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Plinian eruption
From Wikipedia, the free encyclopedia
Plinian eruptions are volcanic eruptions marked by their similarity to the eruption of Mt. Vesuvius in AD 79 (as described in a letter written by Pliny the Younger) that killed Pliny the Elder.
Plinian eruptions are marked by columns of smoke and ash extending high into the stratosphere. The key characteristics are ejection of large amount of pumice and very powerful continuous gas blast eruptions.
Short eruptions can end in less than a day. Longer events can take several days to months. The longer eruptions begin with production of clouds of volcanic ash, optionally with pyroclastic flows. The amount of magma erupted can be so large the top of the volcano may collapse, resulting in a caldera. Fine ash can deposit over large areas. Plinian eruptions are often accompanied by loud noises, such as heard at Krakatau.
The examples of large Plinian eruptions resulting in formation of a caldera are the 1883 Krakatoa eruption, the 1980 eruption of Mount St. Helens, the 1667 & 1739 eruptions of Mount Tarumae in Japan [1], the 1500 BC Thera eruption, and the 4860 BC eruption that formed the Crater Lake, and of course Vesuvius in AD 79, which was the prototypical Plinian Eruption. The lava is usually rhyolitic and rich on silicates; basaltic lavas are unusual for Plinian eruptions, the example is the 1886 eruption of Mount Tarawera.
| “ | I cannot give you a more exact description of its appearance than by comparing to a stone pine tree; for it shot up to a great height in the form of a tall trunk, which spread out at the top as though into branches. ... Occasionally it was brighter, occasionally darker and spotted, as it was either more or less filled with earth and cinders. (Sixth Book of Letters, Letter 16.) | ” |
- ^ Enlightenment activities for improvement on disasters from Tarumae Volcano, Japan, Cities on Volcanoes 4, 23-27 January 2006