Fatal attraction: living with earthquakes, the growth of villages into megacities, and earthquake vulnerability in the modern world.

The great earthquake belt which stretches from the Mediterranean through the Middle East into Central Asia results from the ongoing collision between the Eurasian plate and the African, Arabian and Indian plates to the south. Through much of this belt, the topography is created and controlled by fault movement in earthquakes. Many habitations are located at the foot of the fault-controlled mountain range-fronts that bound inhospitable deserts or elevated plateaus, in positions that are favourable for trade-routes, strategic control of access or for water supply. As a result, they are vulnerable to earthquakes, which often seem to have targeted population centres precisely. For many centuries, an uneasy accommodation was reached between human needs and the earthquake-controlled landscape, sometimes brilliantly exploited by local hydrological engineering, as in Iran. Occasional earthquakes would occur, killing a shocking proportion of the population, but the populations of the settlements themselves would be relatively small. Many once-small rural communities have now grown into towns, cities or megacities, while retaining their vulnerability through poor building standards. Earthquakes that occur in these places today now kill many more than they did in the past, as we have witnessed in the last few years. Extreme catastrophes have been rare only because the exposure of modern megacities to earthquake hazards has been relatively short (approx. 50 years); an increase in the number of such catastrophes now seems to be inevitable.