On average, twenty-seven earthquakes and four or five volcanic eruptions cause disasters each year. The earthquakes kill about 19,000 people and injure 26,000, while the eruptions kill 1000 and injure fewer than 300. These figures represent less than 10 per cent of natural hazard mortality, although nearly 50 per cent of morbidity; and although more than 2 million people are directly affected each year in some way by earthquakes and volcanic eruptions, they are only 1.5 per cent of all people who suffer the effects of natural catastrophe, as many more are affected by floods and droughts (IFRCRCS1997).
Earthquakes and vulcanism are a subset of the general interdisciplinary field of natural hazards. The approach to these varies from geophysical to social and psychological. Between these end members there is a broad spectrum that includes studies of hazard, vulnerability, risk, perception, economic conditions, historical aspects, remote sensing, cartography, and the technical aspects of monitoring and warning. Since they were first conceived, natural hazard studies have maintained a strong applied dimension, sustained by the need to make the environment of life safe against extreme natural events and thus to reduce the toll of casualties and damage.
The role of geographers in studying earthquakes and vulcanism has been secondary to that of many other types of scientist and scholar. Many advances have come from seismologists, vulcanologists and other geophysicists. Engineers, architects, geologists and sociologists have also been highly active in this field.
Nevertheless, small numbers of both physical and human geographers have studied the effects of seismicity and eruptions. In this context, the old aphorism is of little use: geography is not merely what geographers do, it is also what the practitioners of other fields accomplish, overtly or unwittingly, with respect to space and place. Thus, geophysicists and engineering geologists have made good use of cartographic methods for both microzonation, the determination of hazard and risk at the local scale, and macrozonation, the plotting of regional damage distributions and hazard levels. Remote sensing has been used by vulcanologists to investigate igneous landscapes and by geologists to elucidate the surface morphology of active faults. Economists have studied earthquake hazards as regional inverse multipliers, and sociologists have looked at the spatial differentiation of perception and organisational behaviour. Geographers have distinguished themselves with studies of volcanic and seismic landforms, earthquake insurance, regional patterns of post-disaster reconstruction, and hazard and risk perception and zonation.
This chapter will focus on applied geographical work on seismic and volcanic hazards regardless of whether it has been carried out by geographers or not, although their work will be highlighted where appropriate. Relevant studies are those that deal significantly with practical problems of landscape, location or the spatial dimension in general, even in the context of other factors such as social relations, economic trends and geological phenomena.