Iceland is so volcanically active that researchers typically speak about “volcanic systems” rather than individual volcanoes. The island has 30 active volcanic systems, each with many types of volcanoes.

The rocky shell of our planet, known as the crust, is broken and cracked into huge tectonic plates. These plates float on a sea of viscous molten rock. They carry entire continents, slowly drifting around the planet.

There are three main types of earthquakes, depending on the plate movements that occur beneath the Earth's surface. Earthquakes can occur on a convergent boundary, a divergent boundary or a transform fault. Iceland has both transform and divergent boundaries.

Geothermal areas are traditionally divided into high- and low-temperature groups. Low-temperature areas are good for heating homes, greenhouses and swimming pools. High-temperature areas are better for large-scale power generation.