World's major cities on shaky ground

In 1800, there was just one city with more than a million people -- Beijing. Now there are 381 urban areas with at least 1 million inhabitants. Urbanization crossed a threshold last year when, for the first time, more people lived in city settings than rural ones.

According to a recent study by seismologist Roger Bilham of the University of Colorado, over 400 million people live in cities that face significant seismic hazard. READ MORE

REPORT: The seismic future of cities, Roger Bilham

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