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Types of Volcanoes and How They Form

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  1. Shield Volcano

    Formed when low-viscosity basaltic lava spreads far and builds up into a broad, gently sloped, shield-like shape. Hawaii's Mauna Loa and Kilauea are classic examples.

  2. Stratovolcano (Composite Volcano)

    Built from alternating layers of high-viscosity lava and pyroclastic material like ash and volcanic bombs, forming a steep cone shape. These often erupt explosively; Japan's Mount Fuji and Italy's Mount Vesuvius are well-known examples.

  3. Caldera

    A large, hollow basin formed when a volcano's summit collapses after a massive eruption empties the underground magma chamber. Heaven Lake atop Baekdu Mountain and the Yellowstone Caldera in the US are well-known examples.

  4. Lava Dome

    A dome-shaped landform that builds up slowly around a crater when extremely viscous rhyolitic or andesitic lava can't flow far. The lava dome inside the crater of Mount St. Helens in the US is a well-known example.

  5. Cinder Cone (Scoria Cone)

    A small, steep cone formed from small rock fragments (volcanic bombs, scoria) ejected along with volcanic gas, piling up around the vent. These usually form over a relatively short period from a single eruption; Mexico's ParΓ­cutin is a well-known example.

  6. How Volcanoes Form

    Volcanoes form when magma from inside the Earth erupts through weak points in the crust or along plate boundaries. The lava's viscosity and gas content strongly determine the eruption style and the resulting shape of the volcano.

  7. Active, Dormant, and Extinct Volcanoes

    A volcano with a recent eruption history or the potential to erupt again is called active; one that is currently inactive but could erupt again is dormant; and one judged to have essentially no chance of erupting again is extinct.

Why and where do volcanoes form?

Most volcanoes form at plate boundaries or at hotspots of intense magma activity. The lava's viscosity and gas content greatly change how an eruption unfolds, producing everything from gently sloped shield volcanoes to steep stratovolcanoes.

Volcanic activity can also be a source of energy

The geothermal heat produced by volcanic activity is actually used as a renewable energy source β€” one more example of how these dramatic geological forces can be put to practical use.

Frequently Asked Questions

What volcano type is Baekdu Mountain?

Baekdu Mountain, on the China-North Korea border, has a massive caldera lake called Heaven Lake at its summit, and is generally described as a volcano showing characteristics of both a composite stratovolcano and a caldera landform.

What is the Volcanic Explosivity Index (VEI)?

The VEI is a scale from 0 to 8 that rates the size of a volcanic eruption based on factors like the volume of material ejected and the height of the eruption column.