Do Now• Power on your laptops and download the

earthquake PS wave travel time notes.

• Please take out your reference tables.

• H.W. Continue your castle learning assignment questions 31 – 36.

• Reminder:– The 3rd quarter ends next Friday. All missing

work must be in by then or the ZERO stays!!

Topic: Seismic Wave Travel Topic: Seismic Wave Travel TimeTime

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Using the scaleUsing the scale x10x1033 km = 1000 km km = 1000 km

Th

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Ep

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Ep

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3000 k

m

3000 k

m

from

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m

ep

icen

ter

ep

icen

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1200 k

m

1200 k

m

from

fro

m

ep

icen

ter

ep

icen

ter

7000 k

m

7000 k

m

from

fro

m

ep

icen

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ep

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4400 k

m

4400 k

m

from

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ep

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ep

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Time unit is minutesTime unit is minutes

1 minute = 60 1 minute = 60 secondsseconds

0 0 secondsseconds

60 60 secondsseconds

20 20 secondsseconds

40 40 secondsseconds

8 min, 00 sec8 min, 00 sec

11 min, 40 sec11 min, 40 sec

3 min, 20 sec3 min, 20 sec

5 min, 30 5 min, 30 secsec

P waves

S waves

Epicenter

How long does it How long does it take for a P wave take for a P wave

to travel 4000 to travel 4000 km?km?

7 minutes7 minutes

How long does How long does it take for an S it take for an S wave to travel wave to travel

4000 km?4000 km?

12 min 40 sec12 min 40 sec

How far does an How far does an S wave travel in S wave travel in

21 minutes?21 minutes?

8200 km8200 km

How far does an How far does an P wave travel in P wave travel in

6 minutes 20 6 minutes 20 seconds?seconds?

3500 km3500 km

If the epicenter If the epicenter is 2000 km is 2000 km

away, and the P away, and the P wave is wave is

recorded at recorded at 5:04 am, what 5:04 am, what time did the time did the earthquake earthquake

occur?occur? 5:04 am – 4 min 5:04 am – 4 min = 5:00am= 5:00am

Final Question:Final Question:

• How much further does a P wave How much further does a P wave travel in 8 minutes than an S wave travel in 8 minutes than an S wave does?does?

P wave = 4800 P wave = 4800 kmkm

S wave = 2200 S wave = 2200 km km

Difference = Difference = 2600km2600km

Topic: How to Find The Topic: How to Find The Distance From an EpicenterDistance From an Epicenter

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2:30:00

2:36:00

The time different is 6 minutes

• We don’t know We don’t know when the when the earthquake started.earthquake started.

• We do know the We do know the difference between difference between the P&S wave the P&S wave arrival times.arrival times.

• 00:06:00 minutes00:06:00 minutes

• Find where Find where P&S are P&S are separated separated by 6:00 by 6:00 minutes.minutes.

• The distance The distance to the to the epicenter epicenter from the from the seismograph seismograph is 4400 km.is 4400 km.

Final Question:Final Question:

• If a P wave arrives at 6:32 pm at the If a P wave arrives at 6:32 pm at the seismograph, and the S wave arrives seismograph, and the S wave arrives at 6:34 pm, What is the distance to at 6:34 pm, What is the distance to the epicenter?the epicenter?

1400 km

P-wave AT = 6:32 AM

S-wave AT = 6:34 PM

Difference = 0:02 Min

Epicenter Distance = 1400 km