Chapter 9: Problem 5

Why do both P-waves and S-waves gradually bend as they move through the mantle?

Short Answer

Expert verified

Both P-waves and S-waves gradually bend as they move through the Earth's mantle due to the phenomenon of refraction that occurs when they encounter variations in densities and elastic properties of the mantle layers. As the wave velocity changes, the waves bend or refract, providing valuable information about the Earth's interior composition, structure, and properties.

Step by step solution

Understanding P-waves and S-waves

P-waves, also known as primary waves or pressure waves, are seismic waves that travel through the Earth's interior in a compressional motion parallel to the direction of the wave. S-waves, also called secondary waves or shear waves, are seismic waves that travel through the Earth's interior in a transverse motion perpendicular to the direction of the wave. Both P-waves and S-waves are important tools for studying the Earth's interior, as they provide information about the composition, density, and structure of different layers.

Describing the Earth's mantle

The Earth's mantle is the layer between the Earth's crust and its core, characterized by its solid, rocky composition. It is divided into two parts: the upper mantle and the lower mantle. The upper mantle consists of the lithosphere (a rigid, brittle layer) and the asthenosphere (a softer, more ductile layer). The lower mantle is composed mainly of solid rocks that are under immense pressure. As seismic waves travel through the mantle, the mantle's varying properties and composition will influence how the waves behave.

Refraction of seismic waves

When a wave travels through a medium with varying properties, it may change direction. This phenomenon is called refraction. In the context of seismic waves, as the P-waves and S-waves travel through the Earth's mantle, they encounter varying densities and elastic properties of the mantle's different layers. Due to these variations, the wave's velocity will change, causing the waves to refract or bend.

Seismic wave velocity and mantle properties

The velocity of seismic waves depends on several factors, such as the density and elastic properties of the medium through which they travel. In the Earth's mantle, the velocity of seismic waves generally increases with depth as pressure and density increase. This causes the wave to bend or refract towards the area with greater density and elasticity, which is typically deeper in the mantle.

Conclusion

P-waves and S-waves bend gradually as they travel through the Earth's mantle due to the refraction of the seismic waves. This occurs because the waves encounter variations in the densities and elastic properties of the mantle's different layers. As a result, the wave velocity changes, causing the waves to bend or refract. This phenomenon helps scientists study the Earth's interior composition and provides valuable information about the structure and properties of the mantle.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Geography Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Why do both P-waves and S-waves gradually bend as they move through the mantle?

Short Answer

Step by step solution

Understanding P-waves and S-waves

Describing the Earth's mantle

Refraction of seismic waves

Seismic wave velocity and mantle properties

Conclusion

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Geography Textbooks

Migration and Identity

Energy Security

Water Cycle

Diverse Places

Glaciated Landscapes

Living World

Study anywhere. Anytime. Across all devices.