Practice Set #2
In order to determine the location of an epicenter, you not only need to know 3 or more places that
experienced the event, you also need to know or be able to find out how far the epicenter was from
each city. Below is a graph that shows the relationship between distance and P-S lag time. Use that
data to determine the distances the cities were from the epicenter of one or more earthquakes. Then
answer the analysis questions that follow.
S-P Lag Time (m/n)
1 minute 20 seconds
3 minutes 25 seconds
3 minutes 42 seconds
4 minutes 5 seconds
San Fransisco
4 minutes 23 seconds
Los Angeles
5 minutes 8 seconds
Las Vegas
6 minutes 15 seconds
Lake Tahoe
7 minutes 55 seconds
8 minutes 25 seconds
Distance from Epicenter (km)
1. In a graph like this one, which data represents the independent variable?
2. Which data represents the dependent variable?
3. What happens to the distance as the time increases?
4. What happens to the time as distance decreases?
5. What is the relationship between distance and lag time?