Epicenter Inquiry
Name _____________________________________
Use: http://www.sciencecourseware.org/eec/earthquake/ to complete this activity
Part I: Travel Time Graph: Click on the ‘Travel Time’ button, and then the ‘Start’ button. Read over the guide
and then click on the bomb symbol to get started. Follow the instructions in the box on the lower right.
Station 1 Station 2 Station 3 Station 4 Station 5
S-P Lag-Time (interval) (sec)
Distance (km)
*Hint: When ‘drawing’ best fit slope, get the numbers in the Error Sum of Squares blank the smallest you can.
Questions:
1. __________ km
2. __________ sec
Discussion Question: Why do you think the S-P Lag-Time helped you calculate the distance to the
epicenter?
Part II: Epicenter Location and Richter Magnitude: Click on the ‘Epicenter & Magnitude’ button, and
the ‘Start Activity’ button. Read over the guide and click on the ‘Pick an Earthquake’ button at the top, left of the
buttons. Follow the instructions in the box on the lower right. The table below is in order of completion
(amplitude and distance are switched).
Station S-P (sec) Amplitude (mm) Distance (km) Magnitude
Epicenter: Latitude: ____________ Longitude: ______________
Hint: After you record ‘degrees’, minutes follows in increments of 15’.
Discussion Questions: Discuss the discussion question above and the 3 below with a classmate. Be
prepared to share your thoughts with the class. Write your answers on the back of this page.
a. Why do you think the data table only had room for data from 3 stations when more were available?
b. Why do you think you needed both distance and amplitude to find the magnitude?
c. Could you have found the epicenter with less than 3 seismic stations? Explain your answer.