Ignimbrites and ignimbrite-forming eruptions

Abstract

Ignimbrites are the most voluminous of volcanic products. Some are the largest single eruptive units known, covering thousands of square kilometres and having volumes of more than 1000 km3. Although man has never witnessed an eruption giving rise to such large volume units, they must be the most cataclysmic of all geological phenomena. Even small-volume, historic ignimbrite-forming eruptions are awesome: e.g. the 1470 BC eruption of Santorini, which has been linked with the rapid decline of the Bronze Age Minoan civilisation centre on Crete; the AD 79 eruption of Vesuvius, in which the towns of Pompeii and Herculaneum were destroyed; the eruption of Krakatau in 1883 which set in motion tsunamis killing more than 30 000 people on neighbouring islands; Tambora, which in 1815 caused the deaths of more than 90,000 people either directly, or as a result of tsunamis and an ensuing famine; Mt St Helens in 1980; and El Chichón in Mexico in 1982, after which 2000 people were missing.