Seismic Waves & Earth's Structure

What are seismic waves?

Waves that transfer energy through the Earth, commonly produced by earthquakes.

What are P-waves?

Longitudinal seismic waves.

What are S-waves?

Transverse seismic waves.

What type of wave is a P-wave?

Longitudinal.

What type of wave is an S-wave?

Transverse.

Can P-waves travel through solids?

Yes.

Can P-waves travel through liquids?

Yes.

Can S-waves travel through solids?

Yes.

Can S-waves travel through liquids?

No.

Why can't S-waves travel through liquids?

Liquids cannot support the shear forces needed to transmit transverse seismic waves.

Which seismic waves usually travel faster?

P-waves.

Why do P-waves arrive before S-waves at a detector?

P-waves generally travel faster through the Earth.

How do seismic waves provide evidence about Earth's internal structure?

Their speeds, paths and detected arrivals reveal boundaries and material properties inside Earth.

What does the absence of S-waves through Earth's outer core suggest?

The outer core is liquid.

How do P-waves provide evidence for different layers inside Earth?

Their speed and direction change as they pass through materials with different properties.

What happens when seismic waves encounter a boundary between layers?

They may be reflected or refracted.

Why can seismic waves be used to investigate regions that cannot be directly observed?

They travel through Earth and their behaviour reveals the properties of hidden materials.

What is a seismic shadow zone?

A region where particular seismic waves are not detected directly because of refraction or inability to travel through a layer.

How do P-wave and S-wave observations support the model of Earth's core?

S-waves cannot cross the liquid outer core, while P-waves travel through it and are refracted.

Why was seismic-wave evidence important to science?

It allowed scientists to infer Earth's internal structure without directly observing it.