Podcast
Questions and Answers
What is the primary difference between P waves and S waves on a seismogram?
What is the primary difference between P waves and S waves on a seismogram?
What is necessary to locate the epicenter of an earthquake?
What is necessary to locate the epicenter of an earthquake?
What is the primary cause of earthquakes?
What is the primary cause of earthquakes?
What is the primary measure of an earthquake's magnitude?
What is the primary measure of an earthquake's magnitude?
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What is the location where rocks begin to move or break called?
What is the location where rocks begin to move or break called?
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What type of wave can pass through all states of matter?
What type of wave can pass through all states of matter?
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What is the problem with the Richter scale?
What is the problem with the Richter scale?
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What is liquefaction?
What is liquefaction?
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What is the purpose of a seismograph?
What is the purpose of a seismograph?
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What is the primary cause of damage from aftershocks?
What is the primary cause of damage from aftershocks?
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What type of movement is caused by Love waves?
What type of movement is caused by Love waves?
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What is the function of the pen in a seismograph?
What is the function of the pen in a seismograph?
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What is a common consequence of gas leaks after an earthquake?
What is a common consequence of gas leaks after an earthquake?
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What is the typical speed of a tsunami?
What is the typical speed of a tsunami?
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What is the relationship between the distance the pen moves and the strength of an earthquake?
What is the relationship between the distance the pen moves and the strength of an earthquake?
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What is the reason why surface waves cause more damage than P and S waves?
What is the reason why surface waves cause more damage than P and S waves?
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Study Notes
Causes of Earthquakes
- Earthquakes are caused by the release of energy from the Earth's crust
- Common causes of earthquakes include volcanic eruptions, cavern collapses, meteor impacts, and stress built up around faults and plates
- Faults are breaks in the lithosphere where movement has occurred
- Strain builds up due to friction holding plates together, leading to stress release and an earthquake
- The focus is the location where the rocks begin to move or break
- The epicenter is the Earth's surface directly above the focus
Body Waves
- P waves (primary waves) squeeze and stretch rocks and can pass through all states of matter
- S waves (shear waves or secondary waves) cause particles to move at right angles against the direction of the wave and can only travel through solids
Surface Waves
- Love waves cause side-to-side particle movement
- Rayleigh waves have an elliptical pattern of movement and are slower than love waves
- Surface waves cause more damage than P and S waves
Locating and Measuring Earthquakes
- Seismographs detect and record waves produced by earthquakes
- Modern seismograph stations have three seismographs, recording up-and-down, north-south, and east-west movements
- A seismogram is a record sheet that measures the strength of an earthquake
- P waves always arrive at a seismograph station before S waves
- The difference in P and S wave arrival times increases with distance from the epicenter
- A time travel graph shows the relationship between P and S wave arrival times
Locating the Epicenter
- A single seismograph station cannot pinpoint the epicenter
- At least three stations are needed to plot the epicenter's location
Measuring Magnitude
- Seismograms can determine the magnitude of an earthquake
- Magnitude measures the amount of energy released in an earthquake
- The Richter scale is a widely used scale, with each whole number increase representing a 31-fold increase in energy
- The moment magnitude scale more accurately indicates the total energy involved in an earthquake
Damage from Earthquakes
- Earthquakes can cause damage from shaking, liquefaction, and foundation failure
- Liquefaction occurs when loose soil temporarily behaves like a liquid, causing buildings to collapse
- Aftershocks can cause damage to weakened buildings and gas leaks can lead to fires
- Earthquakes can also trigger tsunamis, which are large ocean waves that can travel quickly (750 km/h)
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Description
Learn about the different reasons behind earthquakes, including volcanic eruptions, cavern collapses, and stress built up around faults and plates.
