locating the epicenter
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LOCATING THE EPICENTER
Seismic WavesSeismogramMeasuring Lag TimeFinding the Epicenter
Start here
Seismic WavesThere are three seismic waves
Pri
mary
• P-Waves• These waves
move in a compress and expand motion
• They are the first to arrive to the epicenter S
econd
ary
• S-Waves• These waves
vibrate in a side to side motion
Surface
• L-Waves• These waves
move in an up and down circular motion
• Most destructive wave
Continue to Seismogram
Video of P-wave and S-wave
P-Wave and S-Wave Movement
Back
How the P and S Waves Move
Back to Seismic Waves
How the L Wave Moves
Back to Seismic Waves
•The picture with the squiggly line is called a seismogram•It measures how big the seismic waves are•The seismogram is a piece of paper located on seismograph•A seismograph measures the intensity of the earthquake at a certain location• It does this by having a weight hold a pen as the earth
shakes, the pencil stays still as a squiggly line is created • The more shaking the bigger the lines• The picture to the right is a seismograph
Seismogram
Let’s see how we use this
Seismogram
This is when the P-wave arrives
This is when the S-wave arrives
The difference in time between when the P-wave arrives and when the S-waves arrives, also know as lag time. This is important because it will tell you how far away you are from the epicenter.
How would you find the distance from the epicenter?
A. Locate the how long the P-Wave shakes the seismogram.
B. Find when the S-wave arrives, then the P-wave, and find the lag time between the two.
C. Find when the P-wave arrives, then the S-wave, and find the lag time between the two.
D. HELP!!
I AM SORRY THAT IS INCORRECTTRY AGAIN
This is when the P-wave arrives
This is when the S-wave arrives
The difference in time between when the P-wave arrives and when the S-waves arrives, also know as lag time. This is important because it will tell you how far away you are from the epicenter.
This May HelpTRY AGAIN
This is when the P-wave arrives
This is when the S-wave arrives
The difference in time between when the P-wave arrives and when the S-waves arrives, also know as lag time. This is important because it will tell you how far away you are from the epicenter.
That’s CorrectLets Try Another Question
NE
XT
Which One of These Lag Tables Is Correct?
City P-wave Arrival Time
S-wave Arrival Time
Lag Time
Washington DC 2:10 2:11 1 hourNew York 2:14 2:17 3 minutesChicago 2:19 2:24 4 minutes
City P-wave Arrival Time
S-wave Arrival Time
Lag Time
Washington DC 2:10 2:11 1 minuteNew York 2:14 2:17 3 minutesChicago 2:19 2:24 5 minutes
A.
B.
That is Incorrect
City P-wave Arrival Time
S-wave Arrival Time
Lag Time
Washington DC 2:10 2:11 1 hourNew York 2:14 2:17 3 minutesChicago 2:19 2:24 4 minutes
City P-wave Arrival Time
S-wave Arrival Time
Lag Time
Washington DC 2:10 2:11 1 minuteNew York 2:14 2:17 3 minutesChicago 2:19 2:24 5 minutes
A.
B. This is one should be 1 Minute
This one should be 5 minutes
Correct!Now Let’s See How to Use Your Lag Time to
Locate the Epicenter.
This graph is available at bryonspicci.sslpowered.com
1st Step – Figure out the size of the lag time. Let’s use 1 minute as an example.
2nd Step – Find where the P-wave and S- Wave have the measurement of the lag time.
1. This is how big one minute is
3rd Step - find the distance below.3. Your distance is about 300 miles
2.This is where the lag time is one minute
I do not understand .
Let’s move on
Now Let’s See How to Use Your Lag Time to Locate the Epicenter.
1st Step – Figure out the size of the lag time. Let’s use 1 minute as an example.
2nd Step – Find where the P-wave and S- Wave have the measurement of the lag time.
1. This is how big one minute is
3rd Step - find the distance below.3. Your distance is about 300 miles
2.This is where the lag time is one minute
This graph is available at bryonspicci.sslpowered.com
I do not understand .
Let’s move on
Introduction to Finding the Epicenter
Now You Try
This graph is available at bryonspicci.sslpowered.com
Let say that at your location the P-wave arrives at 9:30 and the S-waves arrives 9:33, how far are you away from the epicenter?
A. 9000 B. 1200C. 1000D. 900
That is IncorrectUse This Hint and Try Again
This graph is available at bryonspicci.sslpowered.com
Let say that at your location the P-wave arrives at 9:30 and the S-waves arrives 9:33, how far are you away from the epicenter?
A. 9000 B. 1200C. 1000D. 900
That is IncorrectHere is Another Hint
Try Again
This graph is available at bryonspicci.sslpowered.com
Let say that at your location the P-wave arrives at 9:30 and the S-waves arrives 9:33, how far are you away from the epicenter?
A. 9000 B. 1200C. 1000D. 900
That is IncorrectThis is Your Final Hint
This graph is available at bryonspicci.sslpowered.com
Let say that at your location the P-wave arrives at 9:30 and the S-waves arrives 9:33, how far are you away from the epicenter?
A. 9000 B. 1200C. 1000D. 900
900
That’s CorrectLets Move on
NE
XT
Here Are Our Three Locations
Washington, DC
New YorkChicago
The Epicenter is Where the Circles Meet
Washington, DC
Washington, DC is 900 miles away click on it
New York is 1200 miles awayclick on it
Chicago is 1900 miles awayClick on it
New YorkChicago
This is epicenter!
Click here to take the quiz.
I think I need more help before taking the quiz
Epicenter Quiz
1. When locating the epicenter, the first thing someone must do is…A. Draw three circles B. Find the arrival time of the p-wave and s-waveC. Find the lag timeD. Locate the focus
2. When locating the epicenter, the second thing someone must do is…A. Draw three circles B. Find the arrival time of the p-wave and s-waveC. Find the lag timeD. Locate the focus
3. Lag time is the difference in time between the _________ and ___________.A. Seismic wave and tsunami B. P wave and T waveC. Shake and AftermathD. P wave and S wave
4. After you find the distance a location is from the epicenter, you need to…A. Draw a circle and find the possible locationsB. Draw a square and find the possible locationsC. Call it a dayD. Decide how big of a circle you need to draw around the epicenter
5. What is the minimum amount of locations you need to locate an epicenter?
Write the answer in the box to the right.
Click here when all questions have been answered
B
CDA3
Correct Answers
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