Questions and Answers
Where is the epicenter of an earthquake located?
On the Earth's surface directly above the place in Earth's interior where the earthquake was generated.
What change in the Earth's surface causes a tsunami?
Displacement of the ocean floor during an earthquake.
Why do some tsunamis get to be such tall waves when they reach the shoreline?
The entire water column is in motion, building great waves as the seafloor shallows.
Where do most earthquakes occur?
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What is the cause of most, if not all, earthquakes in the crust?
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What feature of Earth's interior are deep-focus earthquakes associated with?
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How deep are the deepest earthquakes?
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What is the minimum number of geographically separate seismographs necessary to locate the epicenter of an earthquake?
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What does the time difference between the first arrival of P and S waves tell us about an earthquake?
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What does the amplitude of the seismic signal recorded by a seismograph tell us about an earthquake?
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What is a body wave?
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What is an example of a seismic body wave?
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Which type of wave does not travel through a liquid?
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Which type of wave causes the most damage to buildings?
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Which type of wave is fastest and arrives first at a distant seismograph?
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Which type of wave can travel through the interior of the Earth and propagate through liquid, solid, and gas?
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Which type of wave has a particle motion that is perpendicular to the direction the wave propagates?
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Which type of wave has a particle motion that is parallel to the direction the wave propagates?
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Which building will be shaken more violently during an earthquake: a building on hard bedrock or one on soft sandy deposits?
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Study Notes
Earthquake Epicenter
- The epicenter is located on Earth's surface, directly above the earthquake's underground origin (hypocenter or focus).
Tsunami Formation
- Tsunamis can occur due to the ocean floor's displacement during an earthquake.
Tsunami Behavior
- As tsunamis approach the shore, their entire water column moves, creating tall waves due to the seafloor's shallowing.
Earthquake Locations
- Most earthquakes happen along or near tectonic plate boundaries.
Causes of Shallow-Focus Earthquakes
- Shallow-focus earthquakes are primarily caused by frictional sliding along geological faults.
Deep-Focus Earthquakes
- These earthquakes are associated with the process of subducting lithosphere entering the Earth's mantle.
Depth of Earthquakes
- The deepest recorded earthquakes reach depths of approximately 700 km.
Locating Epicenters
- A minimum of three separate seismographs are needed for triangulating the epicenter of an earthquake.
Seismic Wave Timing
- The time gap between P (primary) and S (secondary) wave arrivals helps determine the distance to the epicenter from a seismograph.
Seismic Wave Amplitude
- The amplitude of the recorded seismic signal indicates the earthquake's magnitude once the distance to the epicenter is established.
Body Waves
- Body waves are seismic waves capable of traveling through Earth's solid interior.
Examples of Body Waves
- The two main types of seismic body waves are P waves and S waves.
S Waves Characteristics
- S waves cannot propagate through liquids.
Surface Waves Damage
- Surface waves are primarily responsible for causing structural damage during earthquakes.
Speed of Seismic Waves
- P waves are the fastest earthquake waves, arriving at distant seismographs first.
P Waves Characteristics
- P waves can travel through solids, liquids, and gases, moving parallel to wave direction.
S Waves Motion
- S waves exhibit perpendicular particle motion to the wave direction, functioning as shear waves.
Building Foundation Effects
- Buildings founded on soft sandy deposits experience more intense shaking (higher amplitude) during earthquakes compared to those built on hard bedrock.
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Description
Explore key concepts related to earthquakes and their effects with these flashcards. Understand terms like epicenter, hypocenter, and the relation between earthquakes and tsunamis. Enhance your knowledge of seismic activity and its consequences.
