describes what and where the epicenter is

1. Locating the Epicenter of an
Earthquake

2. How do scientists locate the epicenter of an earthquake?
Seismologists determine the location of the epicenter of an
earthquake through TRIANGULATION METHOD.
TRIANGULATION METHOD
Method that uses distance information from three seismic
stations to locate the earthquake epicenter. Circles are drawn
on a map around each seismic station. The point where three
circles intersect is the location of the epicenter of an
earthquake.

3.  Missoula, MT
Seismographic Data
 San Francisco, CA
 Denver, CO

4. Use the data from the recording
stations:
• Station A: San Francisco, California
P-Wave arrival 3:02:20 S-Wave arrival 3:06:30

5. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City
1. San Francisco,
CA
3:02:20 3:06:30 4:10
2. Denver, CO
3. Missoula, MT
Data Table

6. 4:10

7. EPICENTER DISTANCE
OF 2800 KM
4:10

8. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. San Francisco,
CA
3:02:20 3:06:30 4:10 2800 km
2. Denver, CO
3. Missoula, MT
Data Table

10. Use the data from the recording
stations:
• Station B: Denver, Colorado
P-Wave arrival 3:01:40 S-Wave arrival 3:05:00

11. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. San Francisco,
CA
3:02:20 3:06:30 4:10 2800 km
2. Denver, CO 3:01:40 3:05:00 3:20
3. Missoula, MT
Data Table

12. 3:20

13. 3:20
EPICENTER DISTANCE
OF 2300 KM

14. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. San Francisco,
CA
3:02:20 3:06:30 4:10 2800 km
2. Denver, CO 3:01:40 3:05:00 3:20 2300 km
3. Missoula, MT
Data Table

16. Use the data from the recording
stations:
• Station C: Missoula, Montana
P-Wave arrival 3:01:00 S-Wave arrival 3:03:00

17. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. San Francisco,
CA
3:02:20 3:06:30 4:10 2800 km
2. Denver, CO 3:01:40 3:05:00 3:20 2300 km
3. Missoula, MT 3:01:00 3:03:00 2:00
Data Table

18. 2:00

19. TAKE A PIECE OF PAPER, AND MARK
OFF THE DIFFERENCE IN ARRIVAL TIME
2:00
EPICENTER DISTANCE
OF 1100 KM

20. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. San Francisco,
CA
3:02:20 3:06:30 4:10 2800 km
2. Denver, CO 3:01:40 3:05:00 3:20 2300 km
3. Missoula, MT 3:01:00 3:03:00 2:00 1100 km
Data Table

22. X

23. Compare your answer to the historical record
Missoula
Denver
San Francisco
X
Syracuse

24. Seismographic Data

25. • Station A: Balboa Heights, Panama
P-Wave arrival 0:19:00 S-Wave arrival 0:23:50
Use the data from the recording
stations:

26. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50
2. Boulder, Colorado
3. Mexico City,
Mexico
Data Table

27. 4:50

28. 4:50
EPICENTER DISTANCE
OF 3200 KM

29. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50 3200 km
2. Boulder, Colorado
3. Mexico City,
Mexico
Data Table

30. Recording Board
Difference in arrival times:

31. • Station B: Boulder, Colorado
P-Wave arrival 0:16:00 S-Wave arrival 0:18:35
Use the data from the recording
stations:

32. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50 3200 km
2. Boulder, Colorado 0:16:00 0:18:35 2:35
3. Mexico City,
Mexico
Data Table

33. 2:35

34. 2:35
EPICENTER DISTANCE
OF 1600 KM

35. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50 3200 km
2. Boulder, Colorado 0:16:00 0:18:35 2:35 1600 km
3. Mexico City,
Mexico
Data Table

36. Recording Board
Difference in arrival times:

37. • Station A:Mexico City, Mexico
P-Wave arrival 0:17:25 S-Wave arrival 0:21:00
Use the data from the recording
stations:

38. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50 3200 km
2. Boulder, Colorado 0:16:00 0:18:35 2:35 1600 km
3. Mexico City,
Mexico
0:17:25 0:21:00 3:35
Data Table

39. 3:35

40. 3:35
EPICENTER DISTANCE
OF 2400 KM

41. City P-wave
arrival
time
S-wave
arrival time
Lag Time
(S-P)
Distance from
City (km)
1. Balboa Heights
Panama
0:19:00 0:23:50 4:50 3200 km
2. Boulder, Colorado 0:16:00 0:18:35 2:35 1600 km
3. Mexico City,
Mexico
0:17:25 0:21:00 3:35 2400 km
Data Table

42. Recording Board
Difference in arrival times:

43. Recording Board
Difference in arrival times:
X