Green crystalline mantle peridotite enclosed by darker volcanic host rock at Peridot Mesa, Arizona.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Crust ×4 thickness. T restores a 35 km reference crust.

Earth's radius is 6,371 km. The outer-core boundary lies 3,480 km from the centre, and the inner core has a radius of 1,221 km.

How to read these results

Dashed mantle interfaces mark phase transitions at depths of 410 and 660 km. Colours and textures distinguish materials in the cutaway.

Earth’s interior

Identify Earth’s main layers and explain how seismic waves provide evidence for a liquid outer core.

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Why it happens

Seismic waves reveal an Earth with layers that differ in composition and physical state. The mantle is mainly solid rock, the outer core is liquid, and the inner core is solid.

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A mantle xenolith brought to the surface by magma: direct evidence of solid rock within Earth's mantle.

Try a comparison

Restore unexploded spacing, then enable P/S waves. Compare transmission through solid mantle and liquid outer core.

Reading the result

The cutaway shows a reference structure; its illustrative wave paths explain transmission rather than calculating earthquake travel times.

A common misunderstanding

The mantle is a continuous layer of liquid magma.

The mantle is predominantly solid rock that can deform slowly over geological time. Partial melting occurs in particular settings and supplies magma, but it does not make the whole mantle liquid. Earth’s liquid outer core is a separate layer composed mainly of metal.

Cases

Exam language

Crust

Earth's outermost compositional layer of solid rock. Oceanic crust averages about 7 km thick; continental crust commonly spans roughly 30–70 km.

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Mantle peridotite carried to the surface as a xenolith within volcanic rock. It provides a sample of solid upper mantle. The lithosphere includes crust and rigid upper mantle; the green xenolith is not a piece of crust.

Mantle

The rocky layer between Earth’s crust and core, extending to about 2,900 km depth. It is predominantly solid but can deform and circulate very slowly. Small amounts of partial melt occur in particular settings; it is not a global magma layer.

Outer core

Earth's liquid metallic layer, mainly iron with nickel and lighter elements, between about 2,890 and 5,150 km depth. It does not transmit shear waves.

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Swarm satellite observations constrain Earth's magnetic field. Its main source is the moving, conducting liquid outer core, not a permanent bar magnet; the solid inner core and the core's temperature are inferred from other evidence too.

Inner core

Earth’s solid central region, composed mainly of an iron-rich alloy and extending about 1,220 km from the centre. High pressure keeps it solid despite its temperature. It is surrounded by the liquid outer core.

P-wave

A compressional seismic wave with particle motion parallel to its travel direction. It travels through solids and liquids and is the faster body-wave type.

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USGS seismometer installation in Puerto Rico. Wave arrival times and recorded ground motion are used to estimate an earthquake's focus, epicentre and magnitude; none of those buried locations is visible in this photograph.

S-wave

A shear seismic wave with particle motion perpendicular to its travel direction. It propagates through solids but not through the liquid outer core.

Lithosphere

Earth’s rigid outer mechanical layer, comprising the crust and the uppermost mantle. It is divided into tectonic plates and overlies the weaker asthenosphere. The lithosphere is therefore thicker than the crust alone.

Geodynamo

The generation of Earth's magnetic field by motion of electrically conducting liquid metal in the outer core, influenced by Earth's rotation.

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