Locating an epicenter discovery lab

Locating an epicenter discovery lab

Kyle C.

2/3/2011

I. GUIDING QUESTION/S (State the guiding question/s):

How can you locate an earthquake's epicenter (meeting point)?

Where will be the epicenter of the 3 cities (Denver, Colorado; Houston, Texas; Chicago, Illinois?)

II.HYPOTHESIS:

I believe that, the epicenter of 3 cities will be approximately around Oklahoma (just a guess); since I assume that it is the middle of the 3 cities.

Materials:

Pencil

Compass

Map

Marker to locate

IV. RECORD & ANALYZE:

Data Table:

City	Difference in P and S Wave Arrival Times	Distance to Epicenter
Denver, Colorado	2 min 40 seconds	1600 km
Houston, Texas	1 min 50 seconds	1000 km
Chicago, Illinois	1 min 10 seconds	600 km

Short Analysis:

By using the Seismic Wave Arrival Times to calculate the distance to/of Epicenter in bold above, I could use the scale of the map to draw a circle. By drawing the circles with the compass in the United States of America (U.S.A), I could find the epicenter. The epicenter is shaped in a triangle, located at south-west of Nashville, Tennessee.

IV. Concept Acquisition (CONCLUSION) and More Analysis:

1. Drawing Conclusions: Observe the three circles you have drawn. Where is the earthquake's epicenter?

The epicenter of the three cities is located at south-west of Nashville, Tennessee.

2. Measuring: Which city on the map is closest to the earthquake epicenter? How far, in kilometers, is the city from the epicenter?

Nashville is the closest city from the epicenter location; the epicenter and the town is nearly 40-50 km

3. Inferring: In which of the three cities listed in the data table would seismographs detect the earthquake first? Last?

Although I might be wrong, I assume that Chicago, Illinois which is the closest (600 km away) from the Epicenter, since the seismograph will locate and tell which earthquake is occurring first and the closest so it will be easier for people there to move hasty before the chaos.

4. About how far from San Francisco is the epicenter that you found? What would be the difference in arrival times of the P Waves and S Waves for a recording station in San Francisco?

The distance from San Francisco to the epicenter will be around 2800 km (round up to 3000 km), the difference in P and S wave arrival will be 4 and 2/3 minutes (4 min 40 sec).

5. Interpreting Data: What happens to the difference in arrival times between P Waves and S Waves as the distance from the earthquake increases?

I assume that when the distance from the earthquake increases, the difference in P and S wave arrival time will increase too (the time) for example the difference in P and S Waves will be larger of San Francisco than Chicago, Illinois since San Francisco will far and it takes more time for the earthquake to arrive.

6. Communicating: Review the procedure you followed in this lab and then answer the following question. When you are trying to locate an epicenter, why is it necessary to know the distance from the epicenter for at least three recording stations?

It is good to know three locations to find the epicenter since it forms a triangle; we can see that locating an earthquake epicenter produces more accuracy when reading.