In the wake of the December 2004 Indian Ocean tsunami, oceanographic experts from around the world were brought together by Unesco to plot the outlines of an early-warning system. It seemed as if technology held all the answers.

Sophisticated buoys and broadband seismographs would be deployed across the region to detect undersea ­rumblings and changes in sea level and ocean pressure. They would broad­cast data to round-the-clock international monitoring centres where experts would identify tsunamis and alert coastal communities within minutes.