Finding an Epicenter

-DeMarco

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.

How can I find out where an earthquake happened?

• You will need data from 3(three) recording stations.

• You will need your ESRT• You will need scrap paper

• You will need a map of the area

• You will need a map scale

• You will need a drawing compass

Use the data from the recording stations:

• Station A: San Francisco, California

P-Wave arrival 11:26:10 S-Wave arrival 11:28:50

What is the time difference between P and S wave arrivals?

Recording BoardDifference in arrival times:

San Francisco: 2:40

Use the data from the recording stations:

• Station B: Denver, Colorado

P-Wave arrival 11:28:50 S-Wave arrival 11:33:50

What is the time difference between P and S wave arrivals?

Recording BoardDifference in arrival times:

San Francisco: 2:40

Denver, Colorado: 5:00

Use the data from the recording stations:

• Station C: Seattle, Washington

P-Wave arrival 11:26:20 S-Wave arrival 11:31:50

What is the time difference between P and S wave arrivals?

Recording BoardDifference in arrival times:

San Francisco: 2:40

Denver, Colorado: 5:00

Seattle, Washington: 5:30

Recording BoardDifference in arrival times:

San Francisco: 2:40

Denver, Colorado: 5:00

Seattle, Washington 5:30

Using your ESRT, find out how far away (in Km) each of the locations must be from the epicenter.

(Use the scrap paper tick mark method!)

=1,600km

=4,000km

=3,400km

Recording BoardDifference in arrival times:

San Francisco: 2:40=1,600km

1,00

0

2,00

0

3,00

0

4,00

0

5,00

0

Open your compass to the EXACT distance on the scale.