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Physical Geology Helpful Lab Hints
Exercise 16: Earthquakes
Problem 1.a.
- The best way
to prepare for this exercise is to complete the virtual earthquake exercise at
http://64.239.9.13/VirtualEarthquake/ for extra credit.
- Use the three
seismograms found on page 314.
- (1) To
locate the distances from each station to the epicenter.
- Use the
edge of a piece of paper to mark the difference between P & S for station A.
- Go to the
graph on page 315. Turn the paper so the marked side is vertical and
find the place on the graph where the S & P lines are separated by that
vertical distance. (This works because the time scales for the
seismograms and the graph are the same.)
- Read down
the edge of the piece of paper to the bottom (X-axis) of the graph and read
the distance in kilometers.
- Draw a line
along the edge of the piece of paper to mark your location.
- Repeat for
stations B & C
- (2)
Go to the map on page 316 and plot the location of each station using the
longitude and latitude provided in the caption at the bottom of the map.
Note: The stations are not located in any city depicted on the map.
- (3)
Using a pencil compass (available in the Bio Lab) draw a circle around each
of the stations.
- Each
circle will have a radius equal to the distance you determined in part
(1). (Careful, each circle has a different radius.)
- The
circles should intersect. If they are close, the intersection will
be a small triangle.
- If the
triangle is large, check your circles to be sure they were drawn
correctly.
- The
epicenter is the point where the three circles intersect OR the center of
the small triangle.
- (3)
Not everyone in the class will have exactly the same location, why not?
(Be sure to answer this question.)
Back to lab 16 help.
copyright © 200 Mike Phillips (includes all
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last updated: 10/22/07