Question

Write a note on earthquake waves.

Answer 1

Instructions:

• Define earthquake.
• Explain the types of earthquake waves and how they behave when they travel through the layers of the Earth.

Solution:

• Earthquakes are shock waves caused by sudden vibrations in the earth’s crust. The vibrations occur due to the movement of tectonic plates. Then these waves spread outwards in all directions from the source point.

Earthquake waves:

• The earthquake waves are classified into two: One is body waves and another one is surface waves.
• Body waves: As the name suggests, the body waves travel within the earth. These waves are further classified into P and S waves.
• Primary or P- waves: P- waves move faster. So, it is the first to reach the earth’s surface. They pass through all the mediums. They tend to vibrate along the direction of their propagation. So, they are called longitudinal waves.
• Secondary or S-waves: They are comparatively slower than the P-waves.S- waves travel only through solids. These waves tend to vibrate perpendicular to the direction of propagation. So, they are called transverse waves.
• Surface waves: Surface waves travel along the earth’s surface. These waves are also known as L- waves. These waves are the slowest among the three waves. But the effect that it creates on the surface is high. Hence it is more destructive.