16 Questions
What is the primary difference between P waves and S waves on a seismogram?
P waves arrive at a seismograph station before S waves
What is necessary to locate the epicenter of an earthquake?
Data from at least three different seismograph stations
What is the primary cause of earthquakes?
Stress built up around faults and plates
What is the primary measure of an earthquake's magnitude?
The amount of energy released
What is the location where rocks begin to move or break called?
Focus
What type of wave can pass through all states of matter?
P wave
What is the problem with the Richter scale?
It doesn't accurately indicate the amounts of energy released in very large earthquakes
What is liquefaction?
The process of soil temporarily taking on some of the properties of a liquid
What is the purpose of a seismograph?
To detect and record waves produced by earthquakes
What is the primary cause of damage from aftershocks?
The weakening of buildings due to the initial earthquake
What type of movement is caused by Love waves?
Side to side particle movement
What is the function of the pen in a seismograph?
To record the movement of the bedrock
What is a common consequence of gas leaks after an earthquake?
Fires
What is the typical speed of a tsunami?
750 km/h
What is the relationship between the distance the pen moves and the strength of an earthquake?
The distance the pen moves is directly proportional to the strength of the earthquake
What is the reason why surface waves cause more damage than P and S waves?
The exact reason is not specified in the text
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)
Learn about the different reasons behind earthquakes, including volcanic eruptions, cavern collapses, and stress built up around faults and plates.
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