The Scenario A large earthquake has happened You

The Scenario: A large earthquake has happened. You need to find the earthquakes epicenter to send help. The process of epicenter location has been used for over 50 years.

Steps to “Calculating an Epicenter” Step #1 Calculate the S-P Interval (subtract) Step #2 Use the Time/Distance chart to determine the distance in km. (Record Data) Step #3 Measure the highest amplitude in mm. (Record Data) Step #4 Using the nomogram, use the amplitude and distance to determine the magnitude. A ruler would be helpful in drawing a straight line. Step #5 Use the distance from Step #2 along with the scale at the bottom of the map. Determine the correct distance on the compass and draw a circle around the appropriate seismic station.

Southern California Fresno, CA Seismic Station

Step #1 Calculate the S-P Interval (subtract) P-Wave This is the most important step try to be as accurate as possible. S-Wave Fresno, CA Seismic Station S-P Interval What is the number? 35 seconds Record the number Here Station S-P Interval Distance Amplitude sec km mm Las Vegas, NV sec km mm Phoenix, AZ sec km mm Fresno, CA 35

Step #2 Use the Time/Distance chart to determine the distance in km. (Record Data) The S-P Interval was 35 sec. Follow 35 across until it hits the S-P interval line, then follow it down to determine the distance. What is it? 340 km

Record the number Here Station S-P Interval Distance Amplitude 35 sec 340 km mm Las Vegas, NV sec km mm Phoenix, AZ sec km mm Fresno, CA

Step #3 Measure the maximum amplitude in mm. (use the largest wave) (Record Data) Look Here And Here Record Here The number is? ? 350 mm Station S-P Interval Distance Amplitude 350 49 sec 478 km Las Vegas, NV sec km mm Phoenix, AZ sec km mm Fresno, CA mm

Using the nomogram, use the amplitude and distance to determine the magnitude. A ruler would be helpful in drawing a straight line. Station S-P Interval Distance Amplitude 35 sec 340 km 350 mm Las Vegas, NV sec km mm Phoenix, AZ sec km mm Fresno, CA

Use the distance from Step #2 along with the scale at the bottom of the map. Determine the correct distance on the compass and draw a circle around the appropriate seismic station. Station S-P Interval Distance Amplitude Fresno, CA 35 sec 340 km 350 mm Las Vegas, NV sec km mm Phoenix, AZ sec km mm

Fresno, CA Distance 340 km Don’t worry if it goes off the paper.