexico
Seismograph #1
Seismograph #2
Seismograph #3
Click on, Submit To Nomogram. The screen that appears will show you where your three amplitudes cross. At
this point, you will estimate what you think the Richter magnitude is. Record this on the screen and below.
San Fransisco
S. California
Japan
Mexico
Estimated
Magnitude:
Click on, Confirm Magnitude. You will either see a message congratulating you for a great job, or one that
tells you the actual magnitude, one that compared poorly to your estimate. You do not need to remeasure the
magnitude.
San Fransisco
Actual
Magnitude:
S. California
Japan
Mexico
Answer the following questions:
1. When did this earthquake occur?
2. What is the name of this earthquake?
a.
b.
Click on, Execute Virtual Earthquake, to study the second earthquake. Scroll down to the bottom of the page.
Click on the circle of the second earthquake you want to study next, and click on, Submit Choice. Continue
through the slides until you have finished collecting data on your second earthquake.
Turn in your worksheet with all of your data recorded on it.
Congratulations! You are a seismologist!