Earthquakes, volcanoes, and mountains are all related to plate tectonics, which is the study of the movement and interaction of the Earth's tectonic plates.
The Earth's lithosphere, which is made up of several large and many small tectonic plates, floats on the underlying asthenosphere. The plates are in constant motion and can interact with each other in several ways, including converging, diverging, and sliding past each other.
When two plates collide, one plate is often forced under the other in a process called subduction. This can lead to the formation of mountains as the overlying plate is lifted up and compressed. The Himalayas, for example, were formed by the collision of the Indian and Eurasian plates.
Volcanoes can also form at plate boundaries, especially where two plates are diverging or spreading apart, and magma from the mantle is able to rise to the surface. The Mid-Atlantic Ridge is an example of a divergent plate boundary where volcanic activity is common.
Earthquakes can occur at all types of plate boundaries as well as within plates. They are often the result of the release of energy that builds up as tectonic plates move and interact with each other. Faults, which are breaks in the Earth's crust, can be created or reactivated as a result of this movement, and the sudden release of energy can cause seismic waves to ripple through the Earth's crust, resulting in an earthquake.
In summary, plate tectonics provides the framework for understanding how the Earth's crust is shaped and altered over time through the forces of tectonic movement, which can lead to the formation of mountains, the eruption of volcanoes, and the occurrence of earthquakes.