STURT W. MANNING AND DAVID A. SEWELL
If you are in the immediate vicinity of an explosive volcanic eruption you face death or at least significant damage to person and property. People may die both from the immediate eruption and its long-term impacts on the environment (ranging from tsunamis to starvation through destruction of the landscape). Such tragedies happened to c.30,000 people in the city of St Pierre in AD 1902 when Mt Pelée erupted, to an unknown number of people, possibly many tens of thousands, due to the eruptions of Mt Krakatoa in AD 1883 and Mt Tambora in AD 1815, or, infamously, to the several thousand inhabitants of Pompeii and Herculaneum when Vesuvius erupted in AD 79 (cf. Blong, 1984; Scarth, 1999).
Occasionally, a large eruption proximate to a major region of civilisation may even, through the destruction of the wider arable environment, force demographic shifts, which in turn may have significant historical impacts within a region. This has been argued to be the case for the Ilopango volcano with regard to Mayan civilisation (Sheets, 1979). Considering such examples, there is no denying the awesome and ruthless majesty of a volcanic eruption. There is an innate tendency to assume that volcanic eruptions are therefore historically important. Over the years, it has been proposed that a number of volcanic eruptions have had significant impacts on a local or regional human population. This is hardly surprising: volcanic eruptions are relatively common events. On average, three moderate (or larger) eruptions occur somewhere on the earth each decade (Simkin and Siebert, 1994; Simkin, 1994; Pyle, 1998).
However, from a global or long-term historical perspective, most volcanic eruptions are very minor events of purely specific and local significance. Some claim that the largest eruption of the last two centuries, Tambora, may have caused a year without a summer in AD 1816 (Rampino et al., 1988:83-5; Harington, 1992; Arnold, 1988:30; Post, 1977). But no other eruption in recent times (AD 1700 onwards) can make such a claim and the experts debate whether Tambora was the primary cause of the poor climate of this period, or merely contributed to a