Your task will be to locate the epicenter for the earthquake using the arrival time of P-waves and S-waves from several seismic stations.
science
Description
Geologic Events Lab Report
Introduction:
Your task will be to
locate the epicenter for the earthquake using the arrival time of P-waves and
S-waves from several seismic stations. Upon completion of the virtual lab, you
will write a laboratory report of your results.
Problem:
How can we use seismic waves to determine the
epicenter of an earthquake?
Hypothesis:
Review the Introduction
tab of the pre-lab within the lesson. Hypothesize how
seismographs will be used to pinpoint the epicenter of the Earthquake.
Materials:
Use the reference image
in the Reading Seismographs tab of
the pre-lab to identify the S-P Time interval of a seismograph reading. Use the
Determining Distance to an Epicenter
tab and the Locating an Epicenter
tab of the pre-lab as practice before completing the procedures below.
Procedures:
- Examine
the reference image under Materials
to learn to identify the S-P time interval of a seismograph reading.
- Under
Data and Observations,
determine the S-P time intervals of all three stations using the time
scale under the seismograph readings. For example, if P wave arrives at
2:02 pm and the S wave arrives at 2:27 pm, the total S-P time interval is
25 minutes.
- Record
the time interval for each station in Table
1 under Data and Observations.
- To
determine the distance from each seismograph to the epicenter, you
multiply the S-P time interval by 10. For example, if the time interval is
25 minutes, 25 x 10 = 250 kilometers.
- Record
the calculated distance to each station from the epicenter in Table 1 under Data and Observations.
- Next,
use the distance scale under Data
and Observations to measure the three circles provided, each with a
radius that equals the distance of each station. To measure, place the
center of each circle at zero. An example measurement is shown below for a
75 km radius.
- Place
each of the measured circles around the station on the map that they
represent. All three circles should have one intersecting point that
matches the epicenter.
- Complete
the Questions and Conclusion
section of the lab report.
Variables:
For this investigation, list the independent, dependent, and
controlled variables.
Data and Observations:
S-P Time Intervals
