What causes vibrations on the surface of the earth during earthquakes?

Earthquakes are vibrations of the Earth that result from the release of energy during the sudden rupture of the Earth.

The Earth is made of four basic layers:

1. A solid crust.

2. A hot, nearly solid mantle.

3. A liquid outer core.

4. A solid inner core.

The solid crust (the outermost layer of rock on Earth) and the top stiff layer of the mantle make up a solid outer region of the Earth called the lithosphere. The lithosphere is not a continuous piece of rocks or continuous landmass, rather it is made up of so many different rocky plates, called tectonic plates. These tectonic plates are constantly shifting as they drift around on the molten rocks, which are found just below the earth's crust.

This non-stop movement causes stress on Earth’s crust, and when the stress becomes too large, it leads to cracks called faults. Since the tectonic plates keep moving, when these plates collide suddenly with the fault line, it produces strong vibrations, which is commonly known as an earthquake.

The location where an earthquake begins is known as the epicenter, near which the most intense shaking of the earth is felt often. However, these vibrations are so strong that they can be felt and detected hundreds, or even thousands of miles away from the epicenter.