8.1 The Global Perspective
3 min read•june 12, 2024
Earth's interior is a complex system of layers with unique properties. from earthquakes help us understand its structure, revealing a solid , liquid , and beneath the we live on.
The Earth's magnetic field, generated by the in the outer , protects us from solar radiation. This field, along with driven by convection, shapes our planet's surface and influences life on Earth.
Earth's Interior Structure and Properties
Seismic waves and Earth's interior
Top images from around the web for Seismic waves and Earth's interior
9.1 Understanding Earth Through Seismology – Physical Geology – 2nd Edition View original
Is this image relevant?
1.5 Fundamentals of Plate Tectonics – Physical Geology View original
Is this image relevant?
9.1 Understanding Earth through Seismology – Physical Geology View original
Is this image relevant?
9.1 Understanding Earth Through Seismology – Physical Geology – 2nd Edition View original
Is this image relevant?
1.5 Fundamentals of Plate Tectonics – Physical Geology View original
Is this image relevant?
1 of 3
Top images from around the web for Seismic waves and Earth's interior
9.1 Understanding Earth Through Seismology – Physical Geology – 2nd Edition View original
Is this image relevant?
1.5 Fundamentals of Plate Tectonics – Physical Geology View original
Is this image relevant?
9.1 Understanding Earth through Seismology – Physical Geology View original
Is this image relevant?
9.1 Understanding Earth Through Seismology – Physical Geology – 2nd Edition View original
Is this image relevant?
1.5 Fundamentals of Plate Tectonics – Physical Geology View original
Is this image relevant?
1 of 3
- Earthquakes generate that propagate through Earth's interior
- Compressional travel through solids and liquids (rock, magma, outer )
- Shear only travel through solids (rock, inner core)
- Changes in seismic wave velocities indicate variations in density and composition of Earth's layers (, mantle, core)
- Seismic waves refract or reflect at boundaries between different layers
- Outer core refracts P-waves
- Inner core reflects P-waves
- Liquid outer core does not allow S-waves to pass through
- Seismic wave provide evidence for Earth's core
- P-wave shadow zone caused by refraction of waves by outer core
- S-wave shadow zone caused by liquid outer core blocking S-waves
Composition of Earth's layers
- Core divided into solid inner core and liquid outer core
- Composed primarily of iron and nickel
- High density (10-13 g/cm)
- High temperature (5000-6000 K)
- Mantle is largest layer of Earth's interior
- Composed of iron- and magnesium-rich silicate rocks ()
- Solid but can deform over long time scales due to high viscosity
- Convection in mantle drives plate tectonics
- Crust is outermost layer of Earth
- Oceanic crust is thinner (6-8 km), denser, and composed of basaltic rocks
- Continental crust is thicker (30-50 km), less dense, and composed of granitic rocks
- The , consisting of the crust and uppermost solid mantle, floats on the more ductile
Earth's magnetic field generation
- Geodynamo generates Earth's magnetic field
- Convection in liquid outer core creates electric currents
- Earth's rotation (Coriolis effect) organizes currents into magnetic field
- Magnetic field is self-sustaining through dynamo effect
- Earth's magnetic field approximates a dipole
- Field lines originate near South geographic pole and terminate near North geographic pole
- Magnetic poles do not perfectly align with geographic poles (magnetic declination)
- Magnetic field affects surrounding space
- Deflects solar wind charged particles, creating
- Traps charged particles in
- Causes (Northern and Southern Lights) when charged particles interact with upper atmosphere
- Protects Earth's surface from most solar wind and cosmic rays
Plate Tectonics and Earth's Dynamic Surface
- The , encompassing all of Earth's solid components, is shaped by plate tectonic processes
- theory proposed the movement of continents over geological time
- at mid-ocean ridges creates new oceanic crust
- zones where oceanic plates sink beneath continental plates recycle crust back into the mantle
- in the mantle drive the movement of tectonic plates
Key Terms to Review (36)
Asthenosphere: The asthenosphere is a layer of the Earth's interior that lies below the lithosphere, the outermost solid shell of the planet. It is a region of relatively soft, hot, and deformable material that allows the tectonic plates of the lithosphere to move and shift over geological timescales.
Auroras: Auroras are natural light displays predominantly seen in high-latitude regions around the Arctic and Antarctic. They occur when charged particles from the solar wind collide with atoms in Earth's atmosphere, causing them to emit light.
Auroras: Auroras are breathtaking natural light displays in the night sky, caused by the interaction between the Earth's magnetic field and charged particles from the Sun. They are a visually stunning manifestation of the complex relationship between our planet and the space environment surrounding it.
Basalt: Basalt is a dark, fine-grained volcanic rock primarily composed of plagioclase and pyroxene minerals. It is the most common rock type found in the Earth's oceanic crust and on other planetary bodies like the Moon and Mars.
Continental Drift: Continental drift is the theory that the continents have slowly drifted apart over geologic time, moving on the Earth's surface and changing position relative to one another. This concept is central to understanding the global perspective, the structure of the Earth's crust, and the evolution of planetary bodies.
Convection currents: Convection currents are the circular patterns that occur in a fluid due to the transfer of heat. In planetary atmospheres, these currents are crucial for the distribution of heat and weather patterns.
Convection Currents: Convection currents are the circular movements of fluids, such as air or water, driven by differences in temperature and density. These currents play a crucial role in transferring heat and energy within various systems, including the Earth's atmosphere and the Sun's interior.
Core: The core is the innermost layer of a planet, primarily composed of metal. It plays a crucial role in generating the planet's magnetic field.
Core: The core refers to the central, innermost region of a planet, star, or other celestial body. It is typically the densest and most massive part of the structure, often composed of highly compressed materials like metals and heavy elements.
