They are also similar to Hawaiian lava fountains in that both eruptive types produce sustained eruption columns maintained by the growth of bubbles that move up at about the same speed as the magma surrounding them.Regions affected by Plinian eruptions are subjected to heavy pumice airfall affecting an area 0.5 to 50 km3 (0 to 12 cu mi) in size. The material in the ash plume eventually finds its way back to the ground, covering the landscape in a thick layer of many cubic kilometers of ash. However the most dangerous eruptive feature are the pyroclastic flows generated by material collapse, which move down the side of the mountain at extreme speeds of up to 700 km (435 mi) per hour and with the ability to extend the reach of the eruption hundreds of kilometers. The ejection of hot material from the volcanos summit melts snowbanks and ice deposits on the volcano, which mixes with tephra to form lahars, fast moving mudflows with the consistency of wet concrete that move at the speed of a river rapid.Major Plinian eruptive events include:

The AD 79 eruption of Mount Vesuvius buried the Roman towns of Pompeii and Herculaneum under a layer of ash and tephra. It is the model Plinian eruption. Mount Vesuvius has erupted several times since then. Its last eruption was in 1944 and caused problems for the allied armies as they advanced through Italy. It was the contemporary report by Pliny the Younger that led scientists to refer to Vesuvian eruptions as "Plinian".
Chorditis is the inflammation of vocal cords (vocal folds) usually as a result of voice abuse but sometimes because of cancer. Types
Chorditis fibrinosa
Chorditis nodosa
Chorditis tuberosa

See also
Vocal fold nodule

References


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