Volcanic activity

Abstract

Of all the geological phenomena that make an impression on the general public, volcanic eruptions must be the most spectacular. The sight of incandescent lava being spewed into the air or creeping down hillsides is a regular standby of television documentaries dealing with the natural world, and the invocation by Old Testament writers of fire and brimstone in their portraits of hell indicates how vivid is the image of volcanic activity that has persisted throughout recorded history. How significant, though, are erupting or exploding volcanoes as killers? Many years ago I paid a standard tourist visit to Pompeii and Herculaneum, the Roman towns destroyed by the eruption of Vesuvius in AD 79. I was duly impressed by the exhumed streets and buildings, but what caught my imagination most were the plaster casts from Pompeii of human beings found in recumbent or prone positions, or huddled against a wall, at the locations where they had been enveloped almost instantaneously by incandescent ash. These had been produced during the nineteenth-century excavations by a team of archaeologists led by an ingenious professor, who poured plaster of Paris down holes in the volcanic rock occupying the rooms of Roman villas. The rock was then removed. Good examples of these plaster casts can be seen in the Naples Museum, and picture postcards are freely available for tourists visiting the Bay of Naples area. They make disturbing mementi mori to send to your friends and relatives. It is not known how many died as a result of the Vesuvius eruptions: perhaps not too many, as most inhabitants had time to escape. This was not the case, though, with the eruption in 1902 of Mont Pelée in Martinique, during which no fewer than 30,000 inhabitants of St. Pierre – ‘the Paris of the West Indies’ – were killed as what is called a nuée ardente smothered the town. There were only two survivors. The term nuée ardente is normally translated as ‘glowing cloud’ or ‘glowing avalanche’, though some of the more frivolous students I have taught have preferred their own mistranslation: ‘ardent nudes’.