• Ring of Fire
    Anak Krakatau is a loop on the circum-Pacific belt—also known as the Ring of Fire.

    Photograph by Paul Tanis, MyShot

    Mountain Ring
    The Ring of Fire is the site of mountain ranges, along with volcanoes and earthquakes. The Andes in South America, the Cascade Range of North America, and the Southern Alps of New Zealand are all associated with the Ring of Fire.

    The Ring of Fire is a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean.

    The Ring of Fire isnt quite a circular ring. Its shaped more like a 40,000-kilometer (25,000-mile) horseshoe. A string of 452 volcanoes stretches from the southern tip of South America, up along the coast of North America, across the Bering Strait, down through Japan, and into New Zealand.

    Plate Boundaries

    The Ring of Fire is the result of plate tectonics. The edges of several tectonic plates meet along the Ring of Fire, resulting in a convergent boundary, a divergent boundary, or a transform boundary.

    A convergent plate boundary is formed by tectonic plates crashing into each other. Convergent boundaries are often subduction zones, where the heavier plate slips under the lighter plate. Subduction zones are frequently sites of volcanoes, as the heavier plate melts back into the Earths mantle.

    Mount St. Helens, in the U.S. state of Washington, is an active volcano in the Ring of Fire. Below Mount St. Helens is a convergent boundary between the Juan de Fuca Plate and the North American Plate. The small Juan de Fuca Plate is associated with the massive, heavy Pacific Plate. Both the Juan de Fuca and Pacific plates are being subducted beneath the North American Plate.

    A divergent boundary is formed by tectonic plates pulling apart from each other. Divergent boundaries are the site of seafloor spreading. Seafloor spreading is the process of magma welling up in the rift as the old crust pulls itself in opposite directions. Cold seawater cools the magma, creating new crust.

    The East Pacific Rise is a site of major seafloor spreading in the Ring of Fire. The East Pacific Rise is located on the divergent boundary between the Pacific Plate and the Cocos Plate (west of Central America), the Nazca Plate (west of South America), and the Antarctic Plate.


    A transform boundary is formed by two tectonic plates sliding next to each other. Transform boundaries are often the site of earthquakes in the Ring of Fire.

    The coast of the U.S. state of California is prone to earthquakes. It lies on the transform boundary between the North American Plate, which is moving south, and the Pacific Plate, which is moving north.

    Active Volcanoes

    The Ring of Fire is the home of most of the active volcanoes on Earth, most of them located on the rings eastern edge. Mount Ruapehu in New Zealand is one of the more active volcanoes in the Ring of Fire, with yearly minor eruptions and major eruptions occurring about every 50 years. It stands 2,797 meters (9,177 feet) high.

    Krakatoa, an island in Indonesia, erupts less often than Mount Ruapehu, but much more spectacularly. Beneath Krakatoa, the Australian Plate is being subducted beneath the Eurasian Plate. An eruption in 1883 destroyed the entire island, sending volcanic gas, ash, and rocks as high as 80 kilometers (50 miles) in the air. A new island volcano, Anak Krakatau, has been forming with minor eruptions ever since.

  • Term Part of Speech Definition Encyclopedic Entry
    active volcano Noun

    volcano that has had a recorded eruption since the last glacial period, about 10,000 years ago.

    Anak Krakatau Noun

    active volcanic island on the site of the former island of Krakatoa in the Sunda Strait in Indonesia.

    Andes Mountains Noun

    mountain range extending along the western coast of South America.

    Bering Strait Noun

    narrow body of water connecting the Bering Sea and the Arctic Ocean, separating the continents of North America and Asia.

    Cascade Range Noun

    mountains extending along the northwest coast of North America.

    coast Noun

    edge of land along the sea or other large body of water.

    Encyclopedic Entry: coast
    convergent plate boundary Noun

    area where two or more tectonic plates bump into each other. Also called a collision zone.

    crust Noun

    rocky outermost layer of Earth or other planet.

    Encyclopedic Entry: crust
    divergent boundary Noun

    area where two or more tectonic plates are moving away from each other. Also called an extensional boundary.

    earthquake Noun

    the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.

    East Pacific Rise Noun

    mid-ocean ridge where several tectonic plates are moving apart from one another.

    eruption Noun

    release of material from an opening in the Earth's crust.

    horseshoe Noun

    C-shaped thick metal sheet nailed to a horse's foot to protect it from damaging surfaces.

    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    Krakatoa Noun

    island in Indonesia, site of major volcanic eruption in 1883. Also called Krakatau.

    magma Noun

    molten, or partially melted, rock beneath the Earth's surface.

    Encyclopedic Entry: magma
    mantle Noun

    middle layer of the Earth, made of mostly solid rock.

    Encyclopedic Entry: mantle
    massive Adjective

    very large or heavy.

    Mount Ruapehu Noun

    volcano in New Zealand.

    Mount St. Helens Noun

    active volcano in the U.S. state of Washington. (2,549 meters/8,364 feet)

    plate tectonics Noun

    movement and interaction of the Earth's plates.

    Ring of Fire Noun

    horseshoe-shaped string of volcanoes and earthquake sites around edges of the Pacific Ocean.

    Encyclopedic Entry: Ring of Fire
    rock Noun

    natural substance composed of solid mineral matter.

    seafloor spreading Noun

    rift in underwater mountain range where new oceanic crust is formed.

    Encyclopedic Entry: seafloor spreading
    seawater Noun

    salty water from an ocean or sea.

    seismic Adjective

    having to do with earthquakes.

    Southern Alps Noun

    mountain range on the South Island of New Zealand.

    spectacular Adjective

    dramatic and impressive.

    subduct Verb

    to pull downward or beneath something.

    subduction zone Noun

    area where one tectonic plate slides under another.

    tectonic plate Noun

    large, moveable segment of the Earth's crust.

    transform boundary Noun

    site of tectonic plates sliding next to each other in opposite directions. Also called a transform fault.

    volcanic ash Noun

    fragments of lava less than 2 millimeters across.

    Encyclopedic Entry: volcanic ash
    volcanic gas Noun

    gas such as water vapor or carbon dioxide that is released into the atmosphere by a volcano.

    volcano Noun

    an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

    Encyclopedic Entry: volcano
    well up Verb

    to swell or build up.

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