Crust: The crust is the outermost solid layer of a planet. It is composed primarily of silicate rocks and varies in thickness.
Crust: The crust is the outermost solid shell of a planet or moon, which is typically composed of relatively light, silicate-rich rock. It is the first and shallowest layer of a terrestrial body, sitting atop the denser mantle and core layers.
Earth’s crust: Earth's crust is the outermost layer of the planet, composed primarily of solid rocks and minerals. It includes both the continental crust, which forms the landmasses, and the oceanic crust beneath the oceans.
Earth’s interior: Earth's interior consists of multiple layers, including the crust, mantle, and core. These layers vary in composition, temperature, and physical state, influencing geological activity on the planet's surface.
Earth’s magnetosphere: Earth's magnetosphere is the region of space surrounding Earth that is controlled by its magnetic field. It protects the planet from solar and cosmic particle radiation and influences atmospheric phenomena.
Earth’s surface: Earth's surface is the outermost layer of the planet, consisting of the crust and upper mantle. It includes landforms such as mountains, valleys, and plains, as well as bodies of water like oceans, seas, and lakes.
Geodynamo: The geodynamo is the mechanism that generates the Earth's magnetic field. It is a self-sustaining dynamo process that occurs in the liquid outer core of the Earth, driven by the convection of molten iron and nickel.
Geosphere: The geosphere is the solid, rocky outer layer of the Earth, which includes the crust and the upper portion of the mantle. It is one of the major components that make up the Earth system, interacting with the other spheres such as the atmosphere, hydrosphere, and biosphere.
Granite: Granite is a coarse-grained igneous rock composed mainly of quartz, feldspar, and mica. It forms from the slow crystallization of magma beneath Earth's surface.
Inner Core: The inner core is the innermost layer of the Earth, situated at the very center of the planet. It is a solid, primarily iron-nickel alloy sphere that plays a crucial role in the Earth's magnetic field and overall structure.
Lithosphere: The lithosphere is the outermost solid shell of a rocky planet, including Earth. It is composed of the crust and the uppermost portion of the mantle, and it is characterized by its rigidity and strength, which sets it apart from the underlying, more ductile asthenosphere.
Magnetosphere: The magnetosphere is the region around a planet dominated by the planet's magnetic field. It protects the planet from solar wind and cosmic radiation.
Magnetosphere: The magnetosphere is the region around a planet or other celestial body where the body's magnetic field dominates and interacts with the solar wind. It acts as a protective shield, deflecting charged particles and cosmic radiation, and plays a crucial role in the planet's overall structure and environment.
Mantle: The mantle is the thick, solid layer of rock between Earth's crust and core, making up about 84% of Earth's volume. It plays a crucial role in plate tectonics and the heat transfer that drives geological activity.
Mantle: The mantle is the thick, rocky layer of the Earth that lies between the crust and the core. It is the largest layer of the Earth, accounting for about 84% of the planet's volume. The mantle is composed of dense, hot, and slowly flowing solid rock.
Outer Core: The outer core is the molten, liquid layer of the Earth that lies between the solid inner core and the mantle. It is primarily composed of iron and nickel and is responsible for generating the Earth's magnetic field through convection currents.
P-waves: P-waves are the first seismic waves generated by an earthquake that travel through the Earth's interior. They are longitudinal, compressional waves that propagate through the Earth's interior, alternately compressing and expanding the medium as they travel.
Peridotite: Peridotite is a type of igneous rock that is composed primarily of the mineral olivine, along with varying amounts of other minerals such as pyroxene and spinel. It is a dense, coarse-grained rock that is typically green or yellow-green in color and is found in the Earth's mantle and upper crust.
Plate Tectonics: Plate tectonics is the scientific theory that describes the large-scale motion of the Earth's lithosphere, which is divided into several rigid plates that move independently over the more fluid asthenosphere. This concept is fundamental to understanding the global perspective, the structure of Earth's crust, the evolution of life and climate, and the geology of other terrestrial planets in our solar system.
S-waves: S-waves, or shear waves, are a type of seismic wave that propagate through the Earth's interior by causing the medium to oscillate perpendicular to the direction of wave propagation. These waves are generated by earthquakes and are an important tool for studying the structure and composition of the Earth's interior.
Seafloor Spreading: Seafloor spreading is a geological process in which new oceanic crust is formed by the upwelling and cooling of molten magma from the Earth's mantle at mid-ocean ridges. This process is a key component of plate tectonics and the continuous renewal of the Earth's surface.
Seismic waves: Seismic waves are energy waves generated by the sudden breaking of rock within the Earth or an explosion. They travel through and around the Earth, providing critical information about its internal structure.
Seismic Waves: Seismic waves are the waves of energy that travel through the Earth's interior or along its surface as a result of earthquakes, volcanic eruptions, or other disturbances. They are a crucial tool for understanding the structure and composition of the Earth's interior.
Shadow Zones: Shadow zones refer to regions in the Earth's interior where seismic waves, such as P-waves and S-waves, are absent or attenuated due to the complex structure and composition of the Earth's interior. These zones provide important information about the Earth's internal structure and composition.
Subduction: Subduction is the process where one tectonic plate moves under another and sinks into the mantle. This typically occurs at convergent boundaries between oceanic and continental plates.
Subduction: Subduction is the process by which one tectonic plate is forced under another, causing the descending plate to be pushed deep into the Earth's mantle. This fundamental plate tectonic process shapes the surface of the planet and drives many geological phenomena.
Van Allen Radiation Belts: The Van Allen radiation belts are regions of high-energy charged particles trapped within Earth's magnetic field. These belts are a critical component of the planet's magnetosphere and play a significant role in understanding both the global perspective and space weather phenomena.