Volcanoes are an example of how plate tectonics work because most volcanoes occur along the edges of Earth's tectonic plates. This is how they are formed:
- Volcanoes form when hot material from below rises and leaks into the crust.
- The hot material, called magma, rising from lower ground, gathers in a reservoir called the magma chamber. Eventually, but not always, the magma erupts onto the surface and forms lava. Strong earthquakes accompany rising lava, and the volcano may swell just before an eruption, as shown below.
The Pacific Ring of Fire is an area where large numbers of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean. As a result, eruptions and earthquakes happen frequently because of the positioning of the Ring of Fire.