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Earth’s structure and composition
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Figure 15: Schematic cross section illustrating the shell structure of the Earth. Figure 18: Profiles of the quality factor (Q; see Table 2), viscosity, and electrical conductivity as functions of depth. The quality factor is determined for shear waves at frequencies of one to 100 hertz (periods of one to 0.01 second).
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Earth’s structure and composition

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Figure 15: Schematic cross section illustrating the shell structure of the Earth.
Figure 15: Schematic cross section illustrating the shell structure of the Earth.

Earth's structure consists of three main layers: the crust, mantle, and core. The crust is the outermost, rigid layer, varying in thickness and composition between continents and oceans. Beneath the crust lies the mantle, a much thicker layer making up about 83% of Earth's volume, primarily composed of silicate minerals. The core, at Earth's center, is largely made of iron and nickel, with a liquid outer core and a solid inner core.123

These layers are understood through the study of seismic waves, which reveal changes in density and physical properties at different depths. The movement of the rigid lithosphere, which includes the crust and upper mantle, over the weaker asthenosphere drives geological processes like earthquakes and volcanism. The Earth's composition is dominated by iron, oxygen, silicon, and magnesium, with these elements concentrated differently in each layer.134

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
5 Britannica Sources
  1. plate tectonics - Earth’s layers
  2. earthquake - Structure of the Earth’s interior
  3. Earth - The interior of Earth
  4. chemical element - Major components
  5. chemical element - The Earth’s mantle

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