University of HawaiiHonolulu Community CollegeGG101 LabLesson 3 Notes |
The compass can be used to scale the time on the travel time curves.
The epicentral distance is on the distance axis at the point where the P and S wave curves are separated by the recorded time.
A piece of paper can be used just as well. Mark the recorded time between P and S waves on the paper and use it to find the point where the P and S waves are separated by that distance.
Here are illustrations showing how to find the epicentral distance for a time difference of 4 minutes.. Click on any of the images for a larger view.
Compare these to the two figures below (also on the lessons page).