Where do Volcanoes occur?

Map showing Earth's plate boundaries

Map showing Earth's plate

Active volcanoes generally occur close to the major tectonic plate boundaries
Many are located along the Earth's plate boundaries. Active volcanoes are rare in Australia because there are no plate boundaries on this continent. However, there are two active volcanoes located 4000 kilometres south west of Perth on the Australian territories, Heard Island and the nearby McDonald Islands.

The other active volcanoes nearest Australia are in New Zealand, Papua New Guinea, Indonesia and the Philippines. Gas-rich sticky magmas dominate the Asia Pacific, making composite volcanoes and calderas the most common varieties in the region. These types of volcanoes severely threaten lives, property, agricultural lands and lifelines throughout south east Asia and the Australian region.

Volcanoes can remain inactive, or dormant, for hundreds or thousands of years before erupting again. During this time they can become covered by vegetation making them difficult to identify. Once a volcano has been dormant for more than 10,000 years, it is termed extinct.

Interesting fact: On average, one or two eruptions per year worldwide originate from volcanoes with no previous historical activity or after being dormant for tens of hundreds of years. The most violent eruptions occur after long periods of inactivity. Eruptions from these types of volcanoes represent some of the worst natural disasters.

Evidence for volcanism throughout geological time can be found in every Australia State and Territory, with extensive volcanism down the east coast during the past 60 million years. This volcanic activity can be divided into areas where large amounts of lava flowed from diffuse dykes and pipes over a wide area and others where volcanism was produced from either a single central vent or a cluster of vents.

It is thought that the central volcanoes were produced as the Australian continent moved over a hot spot in the underlying mantle which melted through the plate to form the volcano. As the continent moved northward, the stationary hot spot formed volcanoes further to the south on the continent. As a result, the rocks of central volcanoes down the east coast become younger as you move southward. Australia's extinct volcanoes.