Unit 3 - Notes / Student Guide

Earthquake Waves, the ESRT, and You

What does the ESRT chart tell us?

 The amount of ______that waves have traveled (x-axis)  The amount of ______that waves have traveled (y-axis)  The distance to the epicenter. (difference in arrival times)

Ex: A) How much time does a P wave take to travel 4000 km? ______

B) How much distance can an S wave travel in 17 min? ______

“Talking Heads”

1. How much time does a P wave take to travel 6200 km? ______

2. How much time does an S wave take to travel 3400 km? ______

3. How much distance can an S wave travel in 9 min 20 sec? ______

4. How much distance can a P wave travel in 7 min 40 sec? ______

5. ______

6. ______

How can we find the distance to an epicenter? (procedure)

Ex: Finding the Distance to the Epicenter using Seismograms

If a seismograph recording station records the arrival times of the P and S waves, how is the distance to the epicenter determined? We use the difference in arrival times between the P and S waves.

Step 1: Determine the difference in arrival times of the P and S waves.

Step 2: Mark the time difference from the y-axis on the edge of your paper.

Step 3: Align the marks vertically between the wave curves on the graph.

Step 4: Read the value from the x-axis to find the distance to the epicenter.