1. Goal  Locate the epicenter of an earthquake

2. What is an Epicenter? A point on the surface of the Earth directly above the FOCUS of the earthquake. The point within the Earth from which earthquake waves originate.

4. Use the data from the recording stations: Station A: San Francisco, California P-Wave arrival 3:02:20S-Wave arrival 3:06:30 What is the time difference between P and S wave arrivals?

5. Use the data from the recording stations: Station B: Denver, Colorado P-Wave arrival 3:01:40S-Wave arrival 3:05:00 What is the time difference between P and S wave arrivals?

6. Use the data from the recording stations: Station C: Missoula, Montana P-Wave arrival 3:01:00S-Wave arrival 3:03:00 What is the time difference between P and S wave arrivals?

7. Difference in arrival times (LAG TIME): San Francisco: 4:10 min. Denver, Colorado: 3:20 min. Missoula, Montana: 2:00 min. 2,800km 1,100km 2,000km

8. Using the distance from the station to the epicenter: San Francisco: 4:10 =2,800km 1,000 2,000 3,000 4,0005,000 Open your compass to the EXACT distance on the scale.

9. ... 2,800km 2,000km 1,100km