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Questions and Answers
What layer of the Earth is located directly above the outer core?
What layer of the Earth is located directly above the outer core?
Which element primarily composes the inner core?
Which element primarily composes the inner core?
What is the temperature of the outer core?
What is the temperature of the outer core?
Which term describes the boundary between the lower mantle and the outer core?
Which term describes the boundary between the lower mantle and the outer core?
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What is the primary function of a seismometer?
What is the primary function of a seismometer?
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Where do seismic waves originate?
Where do seismic waves originate?
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What generates the Earth's magnetic field?
What generates the Earth's magnetic field?
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How thick is the outer core?
How thick is the outer core?
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What is the approximate thickness range of the continental crust?
What is the approximate thickness range of the continental crust?
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Which layer of the Earth composes the majority of its mass?
Which layer of the Earth composes the majority of its mass?
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What is the Moho or Mohorovicic Discontinuity?
What is the Moho or Mohorovicic Discontinuity?
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Which of the following statements is true regarding the Earth’s crust?
Which of the following statements is true regarding the Earth’s crust?
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What type of seismic wave is known for moving the ground both up and down and side-to-side?
What type of seismic wave is known for moving the ground both up and down and side-to-side?
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What is the approximate depth of the Kola Superdeep Borehole?
What is the approximate depth of the Kola Superdeep Borehole?
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Which seismic wave can travel through both solid and liquid layers of the Earth?
Which seismic wave can travel through both solid and liquid layers of the Earth?
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Among the two types of surface waves, which one is considered to be the most destructive?
Among the two types of surface waves, which one is considered to be the most destructive?
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Which type of crust is primarily made up of basalt?
Which type of crust is primarily made up of basalt?
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What is the approximate age of the Earth?
What is the approximate age of the Earth?
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What is the key difference between P-waves and S-waves?
What is the key difference between P-waves and S-waves?
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Which statement about the mantle is correct?
Which statement about the mantle is correct?
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Which method is commonly used to locate the epicenter of an earthquake?
Which method is commonly used to locate the epicenter of an earthquake?
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If the S-wave can only pass through solids, which layer of the Earth can it penetrate?
If the S-wave can only pass through solids, which layer of the Earth can it penetrate?
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What factor is critical in determining the distance of the epicenter from a seismograph station?
What factor is critical in determining the distance of the epicenter from a seismograph station?
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At what approximate speed does a P-wave travel?
At what approximate speed does a P-wave travel?
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Study Notes
Earth's Internal Structure
- Earth is 4.54 billion years old.
- Earth's internal structure is comprised of four layers:
-
Crust: The thinnest layer, only 1% of Earth's volume.
- Solid state.
- 5-100 km thick.
- Comprised of elements like Silicon, Oxygen, Aluminum, Iron, Calcium, Sodium, Potassium, and Magnesium.
- Two types:
- Continental Crust: 35-40 km thick, mostly composed of granite.
- Oceanic Crust: 5-10 km thick, mostly composed of basalt.
-
Mantle: The thickest layer, comprising 84% of Earth's volume and 70% of its mass.
- 2900 km thick.
- Composed of elements like iron, magnesium, silicon, oxygen, calcium, and aluminum.
- Two sub-layers:
- Upper Mantle: Contains the lithosphere (crust and upper mantle) and asthenosphere (where convection currents occur).
- Lower Mantle: Extends from 660 km to 2,700 km beneath Earth's surface, hotter and denser than the upper mantle.
-
Outer Core:
- 2,300 km thick.
- Temperature of 2,000 degrees Celsius.
- Composed primarily of liquid Nickel and Iron.
- Generates Earth's magnetic field.
-
Inner Core:
- 1,220 km in diameter.
- Temperature of 5,000 degrees Celsius.
- Composed of solid Nickel and Iron.
-
Crust: The thinnest layer, only 1% of Earth's volume.
Boundaries Between Layers
- Mohorovicic Discontinuity: The boundary between the Earth's crust and the mantle.
- Gutenberg Discontinuity: The boundary between the lower mantle and the outer core.
- Lehmann Discontinuity: The boundary between the outer core and inner core.
Seismic Waves
- Seismic waves are waves of energy that travel through Earth's layers, generated at the focus of an earthquake.
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Types of Seismic Waves:
-
Surface Waves:
- Travel along Earth's surface.
- Two types:
- Rayleigh waves: Move the ground up and down and side to side.
- Love waves: Move solely side to side horizontally, considered the most destructive.
-
Body Waves:
- Travel through Earth's interior.
- Two types:
-
P-Wave (Primary Wave): Compressional/longitudinal wave. Travels faster than S-wave.
- Can travel through solid and liquid.
- Travels at a rate of 6 km per second.
-
S-Wave (Secondary Wave): Transverse/shear wave. Travels slower than P-waves.
- Can only travel through solids.
- Travels at a rate of 4 km per second.
-
P-Wave (Primary Wave): Compressional/longitudinal wave. Travels faster than S-wave.
-
Surface Waves:
Locating Epicenter
-
Triangulation Method: Used to locate an earthquake's epicenter.
- Uses the difference in arrival times of P and S waves from different seismograph stations.
- Steps:
- Determine the time difference between the arrival of P-waves and S-waves at different stations.
- Use a formula (d = Td) to calculate the distance from each station to the epicenter.
- Convert the distances to centimeters.
- Plot the distances on a map to pinpoint the epicenter.
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Description
Test your knowledge on the Earth's internal structure, including its layers such as the crust and mantle. Explore the composition and characteristics of each layer, including the differences between continental and oceanic crust. This quiz covers essential concepts related to the Earth's geology.
