Epicenter Lab

Maria Los
21/02/2011
Finding the Epicenter Lab Science 7A
Guiding Question: How can we locate an earthquakes epicenter?
Hypothesis: I think that you use measurements in some way to figure out the epicenter.
Materials:
• drawing compass with pencil
• outline map of United States

Procedure:
1. Make a copy of the data table below.

2. Using the graph below find the difference in the arrival times. Then enter this difference into the data table. To do this you must look at the difference between the P and S arrival time. Find this time on the graph and follow it on the line until you reach the curve of the line.

3. Using the scale on your map set the compass so that it is in cm on the map what it would be in km in the real geographical area. Make sure the sharp end is where the “point” is.
4. Now draw a circle with a radius that was discovered in step 4. Do this for all the countries. Here is an example below of what it should look like.


ANALYZING:
1. Measuring: I located the epicenter to be in Nashville, Tennessee. The closest city to the epicenter is Illinois, Chicago. In kilometers this city from the epicenter is 700 kilometers on the map that I used.
2. Inferring: In order of which cities felt the earthquakes would go like this Chicago, Illinois then Houston, Texas and last but not least Denver, Colorado.
3. Estimating: San Fransisco is around 2,800 kilometers away from the epicenter. If it is around 2,800 kilometers we can tell, using our graph, the difference between the P and S waves. With my graph I figured that the difference between the two waves should be about 2 min 20s.
4. Interpreting: As the distance from the earthquake increases the distance between the P and S waves actually decreases. You can see this when you look at the graph with all the points.
5. Communicating: When you are trying to locate an epicenter it in necessary to know the distance from at least three recording stations because then you have a sufficient amount of information from different sources.

CONCLUSION:
1. So to conclude, the earthquakes epicenter is located somewhere around Nashville, Tennessee. To figure this out I had to find the distance to the epicenter using a graph and the time between P and S waves. Using the distances that I found I used my map to locate exactly where the epicenter should be. This lab taught me how to figure out the epicenter and understand the effects of an earthquake and how they travel.