ABSTRACT
Eruptions often make volcanoes notorious, but few cause cataclysms that destroy vast areas and kill thousands of people. In fact, many eruptions take place unseen on the ocean floors and others have merely given rise to swarms of (often nameless) little cones. Only a few outbursts in every century cause big explosions and decapitate mountains, but, on the other hand, emissions repeated for a million years or more can accumulate great volcanic volumes on hotspots and mid-ocean ridges. The transfer of material from the depths to the Earth’s surface thus takes on many different guises. The consequences are seen in cones, domes, lava-flows, blankets of ash, nuées ardentes, debris avalanches, lahars and calderas, whereas altogether weaker emissions give off gas, geysers and boiling mud from sulphurous pits. Not every eruption creates a Vesuvius.
