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Activity 1.1 - Find The Center

The activity aims to teach participants how to locate the epicenter of an earthquake using the triangulation method with hypothetical seismic data from three recording stations. Participants will compute distances based on the time difference between P-wave and S-wave arrivals, draw circles on a map, and identify the intersection point as the epicenter. The document also poses questions regarding the epicenter's location, challenges with limited data, and the importance of determining the epicenter.

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Christopher Caballa
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77 views4 pages

Activity 1.1 - Find The Center

The activity aims to teach participants how to locate the epicenter of an earthquake using the triangulation method with hypothetical seismic data from three recording stations. Participants will compute distances based on the time difference between P-wave and S-wave arrivals, draw circles on a map, and identify the intersection point as the epicenter. The document also poses questions regarding the epicenter's location, challenges with limited data, and the importance of determining the epicenter.

Uploaded by

Christopher Caballa
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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ACTIVITY 1.

1: Find the Center


Group No: ______
Members:
____________________________________________________________
_____________________________________________________________
____________________________________________________________
_____________________________________________________________
____________________________________________________________
_____________________________________________________________
____________________________________________________________
_____________________________________________________________

Objective: At the end of the activity, you should be able to locate the epicenter of an earthquake
using the 1triangulation method.
Materials: hypothetical records of earthquake waves, Philippine map, drawing compass and
ruler
Procedure:
1. Study the data showing the difference in the arrival time of P-wave and S-wave on three
seismic recording stations.
Recording Station Time difference in the Distance of epicenter
arrival time of P-wave and from the station (km)
S-wave (seconds)
Batangas 33.4
Puerto Princesa 37.6
Davao 30.0

2. Compute the distance of the epicenter from each of the stations using this formula:

d= x 100 km
Td
8 seconds

Where: d= distance (km)


Td = time difference in the arrival time of P-wave and S-wave (seconds)
This formula is suited because 8 seconds is the interval between the times of arrival of
the P-wave and S-wave at a distance of 100 km.
3. Choose one of the recording stations and measure the computed distance on the map
scale (the scale of the map in Figure 3 is 2.3 cm: 200 km). Set your compass for that
computed distance.
4. Center your compass on the station you have chosen. Draw a circle.
5. Repeat steps 3 and 4 for the rest of the stations. You should get three circles that
intersect or nearly intersect at a point. This intersection is the epicenter.

Question 1: Where is the epicenter of this hypothetical earthquake?

Question 2: What difficulty will you encounter if you only have data from two recording
stations?

6. The hypothetical earthquake happened locally, that is why we use the formula
stated in the procedure. But, if the earthquake took place at a far greater
distance, seismologists use the distance-time graph similar to the figure below in
determining the location of the epicenter.

1
Question 3. What is
the distance of the
epicenter from the
seismic station?

Question 4. What do
you think is the
importance of
determining the
epicenter of an
earthquake?

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