HI- WHAT IS THE pLINIAN ERUPTION?

Christy

Plinian eruptions are named for the famous Roman naturalist Pliny the Elder. He died during an eruption of Vesuvius in A.D. 79. Pliny the Elder's nephew described the eruption, which is characteristic of Plinian eruptions. Two key characteristics are an exceptionally powerful, continuous gas blast eruption and the ejection of large volumes of pumice (Walker and Crosdale, 1971). Plinian eruptions can last less than a day, such as the short-lived explosions of gas-rich, siliceous magma prior to the eruption of fluid basaltic lava flows in Iceland. Longer-lived, more voluminous Plinian eruptions can last for weeks or months. The longer eruptions start with showers of ash followed by glowing avalanches. In some cases, so much magma is erupted that the summit of the volcano collapses to produce a caldera. Classic examples of collapse to produce a caldera are Krakatau in 1883, Crater Lake about 7,000 years ago, and S santorini in 1500 B.C. During Plinian eruptions fine ash can be dispersed over very large areas. Total volume of tephra erupted during the formation of Crater Lake was 18 cubic miles (75 cubic km). The 1886 eruption of Tarawera is a rare case of a basaltic Plinian eruption. Photograph shows the Plinian eruption of Mount St. Helens on May 18, 1980. Photograph courtesy of U.S. Geological Survey.

Sincerely,
Steve Mattox

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