Seismic WavesPage 26

Types of Waves

P waves – Primary WavesLongitudinal

Compression/RarefactionSpeed: Faster

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Types of Waves

S waves – Shear WavesTransverse

Crest/troughCan not pass through liquid

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Types of Waves

Surface waves – combination of P and SSpeed: Slow moving

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Types of Waves

Ocean waves – TsunamiSize: Above normal by 2 cm to 30 meters

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Tsunami

1. Variables2. Distance in

two hours?Distance in four hours?

3. Easter Island is 3,700 miles away, time?

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Seismograph

Records ground movementsMeasure S and P waves sense they arrive

at different timesNeed three points to determine the locationCan be used to locate underground

resources

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Richter vs. Mercalli Scales