Earthquakes can come in three forms, depending on the plate movements that occur beneath the earth’s surface. They could occur on a Convergent Boundary, Divergent Boundary, or a Transform Fault.

Convergent boundary:
Here, one plate is forced over another plate during movement, creating a thrust fault.

Divergent boundary:
Here, plates are forced apart from each other, usually forming a Rift Zone. This kind is common in ocean floors where new floors are created. An example is the Mid Atlantic Ridge.

Transform fault:
Unlike divergent and convergent, the plates here slip by each other. It is also called Strike-Slip.

Earthquake Waves

There are two types of earthquakes waves, and the difference lies in the way the seismic waves are transmitted. To understand this better, let us see what a seismic wave is.
These are waves of energy that travel through the earth’s layers and other elastic layers, often as a result of earthquakes. A wave, by general definition, is the transfer of energy from one place to another without transferring solid, liquid, or gas matter. Examples include light and sound waves.
During an earthquake, the waves released could be “P” or “S” waves depending on the speed and ways in which they travel.

P-Waves (Primary Waves)

P-waves are longitudinal. The vibrations are in the same direction as the direction of travel. It is also known as compressional waves. P-waves travel faster than S-waves.

S-Waves (Secondary waves)

Here the waves travel at right angles to the direction of travel. They are also known as transverse waves, and an example is a water wave.
With this in mind, you will notice that if you are close to the point where an earthquake struck, you will feel both P and S waves close within the same time frame. If you are further away, you will feel the P-wave first and then the S-wave a bit later.
Both waves can be destructive, but their study helps us to know where the earthquake struck.