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Correlation between P & S Arrivals and Earthquake Depth
Charlena Sieve
Bloomington High School North
Problem: Is their any correlation between the depth of an earthquake and the P and S arrival times?
Objective:
• Recognize and mark the P and S arrivals on a seismogram.
• Compare and contrast the pulses represented by each of the waves associated
with an event.
• Evaluate P and S arrivals and the depth of an earthquake.
Materials:
5 Seismograms
Rulers
Procedure:
1. Acquire seismograms with depth (received at the same location) from 5 different
earthquakes occurring in the same region.
2. Mark the P and S waves on each of the Seismograms. Record times on data table.
3. Calculate the difference between the P and S arrival time.
4. Observe any similarities or major differences in the P or S waves either
within the individual seismogram or among all 5. Record observations.
5. Record depth listed on each seismogram in data table. Note which category
the depth occurs:
Shallow <70 Km
Intermediate 70 – 300 Km
Deep > 300 Km
Observations:
Earthquake Seismograph Similarities Seismograph Differences
Data Table:
Earthquake location Date/Time |
Latitude |
Longitude |
Magnitude |
Depth
of Earthquake |
P-wave
Arrival Time |
S-wave
Arrival Time |
Difference
Between P & S Arrival |
Analysis Questions:
1. Is there a correlation between
the arrival times of the P waves and the depth of the earthquake?
2. Is there a correlation between the difference between the P and S waves and
the depth of the earthquakes?
3. Were there any observable similarities on the seismograms of the deep earthquakes?
4. Were there any observable differences between the seismograms based on their
depth?
5. Did any of these earthquakes coincide with a plate boundary? If so, which
ones?
Conclusion:
Teacher Notes
There are several variations to this Lab. Students can use seismograms which you have printed off for this activity. Students can use the Eqlocate program to assist them in this activity. Students can go into the IRIS Homepage and find events of interest which you can download, and be viewed in the Winquake program for this activity.