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There are volcanoes erupting all over the planet: Iceland, Italy, St. Vincent in the Caribbean, Hawaii and Alaska. The most active region is the Pacific Ring of Fire.

The Ring of Fire includes the Pacific coasts of South America, North America and Kamchatka, and some islands in the western Pacific Ocean. Although there is consensus among geologists about almost all areas which are included in the Ring of Fire, they disagree about the inclusion or exclusion of a few areas, for example, the Antarctic Peninsula and western Indonesia.

The Ring of Fire is a direct result of plate tectonics: specifically the movement, collision and destruction of lithospheric plates under and around the Pacific Ocean.^[3] The collisions have created a nearly continuous series of subduction zones, where volcanoes are created and earthquakes occur. Consumption of oceanic lithosphere at these convergent plate boundaries has formed oceanic trenches, volcanic arcs, back-arc basins and volcanic belts.

The Ring of Fire is not a single geological structure. Volcanic eruptions and earthquakes in each part of the Ring of Fire occur independently of eruptions and earthquakes in the other parts of the Ring.

The Ring of Fire contains approximately 850–1,000 volcanoes that have been active during the last 11,700 years (about two-thirds of the world’s total). The four largest volcanic eruptions on Earth in the last 11,700 years occurred at volcanoes in the Ring of Fire. More than 350 of the Ring of Fire’s volcanoes have been active in historical times.

Beside and among the currently active and dormant volcanoes of the Ring of Fire are belts of older extinct volcanoes, which were formed long ago by subduction in the same way as the currently active and dormant volcanoes; the extinct volcanoes last erupted many thousands or millions of years ago. The Ring of Fire has existed for more than 35 million years but subduction has existed for much longer in some parts of the Ring of Fire.

Most of Earth’s active volcanoes with summits above sea level are located in the Ring of Fire. Many of these subaerial volcanoes are stratovolcanoes (e.g. Mount St Helens), which are formed by explosive eruptions of tephra, alternating with effusive eruptions of lava flows. Lavas at the Ring of Fire’s stratovolcanoes are mainly andesite and basaltic andesite but dacite, rhyolite, basalt and some other rarer types also occur.^[6] Other types of volcano are also found in the Ring of Fire, such as subaerial shield volcanoes (e.g. Plosky Tolbachik), and submarine seamounts (e.g. Monowai).

The world’s highest active volcano is Ojos del Salado (6,893 m (22,615 ft)), which is in the Andes Mountains section of the Ring of Fire. It forms part of the border between Argentina and Chile and it last erupted in AD 750. Another Ring of Fire Andean volcano on the Argentina-Chile border is Llullaillaco (6,739 m (22,110 ft)), which is the world’s highest historically active volcano, last erupting in 1877.

About 76% of the Earth’s seismic energy is released as earthquakes in the Ring of Fire. About 90% of the Earth’s earthquakes and about 81% of the world’s largest earthquakes occur along the Ring of Fire.