Why earthquake happens

Earthquakes occur when the Earth’s tectonic plates move.

Earthquakes occur when the Earth’s tectonic plates move. The plates are made up of both oceanic and continental crust, which are broken into smaller pieces called tectonic plates. These plates shift constantly due to a phenomenon known as plate tectonics. The Earth’s outermost layer is split into several different types of plate, including oceanic, continental and lithospheric (which is made up of both continental and oceanic crust).

The majority of earthquakes happen along plate boundaries. These boundaries are where two or more plates meet and create what is known as a fault line. Earthquakes can also happen within a single plate, but this is less common.

What causes an earthquake?

Earthquake faults

A cross sectional view of the San Andreas Fault in California.
This cross section shows how the San Andreas Fault creates an earthquake fault line where two tectonic plates meet.