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Questions and Answers
What characteristic distinguishes S-waves from P-waves?
What characteristic distinguishes S-waves from P-waves?
- S-waves cannot pass through liquids. (correct)
- S-waves can penetrate through liquids.
- P-waves are slower than S-waves.
- P-waves are produced by volcanic activity.
Which layer of the Earth is referred to as the lithosphere?
Which layer of the Earth is referred to as the lithosphere?
- The mantle.
- The outermost crust. (correct)
- The liquid outer core.
- The dense inner core.
What is primarily responsible for the heat within the Earth's interior?
What is primarily responsible for the heat within the Earth's interior?
- Radioactive elements deep inside the Earth. (correct)
- Reductions in pressure from tectonic activity.
- Solar radiation absorbed by the surface.
- Friction caused by tectonic plate movement.
How do scientists learn about the composition of the Earth's interior?
How do scientists learn about the composition of the Earth's interior?
Which components make up the lithosphere?
Which components make up the lithosphere?
What forms the hydrosphere in relation to the Earth's crust?
What forms the hydrosphere in relation to the Earth's crust?
Which term describes the less dense layers of the Earth that float above denser layers?
Which term describes the less dense layers of the Earth that float above denser layers?
What is the primary source of data used to understand Earth's density and temperature?
What is the primary source of data used to understand Earth's density and temperature?
What primarily composes the core of the Earth?
What primarily composes the core of the Earth?
Which layer of the Earth contains the asthenosphere?
Which layer of the Earth contains the asthenosphere?
At what depth does the Gutenberg Discontinuity occur?
At what depth does the Gutenberg Discontinuity occur?
What is the temperature range of the Earth's core?
What is the temperature range of the Earth's core?
Why does the inner core exist in a solid state?
Why does the inner core exist in a solid state?
What percentage of the Earth's total volume is made up by the mantle?
What percentage of the Earth's total volume is made up by the mantle?
What phenomenon disappears in the outer core, indicating its state?
What phenomenon disappears in the outer core, indicating its state?
The mantle is divided into which two parts?
The mantle is divided into which two parts?
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Study Notes
Earth's Interior Knowledge
- Understanding the Earth's interior is derived from seismic wave analysis, volcanic material studies, and theories of Earth's origin.
- Primary waves (P-waves) reach the Earth's surface, while secondary waves (S-waves) do not penetrate liquids, indicating the presence of liquid layers.
- Scientific instruments that record seismic waves provide insights into the density, pressure, and temperature of the Earth's interior.
- Volcanic eruptions bring molten material from deep magma chambers to the surface, aiding in the understanding of Earth's composition.
- Meteorite analysis supports theories that the Earth consists of materials found in meteorites, lending insight into its elemental makeup.
- The Earth's internal heat is generated by radioactive elements, with thermal studies helping estimate internal temperatures.
Earth's Structure
- The Earth comprises several concentric layers: the crust (lithosphere), hydrosphere (underwater parts), and atmosphere (gaseous blanket around Earth).
- The lithosphere, the outermost crust, is the thinnest layer, enriched with silicates, feldspar, and mica.
- Lithosphere divisions: SIAL (Silica and Aluminium) forms continents and is less dense, while SIMA (Silica and Magnesium) makes up the ocean floor.
Internal Composition
- Earth's interior divided into three layers: Core, Mantle, and Crust.
Core
- The core, the densest region, is approximately 7000 km in diameter, formed mostly of iron (Fe) and nickel (Ni).
- Temperature within the core ranges from 4400°C to 6000°C, contributing to Earth's magnetism, with the magnetic field oriented towards the poles.
- The inner core remains solid due to extreme pressure, while S-waves do not travel through the outer core, indicating a molten state.
Mantle
- Located beneath the crust, the mantle averages 2900 km in thickness and comprises 84% of Earth's total volume.
- Divided into the upper and lower mantle:
- The upper mantle (700 km deep) consists of cooler, solid rocks.
- The lower mantle, from 700 km to 2900 km, is hotter and denser.
- At depths of 100-410 km, the mantle turns partially molten, forming the asthenosphere.
- With increasing pressure, density rises, and temperatures vary from 1000°C to 3700°C.
- The Gutenberg Discontinuity marks the boundary between the mantle and core, beginning at a depth of 2800 km, where seismic wave behavior changes significantly.
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