A movement or vibration in the Earth is most commonly referred to as an earthquake.

Here's why:

* Earthquakes are the result of the sudden release of energy in the Earth's crust, creating seismic waves that travel through the Earth and cause the ground to shake.

* Other vibrations can occur in the Earth, such as those caused by volcanic activity, explosions, or even large machinery. However, these are not typically referred to as earthquakes.

So, while technically other vibrations can occur, the term "earthquake" is usually used for the most significant and widespread movements in the Earth.