Absorption:
* P waves lose energy as they travel through the Earth. This is due to friction between the wave and the medium (rock), and conversion to other wave types (e.g., S waves) at boundaries.
* This energy loss leads to attenuation, meaning the wave amplitude decreases with distance.
* Higher frequency waves (shorter wavelengths) are absorbed more readily than lower frequency waves. This means that high-frequency details of the wave are lost as it travels further.
Reflection:
* When a P wave encounters a boundary between two different materials (e.g., rock layers), it can be reflected, changing direction.
* The angle of reflection is equal to the angle of incidence.
* The amount of reflection depends on the contrast in material properties across the boundary. A larger contrast leads to more reflection.
* Reflected P waves are important for seismic exploration, allowing us to map subsurface layers.
Refraction:
* P waves can also be refracted at boundaries, meaning they change direction and speed.
* This occurs because the wave's speed changes as it enters a material with different density or elasticity.
* The angle of refraction depends on the speed difference between the two materials.
* Refraction can cause P waves to bend as they travel through the Earth, allowing them to reach areas that would otherwise be shadowed.
Summary:
* Absorption: weakens and attenuates P waves, particularly high-frequency waves.
* Reflection: changes the direction of P waves at boundaries, allowing us to image the subsurface.
* Refraction: changes the direction and speed of P waves at boundaries, allowing them to travel through different paths within the Earth.
These processes are essential for understanding how seismic waves propagate through the Earth and how they can be used to study the planet's interior.
