Fault lines are cracks in the earth's crust (which is the surface of the earth). Earthquakes and volcanoes usually happen near fault lines.

There are fault lines all over the world. For example, the Ring of Fire is a set of fault lines that run around the edge of the Pacific Ocean, while the San Andreas fault runs a length of 810miles (1,300km) through California and the United States, first identified by Andrew Lawson in 1895.


This picture shows a fault line, where one plate meets another. You can see the crack between them.
This picture shows a fault line, where one plate meets another. You can see the crack between them.